// Eryn Wells <eryn@erynwells.me>

use super::position::BoardSide;
use crate::{r#move::Castle, Color};
use std::fmt;

#[derive(Clone, Copy, Eq, Hash, PartialEq)]
pub(super) struct Flags(u8);

impl Flags {
    #[inline]
    pub(super) fn player_has_right_to_castle_flag_offset(color: Color, castle: Castle) -> u8 {
        let board_side: BoardSide = castle.into();
        ((color as u8) << 1) + board_side as u8
    }

    pub(super) fn player_has_right_to_castle(&self, color: Color, castle: Castle) -> bool {
        (self.0 & (1 << Self::player_has_right_to_castle_flag_offset(color, castle))) != 0
    }

    pub(super) fn set_player_has_right_to_castle_flag(&mut self, color: Color, castle: Castle) {
        self.0 |= 1 << Self::player_has_right_to_castle_flag_offset(color, castle);
    }

    pub(super) fn clear_player_has_right_to_castle_flag(&mut self, color: Color, castle: Castle) {
        self.0 &= !(1 << Self::player_has_right_to_castle_flag_offset(color, castle));
    }
}

impl fmt::Debug for Flags {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "Flags({:08b})", self.0)
    }
}

impl Default for Flags {
    fn default() -> Self {
        Flags(0b00001111)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{r#move::Castle, Color};

    #[test]
    fn castle_flags() {
        assert_eq!(
            Flags::player_has_right_to_castle_flag_offset(Color::White, Castle::KingSide),
            0
        );
        assert_eq!(
            Flags::player_has_right_to_castle_flag_offset(Color::White, Castle::QueenSide),
            1
        );
        assert_eq!(
            Flags::player_has_right_to_castle_flag_offset(Color::Black, Castle::KingSide),
            2
        );
        assert_eq!(
            Flags::player_has_right_to_castle_flag_offset(Color::Black, Castle::QueenSide),
            3
        );
    }

    #[test]
    fn defaults() {
        let mut flags: Flags = Default::default();
        assert!(flags.player_has_right_to_castle(Color::White, Castle::KingSide));
        assert!(flags.player_has_right_to_castle(Color::White, Castle::QueenSide));
        assert!(flags.player_has_right_to_castle(Color::Black, Castle::KingSide));
        assert!(flags.player_has_right_to_castle(Color::Black, Castle::QueenSide));

        flags.clear_player_has_right_to_castle_flag(Color::White, Castle::QueenSide);
        assert!(flags.player_has_right_to_castle(Color::White, Castle::KingSide));
        assert!(!flags.player_has_right_to_castle(Color::White, Castle::QueenSide));
        assert!(flags.player_has_right_to_castle(Color::Black, Castle::KingSide));
        assert!(flags.player_has_right_to_castle(Color::Black, Castle::QueenSide));

        flags.set_player_has_right_to_castle_flag(Color::White, Castle::QueenSide);
        assert!(flags.player_has_right_to_castle(Color::White, Castle::KingSide));
        assert!(flags.player_has_right_to_castle(Color::White, Castle::QueenSide));
        assert!(flags.player_has_right_to_castle(Color::Black, Castle::KingSide));
        assert!(flags.player_has_right_to_castle(Color::Black, Castle::QueenSide));
    }
}