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use std::str::FromStr;
use crate::{Board, ChessMove, Color, Square};
/// The Result of the game.
#[derive(Copy, Clone, Eq, PartialEq, Default, Debug)]
pub enum GameState {
/// The game is still ongoing.
#[default]
Ongoing,
/// A player is checkmates.
Checkmates(Color),
/// Draw by Stalemate.
Stalemate,
/// Draw by request accepted (ie. Mutual Agreement).
DrawAccepted,
/// Draw declared by a player.
DrawDeclared,
/// The [`Color`] has resigns.
Resigns(Color),
}
impl GameState {
/// Verify if the game is ongoing.
pub fn is_ongoing(&self) -> bool {
matches!(self, GameState::Ongoing)
}
/// Verify if the game is finish.
pub fn is_finish(&self) -> bool {
!matches!(self, GameState::Ongoing)
}
}
/// A Standard Chess game.
///
/// TODO: Add a timer for each player.
#[derive(Clone, Eq, PartialEq, Default, Debug)]
pub struct Chess {
pub(crate) board: Board,
pub(crate) square_focused: Option<Square>,
pub(crate) offer_draw: bool,
pub(crate) state: GameState,
pub(crate) history: Vec<String>,
}
impl Chess {
/// Create a new instance of Chess.
pub fn new(board: Board) -> Self {
Chess {
board,
square_focused: None,
offer_draw: false,
history: vec![],
state: GameState::Ongoing,
}
}
/// Get the history of the game.
///
/// The [`Vec`] contains a FEN-string.
pub fn history(&self) -> Vec<String> {
self.history.clone()
}
/// Go back one step in history.
///
/// If the history is empty, reset the board to it's [`default`][Board::default] value.
///
/// # Examples
///
/// ```
/// use chess::{Chess, Square};
/// let mut chess = Chess::default();
/// let expected = Chess::default();
/// chess.play(Square::A2, Square::A4);
/// chess.undo();
///
/// assert_eq!(chess, expected);
/// ```
pub fn undo(&mut self) {
if let Some(fen) = self.history.pop() {
self.board = Board::from_str(fen.as_str()).expect("valid fen from history");
}
}
/// Reset the Game (board and history).
pub fn reset(&mut self) {
self.board = Board::default();
self.offer_draw = false;
self.square_focused = None;
self.history = vec![];
self.state = GameState::Ongoing;
}
/// Return the [`State`][GameState] of the Game.
pub fn state(&mut self) -> GameState {
self.state
}
/// Base function to call when a user click on the screen.
pub fn play(&mut self, from: Square, to: Square) {
let m = ChessMove::new(from, to);
if self.board.is_legal(m) {
self.history.push(self.board.to_string());
self.board.update(m);
if self.offer_draw {
self.offer_draw = false;
}
self.state = self.board.state();
}
self.square_focused = None;
}
/// The current player offer a draw.
///
/// The offer is cancel when the player play.
pub fn offer_draw(&mut self) {
self.offer_draw = true;
}
/// Accept the draw. Assumes that a draw is offered.
pub fn accept_draw(&mut self) {
self.state = GameState::DrawAccepted;
}
/// Verify if a player can legally declare a draw by 3-fold repetition or 50-move rule.
pub fn can_declare_draw(&self) -> bool {
let t = self.history.len();
if t >= 8 {
let fen_boards = [
self.board
.to_string()
.split_once(' ')
.unwrap()
.0
.to_string(),
self.history[t - 4].split_once(' ').unwrap().0.to_string(),
self.history[t - 8].split_once(' ').unwrap().0.to_string(),
];
if fen_boards[0] == fen_boards[1] && fen_boards[1] == fen_boards[2] {
return true;
}
if self.board.halfmoves() >= 100 {
return true;
}
}
false
}
/// Declare a draw by 3-fold repetition or 50-move rule. Assumes that a draw can be declare.
pub fn declare_draw(&mut self) {
self.state = GameState::DrawDeclared;
}
/// [`Color`] resigns the game.
pub fn resign(&mut self, color: Color) {
self.state = GameState::Resigns(color);
}
}