{{#include quiz1.rs}}

{{#include quiz2.rs}}

{{#include quiz3.rs}}

// primitive_types1.rs
// Fill in the rest of the line that has code missing!
// No hints, there's no tricks, just get used to typing these :)

// I AM NOT DONE

fn main() {
    // Booleans (`bool`)

    let is_morning = true;
    if is_morning {
        println!("Good morning!");
    }

    let // Finish the rest of this line like the example! Or make it be false!
    if is_evening {
        println!("Good evening!");
    }
}

// primitive_types2.rs
// Fill in the rest of the line that has code missing!
// No hints, there's no tricks, just get used to typing these :)

// I AM NOT DONE

fn main() {
    // Characters (`char`)

    // Note the _single_ quotes, these are different from the double quotes
    // you've been seeing around.
    let my_first_initial = 'C';
    if my_first_initial.is_alphabetic() {
        println!("Alphabetical!");
    } else if my_first_initial.is_numeric() {
        println!("Numerical!");
    } else {
        println!("Neither alphabetic nor numeric!");
    }

    let // Finish this line like the example! What's your favorite character?
    // Try a letter, try a number, try a special character, try a character
    // from a different language than your own, try an emoji!
    if your_character.is_alphabetic() {
        println!("Alphabetical!");
    } else if your_character.is_numeric() {
        println!("Numerical!");
    } else {
        println!("Neither alphabetic nor numeric!");
    }
}

// primitive_types3.rs
// Create an array with at least 100 elements in it where the ??? is.
// Execute `rustlings hint primitive_types3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let a = ???

    if a.len() >= 100 {
        println!("Wow, that's a big array!");
    } else {
        println!("Meh, I eat arrays like that for breakfast.");
    }
}

// primitive_types4.rs
// Get a slice out of Array a where the ??? is so that the test passes.
// Execute `rustlings hint primitive_types4` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let a = [1, 2, 3, 4, 5];

    let nice_slice = ???

    assert_eq!([2, 3, 4], nice_slice)
}

// primitive_types5.rs
// Destructure the `cat` tuple so that the println will work.
// Execute `rustlings hint primitive_types5` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let cat = ("Furry McFurson", 3.5);
    let /* your pattern here */ = cat;

    println!("{} is {} years old.", name, age);
}

// primitive_types6.rs
// Use a tuple index to access the second element of `numbers`.
// You can put the expression for the second element where ??? is so that the test passes.
// Execute `rustlings hint primitive_types6` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

#[test]
fn indexing_tuple() {
    let numbers = (1, 2, 3);
    // Replace below ??? with the tuple indexing syntax.
    let second = ???;

    assert_eq!(2, second,
        "This is not the 2nd number in the tuple!")
}

// strings1.rs
// Make me compile without changing the function signature!
// Execute `rustlings hint strings1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let answer = current_favorite_color();
    println!("My current favorite color is {}", answer);
}

fn current_favorite_color() -> String {
    "blue"
}

// strings2.rs
// Make me compile without changing the function signature!
// Execute `rustlings hint strings2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let word = String::from("green"); // Try not changing this line :)
    if is_a_color_word(word) {
        println!("That is a color word I know!");
    } else {
        println!("That is not a color word I know.");
    }
}

fn is_a_color_word(attempt: &str) -> bool {
    attempt == "green" || attempt == "blue" || attempt == "red"
}

// strings3.rs
// Execute `rustlings hint strings3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn trim_me(input: &str) -> String {
    // TODO: Remove whitespace from both ends of a string!
    ? ? ?
}

fn compose_me(input: &str) -> String {
    // TODO: Add " world!" to the string! There's multiple ways to do this!
    ? ? ?
}

fn replace_me(input: &str) -> String {
    // TODO: Replace "cars" in the string with "balloons"!
    ? ? ?
}

// convert unit tests to main
fn main() {
    fn trim_a_string() {
        assert_eq!(trim_me("Hello!     "), "Hello!");
        assert_eq!(trim_me("  What's up!"), "What's up!");
        assert_eq!(trim_me("   Hola!  "), "Hola!");
    }

    fn compose_a_string() {
        assert_eq!(compose_me("Hello"), "Hello world!");
        assert_eq!(compose_me("Goodbye"), "Goodbye world!");
    }

    fn replace_a_string() {
        assert_eq!(replace_me("I think cars are cool"), "I think balloons are cool");
        assert_eq!(replace_me("I love to look at cars"), "I love to look at balloons");
    }
    trim_a_string();
    compose_a_string();
    replace_a_string();
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn trim_a_string() {
        assert_eq!(trim_me("Hello!     "), "Hello!");
        assert_eq!(trim_me("  What's up!"), "What's up!");
        assert_eq!(trim_me("   Hola!  "), "Hola!");
    }

    #[test]
    fn compose_a_string() {
        assert_eq!(compose_me("Hello"), "Hello world!");
        assert_eq!(compose_me("Goodbye"), "Goodbye world!");
    }

    #[test]
    fn replace_a_string() {
        assert_eq!(replace_me("I think cars are cool"), "I think balloons are cool");
        assert_eq!(replace_me("I love to look at cars"), "I love to look at balloons");
    }
}

// strings4.rs

// Ok, here are a bunch of values-- some are `String`s, some are `&str`s. Your
// task is to call one of these two functions on each value depending on what
// you think each value is. That is, add either `string_slice` or `string`
// before the parentheses on each line. If you're right, it will compile!
// No hints this time!

// I AM NOT DONE

fn string_slice(arg: &str) {
    println!("{}", arg);
}
fn string(arg: String) {
    println!("{}", arg);
}

fn main() {
    ???("blue");
    ???("red".to_string());
    ???(String::from("hi"));
    ???("rust is fun!".to_owned());
    ???("nice weather".into());
    ???(format!("Interpolation {}", "Station"));
    ???(&String::from("abc")[0..1]);
    ???("  hello there ".trim());
    ???("Happy Monday!".to_string().replace("Mon", "Tues"));
    ???("mY sHiFt KeY iS sTiCkY".to_lowercase());
}

// vecs1.rs
// Your task is to create a `Vec` which holds the exact same elements
// as in the array `a`.
// Make me compile and pass the test!
// Execute `rustlings hint vecs1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn array_and_vec() -> ([i32; 4], Vec<i32>) {
    let a = [10, 20, 30, 40]; // a plain array
    let v = // TODO: declare your vector here with the macro for vectors

    (a, v)
}

// convert unit tests to main here
fn main() {
    let (a, v) = array_and_vec();
    assert_eq!(a, v[..]);
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_array_and_vec_similarity() {
        let (a, v) = array_and_vec();
        assert_eq!(a, v[..]);
    }
}

// vecs2.rs
// A Vec of even numbers is given. Your task is to complete the loop
// so that each number in the Vec is multiplied by 2.
//
// Make me pass the test!
//
// Execute `rustlings hint vecs2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
    for i in v.iter_mut() {
        // TODO: Fill this up so that each element in the Vec `v` is
        // multiplied by 2.
        ???
    }

    // At this point, `v` should be equal to [4, 8, 12, 16, 20].
    v
}

fn vec_map(v: &Vec<i32>) -> Vec<i32> {
    v.iter().map(|num| {
        // TODO: Do the same thing as above - but instead of mutating the
        // Vec, you can just return the new number!
        ???
    }).collect()
}

// convert unit tests to main here
fn main(){
    fn test_vec_loop() {
        let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
        let ans = vec_loop(v.clone());

        assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
    }

    fn test_vec_map() {
        let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
        let ans = vec_map(&v);

        assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
    }
    test_vec_loop();
    test_vec_map();

}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_vec_loop() {
        let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
        let ans = vec_loop(v.clone());

        assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
    }

    #[test]
    fn test_vec_map() {
        let v: Vec<i32> = (1..).filter(|x| x % 2 == 0).take(5).collect();
        let ans = vec_map(&v);

        assert_eq!(ans, v.iter().map(|x| x * 2).collect::<Vec<i32>>());
    }
}

// hashmaps1.rs
// A basket of fruits in the form of a hash map needs to be defined.
// The key represents the name of the fruit and the value represents
// how many of that particular fruit is in the basket. You have to put
// at least three different types of fruits (e.g apple, banana, mango)
// in the basket and the total count of all the fruits should be at
// least five.
//
// Make me compile and pass the tests!
//
// Execute `rustlings hint hashmaps1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

use std::collections::HashMap;

fn fruit_basket() -> HashMap<String, u32> {
    let mut basket = // TODO: declare your hash map here.

    // Two bananas are already given for you :)
    basket.insert(String::from("banana"), 2);

    // TODO: Put more fruits in your basket here.

    basket
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn at_least_three_types_of_fruits() {
        let basket = fruit_basket();
        assert!(basket.len() >= 3);
    }

    #[test]
    fn at_least_five_fruits() {
        let basket = fruit_basket();
        assert!(basket.values().sum::<u32>() >= 5);
    }
}

// hashmaps2.rs

// A basket of fruits in the form of a hash map is given. The key
// represents the name of the fruit and the value represents how many
// of that particular fruit is in the basket. You have to put *MORE
// THAN 11* fruits in the basket. Three types of fruits - Apple (4),
// Mango (2) and Lychee (5) are already given in the basket. You are
// not allowed to insert any more of these fruits!
//
// Make me pass the tests!
//
// Execute `rustlings hint hashmaps2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

use std::collections::HashMap;

#[derive(Hash, PartialEq, Eq)]
enum Fruit {
    Apple,
    Banana,
    Mango,
    Lychee,
    Pineapple,
}

fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
    let fruit_kinds = vec![
        Fruit::Apple,
        Fruit::Banana,
        Fruit::Mango,
        Fruit::Lychee,
        Fruit::Pineapple,
    ];

    for fruit in fruit_kinds {
        // TODO: Put new fruits if not already present. Note that you
        // are not allowed to put any type of fruit that's already
        // present!
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn get_fruit_basket() -> HashMap<Fruit, u32> {
        let mut basket = HashMap::<Fruit, u32>::new();
        basket.insert(Fruit::Apple, 4);
        basket.insert(Fruit::Mango, 2);
        basket.insert(Fruit::Lychee, 5);

        basket
    }

    #[test]
    fn test_given_fruits_are_not_modified() {
        let mut basket = get_fruit_basket();
        fruit_basket(&mut basket);
        assert_eq!(*basket.get(&Fruit::Apple).unwrap(), 4);
        assert_eq!(*basket.get(&Fruit::Mango).unwrap(), 2);
        assert_eq!(*basket.get(&Fruit::Lychee).unwrap(), 5);
    }

    #[test]
    fn at_least_five_types_of_fruits() {
        let mut basket = get_fruit_basket();
        fruit_basket(&mut basket);
        let count_fruit_kinds = basket.len();
        assert!(count_fruit_kinds >= 5);
    }

    #[test]
    fn greater_than_eleven_fruits() {
        let mut basket = get_fruit_basket();
        fruit_basket(&mut basket);
        let count = basket.values().sum::<u32>();
        assert!(count > 11);
    }
}

// hashmaps3.rs

// A list of scores (one per line) of a soccer match is given. Each line
// is of the form :
// <team_1_name>,<team_2_name>,<team_1_goals>,<team_2_goals>
// Example: England,France,4,2 (England scored 4 goals, France 2).

// You have to build a scores table containing the name of the team, goals
// the team scored, and goals the team conceded. One approach to build
// the scores table is to use a Hashmap. The solution is partially
// written to use a Hashmap, complete it to pass the test.

// Make me pass the tests!

// Execute `rustlings hint hashmaps3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

use std::collections::HashMap;

// A structure to store team name and its goal details.
struct Team {
    name: String,
    goals_scored: u8,
    goals_conceded: u8,
}

fn build_scores_table(results: String) -> HashMap<String, Team> {
    // The name of the team is the key and its associated struct is the value.
    let mut scores: HashMap<String, Team> = HashMap::new();

    for r in results.lines() {
        let v: Vec<&str> = r.split(',').collect();
        let team_1_name = v[0].to_string();
        let team_1_score: u8 = v[2].parse().unwrap();
        let team_2_name = v[1].to_string();
        let team_2_score: u8 = v[3].parse().unwrap();
        // TODO: Populate the scores table with details extracted from the
        // current line. Keep in mind that goals scored by team_1
        // will be the number of goals conceded from team_2, and similarly
        // goals scored by team_2 will be the number of goals conceded by
        // team_1.
    }
    scores
}

#[cfg(test)]
mod tests {
    use super::*;

    fn get_results() -> String {
        let results = "".to_string()
            + "England,France,4,2\n"
            + "France,Italy,3,1\n"
            + "Poland,Spain,2,0\n"
            + "Germany,England,2,1\n";
        results
    }

    #[test]
    fn build_scores() {
        let scores = build_scores_table(get_results());

        let mut keys: Vec<&String> = scores.keys().collect();
        keys.sort();
        assert_eq!(
            keys,
            vec!["England", "France", "Germany", "Italy", "Poland", "Spain"]
        );
    }

    #[test]
    fn validate_team_score_1() {
        let scores = build_scores_table(get_results());
        let team = scores.get("England").unwrap();
        assert_eq!(team.goals_scored, 5);
        assert_eq!(team.goals_conceded, 4);
    }

    #[test]
    fn validate_team_score_2() {
        let scores = build_scores_table(get_results());
        let team = scores.get("Spain").unwrap();
        assert_eq!(team.goals_scored, 0);
        assert_eq!(team.goals_conceded, 2);
    }
}

// structs1.rs
// Address all the TODOs to make the tests pass!
// Execute `rustlings hint structs1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

struct ColorClassicStruct {
    // TODO: Something goes here
}

struct ColorTupleStruct(/* TODO: Something goes here */);

#[derive(Debug)]
struct UnitLikeStruct;

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn classic_c_structs() {
        // TODO: Instantiate a classic c struct!
        // let green =

        assert_eq!(green.red, 0);
        assert_eq!(green.green, 255);
        assert_eq!(green.blue, 0);
    }

    #[test]
    fn tuple_structs() {
        // TODO: Instantiate a tuple struct!
        // let green =

        assert_eq!(green.0, 0);
        assert_eq!(green.1, 255);
        assert_eq!(green.2, 0);
    }

    #[test]
    fn unit_structs() {
        // TODO: Instantiate a unit-like struct!
        // let unit_like_struct =
        let message = format!("{:?}s are fun!", unit_like_struct);

        assert_eq!(message, "UnitLikeStructs are fun!");
    }
}

// structs2.rs
// Address all the TODOs to make the tests pass!
// Execute `rustlings hint structs2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

#[derive(Debug)]
struct Order {
    name: String,
    year: u32,
    made_by_phone: bool,
    made_by_mobile: bool,
    made_by_email: bool,
    item_number: u32,
    count: u32,
}

fn create_order_template() -> Order {
    Order {
        name: String::from("Bob"),
        year: 2019,
        made_by_phone: false,
        made_by_mobile: false,
        made_by_email: true,
        item_number: 123,
        count: 0,
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn your_order() {
        let order_template = create_order_template();
        // TODO: Create your own order using the update syntax and template above!
        // let your_order =
        assert_eq!(your_order.name, "Hacker in Rust");
        assert_eq!(your_order.year, order_template.year);
        assert_eq!(your_order.made_by_phone, order_template.made_by_phone);
        assert_eq!(your_order.made_by_mobile, order_template.made_by_mobile);
        assert_eq!(your_order.made_by_email, order_template.made_by_email);
        assert_eq!(your_order.item_number, order_template.item_number);
        assert_eq!(your_order.count, 1);
    }
}

// structs3.rs
// Structs contain data, but can also have logic. In this exercise we have
// defined the Package struct and we want to test some logic attached to it.
// Make the code compile and the tests pass!
// Execute `rustlings hint structs3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

#[derive(Debug)]
struct Package {
    sender_country: String,
    recipient_country: String,
    weight_in_grams: i32,
}

impl Package {
    fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
        if weight_in_grams <= 0 {
            panic!("Can not ship a weightless package.")
        } else {
            Package {
                sender_country,
                recipient_country,
                weight_in_grams,
            }
        }
    }

    fn is_international(&self) -> ??? {
        // Something goes here...
    }

    fn get_fees(&self, cents_per_gram: i32) -> ??? {
        // Something goes here...
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    #[should_panic]
    fn fail_creating_weightless_package() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Austria");

        Package::new(sender_country, recipient_country, -2210);
    }

    #[test]
    fn create_international_package() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Russia");

        let package = Package::new(sender_country, recipient_country, 1200);

        assert!(package.is_international());
    }

    #[test]
    fn create_local_package() {
        let sender_country = String::from("Canada");
        let recipient_country = sender_country.clone();

        let package = Package::new(sender_country, recipient_country, 1200);

        assert!(!package.is_international());
    }

    #[test]
    fn calculate_transport_fees() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Spain");

        let cents_per_gram = 3;

        let package = Package::new(sender_country, recipient_country, 1500);

        assert_eq!(package.get_fees(cents_per_gram), 4500);
        assert_eq!(package.get_fees(cents_per_gram * 2), 9000);
    }
}

// enums1.rs
// No hints this time! ;)

// I AM NOT DONE

#[derive(Debug)]
enum Message {
    // TODO: define a few types of messages as used below
}

fn main() {
    println!("{:?}", Message::Quit);
    println!("{:?}", Message::Echo);
    println!("{:?}", Message::Move);
    println!("{:?}", Message::ChangeColor);
}

// enums2.rs
// Execute `rustlings hint enums2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

#[derive(Debug)]
enum Message {
    // TODO: define the different variants used below
}

impl Message {
    fn call(&self) {
        println!("{:?}", self);
    }
}

fn main() {
    let messages = [
        Message::Move { x: 10, y: 30 },
        Message::Echo(String::from("hello world")),
        Message::ChangeColor(200, 255, 255),
        Message::Quit,
    ];

    for message in &messages {
        message.call();
    }
}

// enums3.rs
// Address all the TODOs to make the tests pass!
// Execute `rustlings hint enums3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

enum Message {
    // TODO: implement the message variant types based on their usage below
}

struct Point {
    x: u8,
    y: u8,
}

struct State {
    color: (u8, u8, u8),
    position: Point,
    quit: bool,
}

impl State {
    fn change_color(&mut self, color: (u8, u8, u8)) {
        self.color = color;
    }

    fn quit(&mut self) {
        self.quit = true;
    }

    fn echo(&self, s: String) {
        println!("{}", s);
    }

    fn move_position(&mut self, p: Point) {
        self.position = p;
    }

    fn process(&mut self, message: Message) {
        // TODO: create a match expression to process the different message variants
        // Remember: When passing a tuple as a function argument, you'll need extra parentheses: fn function((t, u, p, l, e))
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_match_message_call() {
        let mut state = State {
            quit: false,
            position: Point { x: 0, y: 0 },
            color: (0, 0, 0),
        };
        state.process(Message::ChangeColor(255, 0, 255));
        state.process(Message::Echo(String::from("hello world")));
        state.process(Message::Move(Point { x: 10, y: 15 }));
        state.process(Message::Quit);

        assert_eq!(state.color, (255, 0, 255));
        assert_eq!(state.position.x, 10);
        assert_eq!(state.position.y, 15);
        assert_eq!(state.quit, true);
    }
}

// iterators1.rs
//
//  Make me compile by filling in the `???`s
//
// When performing operations on elements within a collection, iterators are essential.
// This module helps you get familiar with the structure of using an iterator and
// how to go through elements within an iterable collection.
//
// Execute `rustlings hint iterators1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main () {
    let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];

    let mut my_iterable_fav_fruits = ???;   // TODO: Step 1

    assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2
    assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 3
    assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 4
}

// iterators2.rs
// In this exercise, you'll learn some of the unique advantages that iterators
// can offer. Follow the steps to complete the exercise.
// Execute `rustlings hint iterators2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

// Step 1.
// Complete the `capitalize_first` function.
// "hello" -> "Hello"
pub fn capitalize_first(input: &str) -> String {
    let mut c = input.chars();
    match c.next() {
        None => String::new(),
        Some(first) => ???,
    }
}

// Step 2.
// Apply the `capitalize_first` function to a slice of string slices.
// Return a vector of strings.
// ["hello", "world"] -> ["Hello", "World"]
pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
    vec![]
}

// Step 3.
// Apply the `capitalize_first` function again to a slice of string slices.
// Return a single string.
// ["hello", " ", "world"] -> "Hello World"
pub fn capitalize_words_string(words: &[&str]) -> String {
    String::new()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_success() {
        assert_eq!(capitalize_first("hello"), "Hello");
    }

    #[test]
    fn test_empty() {
        assert_eq!(capitalize_first(""), "");
    }

    #[test]
    fn test_iterate_string_vec() {
        let words = vec!["hello", "world"];
        assert_eq!(capitalize_words_vector(&words), ["Hello", "World"]);
    }

    #[test]
    fn test_iterate_into_string() {
        let words = vec!["hello", " ", "world"];
        assert_eq!(capitalize_words_string(&words), "Hello World");
    }
}

// iterators3.rs
// This is a bigger exercise than most of the others! You can do it!
// Here is your mission, should you choose to accept it:
// 1. Complete the divide function to get the first four tests to pass.
// 2. Get the remaining tests to pass by completing the result_with_list and
//    list_of_results functions.
// Execute `rustlings hint iterators3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

#[derive(Debug, PartialEq, Eq)]
pub enum DivisionError {
    NotDivisible(NotDivisibleError),
    DivideByZero,
}

#[derive(Debug, PartialEq, Eq)]
pub struct NotDivisibleError {
    dividend: i32,
    divisor: i32,
}

// Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
// Otherwise, return a suitable error.
pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
    todo!();
}

// Complete the function and return a value of the correct type so the test passes.
// Desired output: Ok([1, 11, 1426, 3])
fn result_with_list() -> () {
    let numbers = vec![27, 297, 38502, 81];
    let division_results = numbers.into_iter().map(|n| divide(n, 27));
}

// Complete the function and return a value of the correct type so the test passes.
// Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)]
fn list_of_results() -> () {
    let numbers = vec![27, 297, 38502, 81];
    let division_results = numbers.into_iter().map(|n| divide(n, 27));
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_success() {
        assert_eq!(divide(81, 9), Ok(9));
    }

    #[test]
    fn test_not_divisible() {
        assert_eq!(
            divide(81, 6),
            Err(DivisionError::NotDivisible(NotDivisibleError {
                dividend: 81,
                divisor: 6
            }))
        );
    }

    #[test]
    fn test_divide_by_0() {
        assert_eq!(divide(81, 0), Err(DivisionError::DivideByZero));
    }

    #[test]
    fn test_divide_0_by_something() {
        assert_eq!(divide(0, 81), Ok(0));
    }

    #[test]
    fn test_result_with_list() {
        assert_eq!(format!("{:?}", result_with_list()), "Ok([1, 11, 1426, 3])");
    }

    #[test]
    fn test_list_of_results() {
        assert_eq!(
            format!("{:?}", list_of_results()),
            "[Ok(1), Ok(11), Ok(1426), Ok(3)]"
        );
    }
}

// iterators4.rs
// Execute `rustlings hint iterators4` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

pub fn factorial(num: u64) -> u64 {
    // Complete this function to return the factorial of num
    // Do not use:
    // - return
    // Try not to use:
    // - imperative style loops (for, while)
    // - additional variables
    // For an extra challenge, don't use:
    // - recursion
    // Execute `rustlings hint iterators4` for hints.
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn factorial_of_0() {
        assert_eq!(1, factorial(0));
    }

    #[test]
    fn factorial_of_1() {
        assert_eq!(1, factorial(1));
    }
    #[test]
    fn factorial_of_2() {
        assert_eq!(2, factorial(2));
    }

    #[test]
    fn factorial_of_4() {
        assert_eq!(24, factorial(4));
    }
}

// iterators5.rs
// Let's define a simple model to track Rustlings exercise progress. Progress
// will be modelled using a hash map. The name of the exercise is the key and
// the progress is the value. Two counting functions were created to count the
// number of exercises with a given progress. These counting functions use
// imperative style for loops. Recreate this counting functionality using
// iterators. Only the two iterator methods (count_iterator and
// count_collection_iterator) need to be modified.
// Execute `rustlings hint iterators5` or use the `hint` watch subcommand for a hint.
//
// Make the code compile and the tests pass.

// I AM NOT DONE

use std::collections::HashMap;

#[derive(Clone, Copy, PartialEq, Eq)]
enum Progress {
    None,
    Some,
    Complete,
}

fn count_for(map: &HashMap<String, Progress>, value: Progress) -> usize {
    let mut count = 0;
    for val in map.values() {
        if val == &value {
            count += 1;
        }
    }
    count
}

fn count_iterator(map: &HashMap<String, Progress>, value: Progress) -> usize {
    // map is a hashmap with String keys and Progress values.
    // map = { "variables1": Complete, "from_str": None, ... }
    todo!();
}

fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
    let mut count = 0;
    for map in collection {
        for val in map.values() {
            if val == &value {
                count += 1;
            }
        }
    }
    count
}

fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
    // collection is a slice of hashmaps.
    // collection = [{ "variables1": Complete, "from_str": None, ... },
    //     { "variables2": Complete, ... }, ... ]
    todo!();
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn count_complete() {
        let map = get_map();
        assert_eq!(3, count_iterator(&map, Progress::Complete));
    }

    #[test]
    fn count_equals_for() {
        let map = get_map();
        assert_eq!(
            count_for(&map, Progress::Complete),
            count_iterator(&map, Progress::Complete)
        );
    }

    #[test]
    fn count_collection_complete() {
        let collection = get_vec_map();
        assert_eq!(
            6,
            count_collection_iterator(&collection, Progress::Complete)
        );
    }

    #[test]
    fn count_collection_equals_for() {
        let collection = get_vec_map();
        assert_eq!(
            count_collection_for(&collection, Progress::Complete),
            count_collection_iterator(&collection, Progress::Complete)
        );
    }

    fn get_map() -> HashMap<String, Progress> {
        use Progress::*;

        let mut map = HashMap::new();
        map.insert(String::from("variables1"), Complete);
        map.insert(String::from("functions1"), Complete);
        map.insert(String::from("hashmap1"), Complete);
        map.insert(String::from("arc1"), Some);
        map.insert(String::from("as_ref_mut"), None);
        map.insert(String::from("from_str"), None);

        map
    }

    fn get_vec_map() -> Vec<HashMap<String, Progress>> {
        use Progress::*;

        let map = get_map();

        let mut other = HashMap::new();
        other.insert(String::from("variables2"), Complete);
        other.insert(String::from("functions2"), Complete);
        other.insert(String::from("if1"), Complete);
        other.insert(String::from("from_into"), None);
        other.insert(String::from("try_from_into"), None);

        vec![map, other]
    }
}

// box1.rs
//
// At compile time, Rust needs to know how much space a type takes up. This becomes problematic
// for recursive types, where a value can have as part of itself another value of the same type.
// To get around the issue, we can use a `Box` - a smart pointer used to store data on the heap,
// which also allows us to wrap a recursive type.
//
// The recursive type we're implementing in this exercise is the `cons list` - a data structure
// frequently found in functional programming languages. Each item in a cons list contains two
// elements: the value of the current item and the next item. The last item is a value called `Nil`.
//
// Step 1: use a `Box` in the enum definition to make the code compile
// Step 2: create both empty and non-empty cons lists by replacing `todo!()`
//
// Note: the tests should not be changed
//
// Execute `rustlings hint box1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

#[derive(PartialEq, Debug)]
pub enum List {
    Cons(i32, List),
    Nil,
}

fn main() {
    println!("This is an empty cons list: {:?}", create_empty_list());
    println!(
        "This is a non-empty cons list: {:?}",
        create_non_empty_list()
    );
    // convert unit tests to main
    fn test_create_empty_list() {
        assert_eq!(List::Nil, create_empty_list())
    }

    fn test_create_non_empty_list() {
        assert_ne!(create_empty_list(), create_non_empty_list())
    }
    test_create_empty_list();
    test_create_non_empty_list();
}

pub fn create_empty_list() -> List {
    todo!()
}

pub fn create_non_empty_list() -> List {
    todo!()
}


#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_create_empty_list() {
        assert_eq!(List::Nil, create_empty_list())
    }

    #[test]
    fn test_create_non_empty_list() {
        assert_ne!(create_empty_list(), create_non_empty_list())
    }
}

// cow1.rs

// This exercise explores the Cow, or Clone-On-Write type.
// Cow is a clone-on-write smart pointer.
// It can enclose and provide immutable access to borrowed data, and clone the data lazily when mutation or ownership is required.
// The type is designed to work with general borrowed data via the Borrow trait.
//
// This exercise is meant to show you what to expect when passing data to Cow.
// Fix the unit tests by checking for Cow::Owned(_) and Cow::Borrowed(_) at the TODO markers.

// I AM NOT DONE

use std::borrow::Cow;

fn abs_all<'a, 'b>(input: &'a mut Cow<'b, [i32]>) -> &'a mut Cow<'b, [i32]> {
    for i in 0..input.len() {
        let v = input[i];
        if v < 0 {
            // Clones into a vector if not already owned.
            input.to_mut()[i] = -v;
        }
    }
    input
}

// convert unit tests to main
fn main() {
    fn reference_mutation() -> Result<(), &'static str> {
        // Clone occurs because `input` needs to be mutated.
        let slice = [-1, 0, 1];
        let mut input = Cow::from(&slice[..]);
        match abs_all(&mut input) {
            Cow::Owned(_) => Ok(()),
            _ => Err("Expected owned value"),
        }
    }

    fn reference_no_mutation() -> Result<(), &'static str> {
        // No clone occurs because `input` doesn't need to be mutated.
        let slice = [0, 1, 2];
        let mut input = Cow::from(&slice[..]);
        match abs_all(&mut input) {
            // TODO
        }
    }

    fn owned_no_mutation() -> Result<(), &'static str> {
        // We can also pass `slice` without `&` so Cow owns it directly.
        // In this case no mutation occurs and thus also no clone,
        // but the result is still owned because it always was.
        let slice = vec![0, 1, 2];
        let mut input = Cow::from(slice);
        match abs_all(&mut input) {
            // TODO
        }
    }

    fn owned_mutation() -> Result<(), &'static str> {
        // Of course this is also the case if a mutation does occur.
        // In this case the call to `to_mut()` returns a reference to
        // the same data as before.
        let slice = vec![-1, 0, 1];
        let mut input = Cow::from(slice);
        match abs_all(&mut input) {
            // TODO
        }
    }
    reference_mutation();
    reference_no_mutation();
    owned_no_mutation();
    owned_mutation();
}


#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn reference_mutation() -> Result<(), &'static str> {
        // Clone occurs because `input` needs to be mutated.
        let slice = [-1, 0, 1];
        let mut input = Cow::from(&slice[..]);
        match abs_all(&mut input) {
            Cow::Owned(_) => Ok(()),
            _ => Err("Expected owned value"),
        }
    }

    #[test]
    fn reference_no_mutation() -> Result<(), &'static str> {
        // No clone occurs because `input` doesn't need to be mutated.
        let slice = [0, 1, 2];
        let mut input = Cow::from(&slice[..]);
        match abs_all(&mut input) {
            // TODO
        }
    }

    #[test]
    fn owned_no_mutation() -> Result<(), &'static str> {
        // We can also pass `slice` without `&` so Cow owns it directly.
        // In this case no mutation occurs and thus also no clone,
        // but the result is still owned because it always was.
        let slice = vec![0, 1, 2];
        let mut input = Cow::from(slice);
        match abs_all(&mut input) {
            // TODO
        }
    }

    #[test]
    fn owned_mutation() -> Result<(), &'static str> {
        // Of course this is also the case if a mutation does occur.
        // In this case the call to `to_mut()` returns a reference to
        // the same data as before.
        let slice = vec![-1, 0, 1];
        let mut input = Cow::from(slice);
        match abs_all(&mut input) {
            // TODO
        }
    }
}

// rc1.rs
// In this exercise, we want to express the concept of multiple owners via the Rc<T> type.
// This is a model of our solar system - there is a Sun type and multiple Planets.
// The Planets take ownership of the sun, indicating that they revolve around the sun.

// Make this code compile by using the proper Rc primitives to express that the sun has multiple owners.

// I AM NOT DONE

use std::rc::Rc;

#[derive(Debug)]
struct Sun {}

#[derive(Debug)]
enum Planet {
    Mercury(Rc<Sun>),
    Venus(Rc<Sun>),
    Earth(Rc<Sun>),
    Mars(Rc<Sun>),
    Jupiter(Rc<Sun>),
    Saturn(Rc<Sun>),
    Uranus(Rc<Sun>),
    Neptune(Rc<Sun>),
}

impl Planet {
    fn details(&self) {
        println!("Hi from {:?}!", self)
    }
}

fn main() {
    let sun = Rc::new(Sun {});
    println!("reference count = {}", Rc::strong_count(&sun)); // 1 reference

    let mercury = Planet::Mercury(Rc::clone(&sun));
    println!("reference count = {}", Rc::strong_count(&sun)); // 2 references
    mercury.details();

    let venus = Planet::Venus(Rc::clone(&sun));
    println!("reference count = {}", Rc::strong_count(&sun)); // 3 references
    venus.details();

    let earth = Planet::Earth(Rc::clone(&sun));
    println!("reference count = {}", Rc::strong_count(&sun)); // 4 references
    earth.details();

    let mars = Planet::Mars(Rc::clone(&sun));
    println!("reference count = {}", Rc::strong_count(&sun)); // 5 references
    mars.details();

    let jupiter = Planet::Jupiter(Rc::clone(&sun));
    println!("reference count = {}", Rc::strong_count(&sun)); // 6 references
    jupiter.details();

    // TODO
    let saturn = Planet::Saturn(Rc::new(Sun {}));
    println!("reference count = {}", Rc::strong_count(&sun)); // 7 references
    saturn.details();

    // TODO
    let uranus = Planet::Uranus(Rc::new(Sun {}));
    println!("reference count = {}", Rc::strong_count(&sun)); // 8 references
    uranus.details();

    // TODO
    let neptune = Planet::Neptune(Rc::new(Sun {}));
    println!("reference count = {}", Rc::strong_count(&sun)); // 9 references
    neptune.details();

    assert_eq!(Rc::strong_count(&sun), 9);

    drop(neptune);
    println!("reference count = {}", Rc::strong_count(&sun)); // 8 references

    drop(uranus);
    println!("reference count = {}", Rc::strong_count(&sun)); // 7 references

    drop(saturn);
    println!("reference count = {}", Rc::strong_count(&sun)); // 6 references

    drop(jupiter);
    println!("reference count = {}", Rc::strong_count(&sun)); // 5 references

    drop(mars);
    println!("reference count = {}", Rc::strong_count(&sun)); // 4 references

    // TODO
    println!("reference count = {}", Rc::strong_count(&sun)); // 3 references

    // TODO
    println!("reference count = {}", Rc::strong_count(&sun)); // 2 references

    // TODO
    println!("reference count = {}", Rc::strong_count(&sun)); // 1 reference

    assert_eq!(Rc::strong_count(&sun), 1);
}

use std::rc::Rc;

struct Node {
    value: i32,
    parent: Option<Rc<Node>>,
    children: Vec<Rc<Node>>,
}

impl Node {
    fn new(value: i32) -> Rc<Self> {
        Rc::new(Self {
            value,
            parent: None,
            children: Vec::new(),
        })
    }

    fn add_child(&mut self, child: Rc<Self>) {
        self.children.push(child);
        child.parent = Some(Rc::clone(&self));
    }
}

fn main() {
    let root = Node::new(0);
    let child1 = Node::new(1);
    let child2 = Node::new(2);
    child1.add_child(Rc::clone(&child2));
    child2.add_child(Rc::clone(&child1));
    root.add_child(child1);
    root.add_child(child2);
    println!("{}", root.value);
}

// Type casting in Rust is done via the usage of the `as` operator.
// Please note that the `as` operator is not only used when type casting.
// It also helps with renaming imports.
//
// The goal is to make sure that the division does not fail to compile
// and returns the proper type.
// Execute `rustlings hint using_as` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn average(values: &[f64]) -> f64 {
    let total = values.iter().sum::<f64>();
    total / values.len()
}

fn main() {
    let values = [3.5, 0.3, 13.0, 11.7];
    println!("{}", average(&values));
    // convert unit tests to here to run in the rust playground
    fn returns_proper_type_and_value() {
        assert_eq!(average(&[3.5, 0.3, 13.0, 11.7]), 7.125);
    }
    returns_proper_type_and_value();
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn returns_proper_type_and_value() {
        assert_eq!(average(&[3.5, 0.3, 13.0, 11.7]), 7.125);
    }
}

// The From trait is used for value-to-value conversions.
// If From is implemented correctly for a type, the Into trait should work conversely.
// You can read more about it at https://doc.rust-lang.org/std/convert/trait.From.html
// Execute `rustlings hint from_into` or use the `hint` watch subcommand for a hint.

#[derive(Debug)]
struct Person {
    name: String,
    age: usize,
}

// We implement the Default trait to use it as a fallback
// when the provided string is not convertible into a Person object
impl Default for Person {
    fn default() -> Person {
        Person {
            name: String::from("John"),
            age: 30,
        }
    }
}

// Your task is to complete this implementation
// in order for the line `let p = Person::from("Mark,20")` to compile
// Please note that you'll need to parse the age component into a `usize`
// with something like `"4".parse::<usize>()`. The outcome of this needs to
// be handled appropriately.
//
// Steps:
// 1. If the length of the provided string is 0, then return the default of Person
// 2. Split the given string on the commas present in it
// 3. Extract the first element from the split operation and use it as the name
// 4. If the name is empty, then return the default of Person
// 5. Extract the other element from the split operation and parse it into a `usize` as the age
// If while parsing the age, something goes wrong, then return the default of Person
// Otherwise, then return an instantiated Person object with the results

// I AM NOT DONE

impl From<&str> for Person {
    fn from(s: &str) -> Person {}
}

fn main() {
    // Use the `from` function
    let p1 = Person::from("Mark,20");
    // Since From is implemented for Person, we should be able to use Into
    let p2: Person = "Gerald,70".into();
    println!("{:?}", p1);
    println!("{:?}", p2);
    // convert unit tests to here to run in the rust playground
    // Test that the default person is 30 year old John
    let dp = Person::default();
    assert_eq!(dp.name, "John");
    assert_eq!(dp.age, 30);
    // Test that John is returned when bad string is provided
    let p = Person::from("");
    assert_eq!(p.name, "John");
    assert_eq!(p.age, 30);
    // Test that "Mark,20" works
    let p = Person::from("Mark,20");
    assert_eq!(p.name, "Mark");
    assert_eq!(p.age, 20);
    // Test that "Mark,twenty" will return the default person due to an error in parsing age
    let p = Person::from("Mark,twenty");
    assert_eq!(p.name, "John");
    assert_eq!(p.age, 30);

    let p: Person = Person::from("Mark");
    assert_eq!(p.name, "John");
    assert_eq!(p.age, 30);

    let p: Person = Person::from("Mark,");
    assert_eq!(p.name, "John");
    assert_eq!(p.age, 30);

    let p: Person = Person::from(",1");
    assert_eq!(p.name, "John");
    assert_eq!(p.age, 30);

    let p: Person = Person::from(",");
    assert_eq!(p.name, "John");
    assert_eq!(p.age, 30);

    let p: Person = Person::from(",one");
    assert_eq!(p.name, "John");
    assert_eq!(p.age, 30);

    let p: Person = Person::from("Mike,32,");
    assert_eq!(p.name, "John");
    assert_eq!(p.age, 30);

    let p: Person = Person::from("Mike,32,man");
    assert_eq!(p.name, "John");
    assert_eq!(p.age, 30);
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_default() {
        // Test that the default person is 30 year old John
        let dp = Person::default();
        assert_eq!(dp.name, "John");
        assert_eq!(dp.age, 30);
    }

    #[test]
    fn test_bad_convert() {
        // Test that John is returned when bad string is provided
        let p = Person::from("");
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 30);
    }

    #[test]
    fn test_good_convert() {
        // Test that "Mark,20" works
        let p = Person::from("Mark,20");
        assert_eq!(p.name, "Mark");
        assert_eq!(p.age, 20);
    }

    #[test]
    fn test_bad_age() {
        // Test that "Mark,twenty" will return the default person due to an error in parsing age
        let p = Person::from("Mark,twenty");
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 30);
    }

    #[test]
    fn test_missing_comma_and_age() {
        let p: Person = Person::from("Mark");
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 30);
    }

    #[test]
    fn test_missing_age() {
        let p: Person = Person::from("Mark,");
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 30);
    }

    #[test]
    fn test_missing_name() {
        let p: Person = Person::from(",1");
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 30);
    }

    #[test]
    fn test_missing_name_and_age() {
        let p: Person = Person::from(",");
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 30);
    }

    #[test]
    fn test_missing_name_and_invalid_age() {
        let p: Person = Person::from(",one");
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 30);
    }

    #[test]
    fn test_trailing_comma() {
        let p: Person = Person::from("Mike,32,");
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 30);
    }

    #[test]
    fn test_trailing_comma_and_some_string() {
        let p: Person = Person::from("Mike,32,man");
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 30);
    }
}

// try_from_into.rs
// TryFrom is a simple and safe type conversion that may fail in a controlled way under some circumstances.
// Basically, this is the same as From. The main difference is that this should return a Result type
// instead of the target type itself.
// You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
// Execute `rustlings hint try_from_into` or use the `hint` watch subcommand for a hint.

use std::convert::{TryFrom, TryInto};

#[derive(Debug, PartialEq)]
struct Color {
    red: u8,
    green: u8,
    blue: u8,
}

// We will use this error type for these `TryFrom` conversions.
#[derive(Debug, PartialEq)]
enum IntoColorError {
    // Incorrect length of slice
    BadLen,
    // Integer conversion error
    IntConversion,
}

// I AM NOT DONE

// Your task is to complete this implementation
// and return an Ok result of inner type Color.
// You need to create an implementation for a tuple of three integers,
// an array of three integers, and a slice of integers.
//
// Note that the implementation for tuple and array will be checked at compile time,
// but the slice implementation needs to check the slice length!
// Also note that correct RGB color values must be integers in the 0..=255 range.

// Tuple implementation
impl TryFrom<(i16, i16, i16)> for Color {
    type Error = IntoColorError;
    fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {
    }
}

// Array implementation
impl TryFrom<[i16; 3]> for Color {
    type Error = IntoColorError;
    fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {
    }
}

// Slice implementation
impl TryFrom<&[i16]> for Color {
    type Error = IntoColorError;
    fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {
    }
}

fn main() {
    // Use the `try_from` function
    let c1 = Color::try_from((183, 65, 14));
    println!("{:?}", c1);

    // Since TryFrom is implemented for Color, we should be able to use TryInto
    let c2: Result<Color, _> = [183, 65, 14].try_into();
    println!("{:?}", c2);

    let v = vec![183, 65, 14];
    // With slice we should use `try_from` function
    let c3 = Color::try_from(&v[..]);
    println!("{:?}", c3);
    // or take slice within round brackets and use TryInto
    let c4: Result<Color, _> = (&v[..]).try_into();
    println!("{:?}", c4);
    // convert unit tests to here to run in the rust playground
    fn test_tuple_out_of_range_positive() {
        assert_eq!(
            Color::try_from((256, 1000, 10000)),
            Err(IntoColorError::IntConversion)
        );
    }
    fn test_tuple_out_of_range_negative() {
        assert_eq!(
            Color::try_from((-1, -10, -256)),
            Err(IntoColorError::IntConversion)
        );
    }
    fn test_tuple_sum() {
        assert_eq!(
            Color::try_from((-1, 255, 255)),
            Err(IntoColorError::IntConversion)
        );
    }
    fn test_tuple_correct() {
        let c: Result<Color, _> = (183, 65, 14).try_into();
        assert!(c.is_ok());
        assert_eq!(
            c.unwrap(),
            Color {
                red: 183,
                green: 65,
                blue: 14
            }
        );
    }
    fn test_array_out_of_range_positive() {
        let c: Result<Color, _> = [1000, 10000, 256].try_into();
        assert_eq!(c, Err(IntoColorError::IntConversion));
    }
    fn test_array_out_of_range_negative() {
        let c: Result<Color, _> = [-10, -256, -1].try_into();
        assert_eq!(c, Err(IntoColorError::IntConversion));
    }
    fn test_array_sum() {
        let c: Result<Color, _> = [-1, 255, 255].try_into();
        assert_eq!(c, Err(IntoColorError::IntConversion));
    }
    fn test_array_correct() {
        let c: Result<Color, _> = [183, 65, 14].try_into();
        assert!(c.is_ok());
        assert_eq!(
            c.unwrap(),
            Color {
                red: 183,
                green: 65,
                blue: 14
            }
        );
    }
    fn test_slice_out_of_range_positive() {
        let arr = [10000, 256, 1000];
        assert_eq!(
            Color::try_from(&arr[..]),
            Err(IntoColorError::IntConversion)
        );
    }
    fn test_slice_out_of_range_negative() {
        let arr = [-256, -1, -10];
        assert_eq!(
            Color::try_from(&arr[..]),
            Err(IntoColorError::IntConversion)
        );
    }
    fn test_slice_sum() {
        let arr = [-1, 255, 255];
        assert_eq!(
            Color::try_from(&arr[..]),
            Err(IntoColorError::IntConversion)
        );
    }
    fn test_slice_correct() {
        let v = vec![183, 65, 14];
        let c: Result<Color, _> = Color::try_from(&v[..]);
        assert!(c.is_ok());
        assert_eq!(
            c.unwrap(),
            Color {
                red: 183,
                green: 65,
                blue: 14
            }
        );
    }
    fn test_slice_excess_length() {
        let v = vec![0, 0, 0, 0];
        assert_eq!(Color::try_from(&v[..]), Err(IntoColorError::BadLen));
    }
    fn test_slice_insufficient_length() {
        let v = vec![0, 0];
        assert_eq!(Color::try_from(&v[..]), Err(IntoColorError::BadLen));
    }
    test_tuple_out_of_range_positive();
    test_tuple_out_of_range_negative();
    test_tuple_sum();
    test_tuple_correct();
    test_array_out_of_range_positive();
    test_array_out_of_range_negative();
    test_array_sum();
    test_array_correct();
    test_slice_out_of_range_positive();
    test_slice_out_of_range_negative();
    test_slice_sum();
    test_slice_correct();
    test_slice_excess_length();
    test_slice_insufficient_length();
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_tuple_out_of_range_positive() {
        assert_eq!(
            Color::try_from((256, 1000, 10000)),
            Err(IntoColorError::IntConversion)
        );
    }
    #[test]
    fn test_tuple_out_of_range_negative() {
        assert_eq!(
            Color::try_from((-1, -10, -256)),
            Err(IntoColorError::IntConversion)
        );
    }
    #[test]
    fn test_tuple_sum() {
        assert_eq!(
            Color::try_from((-1, 255, 255)),
            Err(IntoColorError::IntConversion)
        );
    }
    #[test]
    fn test_tuple_correct() {
        let c: Result<Color, _> = (183, 65, 14).try_into();
        assert!(c.is_ok());
        assert_eq!(
            c.unwrap(),
            Color {
                red: 183,
                green: 65,
                blue: 14
            }
        );
    }
    #[test]
    fn test_array_out_of_range_positive() {
        let c: Result<Color, _> = [1000, 10000, 256].try_into();
        assert_eq!(c, Err(IntoColorError::IntConversion));
    }
    #[test]
    fn test_array_out_of_range_negative() {
        let c: Result<Color, _> = [-10, -256, -1].try_into();
        assert_eq!(c, Err(IntoColorError::IntConversion));
    }
    #[test]
    fn test_array_sum() {
        let c: Result<Color, _> = [-1, 255, 255].try_into();
        assert_eq!(c, Err(IntoColorError::IntConversion));
    }
    #[test]
    fn test_array_correct() {
        let c: Result<Color, _> = [183, 65, 14].try_into();
        assert!(c.is_ok());
        assert_eq!(
            c.unwrap(),
            Color {
                red: 183,
                green: 65,
                blue: 14
            }
        );
    }
    #[test]
    fn test_slice_out_of_range_positive() {
        let arr = [10000, 256, 1000];
        assert_eq!(
            Color::try_from(&arr[..]),
            Err(IntoColorError::IntConversion)
        );
    }
    #[test]
    fn test_slice_out_of_range_negative() {
        let arr = [-256, -1, -10];
        assert_eq!(
            Color::try_from(&arr[..]),
            Err(IntoColorError::IntConversion)
        );
    }
    #[test]
    fn test_slice_sum() {
        let arr = [-1, 255, 255];
        assert_eq!(
            Color::try_from(&arr[..]),
            Err(IntoColorError::IntConversion)
        );
    }
    #[test]
    fn test_slice_correct() {
        let v = vec![183, 65, 14];
        let c: Result<Color, _> = Color::try_from(&v[..]);
        assert!(c.is_ok());
        assert_eq!(
            c.unwrap(),
            Color {
                red: 183,
                green: 65,
                blue: 14
            }
        );
    }
    #[test]
    fn test_slice_excess_length() {
        let v = vec![0, 0, 0, 0];
        assert_eq!(Color::try_from(&v[..]), Err(IntoColorError::BadLen));
    }
    #[test]
    fn test_slice_insufficient_length() {
        let v = vec![0, 0];
        assert_eq!(Color::try_from(&v[..]), Err(IntoColorError::BadLen));
    }
}

// AsRef and AsMut allow for cheap reference-to-reference conversions.
// Read more about them at https://doc.rust-lang.org/std/convert/trait.AsRef.html
// and https://doc.rust-lang.org/std/convert/trait.AsMut.html, respectively.
// Execute `rustlings hint as_ref_mut` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

// Obtain the number of bytes (not characters) in the given argument.
// TODO: Add the AsRef trait appropriately as a trait bound.
fn byte_counter<T>(arg: T) -> usize {
    arg.as_ref().as_bytes().len()
}

// Obtain the number of characters (not bytes) in the given argument.
// TODO: Add the AsRef trait appropriately as a trait bound.
fn char_counter<T>(arg: T) -> usize {
    arg.as_ref().chars().count()
}

// Squares a number using as_mut().
// TODO: Add the appropriate trait bound.
fn num_sq<T>(arg: &mut T) {
    // TODO: Implement the function body.
    ? ? ?
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn different_counts() {
        let s = "Café au lait";
        assert_ne!(char_counter(s), byte_counter(s));
    }

    #[test]
    fn same_counts() {
        let s = "Cafe au lait";
        assert_eq!(char_counter(s), byte_counter(s));
    }

    #[test]
    fn different_counts_using_string() {
        let s = String::from("Café au lait");
        assert_ne!(char_counter(s.clone()), byte_counter(s));
    }

    #[test]
    fn same_counts_using_string() {
        let s = String::from("Cafe au lait");
        assert_eq!(char_counter(s.clone()), byte_counter(s));
    }

    #[test]
    fn mult_box() {
        let mut num: Box<u32> = Box::new(3);
        num_sq(&mut num);
        assert_eq!(*num, 9);
    }
}

// convert the unit test to main
fn main() {
    // different_counts()
    let s = "Café au lait";
    assert_ne!(char_counter(s), byte_counter(s));
    // same_counts
    let s = "Cafe au lait";
    assert_eq!(char_counter(s), byte_counter(s));
    // different_counts_using_string
    let s = String::from("Café au lait");
    assert_ne!(char_counter(s.clone()), byte_counter(s));
    // same_counts_using_string
    let s = String::from("Cafe au lait");
    assert_eq!(char_counter(s.clone()), byte_counter(s));
    // mult_box
    let mut num: Box<u32> = Box::new(3);
    num_sq(&mut num);
    assert_eq!(*num, 9);
}

// from_str.rs
// This is similar to from_into.rs, but this time we'll implement `FromStr`
// and return errors instead of falling back to a default value.
// Additionally, upon implementing FromStr, you can use the `parse` method
// on strings to generate an object of the implementor type.
// You can read more about it at https://doc.rust-lang.org/std/str/trait.FromStr.html
// Execute `rustlings hint from_str` or use the `hint` watch subcommand for a hint.

use std::num::ParseIntError;
use std::str::FromStr;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: usize,
}

// We will use this error type for the `FromStr` implementation.
#[derive(Debug, PartialEq)]
enum ParsePersonError {
    // Empty input string
    Empty,
    // Incorrect number of fields
    BadLen,
    // Empty name field
    NoName,
    // Wrapped error from parse::<usize>()
    ParseInt(ParseIntError),
}

// I AM NOT DONE

// Steps:
// 1. If the length of the provided string is 0, an error should be returned
// 2. Split the given string on the commas present in it
// 3. Only 2 elements should be returned from the split, otherwise return an error
// 4. Extract the first element from the split operation and use it as the name
// 5. Extract the other element from the split operation and parse it into a `usize` as the age
//    with something like `"4".parse::<usize>()`
// 6. If while extracting the name and the age something goes wrong, an error should be returned
// If everything goes well, then return a Result of a Person object
//
// As an aside: `Box<dyn Error>` implements `From<&'_ str>`. This means that if you want to return a
// string error message, you can do so via just using return `Err("my error message".into())`.

impl FromStr for Person {
    type Err = ParsePersonError;
    fn from_str(s: &str) -> Result<Person, Self::Err> {}
}

fn main() {
    let p = "Mark,20".parse::<Person>().unwrap();
    println!("{:?}", p);
    // convert unit tests to here to run in the rust playground
    assert_eq!("".parse::<Person>(), Err(ParsePersonError::Empty));
    let p = "John,32".parse::<Person>();
    assert!(p.is_ok());
    let p = p.unwrap();
    assert_eq!(p.name, "John");
    assert_eq!(p.age, 32);
    assert!(matches!(
            "John,".parse::<Person>(),
            Err(ParsePersonError::ParseInt(_))
        ));

    assert!(matches!(
            "John,twenty".parse::<Person>(),
            Err(ParsePersonError::ParseInt(_))
        ));

    assert_eq!("John".parse::<Person>(), Err(ParsePersonError::BadLen));

    assert_eq!(",1".parse::<Person>(), Err(ParsePersonError::NoName));

    assert!(matches!(
            ",".parse::<Person>(),
            Err(ParsePersonError::NoName | ParsePersonError::ParseInt(_))
        ));

    assert!(matches!(
            ",one".parse::<Person>(),
            Err(ParsePersonError::NoName | ParsePersonError::ParseInt(_))
        ));

    assert_eq!("John,32,".parse::<Person>(), Err(ParsePersonError::BadLen));

    assert_eq!(
        "John,32,man".parse::<Person>(),
        Err(ParsePersonError::BadLen)
    );
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn empty_input() {
        assert_eq!("".parse::<Person>(), Err(ParsePersonError::Empty));
    }

    #[test]
    fn good_input() {
        let p = "John,32".parse::<Person>();
        assert!(p.is_ok());
        let p = p.unwrap();
        assert_eq!(p.name, "John");
        assert_eq!(p.age, 32);
    }

    #[test]
    fn missing_age() {
        assert!(matches!(
            "John,".parse::<Person>(),
            Err(ParsePersonError::ParseInt(_))
        ));
    }

    #[test]
    fn invalid_age() {
        assert!(matches!(
            "John,twenty".parse::<Person>(),
            Err(ParsePersonError::ParseInt(_))
        ));
    }

    #[test]
    fn missing_comma_and_age() {
        assert_eq!("John".parse::<Person>(), Err(ParsePersonError::BadLen));
    }

    #[test]
    fn missing_name() {
        assert_eq!(",1".parse::<Person>(), Err(ParsePersonError::NoName));
    }

    #[test]
    fn missing_name_and_age() {
        assert!(matches!(
            ",".parse::<Person>(),
            Err(ParsePersonError::NoName | ParsePersonError::ParseInt(_))
        ));
    }

    #[test]
    fn missing_name_and_invalid_age() {
        assert!(matches!(
            ",one".parse::<Person>(),
            Err(ParsePersonError::NoName | ParsePersonError::ParseInt(_))
        ));
    }

    #[test]
    fn trailing_comma() {
        assert_eq!("John,32,".parse::<Person>(), Err(ParsePersonError::BadLen));
    }

    #[test]
    fn trailing_comma_and_some_string() {
        assert_eq!(
            "John,32,man".parse::<Person>(),
            Err(ParsePersonError::BadLen)
        );
    }
}

// errors1.rs
// This function refuses to generate text to be printed on a nametag if
// you pass it an empty string. It'd be nicer if it explained what the problem
// was, instead of just sometimes returning `None`. Thankfully, Rust has a similar
// construct to `Option` that can be used to express error conditions. Let's use it!
// Execute `rustlings hint errors1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

pub fn generate_nametag_text(name: String) -> Option<String> {
    if name.is_empty() {
        // Empty names aren't allowed.
        None
    } else {
        Some(format!("Hi! My name is {}", name))
    }
}

// convert unit tests to main
fn main() {
    fn generates_nametag_text_for_a_nonempty_name() {
        assert_eq!(
            generate_nametag_text("Beyoncé".into()),
            Ok("Hi! My name is Beyoncé".into())
        );
    }

    fn explains_why_generating_nametag_text_fails() {
        assert_eq!(
            generate_nametag_text("".into()),
            // Don't change this line
            Err("`name` was empty; it must be nonempty.".into())
        );
    }
    generates_nametag_text_for_a_nonempty_name();
    explains_why_generating_nametag_text_fails();
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn generates_nametag_text_for_a_nonempty_name() {
        assert_eq!(
            generate_nametag_text("Beyoncé".into()),
            Ok("Hi! My name is Beyoncé".into())
        );
    }

    #[test]
    fn explains_why_generating_nametag_text_fails() {
        assert_eq!(
            generate_nametag_text("".into()),
            // Don't change this line
            Err("`name` was empty; it must be nonempty.".into())
        );
    }
}

// errors2.rs
// Say we're writing a game where you can buy items with tokens. All items cost
// 5 tokens, and whenever you purchase items there is a processing fee of 1
// token. A player of the game will type in how many items they want to buy,
// and the `total_cost` function will calculate the total number of tokens.
// Since the player typed in the quantity, though, we get it as a string-- and
// they might have typed anything, not just numbers!

// Right now, this function isn't handling the error case at all (and isn't
// handling the success case properly either). What we want to do is:
// if we call the `parse` function on a string that is not a number, that
// function will return a `ParseIntError`, and in that case, we want to
// immediately return that error from our function and not try to multiply
// and add.

// There are at least two ways to implement this that are both correct-- but
// one is a lot shorter!
// Execute `rustlings hint errors2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

use std::num::ParseIntError;

pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
    let processing_fee = 1;
    let cost_per_item = 5;
    let qty = item_quantity.parse::<i32>();

    Ok(qty * cost_per_item + processing_fee)
}

// convert unit tests to main
fn main() {
    fn item_quantity_is_a_valid_number() {
        assert_eq!(total_cost("34"), Ok(171));
    }

    fn item_quantity_is_an_invalid_number() {
        assert_eq!(
            total_cost("beep boop").unwrap_err().to_string(),
            "invalid digit found in string"
        );
    }
    item_quantity_is_a_valid_number();
    item_quantity_is_an_invalid_number()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn item_quantity_is_a_valid_number() {
        assert_eq!(total_cost("34"), Ok(171));
    }

    #[test]
    fn item_quantity_is_an_invalid_number() {
        assert_eq!(
            total_cost("beep boop").unwrap_err().to_string(),
            "invalid digit found in string"
        );
    }
}

// errors3.rs
// This is a program that is trying to use a completed version of the
// `total_cost` function from the previous exercise. It's not working though!
// Why not? What should we do to fix it?
// Execute `rustlings hint errors3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

use std::num::ParseIntError;

fn main() {
    let mut tokens = 100;
    let pretend_user_input = "8";

    let cost = total_cost(pretend_user_input)?;

    if cost > tokens {
        println!("You can't afford that many!");
    } else {
        tokens -= cost;
        println!("You now have {} tokens.", tokens);
    }
}

pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
    let processing_fee = 1;
    let cost_per_item = 5;
    let qty = item_quantity.parse::<i32>()?;

    Ok(qty * cost_per_item + processing_fee)
}

// errors4.rs
// Execute `rustlings hint errors4` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

#[derive(PartialEq, Debug)]
struct PositiveNonzeroInteger(u64);

#[derive(PartialEq, Debug)]
enum CreationError {
    Negative,
    Zero,
}

impl PositiveNonzeroInteger {
    fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
        // Hmm...? Why is this only returning an Ok value?
        Ok(PositiveNonzeroInteger(value as u64))
    }
}

// convert unit tests to main
fn main() {
    fn test_creation() {
        assert!(PositiveNonzeroInteger::new(10).is_ok());
        assert_eq!(
            Err(CreationError::Negative),
            PositiveNonzeroInteger::new(-10)
        );
        assert_eq!(Err(CreationError::Zero), PositiveNonzeroInteger::new(0));
    }
    test_creation();
}

#[test]
fn test_creation() {
    assert!(PositiveNonzeroInteger::new(10).is_ok());
    assert_eq!(
        Err(CreationError::Negative),
        PositiveNonzeroInteger::new(-10)
    );
    assert_eq!(Err(CreationError::Zero), PositiveNonzeroInteger::new(0));
}

// errors5.rs

// This program uses an altered version of the code from errors4.

// This exercise uses some concepts that we won't get to until later in the course, like `Box` and the
// `From` trait. It's not important to understand them in detail right now, but you can read ahead if you like.
// For now, think of the `Box<dyn ...>` type as an "I want anything that does ???" type, which, given
// Rust's usual standards for runtime safety, should strike you as somewhat lenient!

// In short, this particular use case for boxes is for when you want to own a value and you care only that it is a
// type which implements a particular trait. To do so, The Box is declared as of type Box<dyn Trait> where Trait is the trait
// the compiler looks for on any value used in that context. For this exercise, that context is the potential errors
// which can be returned in a Result.

// What can we use to describe both errors? In other words, is there a trait which both errors implement?

// Execute `rustlings hint errors5` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

use std::error;
use std::fmt;
use std::num::ParseIntError;

// TODO: update the return type of `main()` to make this compile.
fn main() -> Result<(), Box<dyn ???>> {
    let pretend_user_input = "42";
    let x: i64 = pretend_user_input.parse()?;
    println!("output={:?}", PositiveNonzeroInteger::new(x)?);
    Ok(())
}

// Don't change anything below this line.

#[derive(PartialEq, Debug)]
struct PositiveNonzeroInteger(u64);

#[derive(PartialEq, Debug)]
enum CreationError {
    Negative,
    Zero,
}

impl PositiveNonzeroInteger {
    fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
        match value {
            x if x < 0 => Err(CreationError::Negative),
            x if x == 0 => Err(CreationError::Zero),
            x => Ok(PositiveNonzeroInteger(x as u64)),
        }
    }
}

// This is required so that `CreationError` can implement `error::Error`.
impl fmt::Display for CreationError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let description = match *self {
            CreationError::Negative => "number is negative",
            CreationError::Zero => "number is zero",
        };
        f.write_str(description)
    }
}

impl error::Error for CreationError {}

// errors6.rs

// Using catch-all error types like `Box<dyn error::Error>` isn't recommended
// for library code, where callers might want to make decisions based on the
// error content, instead of printing it out or propagating it further. Here,
// we define a custom error type to make it possible for callers to decide
// what to do next when our function returns an error.

// Execute `rustlings hint errors6` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

use std::num::ParseIntError;

// This is a custom error type that we will be using in `parse_pos_nonzero()`.
#[derive(PartialEq, Debug)]
enum ParsePosNonzeroError {
    Creation(CreationError),
    ParseInt(ParseIntError),
}

impl ParsePosNonzeroError {
    fn from_creation(err: CreationError) -> ParsePosNonzeroError {
        ParsePosNonzeroError::Creation(err)
    }
    // TODO: add another error conversion function here.
    // fn from_parseint...
}

fn parse_pos_nonzero(s: &str) -> Result<PositiveNonzeroInteger, ParsePosNonzeroError> {
    // TODO: change this to return an appropriate error instead of panicking
    // when `parse()` returns an error.
    let x: i64 = s.parse().unwrap();
    PositiveNonzeroInteger::new(x).map_err(ParsePosNonzeroError::from_creation)
}

// Don't change anything below this line.

#[derive(PartialEq, Debug)]
struct PositiveNonzeroInteger(u64);

#[derive(PartialEq, Debug)]
enum CreationError {
    Negative,
    Zero,
}

impl PositiveNonzeroInteger {
    fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
        match value {
            x if x < 0 => Err(CreationError::Negative),
            x if x == 0 => Err(CreationError::Zero),
            x => Ok(PositiveNonzeroInteger(x as u64)),
        }
    }
}

// convert unit tests to main
fn main() {
    fn test_parse_error() {
        // We can't construct a ParseIntError, so we have to pattern match.
        assert!(matches!(
            parse_pos_nonzero("not a number"),
            Err(ParsePosNonzeroError::ParseInt(_))
        ));
    }

    fn test_negative() {
        assert_eq!(
            parse_pos_nonzero("-555"),
            Err(ParsePosNonzeroError::Creation(CreationError::Negative))
        );
    }

    fn test_zero() {
        assert_eq!(
            parse_pos_nonzero("0"),
            Err(ParsePosNonzeroError::Creation(CreationError::Zero))
        );
    }

    fn test_positive() {
        let x = PositiveNonzeroInteger::new(42);
        assert!(x.is_ok());
        assert_eq!(parse_pos_nonzero("42"), Ok(x.unwrap()));
    }
    test_parse_error();
    test_negative();
    test_zero();
    test_positive();
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_parse_error() {
        // We can't construct a ParseIntError, so we have to pattern match.
        assert!(matches!(
            parse_pos_nonzero("not a number"),
            Err(ParsePosNonzeroError::ParseInt(_))
        ));
    }

    #[test]
    fn test_negative() {
        assert_eq!(
            parse_pos_nonzero("-555"),
            Err(ParsePosNonzeroError::Creation(CreationError::Negative))
        );
    }

    #[test]
    fn test_zero() {
        assert_eq!(
            parse_pos_nonzero("0"),
            Err(ParsePosNonzeroError::Creation(CreationError::Zero))
        );
    }

    #[test]
    fn test_positive() {
        let x = PositiveNonzeroInteger::new(42);
        assert!(x.is_ok());
        assert_eq!(parse_pos_nonzero("42"), Ok(x.unwrap()));
    }
}

// traits1.rs
// Time to implement some traits!
//
// Your task is to implement the trait
// `AppendBar` for the type `String`.
//
// The trait AppendBar has only one function,
// which appends "Bar" to any object
// implementing this trait.
// Execute `rustlings hint traits1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

trait AppendBar {
    fn append_bar(self) -> Self;
}

impl AppendBar for String {
    // TODO: Implement `AppendBar` for type `String`.
}

fn main() {
    let s = String::from("Foo");
    let s = s.append_bar();
    println!("s: {}", s);
    // convert unit test to play in playground
    assert_eq!(
        String::from("Foo").append_bar(),
        String::from("FooBar")
    );

    assert_eq!(
        String::from("").append_bar().append_bar(),
        String::from("BarBar")
    );
}

// #[cfg(test)]
// mod tests {
//     use super::*;
//
//     #[test]
//     fn is_foo_bar() {
//         assert_eq!(String::from("Foo").append_bar(), String::from("FooBar"));
//     }
//
//     #[test]
//     fn is_bar_bar() {
//         assert_eq!(
//             String::from("").append_bar().append_bar(),
//             String::from("BarBar")
//         );
//     }
// }

// traits2.rs
//
// Your task is to implement the trait
// `AppendBar` for a vector of strings.
//
// To implement this trait, consider for
// a moment what it means to 'append "Bar"'
// to a vector of strings.
//
// No boiler plate code this time,
// you can do this!
// Execute `rustlings hint traits2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

trait AppendBar {
    fn append_bar(self) -> Self;
}

// TODO: Implement trait `AppendBar` for a vector of strings.

// #[cfg(test)]
// mod tests {
//     use super::*;
//
//     #[test]
//     fn is_vec_pop_eq_bar() {
//         let mut foo = vec![String::from("Foo")].append_bar();
//         assert_eq!(foo.pop().unwrap(), String::from("Bar"));
//         assert_eq!(foo.pop().unwrap(), String::from("Foo"));
//     }
// }

fn main() {
    // convert unit test to main to play in playground
    let mut foo = vec![String::from("Foo")].append_bar();
    assert_eq!(foo.pop().unwrap(), String::from("Bar"));
    assert_eq!(foo.pop().unwrap(), String::from("Foo"));
}

// traits3.rs
//
// Your task is to implement the Licensed trait for
// both structures and have them return the same
// information without writing the same function twice.
//
// Consider what you can add to the Licensed trait.
// Execute `rustlings hint traits3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

pub trait Licensed {
    fn licensing_info(&self) -> String;
}

struct SomeSoftware {
    version_number: i32,
}

struct OtherSoftware {
    version_number: String,
}

impl Licensed for SomeSoftware {} // Don't edit this line
impl Licensed for OtherSoftware {} // Don't edit this line

// #[cfg(test)]
// mod tests {
//     use super::*;
//
//     #[test]
//     fn is_licensing_info_the_same() {
//         let licensing_info = String::from("Some information");
//         let some_software = SomeSoftware { version_number: 1 };
//         let other_software = OtherSoftware {
//             version_number: "v2.0.0".to_string(),
//         };
//         assert_eq!(some_software.licensing_info(), licensing_info);
//         assert_eq!(other_software.licensing_info(), licensing_info);
//     }
// }

fn main() {
    // convert unit test to main to play in playground
    let licensing_info = String::from("Some information");
    let some_software = SomeSoftware { version_number: 1 };
    let other_software = OtherSoftware {
        version_number: "v2.0.0".to_string(),
    };
    assert_eq!(some_software.licensing_info(), licensing_info);
}

// traits4.rs
//
// Your task is to replace the '??' sections so the code compiles.
// Don't change any line other than the marked one.
// Execute `rustlings hint traits4` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

pub trait Licensed {
    fn licensing_info(&self) -> String {
        "some information".to_string()
    }
}

struct SomeSoftware {}

struct OtherSoftware {}

impl Licensed for SomeSoftware {}

impl Licensed for OtherSoftware {}

// YOU MAY ONLY CHANGE THE NEXT LINE
fn compare_license_types(software: ? ?, software_two: ? ?) -> bool {
    software.licensing_info() == software_two.licensing_info()
}

// #[cfg(test)]
// mod tests {
//     use super::*;
//
//     #[test]
//     fn compare_license_information() {
//         let some_software = SomeSoftware {};
//         let other_software = OtherSoftware {};
//
//         assert!(compare_license_types(some_software, other_software));
//     }
//
//     #[test]
//     fn compare_license_information_backwards() {
//         let some_software = SomeSoftware {};
//         let other_software = OtherSoftware {};
//
//         assert!(compare_license_types(other_software, some_software));
//     }
// }

fn main() {
    // convert unit test to main to play in playground
    // compare_license_information
    let some_software = SomeSoftware {};
    let other_software = OtherSoftware {};

    assert!(compare_license_types(some_software, other_software));

    // compare_license_information_backwards
    let some_software = SomeSoftware {};
    let other_software = OtherSoftware {};

    assert!(compare_license_types(other_software, some_software));
}

// traits5.rs
//
// Your task is to replace the '??' sections so the code compiles.
// Don't change any line other than the marked one.
// Execute `rustlings hint traits5` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

pub trait SomeTrait {
    fn some_function(&self) -> bool {
        true
    }
}

pub trait OtherTrait {
    fn other_function(&self) -> bool {
        true
    }
}

struct SomeStruct {}
struct OtherStruct {}

impl SomeTrait for SomeStruct {}
impl OtherTrait for SomeStruct {}
impl SomeTrait for OtherStruct {}
impl OtherTrait for OtherStruct {}

// YOU MAY ONLY CHANGE THE NEXT LINE
fn some_func(item: ??) -> bool {
    item.some_function() && item.other_function()
}

fn main() {
    some_func(SomeStruct {});
    some_func(OtherStruct {});
}

// macros1.rs
// Execute `rustlings hint macros1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

macro_rules! my_macro {
    () => {
        println!("Check out my macro!");
    };
}

fn main() {
    my_macro();
}

// macros2.rs
// Execute `rustlings hint macros2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    my_macro!();
}

macro_rules! my_macro {
    () => {
        println!("Check out my macro!");
    };
}

// macros3.rs
// Make me compile, without taking the macro out of the module!
// Execute `rustlings hint macros3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

mod macros {
    macro_rules! my_macro {
        () => {
            println!("Check out my macro!");
        };
    }
}

fn main() {
    my_macro!();
}

// macros4.rs
// Execute `rustlings hint macros4` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

macro_rules! my_macro {
    () => {
        println!("Check out my macro!");
    }
    ($val:expr) => {
        println!("Look at this other macro: {}", $val);
    }
}

fn main() {
    my_macro!();
    my_macro!(7777);
}

// clippy1.rs
// The Clippy tool is a collection of lints to analyze your code
// so you can catch common mistakes and improve your Rust code.
//
// For these exercises the code will fail to compile when there are clippy warnings
// check clippy's suggestions from the output to solve the exercise.
// Execute `rustlings hint clippy1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

use std::f32;

fn main() {
    let pi = 3.14f32;
    let radius = 5.00f32;

    let area = pi * f32::powi(radius, 2);

    println!(
        "The area of a circle with radius {:.2} is {:.5}!",
        radius, area
    )
}

// clippy2.rs
// Execute `rustlings hint clippy2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let mut res = 42;
    let option = Some(12);
    for x in option {
        res += x;
    }
    println!("{}", res);
}

// clippy3.rs
// Here's a couple more easy Clippy fixes, so you can see its utility.

// I AM NOT DONE

#[allow(unused_variables, unused_assignments)]
fn main() {
    let my_option: Option<()> = None;
    if my_option.is_none() {
        my_option.unwrap();
    }

    let my_arr = &[
        -1, -2, -3
        -4, -5, -6
    ];
    println!("My array! Here it is: {:?}", my_arr);

    let my_empty_vec = vec![1, 2, 3, 4, 5].resize(0, 5);
    println!("This Vec is empty, see? {:?}", my_empty_vec);

    let mut value_a = 45;
    let mut value_b = 66;
    // Let's swap these two!
    value_a = value_b;
    value_b = value_a;
    println!("value a: {}; value b: {}", value_a, value_b);
}

// functions1.rs
// Execute `rustlings hint functions1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    call_me();
}

// functions2.rs
// Execute `rustlings hint functions2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    call_me(3);
}

fn call_me(num:) {
    for i in 0..num {
        println!("Ring! Call number {}", i + 1);
    }
}

// functions3.rs
// Execute `rustlings hint functions3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    call_me();
}

fn call_me(num: u32) {
    for i in 0..num {
        println!("Ring! Call number {}", i + 1);
    }
}

// functions4.rs
// Execute `rustlings hint functions4` or use the `hint` watch subcommand for a hint.

// This store is having a sale where if the price is an even number, you get
// 10 Rustbucks off, but if it's an odd number, it's 3 Rustbucks off.
// (Don't worry about the function bodies themselves, we're only interested
// in the signatures for now. If anything, this is a good way to peek ahead
// to future exercises!)

// I AM NOT DONE

fn main() {
    let original_price = 51;
    println!("Your sale price is {}", sale_price(original_price));
}

fn sale_price(price: i32) -> {
    if is_even(price) {
        price - 10
    } else {
        price - 3
    }
}

fn is_even(num: i32) -> bool {
    num % 2 == 0
}

// functions5.rs
// Execute `rustlings hint functions5` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let answer = square(3);
    println!("The square of 3 is {}", answer);
}

fn square(num: i32) -> i32 {
    num * num;
}

// if1.rs
// Execute `rustlings hint if1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

pub fn bigger(a: i32, b: i32) -> i32 {
    // Complete this function to return the bigger number!
    // Do not use:
    // - another function call
    // - additional variables
}

// Don't mind this for now :)
#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn ten_is_bigger_than_eight() {
        assert_eq!(10, bigger(10, 8));
    }

    #[test]
    fn fortytwo_is_bigger_than_thirtytwo() {
        assert_eq!(42, bigger(32, 42));
    }
}

// if2.rs

// Step 1: Make me compile!
// Step 2: Get the bar_for_fuzz and default_to_baz tests passing!
// Execute `rustlings hint if2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

pub fn foo_if_fizz(fizzish: &str) -> &str {
    if fizzish == "fizz" {
        "foo"
    } else {
        1
    }
}

// No test changes needed!
#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn foo_for_fizz() {
        assert_eq!(foo_if_fizz("fizz"), "foo")
    }

    #[test]
    fn bar_for_fuzz() {
        assert_eq!(foo_if_fizz("fuzz"), "bar")
    }

    #[test]
    fn default_to_baz() {
        assert_eq!(foo_if_fizz("literally anything"), "baz")
    }
}

// modules1.rs
// Execute `rustlings hint modules1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

mod sausage_factory {
    // Don't let anybody outside of this module see this!
    fn get_secret_recipe() -> String {
        String::from("Ginger")
    }

    fn make_sausage() {
        get_secret_recipe();
        println!("sausage!");
    }
}

fn main() {
    sausage_factory::make_sausage();
}

// modules2.rs
// You can bring module paths into scopes and provide new names for them with the
// 'use' and 'as' keywords. Fix these 'use' statements to make the code compile.
// Execute `rustlings hint modules2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

mod delicious_snacks {
    // TODO: Fix these use statements
    use self::fruits::PEAR as ???
    use self::veggies::CUCUMBER as ???

    mod fruits {
        pub const PEAR: &'static str = "Pear";
        pub const APPLE: &'static str = "Apple";
    }

    mod veggies {
        pub const CUCUMBER: &'static str = "Cucumber";
        pub const CARROT: &'static str = "Carrot";
    }
}

fn main() {
    println!(
        "favorite snacks: {} and {}",
        delicious_snacks::fruit,
        delicious_snacks::veggie
    );
}

// modules3.rs
// You can use the 'use' keyword to bring module paths from modules from anywhere
// and especially from the Rust standard library into your scope.
// Bring SystemTime and UNIX_EPOCH
// from the std::time module. Bonus style points if you can do it with one line!
// Execute `rustlings hint modules3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

// TODO: Complete this use statement
use ???

fn main() {
    match SystemTime::now().duration_since(UNIX_EPOCH) {
        Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
        Err(_) => panic!("SystemTime before UNIX EPOCH!"),
    }
}

// move_semantics1.rs
// Execute `rustlings hint move_semantics1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let vec0 = Vec::new();

    let vec1 = fill_vec(vec0);

    // let vec1 = fill_vec(&vec0);
    // vec0.push(24); // Try accessing `vec0` after having called `fill_vec()`. See what happens!

    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);

    vec1.push(88);

    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
}

fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
    let mut vec = vec;

    vec.push(22);
    vec.push(44);
    vec.push(66);

    vec
}

// move_semantics2.rs
// Make me compile without changing line 13 or moving line 10!
// Execute `rustlings hint move_semantics2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let vec0 = Vec::new();

    let mut vec1 = fill_vec(vec0);

    // Do not change the following line!
    println!("{} has length {} content `{:?}`", "vec0", vec0.len(), vec0);

    vec1.push(88);

    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
}

fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
    let mut vec = vec;

    vec.push(22);
    vec.push(44);
    vec.push(66);

    vec
}

// move_semantics3.rs
// Make me compile without adding new lines-- just changing existing lines!
// (no lines with multiple semicolons necessary!)
// Execute `rustlings hint move_semantics3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let vec0 = Vec::new();

    let mut vec1 = fill_vec(vec0);

    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);

    vec1.push(88);

    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
}

fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
    vec.push(22);
    vec.push(44);
    vec.push(66);

    vec
}

// move_semantics4.rs
// Refactor this code so that instead of passing `vec0` into the `fill_vec` function,
// the Vector gets created in the function itself and passed back to the main
// function.
// Execute `rustlings hint move_semantics4` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let vec0 = Vec::new();

    let mut vec1 = fill_vec(vec0);

    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);

    vec1.push(88);

    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
}

// `fill_vec()` no longer takes `vec: Vec<i32>` as argument
fn fill_vec() -> Vec<i32> {
    let mut vec = vec;

    vec.push(22);
    vec.push(44);
    vec.push(66);

    vec
}

// move_semantics5.rs
// Make me compile only by reordering the lines in `main()`, but without
// adding, changing or removing any of them.
// Execute `rustlings hint move_semantics5` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let mut x = 100;
    let y = &mut x;
    let z = &mut x;
    *y += 100;
    *z += 1000;
    assert_eq!(x, 1200);
}

// move_semantics6.rs
// Execute `rustlings hint move_semantics6` or use the `hint` watch subcommand for a hint.
// You can't change anything except adding or removing references.

// I AM NOT DONE

fn main() {
    let data = "Rust is great!".to_string();

    get_char(data);

    string_uppercase(&data);
}

// Should not take ownership
fn get_char(data: String) -> char {
    data.chars().last().unwrap()
}

// Should take ownership
fn string_uppercase(mut data: &String) {
    data = &data.to_uppercase();

    println!("{}", data);
}

// tests1.rs
// Tests are important to ensure that your code does what you think it should do.
// Tests can be run on this file with the following command:
// rustlings run tests1

// This test has a problem with it -- make the test compile! Make the test
// pass! Make the test fail!
// Execute `rustlings hint tests1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

#[cfg(test)]
mod tests {
    #[test]
    fn you_can_assert() {
        assert!();
    }
}

// tests2.rs
// This test has a problem with it -- make the test compile! Make the test
// pass! Make the test fail!
// Execute `rustlings hint tests2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

#[cfg(test)]
mod tests {
    #[test]
    fn you_can_assert_eq() {
        assert_eq!();
    }
}

// tests3.rs
// This test isn't testing our function -- make it do that in such a way that
// the test passes. Then write a second test that tests whether we get the result
// we expect to get when we call `is_even(5)`.
// Execute `rustlings hint tests3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

pub fn is_even(num: i32) -> bool {
    num % 2 == 0
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn is_true_when_even() {
        assert!();
    }

    #[test]
    fn is_false_when_odd() {
        assert!();
    }
}

// threads1.rs
// Execute `rustlings hint threads1` or use the `hint` watch subcommand for a hint.

// This program spawns multiple threads that each run for at least 250ms,
// and each thread returns how much time they took to complete.
// The program should wait until all the spawned threads have finished and
// should collect their return values into a vector.

// I AM NOT DONE

use std::thread;
use std::time::{Duration, Instant};

fn main() {
    let mut handles = vec![];
    for i in 0..10 {
        handles.push(thread::spawn(move || {
            let start = Instant::now();
            thread::sleep(Duration::from_millis(250));
            println!("thread {} is complete", i);
            start.elapsed().as_millis()
        }));
    }

    let mut results: Vec<u128> = vec![];
    for handle in handles {
        // TODO: a struct is returned from thread::spawn, can you use it?
    }

    if results.len() != 10 {
        panic!("Oh no! All the spawned threads did not finish!");
    }
    
    println!();
    for (i, result) in results.into_iter().enumerate() {
        println!("thread {} took {}ms", i, result);
    }
}

// threads2.rs
// Execute `rustlings hint threads2` or use the `hint` watch subcommand for a hint.
// Building on the last exercise, we want all of the threads to complete their work but this time
// the spawned threads need to be in charge of updating a shared value: JobStatus.jobs_completed

// I AM NOT DONE

use std::sync::Arc;
use std::thread;
use std::time::Duration;

struct JobStatus {
    jobs_completed: u32,
}

fn main() {
    let status = Arc::new(JobStatus { jobs_completed: 0 });
    let mut handles = vec![];
    for _ in 0..10 {
        let status_shared = Arc::clone(&status);
        let handle = thread::spawn(move || {
            thread::sleep(Duration::from_millis(250));
            // TODO: You must take an action before you update a shared value
            status_shared.jobs_completed += 1;
        });
        handles.push(handle);
    }
    for handle in handles {
        handle.join().unwrap();
        // TODO: Print the value of the JobStatus.jobs_completed. Did you notice anything
        // interesting in the output? Do you have to 'join' on all the handles?
        println!("jobs completed {}", ???);
    }
}

// threads3.rs
// Execute `rustlings hint threads3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

use std::sync::mpsc;
use std::sync::Arc;
use std::thread;
use std::time::Duration;

struct Queue {
    length: u32,
    first_half: Vec<u32>,
    second_half: Vec<u32>,
}

impl Queue {
    fn new() -> Self {
        Queue {
            length: 10,
            first_half: vec![1, 2, 3, 4, 5],
            second_half: vec![6, 7, 8, 9, 10],
        }
    }
}

fn send_tx(q: Queue, tx: mpsc::Sender<u32>) -> () {
    let qc = Arc::new(q);
    let qc1 = Arc::clone(&qc);
    let qc2 = Arc::clone(&qc);

    thread::spawn(move || {
        for val in &qc1.first_half {
            println!("sending {:?}", val);
            tx.send(*val).unwrap();
            thread::sleep(Duration::from_secs(1));
        }
    });

    thread::spawn(move || {
        for val in &qc2.second_half {
            println!("sending {:?}", val);
            tx.send(*val).unwrap();
            thread::sleep(Duration::from_secs(1));
        }
    });
}

fn main() {
    let (tx, rx) = mpsc::channel();
    let queue = Queue::new();
    let queue_length = queue.length;

    send_tx(queue, tx);

    let mut total_received: u32 = 0;
    for received in rx {
        println!("Got: {}", received);
        total_received += 1;
    }

    println!("total numbers received: {}", total_received);
    assert_eq!(total_received, queue_length)
}

// variables1.rs
// Make me compile!
// Execute `rustlings hint variables1` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    x = 5;
    println!("x has the value {}", x);
}

// variables2.rs
// Execute `rustlings hint variables2` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let x;
    if x == 10 {
        println!("x is ten!");
    } else {
        println!("x is not ten!");
    }
}

// variables3.rs
// Execute `rustlings hint variables3` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let x: i32;
    println!("Number {}", x);
}

// variables4.rs
// Execute `rustlings hint variables4` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let x = 3;
    println!("Number {}", x);
    x = 5; // don't change this line
    println!("Number {}", x);
}

// variables5.rs
// Execute `rustlings hint variables5` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

fn main() {
    let number = "T-H-R-E-E"; // don't change this line
    println!("Spell a Number : {}", number);
    number = 3; // don't rename this variable
    println!("Number plus two is : {}", number + 2);
}

// variables6.rs
// Execute `rustlings hint variables6` or use the `hint` watch subcommand for a hint.

// I AM NOT DONE

const NUMBER = 3;
fn main() {
    println!("Number {}", NUMBER);
}