use crate::board::Color;

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub struct State {
    side_to_move: Color,
    castling_ability: [Castle; 2],
    en_passant_target_square: Option<usize>,
    halfmove_clock: u8,
    fullmove_counter: u8,
}

impl State {
    pub const fn new() -> Self {
        Self {
            side_to_move: Color::White,
            castling_ability: [Castle::Both, Castle::Both],
            en_passant_target_square: None,
            halfmove_clock: 0,
            fullmove_counter: 1,
        }
    }

    pub const fn load_state(
        side_to_move: Color,
        castling_ability: [Castle; 2],
        en_passant_target_square: Option<usize>,
        halfmove_clock: u8,
        fullmove_counter: u8,
    ) -> Self {
        Self {
            side_to_move,
            castling_ability,
            en_passant_target_square,
            halfmove_clock,
            fullmove_counter,
        }
    }

    pub const fn en_passant_target_square(&self) -> Option<usize> {
        self.en_passant_target_square
    }

    pub fn set_castling_ability(&mut self, color: Color, castle: Castle) {
        match color {
            Color::White => self.castling_ability[0] = castle,
            Color::Black => self.castling_ability[1] = castle,
        }
    }

    pub fn update_castling_state_quiet(&mut self, src: usize, color: Color) {
        self.update_castling_state_capture(src, color);

        match (src, color) {
            (4, Color::White) => self.set_castling_ability(color, Castle::None),
            (60, Color::Black) => self.set_castling_ability(color, Castle::None),
            _ => (),
        }
    }

    pub fn update_castling_state_capture(&mut self, target: usize, color: Color) {
        let (short_square, long_square) = match color {
            Color::White => (7, 0),
            Color::Black => (63, 56),
        };

        if target == short_square {
            match self.castling_ability(color) {
                Castle::Both => self.set_castling_ability(color, Castle::Long),
                Castle::Short => self.set_castling_ability(color, Castle::None),
                _ => (),
            }
        }

        if target == long_square {
            match self.castling_ability(color) {
                Castle::Both => self.set_castling_ability(color, Castle::Short),
                Castle::Long => self.set_castling_ability(color, Castle::None),
                _ => (),
            }
        }
    }

    pub fn change_side(&mut self) {
        self.side_to_move = match self.side_to_move {
            Color::White => Color::Black,
            Color::Black => Color::White,
        }
    }

    pub const fn next_turn(&self) -> Color {
        self.side_to_move
    }

    pub fn set_en_passant_target_square(&mut self, square: Option<usize>) {
        self.en_passant_target_square = square;
    }

    pub const fn castling_ability(&self, color: Color) -> Castle {
        match color {
            Color::White => self.castling_ability[0],
            Color::Black => self.castling_ability[1],
        }
    }
}

impl Default for State {
    fn default() -> Self {
        Self::new()
    }
}

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum Castle {
    Short,
    Long,
    Both,
    None,
}