use rand::prelude::*;
use std::str::FromStr;

/// Represents the `item` on the TTT board (X or O)
#[derive(Copy, Clone, Debug, PartialEq)]
enum Item {
    X,
    O,
    Empty,
}

impl Into<String> for Item {
    fn into(self) -> String {
        match self {
            Self::X => "X".to_string(),
            Self::O => "O".to_string(),
            Self::Empty => "_".to_string(),
        }
    }
}

impl TryFrom<String> for Item {
    type Error = String;
    fn try_from(item: String) -> Result<Self, Self::Error> {
        match &item[..] {
            "X" | "x" => Ok(Self::X),
            "O" | "o" => Ok(Self::O),
            _ => Err("unknown item, retry!".to_string()),
        }
    }
}

impl Item {
    fn next(&self) -> Self {
        match self {
            Item::X => Item::O,
            Item::O => Item::X,
            Item::Empty => Item::Empty,
        }
    }
}

/// In order to visualize the board game
trait Displayer {
    fn show(&self);
}

/// Represents the **Tic-Tac-Toe** board game
struct Board {
    // board array is reprensented as follow:
    // [ 0, 1, 2 ]
    // [ 3, 4, 5 ]
    // [ 6, 7, 8 ]
    items: [Item; 9],
}

impl Board {
    fn new() -> Board {
        Board {
            items: [Item::Empty; 9],
        }
    }

    fn base_display(group_items: Vec<String>) {
        // output:       X   |   _   |   O
        println!(
            "{}",
            format!(
                "{:<5} {} {:<2}|{:<2} {} {:<2}|{:<2} {}",
                "", group_items[0], "", "", group_items[1], "", "", group_items[2]
            )
        );
    }

    /// checks whether the board is item's full (quit the game)
    fn is_full(&self) -> bool {
        for item in self.items {
            match item {
                Item::Empty => return false,
                _ => continue,
            };
        }
        true
    }

    /// returns the available/free board indexes
    fn get_available_indexes(&self) -> Vec<usize> {
        let mut availables = vec![];
        for (idx, item) in self.items.iter().enumerate() {
            if item == &Item::Empty {
                availables.push(idx);
            }
        }
        availables
    }

    fn set_item(&mut self, item: Item, idx: usize) -> Result<(), &str> {
        if idx == 0 || idx > 9 {
            return Err("invalid input, must be between 1 <= x <= 9");
        }
        match self.items[idx - 1] {
            Item::X => Err("already set, choose another one!"),
            Item::O => Err("already set, choose another one!"),
            Item::Empty => {
                self.items[idx - 1] = item;
                return Ok(());
            }
        }
    }

    fn check_first_line(&self, item: Item) -> bool {
        self.items[0] == item && self.items[1] == item && self.items[2] == item
    }

    fn check_second_line(&self, item: Item) -> bool {
        self.items[3] == item && self.items[4] == item && self.items[5] == item
    }

    fn check_last_line(&self, item: Item) -> bool {
        self.items[6] == item && self.items[7] == item && self.items[8] == item
    }

    fn check_first_col(&self, item: Item) -> bool {
        self.items[0] == item && self.items[3] == item && self.items[6] == item
    }

    fn check_second_col(&self, item: Item) -> bool {
        self.items[1] == item && self.items[4] == item && self.items[7] == item
    }

    fn check_last_col(&self, item: Item) -> bool {
        self.items[2] == item && self.items[5] == item && self.items[8] == item
    }

    fn check_first_diag(&self, item: Item) -> bool {
        self.items[0] == item && self.items[4] == item && self.items[8] == item
    }

    fn check_last_diag(&self, item: Item) -> bool {
        self.items[2] == item && self.items[4] == item && self.items[6] == item
    }

    /// instead of scanning all the board, checks input "win" combinaison
    fn check_win(&self, item: Item, idx: usize) -> bool {
        match idx {
            0 => {
                self.check_first_col(item)
                    || self.check_first_line(item)
                    || self.check_first_diag(item)
            }
            1 => self.check_first_line(item) || self.check_second_col(item),
            2 => {
                self.check_first_line(item)
                    || self.check_last_col(item)
                    || self.check_last_diag(item)
            }
            3 => self.check_first_col(item) || self.check_second_line(item),
            4 => {
                self.check_second_col(item)
                    || self.check_second_line(item)
                    || self.check_last_diag(item)
                    || self.check_first_diag(item)
            }
            5 => self.check_last_col(item) || self.check_second_line(item),
            6 => {
                self.check_first_col(item)
                    || self.check_last_line(item)
                    || self.check_last_diag(item)
            }
            7 => self.check_last_line(item) || self.check_second_col(item),
            8 => {
                self.check_last_line(item)
                    || self.check_last_col(item)
                    || self.check_first_diag(item)
            }
            _ => false,
        }
    }
}

impl Displayer for Board {
    /// loops over board items, groups items by 3 (multi dim array representation) and display it
    /// also displays board index number (empty item) for easy use
    fn show(&self) {
        println!("\n");
        println!("{:<3}{:-<23}", "", "");

        let mut group_items: Vec<String> = vec![];
        let items: Vec<String> = self
            .items
            .iter()
            .enumerate()
            .map(|(idx, x)| {
                if x != &Item::Empty {
                    Into::<String>::into(*x)
                } else {
                    format!("{}", idx + 1)
                }
            })
            .collect();

        for item in items {
            group_items.push(item);
            if group_items.len() != 3 {
                continue;
            }
            Board::base_display(group_items.clone());
            group_items.clear();
            println!("{:<3}{:-<23}", "", "");
        }

        println!("\n");
    }
}

#[derive(Copy, Clone)]
struct Player {
    item: Item,
    is_bot: bool,
}

impl Player {
    fn new(item: Item, is_bot: bool) -> Self {
        Player { item, is_bot }
    }
}

impl Default for Player {
    fn default() -> Self {
        Player {
            item: Item::Empty,
            is_bot: false,
        }
    }
}

impl Player {
    /// init players with the game type
    fn from_game_type(game_type: GameType) -> Vec<Player> {
        match game_type {
            GameType::TwoPlayers => vec![
                Player::new(Item::Empty, false),
                Player::new(Item::Empty, false),
            ],
            GameType::Bot => vec![
                Player::new(Item::Empty, false),
                Player::new(Item::Empty, true),
            ],
            GameType::Unknown => vec![],
        }
    }
}

/// Two `GameType` availables:
/// * TwoPlayers: no bot
/// * Bot: player against the bot
#[derive(Copy, Clone)]
enum GameType {
    TwoPlayers,
    Bot,
    Unknown,
}

impl From<String> for GameType {
    fn from(game_type: String) -> Self {
        match &game_type[..] {
            "0" => Self::TwoPlayers,
            "1" => Self::Bot,
            _ => Self::Unknown,
        }
    }
}

#[allow(dead_code)]
struct TicTacToe {
    board: Board,
    players: Vec<Player>,
    game_type: GameType,
    turn: u8,
}

impl Default for TicTacToe {
    fn default() -> Self {
        TicTacToe {
            board: Board::new(),
            game_type: GameType::Unknown,
            players: vec![],
            turn: 1,
        }
    }
}

impl TicTacToe {
    /// associated func in order to get user input
    fn get_user_input(message: &str) -> String {
        info(message.to_string());
        let mut input = String::new();
        std::io::stdin()
            .read_line(&mut input)
            .expect("IO error: unable to read the stdin input");
        input.trim().to_string()
    }

    fn set_game_type(&mut self, game_type: GameType) {
        self.game_type = game_type;
    }

    fn set_players_item(&mut self, first_item: Item) -> Result<(), String> {
        if self.players.len() != 2 {
            return Err(
                "unable to initialize players item, 2 players must be initialized".to_string(),
            );
        }

        self.players[0].item = first_item;
        self.players[1].item = first_item.next();

        Ok(())
    }

    /// on each turn, set the next player who has to play (players vec swapped)
    fn get_next_player(&mut self) -> Result<Player, String> {
        if self.players.len() != 2 {
            return Err("unable to get next player, 2 players must be initialized".to_string());
        }

        // on first turn, no need to swap
        if self.turn > 1 {
            self.players.swap(0, 1);
        }
        self.turn += 1;

        Ok(self.players[0])
    }

    /// set the item for the first player (the one that starts)
    fn select_first_player_item(&mut self) {
        let mut attempt = 0;
        loop {
            if attempt == 2 {
                error("come on... you can do better!".to_string());
                std::process::exit(1);
            }

            let input = TicTacToe::get_user_input("first player, choose your item: ('X' or 'O')");
            let item_start = Item::try_from(input);
            match item_start {
                Ok(item) => {
                    match self.set_players_item(item) {
                        Ok(()) => break,
                        Err(e) => fatal(e),
                    }
                    break;
                }
                Err(e) => error(e.to_string()),
            }
            attempt += 1;
        }
    }

    /// select game type and init players
    fn select_game_type(&mut self) {
        let mut attempt = 0;
        loop {
            if attempt == 2 {
                error("come on... you can do better!".to_string());
                std::process::exit(1);
            }

            let input = TicTacToe::get_user_input("choose your game type: ('0': versus, '1': bot)");
            let game_type = GameType::from(input);
            match game_type {
                GameType::Unknown => error("incorrect game type selected, retry!".to_string()),
                _ => {
                    self.set_game_type(game_type);
                    break;
                }
            }
            attempt += 1;
        }
        // init players
        self.players = Player::from_game_type(self.game_type);
    }

    fn select_player_item(&self) -> Result<usize, String> {
        if self.players.len() != 2 {
            return Err(
                "unable to get player item input, 2 players must be initialized".to_string(),
            );
        }

        let player = self.players[0];
        let item_icon: String = player.item.into();

        if !player.is_bot {
            let turn_message = format!("{} turn, which case do you want to fill ?", item_icon);
            let idx = TicTacToe::get_user_input(&turn_message);
            match usize::from_str(&idx) {
                Ok(v) => return Ok(v),
                Err(e) => return Err(e.to_string()),
            }
        }

        // for now, use a dummy bot
        let mut rng = rand::thread_rng();
        let mut available_indexes = self.board.get_available_indexes();
        available_indexes.shuffle(&mut rng);

        Ok(available_indexes[0] + 1)
    }

    fn run(&mut self) {
        self.select_game_type();
        self.select_first_player_item();

        loop {
            if self.board.is_full() {
                info("game over!".to_string());
                self.board.show();
                break;
            }

            let mut player = Player::default();
            match self.get_next_player() {
                Ok(p) => player = p,
                Err(e) => fatal(e),
            }

            if !player.is_bot {
                self.board.show();
            }

            let item_icon: String = player.item.into();
            let mut item_position;

            loop {
                match self.select_player_item() {
                    Ok(pos) => {
                        item_position = pos;
                        match self.board.set_item(player.item, pos) {
                            Ok(_) => break,
                            Err(e) => {
                                error(e.to_string());
                            }
                        }
                    }
                    Err(e) => {
                        error(e.to_string());
                    }
                }
            }

            // check after the 5th round if there's a winner
            if self.turn > 4 && self.board.check_win(player.item, item_position - 1) {
                info(format!("{} wins!", item_icon));
                self.board.show();
                break;
            }
        }
    }
}

fn info(msg: String) {
    println!("{}", format!("[tic-tac-toe] [info] => {}", msg))
}

fn error(msg: String) {
    eprintln!("{}", format!("[tic-tac-toe] [error] => {}", msg))
}

fn fatal(msg: String) {
    eprintln!("{}", format!("[tic-tac-toe] [fatal] => {}", msg));
    std::process::exit(1);
}

fn main() {
    let mut game = TicTacToe::default();
    game.run();
}