import std.stdio;
import std.traits;
import std.range;

enum Color {
    White, Black
}

Color invert(Color c) {
    return c == Color.White ? Color.Black : Color.White;
}

enum Piece {
    King, Queen, Rook, Bishop, Knight, Pawn
}

string toString(Color color, Piece piece) {
    string[6][2] table =
        [
        [ "\u2654", "\u2655", "\u2656", "\u2657", "\u2658", "\u2659" ],
        [ "\u265A", "\u265B", "\u265C", "\u265D", "\u265E", "\u265F" ]
        ];
    return table[color][piece];
}

struct Square {
    this(Color color_, Piece piece_) {
        occupied = true;
        color = color_;
        piece = piece_;
    }

    bool  occupied = false;
    Color color;
    Piece piece;
}

enum File {
    _A, _B, _C, _D, _E, _F, _G, _H
}

char toChar(File f) {
    char[8] table = [ 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h' ];
    return table[f];
}

enum Rank {
    _1, _2, _3, _4, _5, _6, _7, _8
}

char toChar(Rank r) {
    char[8] table = [ '1', '2', '3', '4', '5', '6', '7', '8' ];
    return table[r];
}

struct Coord {
    File file;
    Rank rank;
}

struct Move {
    Coord source;
    Coord dest;
}

struct Board {
    this(Board board, Move move) {
        squares = board.squares;
        apply(move);
    }

    Square square(Coord coord) const {
        return squares[coord.file][coord.rank];
    }

private:
    Square * square(Coord coord) {
        return &squares[coord.file][coord.rank];
    }

    void apply(Move move) {
        auto sq1 = square(move.source);
        auto sq2 = square(move.dest);

        if (sq1.piece == Piece.Pawn && move.dest.file != move.source.file) {
            // en-passant
        }
        else if (sq1.piece == Piece.King && move.dest.file - move.source.file > 1) {
            // castle
        }
        else {
            *sq2 = *sq1;
            sq1.occupied = false;
        }
    }

    Square[8][8] squares =
        [
        [ Square(Color.White, Piece.Rook),   Square(Color.White, Piece.Pawn), Square(), Square(), Square(), Square(), Square(Color.Black, Piece.Pawn), Square(Color.Black, Piece.Rook)   ],
        [ Square(Color.White, Piece.Knight), Square(Color.White, Piece.Pawn), Square(), Square(), Square(), Square(), Square(Color.Black, Piece.Pawn), Square(Color.Black, Piece.Knight) ],
        [ Square(Color.White, Piece.Bishop), Square(Color.White, Piece.Pawn), Square(), Square(), Square(), Square(), Square(Color.Black, Piece.Pawn), Square(Color.Black, Piece.Bishop) ],
        [ Square(Color.White, Piece.Queen),  Square(Color.White, Piece.Pawn), Square(), Square(), Square(), Square(), Square(Color.Black, Piece.Pawn), Square(Color.Black, Piece.Queen)  ],
        [ Square(Color.White, Piece.King),   Square(Color.White, Piece.Pawn), Square(), Square(), Square(), Square(), Square(Color.Black, Piece.Pawn), Square(Color.Black, Piece.King)   ],
        [ Square(Color.White, Piece.Bishop), Square(Color.White, Piece.Pawn), Square(), Square(), Square(), Square(), Square(Color.Black, Piece.Pawn), Square(Color.Black, Piece.Bishop) ],
        [ Square(Color.White, Piece.Knight), Square(Color.White, Piece.Pawn), Square(), Square(), Square(), Square(), Square(Color.Black, Piece.Pawn), Square(Color.Black, Piece.Knight) ],
        [ Square(Color.White, Piece.Rook),   Square(Color.White, Piece.Pawn), Square(), Square(), Square(), Square(), Square(Color.Black, Piece.Pawn), Square(Color.Black, Piece.Rook)   ]
        ];
}

void dump(in Board board) {
    Color color = Color.White;

    foreach_reverse(r; EnumMembers!Rank) {
        write(toChar(r));
        foreach(f; EnumMembers!File) {

            if (color == Color.White) {
                write("\033[47m");
            }
            else {
                write("\033[40m");
            }

            Square square = board.square(Coord(f, r));
            if (square.occupied) {
                write(toString(square.color, square.piece));
            }
            else {
                write(" ");
            }

            color = invert(color);
        }
        writeln("\033[0m");

        color = invert(color);
    }

    write(" ");
    foreach(f; EnumMembers!File) {
        writef("%s", toChar(f));
    }
    writeln("");
}

void main(string[] args) {
    Board board;
    dump(board);
}