// Eryn Wells <eryn@erynwells.me>

use crate::bitboard::BitBoard;
use std::fmt;

mod color {
    const WHITE: u8 = 0;
    const BLACK: u8 = 1;
}

mod piece {
    const PAWN: u8 = 0;
    const KNIGHT: u8 = 1;
    const BISHOP: u8 = 2;
    const ROOK: u8 = 3;
    const QUEEN: u8 = 4;
    const KING: u8 = 5;
}

#[derive(Clone, Debug, Eq, Hash, PartialEq)]
pub struct Position {
    /// Composite bitboards for all the pieces of a particular color.
    pieces_per_color: [BitBoard; 2],

    /// Bitboards representing positions of particular piece types per color.
    pieces_per_type: [[BitBoard; 6]; 2],
}

impl Position {
    fn empty() -> Position {
        Position {
            pieces_per_color: [BitBoard::empty(), BitBoard::empty()],
            pieces_per_type: [
                [
                    BitBoard::empty(),
                    BitBoard::empty(),
                    BitBoard::empty(),
                    BitBoard::empty(),
                    BitBoard::empty(),
                    BitBoard::empty(),
                ],
                [
                    BitBoard::empty(),
                    BitBoard::empty(),
                    BitBoard::empty(),
                    BitBoard::empty(),
                    BitBoard::empty(),
                    BitBoard::empty(),
                ],
            ],
        }
    }

    /// Return a starting position.
    fn starting() -> Position {
        let white_pieces = [
            BitBoard::from_bit_field(0x00FF000000000000),
            BitBoard::from_bit_field(0x4200000000000000),
            BitBoard::from_bit_field(0x2400000000000000),
            BitBoard::from_bit_field(0x8100000000000000),
            BitBoard::from_bit_field(0x1000000000000000),
            BitBoard::from_bit_field(0x8000000000000000),
        ];

        let black_pieces = [
            BitBoard::from_bit_field(0xFF00),
            BitBoard::from_bit_field(0x0042),
            BitBoard::from_bit_field(0x0024),
            BitBoard::from_bit_field(0x0081),
            BitBoard::from_bit_field(0x0010),
            BitBoard::from_bit_field(0x0080),
        ];

        Position {
            pieces_per_color: [
                white_pieces.iter().fold(BitBoard::empty(), |a, b| a | b),
                black_pieces.iter().fold(BitBoard::empty(), |a, b| a | b),
            ],
            pieces_per_type: [white_pieces, black_pieces],
        }
    }

    fn piece_at_square(&self, sq: &str) {}
}

impl fmt::Display for Position {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "abcdefg")
    }
}