// Eryn Wells <eryn@erynwells.me>

use crate::{
    display::{ASCIIDisplay, FENDisplay, UnicodeDisplay},
    Square,
};
use std::fmt;
use std::slice::Iter;

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum Color {
    White = 0,
    Black = 1,
}

impl Color {
    pub fn iter() -> impl Iterator<Item = Color> {
        [Color::White, Color::Black].into_iter()
    }

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

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum Shape {
    Pawn = 0,
    Knight = 1,
    Bishop = 2,
    Rook = 3,
    Queen = 4,
    King = 5,
}

impl Shape {
    pub fn iter() -> Iter<'static, Shape> {
        const ALL_SHAPES: [Shape; 6] = [
            Shape::Pawn,
            Shape::Knight,
            Shape::Bishop,
            Shape::Rook,
            Shape::Queen,
            Shape::King,
        ];

        ALL_SHAPES.iter()
    }

    pub fn promotable() -> Iter<'static, Shape> {
        const PROMOTABLE_SHAPES: [Shape; 4] =
            [Shape::Queen, Shape::Rook, Shape::Bishop, Shape::Knight];

        PROMOTABLE_SHAPES.iter()
    }

    fn _ascii_representation(&self) -> char {
        match self {
            Shape::Pawn => 'P',
            Shape::Knight => 'N',
            Shape::Bishop => 'B',
            Shape::Rook => 'R',
            Shape::Queen => 'Q',
            Shape::King => 'K',
        }
    }
}

#[derive(Debug, Eq, PartialEq)]
pub struct TryFromError;

impl TryFrom<char> for Shape {
    type Error = TryFromError;

    fn try_from(value: char) -> Result<Self, Self::Error> {
        match value {
            'p' => Ok(Shape::Pawn),
            'N' => Ok(Shape::Knight),
            'B' => Ok(Shape::Bishop),
            'R' => Ok(Shape::Rook),
            'Q' => Ok(Shape::Queen),
            'K' => Ok(Shape::King),
            _ => Err(TryFromError),
        }
    }
}

impl TryFrom<&str> for Shape {
    type Error = TryFromError;

    fn try_from(value: &str) -> Result<Self, Self::Error> {
        let first_char = value.chars().nth(0).ok_or(TryFromError)?;
        Shape::try_from(first_char)
    }
}

impl Into<char> for &Shape {
    fn into(self) -> char {
        self._ascii_representation()
    }
}

impl Into<char> for Shape {
    fn into(self) -> char {
        self._ascii_representation()
    }
}

impl fmt::Display for Shape {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let self_char: char = self.into();
        write!(f, "{}", self_char)
    }
}

#[derive(Debug, Eq, PartialEq)]
pub enum PiecePlacementError {
    ExistsOnSquare,
}

#[macro_export]
macro_rules! piece {
    ($color:ident $shape:ident) => {
        Piece::new(Color::$color, Shape::$shape)
    };
    ($color:ident $shape:ident on $square:ident) => {
        PlacedPiece::new(piece!($color $shape), Square::$square)
    }
}

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct Piece {
    color: Color,
    shape: Shape,
}

macro_rules! piece_constructor {
    ($func_name:ident, $type:tt) => {
        pub fn $func_name(color: Color) -> Piece {
            Piece {
                color,
                shape: Shape::$type,
            }
        }
    };
}

impl Piece {
    pub fn new(color: Color, shape: Shape) -> Piece {
        Piece { color, shape }
    }

    piece_constructor!(pawn, Pawn);
    piece_constructor!(knight, Knight);
    piece_constructor!(bishop, Bishop);
    piece_constructor!(rook, Rook);
    piece_constructor!(queen, Queen);
    piece_constructor!(king, King);

    pub fn color(&self) -> Color {
        self.color
    }

    pub fn shape(&self) -> Shape {
        self.shape
    }
}

impl fmt::Display for Piece {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        UnicodeDisplay::fmt(self, f)
    }
}

impl ASCIIDisplay for Piece {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", Into::<char>::into(self.shape()))
    }
}

impl UnicodeDisplay for Piece {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "{}",
            match (self.color, self.shape) {
                (Color::White, Shape::Pawn) => '♟',
                (Color::White, Shape::Knight) => '♞',
                (Color::White, Shape::Bishop) => '♝',
                (Color::White, Shape::Rook) => '♜',
                (Color::White, Shape::Queen) => '♛',
                (Color::White, Shape::King) => '♚',
                (Color::Black, Shape::Pawn) => '♙',
                (Color::Black, Shape::Knight) => '♘',
                (Color::Black, Shape::Bishop) => '♗',
                (Color::Black, Shape::Rook) => '♖',
                (Color::Black, Shape::Queen) => '♕',
                (Color::Black, Shape::King) => '♔',
            }
        )
    }
}

impl FENDisplay for Piece {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let ascii = self.shape()._ascii_representation();
        write!(
            f,
            "{}",
            match self.color {
                Color::White => ascii.to_ascii_uppercase(),
                Color::Black => ascii.to_ascii_lowercase(),
            }
        )
    }
}

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct PlacedPiece {
    piece: Piece,
    square: Square,
}

impl PlacedPiece {
    pub const fn new(piece: Piece, square: Square) -> PlacedPiece {
        PlacedPiece { piece, square }
    }

    #[inline]
    pub fn piece(&self) -> Piece {
        self.piece
    }

    #[inline]
    pub fn square(&self) -> Square {
        self.square
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn shape_try_from() {
        assert_eq!(Shape::try_from('p'), Ok(Shape::Pawn));
        assert_eq!(Shape::try_from("p"), Ok(Shape::Pawn));
    }

    #[test]
    fn shape_into_char() {
        assert_eq!(<Shape as Into<char>>::into(Shape::Pawn) as char, 'p');
    }
}