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pub mod pawn;

use std::fmt::Debug;

use crate::bitboard::BitBoard;
use crate::game::position::Position;
use crate::game::Move;

/// The A file.
#[allow(dead_code)]
pub const FILE_A: BitBoard =
    BitBoard(0b0000000100000001000000010000000100000001000000010000000100000001);

/// The B file
#[allow(dead_code)]
pub const FILE_B: BitBoard = BitBoard(FILE_A.0 << 1);

/// The C file
#[allow(dead_code)]
pub const FILE_C: BitBoard = BitBoard(FILE_A.0 << 2);

/// The D file
#[allow(dead_code)]
pub const FILE_D: BitBoard = BitBoard(FILE_A.0 << 3);

/// The E file
#[allow(dead_code)]
pub const FILE_E: BitBoard = BitBoard(FILE_A.0 << 4);

/// The F file
#[allow(dead_code)]
pub const FILE_F: BitBoard = BitBoard(FILE_A.0 << 5);

/// The G file
#[allow(dead_code)]
pub const FILE_G: BitBoard = BitBoard(FILE_A.0 << 6);

/// The H file
#[allow(dead_code)]
pub const FILE_H: BitBoard = BitBoard(FILE_A.0 << 7);

/// A chess piece.
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub enum Pieces {
    Pawn(Color, Position),
    Rook(Color, Position),
    Knight(Color, Position),
    Bishop(Color, Position),
    Queen(Color, Position),
    King(Color, Position),
}

impl Pieces {
    /// Get the color of the piece.
    pub fn get_color(&self) -> Color {
        match self {
            Pieces::Pawn(color, _) => *color,
            Pieces::Rook(color, _) => *color,
            Pieces::Knight(color, _) => *color,
            Pieces::Bishop(color, _) => *color,
            Pieces::Queen(color, _) => *color,
            Pieces::King(color, _) => *color,
        }
    }

    /// Get the position of the piece.
    pub fn get_position(&self) -> Position {
        match self {
            Pieces::Pawn(_, position) => *position,
            Pieces::Rook(_, position) => *position,
            Pieces::Knight(_, position) => *position,
            Pieces::Bishop(_, position) => *position,
            Pieces::Queen(_, position) => *position,
            Pieces::King(_, position) => *position,
        }
    }

    /// Whether the piece is a `Pawn`.
    pub fn is_pawn(&self) -> bool {
        matches!(self, Pieces::Pawn(_, _))
    }

    /// Whether the piece is a `Rook`.
    pub fn is_rook(&self) -> bool {
        matches!(self, Pieces::Rook(_, _))
    }

    /// Whether the piece is a `Knight`.
    pub fn is_knight(&self) -> bool {
        matches!(self, Pieces::Knight(_, _))
    }

    /// Whether the piece is a `Bishop`.
    pub fn is_bishop(&self) -> bool {
        matches!(self, Pieces::Bishop(_, _))
    }

    /// Whether the piece is a `Queen`.
    pub fn is_queen(&self) -> bool {
        matches!(self, Pieces::Queen(_, _))
    }

    /// Whether the piece is a `King`.
    pub fn is_king(&self) -> bool {
        matches!(self, Pieces::King(_, _))
    }

    /// Whether the piece is black.
    pub fn is_black(&self) -> bool {
        matches!(self.get_color(), Color::Black)
    }

    /// Whether the piece is white.
    pub fn is_white(&self) -> bool {
        matches!(self.get_color(), Color::White)
    }
}

/// When the king moves, find whether it was a castling action.
/// If it is a castling move, return the corresponding `Move` for the rook.
pub fn get_castling_rook_move(king_move: &Move) -> Option<Move> {
    if *king_move == ("e1", "c1").into() {
        // White Queenside (O-O-O)
        Some(("a1", "d1").into())
    } else if *king_move == ("e1", "g1").into() {
        // White Kingside (O-O)
        Some(("h1", "f1").into())
    } else if *king_move == ("e8", "c8").into() {
        // Black Queenside (O-O-O)
        Some(("a8", "d8").into())
    } else if *king_move == ("e8", "g8").into() {
        // Black Kingside (O-O)
        Some(("h8", "f8").into())
    } else {
        None
    }
}

/// Whether the move was a pawn "two-step" (when they move by 2 from their original position).
/// This function assumes the piece is already determined to be a pawn.
pub fn is_pawn_two_step(pawn_move: &Move) -> bool {
    let Move(origin, destination, _) = pawn_move;
    origin.distance_rank(destination) == 2 && (origin.rank_y == 2 || origin.rank_y == 7)
}

/// A chess piece set (white or black).
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub enum Color {
    White,
    Black,
}

impl Color {
    pub fn opposite(&self) -> Self {
        match self {
            Self::White => Self::Black,
            Self::Black => Self::White,
        }
    }
}