//! # Chess turn engine
//! Turn engine fully implements all chess rules so it could be used to play
//! chess or to make chess simulations.
//!
//! Engine provides a list of available and playable turns after each turn
//! is played. Any turn from the list can be played.
//! Any played turn can be undone.
//!
//! Input for the engine are chess turns written in algebraic chess notation
//! format. But for the simplicity sake, one can use `AvailableTurn` struct to
//! transform simple layman's turn *Move piece from square A to square B* into a
//! chess notation turn.
//!
//! ## Display
//! Chess engine provides a basic set of tools to print out the board state in
//! ASCII format. Few options are available for printing out the board state.
//! Turn history can be printed out. Captured pieces can be printed out.
//! ### `ViewMode::SimpleAscii` - Quite simple display format
//! #### Legend
//!    - `b`: Black player
//!    - `w`: White player
//!    - `P`: Pawn
//!    - `N`: Knight
//!    - `B`: Bishop
//!    - `R`: Rook
//!    - `K`: King
//!    - `Q`: Queen
//!
//!  #### Example
//!  ```text
//!  8 bR bN bB bQ bK bB bN bR
//!  7 bP bP bP bP bP bP bP bP
//!  6  -  +  -  +  -  +  -  +
//!  5  +  -  +  -  +  -  +  -
//!  4  -  +  -  +  -  +  -  +
//!  3  +  -  +  -  +  -  +  -
//!  2 wP wP wP wP wP wP wP wP
//!  1 wR wN wB wQ wK wB wN wR
//!     a  b  c  d  e  f  g  h
//!  ```
//! ### `ViewMode::FancyTui` - Colorful terminal ASCII display format
//! Note: *colors are not visible in documentation pages*
//!
//! #### Example
//! ```text
//! 8  ♜  ♞  ♝  ♛  ♚  ♝  ♞  ♜
//! 7  ♟  ♟  ♟  ♟  ♟  ♟  ♟  ♟
//! 6
//! 5
//! 4
//! 3
//! 2  ♙  ♙  ♙  ♙  ♙  ♙  ♙  ♙
//! 1  ♖  ♘  ♗  ♕  ♔  ♗  ♘  ♖
//!    a  b  c  d  e  f  g  h
//! ```
//! ## Example with six straightforward turns played
//! ```
//! # use chess_turn_engine::{
//! #     ChessTurnEngine, DisplayOption, Setup, ViewMode, Gamestate
//! # };
//! #
//! let mut cte = ChessTurnEngine::new(Setup::Normal).unwrap();
//! let turns = ["h4", "Na6", "h5", "b5", "d3", "g6"];
//!
//! turns.iter().for_each(|turn| {
//!     cte.play_turn(turn);
//! });
//!
//! for turn in cte.available_turns() {
//!     println!("{}", turn);
//! }
//!
//! // Output:
//! // AvailableTurn (src: h5, dst: h6, piece: Pawn, captured: None, turn: h6
//! // AvailableTurn (src: h5, dst: g6, piece: Pawn, captured: Some("Pawn"), turn: hxg6
//! // AvailableTurn (src: d3, dst: d4, piece: Pawn, captured: None, turn: d4
//! // AvailableTurn (src: a2, dst: a3, piece: Pawn, captured: None, turn: a3
//! // AvailableTurn (src: a2, dst: a4, piece: Pawn, captured: None, turn: a4
//! // AvailableTurn (src: b2, dst: b3, piece: Pawn, captured: None, turn: b3
//! // AvailableTurn (src: b2, dst: b4, piece: Pawn, captured: None, turn: b4
//! // AvailableTurn (src: c2, dst: c3, piece: Pawn, captured: None, turn: c3
//! // AvailableTurn (src: c2, dst: c4, piece: Pawn, captured: None, turn: c4
//! // AvailableTurn (src: e2, dst: e3, piece: Pawn, captured: None, turn: e3
//! // AvailableTurn (src: e2, dst: e4, piece: Pawn, captured: None, turn: e4
//! // AvailableTurn (src: f2, dst: f3, piece: Pawn, captured: None, turn: f3
//! // AvailableTurn (src: f2, dst: f4, piece: Pawn, captured: None, turn: f4
//! // AvailableTurn (src: g2, dst: g3, piece: Pawn, captured: None, turn: g3
//! // AvailableTurn (src: g2, dst: g4, piece: Pawn, captured: None, turn: g4
//! // AvailableTurn (src: b1, dst: c3, piece: Knight, captured: None, turn: Nc3
//! // AvailableTurn (src: b1, dst: a3, piece: Knight, captured: None, turn: Na3
//! // AvailableTurn (src: b1, dst: d2, piece: Knight, captured: None, turn: Nd2
//! // AvailableTurn (src: c1, dst: d2, piece: Bishop, captured: None, turn: Bd2
//! // AvailableTurn (src: c1, dst: e3, piece: Bishop, captured: None, turn: Be3
//! // AvailableTurn (src: c1, dst: f4, piece: Bishop, captured: None, turn: Bf4
//! // AvailableTurn (src: c1, dst: g5, piece: Bishop, captured: None, turn: Bg5
//! // AvailableTurn (src: c1, dst: h6, piece: Bishop, captured: None, turn: Bh6
//! // AvailableTurn (src: d1, dst: d2, piece: Queen, captured: None, turn: Qd2
//! // AvailableTurn (src: e1, dst: d2, piece: King, captured: None, turn: Kd2
//! // AvailableTurn (src: g1, dst: h3, piece: Knight, captured: None, turn: Nh3
//! // AvailableTurn (src: g1, dst: f3, piece: Knight, captured: None, turn: Nf3
//! // AvailableTurn (src: h1, dst: h2, piece: Rook, captured: None, turn: Rh2
//! // AvailableTurn (src: h1, dst: h3, piece: Rook, captured: None, turn: Rh3
//! // AvailableTurn (src: h1, dst: h4, piece: Rook, captured: None, turn: Rh4
//! ```
//! ## Example with two turns played
//! ```
//! # use chess_turn_engine::{
//! #     ChessTurnEngine, DisplayOption, Setup, ViewMode, Gamestate
//! # };
//! #
//! let mut cte = ChessTurnEngine::new(Setup::Normal).unwrap();
//! assert!(cte.play_turn("d4").is_ok()); // Play "d4", starting turn
//!
//! // Play a random turn for the black player
//! let mut next_random_turn =
//!     String::from(cte.available_turns().first().unwrap().get_turn());
//! assert!(cte.play_turn(&next_random_turn).is_ok());
//!
//! // Play "a3" turn using only info about the source and destination squares
//! for turn in cte.available_turns() {
//!     if turn.src != String::from("a2") && turn.dst != String::from("a3") {
//!         continue;
//!     }
//!     next_random_turn = String::from(turn.get_turn());
//!     break;
//! }
//! assert!(cte.play_turn(&next_random_turn).is_ok());
//! assert_eq!(cte.gamestate(), Gamestate::Ongoing);
//!
//! cte.display_on_screen(DisplayOption::BoardView(ViewMode::SimpleAscii));
//! // 8 bR bN bB bQ bK bB bN bR
//! // 7 bP bP bP  - bP bP bP bP
//! // 6  -  +  -  +  -  +  -  +
//! // 5  +  -  + bP  +  -  +  -
//! // 4  -  +  - wP  -  +  -  +
//! // 3 wP  -  +  -  +  -  +  -
//! // 2  - wP wP  + wP wP wP wP
//! // 1 wR wN wB wQ wK wB wN wR
//! //    a  b  c  d  e  f  g  h
//! ```

mod game;

pub use game::availableturn::AvailableTurn;
pub use game::game_error::GameError;
pub use game::gamestate::Gamestate;
use game::Game;

/// Game engine
pub struct ChessTurnEngine {
    /// Game
    game: Game,
}

/// View modes for `BoardView`
#[derive(Copy, Clone)]
pub enum ViewMode {
    /// Display board in plain ASCII format
    SimpleAscii,

    /// Display board in colorful ASCII format for terminal purposes
    FancyTui,
}

/// Display option
#[derive(Copy, Clone)]
pub enum DisplayOption {
    /// Display board state
    BoardView(ViewMode),

    /// Display turn history in plain ASCII format
    TurnHistory,

    /// Display capture history in plain ASCII format
    CaptureHistory,
}

/// Chessboard setup
#[derive(Copy, Clone)]
pub enum Setup {
    /// **Default** board setup
    Normal,

    /// **Custom setup** (experimental usage)
    ///
    /// Note: *Castling turns are not possible in custom setups*
    ///
    /// Format for the custom setup is:
    ///     ```(`Square`,`Player`,`Piece` )+```
    /// - `Square`
    ///     - Must be specified with lowercase letters: e.g. `a1`
    /// - `Player`
    ///     - `w` for White
    ///     - `b` for Black
    /// - `Piece`
    ///     - `P`: Pawn
    ///     - `R`: Rook
    ///     - `B`: Bishop
    ///     - `N`: Knight
    ///     - `Q`: Queen
    ///     - `K`: King - Note: *game always must have two kings*
    ///
    /// Below is an example of how default chess setup looks like:
    ///
    /// ```
    /// let default_setup =
    ///    "a1,w,R b1,w,N c1,w,B d1,w,Q e1,w,K f1,w,B g1,w,N h1,w,R \
    ///     a2,w,P b2,w,P c2,w,P d2,w,P e2,w,P f2,w,P g2,w,P h2,w,P \
    ///     a7,b,P b7,b,P c7,b,P d7,b,P e7,b,P f7,b,P g7,b,P h7,b,P \
    ///     a8,b,R b8,b,N c8,b,B d8,b,Q e8,b,K f8,b,B g8,b,N h8,b,R";
    ///  ```
    Custom(&'static str),
}

impl ChessTurnEngine {
    /// Create and setup a new game
    ///
    /// # Arguments
    ///
    /// * `setup` - Game setup
    pub fn new(setup: Setup) -> Result<ChessTurnEngine, &'static str> {
        let setup = match setup {
            Setup::Normal => game::NORMAL_SETUP,
            Setup::Custom(setup) => setup,
        };

        let game = Game::new(setup)?;
        Ok(ChessTurnEngine { game })
    }

    /// Provide a displayable `String` of the chessboard
    ///
    /// # Arguments
    ///
    /// * `opt` - Display option
    pub fn display(&self, opt: DisplayOption) -> String {
        self.game.display(opt)
    }

    /// Display chessboard on the screen
    ///
    /// # Arguments
    ///
    /// * `opt` - Display option
    pub fn display_on_screen(&self, opt: DisplayOption) {
        println!("{}", self.game.display(opt));
    }

    /// Play provided turn.
    ///
    /// # Return value
    ///  - `Ok` - Latest game status.
    ///  - `Err` - `GameError` in case turn is not playable.
    ///
    /// # Arguments
    ///
    /// * `turn` - Turn provided in chess notation format
    pub fn play_turn(&mut self, turn: &str) -> Result<Gamestate, GameError> {
        self.game.play_turn(turn)
    }

    /// Get game status
    pub fn gamestate(&self) -> Gamestate {
        self.game.gamestate()
    }

    /// Undo turn and restore previous board state
    pub fn undo_turn(&mut self) -> Result<(), GameError> {
        Ok(self.game.undo_turn()?)
    }

    /// Get list of available turns
    pub fn available_turns(&self) -> &Vec<AvailableTurn> {
        &self.game.available_turns()
    }
}