import {
    Chess,
    Move,
    Square,
    Ox88,
    DEFAULT_POSITION,
    SQUARES,
    rank,
    file,
    Piece,
    WHITE,
    BLACK,
    KING,
    PieceSymbol,
    Color,
    PIECE_SYMBOLS,
} from "./chess.js";

type Player = (_: Chess) => string;

function with_move(board: Chess, move: string): Chess {
    let new_board = new Chess(board.fen());
    new_board.move(move);
    return new_board;
}

// function max_move_by(board: Chess, score: (_: Chess) => number): string {
//     let best_score = 0;
//     let best_move = "";

//     for (const move in board.moves()) {
//         let new_board = with_move(board, move);
//         let new_score = score(new_board);

//         if (
//             new_score > best_score ||
//             (new_score == new_score && Math.random() > 0.5)
//         ) {
//             best_score = new_score;
//             best_move = move;
//         }
//     }

//     return best_move;
// }

// could return early if zero but meh
function min_move_by(board: Chess, score: (_: Chess) => number): string {
    let best_score = Infinity;
    let best_move = "";

    let moves = board.moves();
    // console.log(moves);
    for (const i in moves) {
        let move = moves[i];
        try {
            let new_board = with_move(board, move);
            let new_score = score(new_board);
            // console.log({ move, best_score, new_score, best_move });

            if (
                new_score < best_score ||
                (new_score == best_score && Math.random() > 0.5)
            ) {
                console.log("New best (or equal): ", new_score, move);
                best_score = new_score;
                best_move = move;
            }
        } catch (e) {
            console.error(e);
            continue;
        }
    }
    return best_move;
}

// D --> movelist users (bad name whatever)
const random_move: Player = board => {
    const moves = board.moves();
    const move = moves[Math.floor(Math.random() * moves.length)];
    return move;
};

function make_lexo(m: Move): [number, number, number, number, PieceSymbol] {
    let { rank: src_row, file: src_col } = rank_and_file(m.from);
    let { rank: dst_row, file: dst_col } = rank_and_file(m.to);
    let promote_to = m.promotion;

    return [src_row, src_col, dst_row, dst_col, promote_to];
}

function lexo_sort_moves(a: Move, b: Move): -1 | 0 | 1 {
    let al = make_lexo(a);
    let bl = make_lexo(a);
    for (const i in al) {
        if (al[i] < bl[i]) {
            return -1;
        } else if (al[i] > bl[i]) {
            return 1;
        }
    }

    return 0;
}

const first_move: Player = board => {
    const moves = board.moves({ verbose: true }).sort(lexo_sort_moves);
    return moves[0].san;
};

const alphabetical: Player = board => {
    const moves = board.moves();
    moves.sort();

    return moves[0];
};

// i believe the actual one tracks things better (pawns are treated as different)
// yeah this version sucks butttttt uh
// yeah
// prettier-ignore
var equalizer_state: {
    piece_moves: Record<PieceSymbol, number>;
    square_visits: Record<Square, number>;
} = {
    piece_moves: {
        p: 0,
        b: 0,
        n: 0,
        r: 0,
        q: 0,
        k: 0,
    },
    // bad
    square_visits: {
        a8: 0, b8: 0, c8: 0, d8: 0, e8: 0, f8: 0, g8: 0, h8: 0,
        a7: 0, b7: 0, c7: 0, d7: 0, e7: 0, f7: 0, g7: 0, h7: 0,
        a6: 0, b6: 0, c6: 0, d6: 0, e6: 0, f6: 0, g6: 0, h6: 0,
        a5: 0, b5: 0, c5: 0, d5: 0, e5: 0, f5: 0, g5: 0, h5: 0,
        a4: 0, b4: 0, c4: 0, d4: 0, e4: 0, f4: 0, g4: 0, h4: 0,
        a3: 0, b3: 0, c3: 0, d3: 0, e3: 0, f3: 0, g3: 0, h3: 0,
        a2: 0, b2: 0, c2: 0, d2: 0, e2: 0, f2: 0, g2: 0, h2: 0,
        a1: 0, b1: 0, c1: 0, d1: 0, e1: 0, f1: 0, g1: 0, h1: 0
    }
};

const equalizer: Player = board => {
    let best_move: Move;
    let least_moved_found = Infinity;
    let least_visited_found = Infinity;
    let piece_moving: PieceSymbol = "k";
    let square_visiting: Square = "a1";

    // let least_moved = PIECE_SYMBOLS.sort(
    //     (a, b) =>
    //         equalizer_state.piece_moves[a] - equalizer_state.piece_moves[b]
    // )[0];
    // let least_visited = SQUARES.sort(
    //     (a, b) =>
    //         equalizer_state.square_visits[a] - equalizer_state.square_visits[b]
    // )[0];

    // cbb to do the proper randomness (23:41)
    for (const move of board.moves({ verbose: true })) {
        if (
            equalizer_state.piece_moves[move.piece] < least_moved_found ||
            (equalizer_state.piece_moves[move.piece] == least_moved_found &&
                equalizer_state.square_visits[move.to] < least_visited_found)
        ) {
            best_move = move;
            least_moved_found = equalizer_state.piece_moves[move.piece];
            least_visited_found = equalizer_state.square_visits[move.to];
            piece_moving = move.piece;
            square_visiting = move.to;
        }
    }

    equalizer_state.piece_moves[piece_moving] += 1;
    equalizer_state.square_visits[square_visiting] += 1;

    return best_move.san;
};

// D --> min-maxxing some score of the board after moving
const min_oppt_move: Player = board => {
    let num_moves = b => b.moves().length;
    return min_move_by(board, num_moves);
};

function num_pieces_on_own_color(b: Chess): number {
    let count = 0;
    for (const square of SQUARES) {
        let piece = b.get(square);
        if (typeof piece == "boolean") {
            continue;
        }
        if (piece.color == b.squareColor(square)) {
            count += 1;
        }
    }
    return count;
}

const same_color: Player = board => {
    return min_move_by(board, b => 64 - num_pieces_on_own_color(b));
};

const opposite_color: Player = board => {
    return min_move_by(board, num_pieces_on_own_color);
};

function rank_and_file(s: Square): { rank: number; file: number } {
    return { rank: rank(Ox88[s]), file: file(Ox88[s]) };
}

function chebyshev_distance(a: Square, b: Square): number {
    let { rank: r1, file: f1 } = rank_and_file(a);
    let { rank: r2, file: f2 } = rank_and_file(b);
    // forgot the abs UGH
    return Math.max(Math.abs(r2 - r1), Math.abs(f2 - f1));
}

const START_BOARD: Chess = new Chess(DEFAULT_POSITION);

// good enough
function move_distance(piece: { square: Square; type: PieceSymbol }): number {
    let rank = rank_and_file(piece.square).rank;
    let file = rank_and_file(piece.square).file;
    switch (piece.type) {
        case "k":
            return chebyshev_distance(
                piece.square,
                find({ color: HUMAN_COLOR, type: "k" }, START_BOARD)
            );
        case "p":
            return Math.abs(rank - 6);
        case "r":
            return (
                Math.abs(rank - 7) +
                Math.min(Math.abs(file - 7), Math.abs(file - 0))
            );
        case "n":
            // inauthentic
            return pieces_of_color(START_BOARD, HUMAN_COLOR)
                .filter(p => p.type == "k")
                .map(p => chebyshev_distance(piece.square, p.square))
                .reduce((a, b) => Math.max(a, b));
        case "b":
            let is_black = START_BOARD.squareColor(piece.square) == "b";
            let dest_col = is_black ? 2 : 5;
            let dr = Math.abs(rank - 7);
            let dc = Math.abs(file - dest_col);
            return Math.max(dr, dc);
        case "q":
            return Math.max(Math.abs(rank - 7), Math.abs(file - 3));
    }
}

// oh gosh i can do symmetry by making the "distance" just a score fn which
// would... work but dang so many things have done something similar in hindsight
// actually hm symmetry is weird
function minimize_distances(
    distance_fn: (piece: { square: Square; type: PieceSymbol }) => number
): Player {
    const player_score = (board: Chess) => {
        let total_distance = 0;

        for (const piece of pieces_of_color(board, ROBOT_COLOR)) {
            total_distance += distance_fn(piece);
        }

        return total_distance;
    };

    return b => min_move_by(b, player_score);
}

const reverse_starting: Player = minimize_distances(move_distance);

// or lens :]
function mirror_player(mirror_fn: (_: Square) => Square): Player {
    let player_score = (b: Chess) => {
        // it's worrying how the strategies have shifted, before it was more
        // common for them to weigh your pieces equally, meaning they might take
        // them to make the score better; silver lining: a bit easier to tell
        // apart potentially

        // the penalties are taken from the og code (the last four are the ones
        // where i finally figured out where to find the players (curse_you
        // UpperCamelCase))
        // the behavior is likely still slightly different
        let total = 0;
        for (const square of SQUARES) {
            let reflected = mirror_fn(square);
            console.log(square, reflected);
            let piece = b.get(square);
            let reflection = b.get(reflected);

            if (typeof piece == "boolean" && typeof reflection == "boolean") {
                continue;
            }

            if (typeof piece == "boolean") {
                total += 10;
                continue;
            }

            if (typeof reflection == "boolean") {
                total += 10;
                continue;
            }

            if (piece.color == reflection.color) {
                total += 5;
                continue;
            }

            if (piece.type != reflection.type) {
                total += 1;
                continue;
            }
        }

        return total;
    };

    return b => min_move_by(b, player_score);
}

function rank_and_file_to_algebraic(rf: {
    rank: number;
    file: number;
}): Square {
    let r: "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" = "8";
    let f: "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" = "h";

    // vim's <C-a> was very helpful here :]
    // I WAS MIRRORING AND THEN MIRRORING AGAIN OH MY GOOOOOSH
    // prettier-ignore
    switch (rf.rank) {
        case 0: r = "8"; break;
        case 1: r = "7"; break;
        case 2: r = "6"; break;
        case 3: r = "5"; break;
        case 4: r = "4"; break;
        case 5: r = "3"; break;
        case 6: r = "7"; break;
        case 7: r = "1"; break;
    }

    // prettier-ignore
    switch (rf.file) {
        case 0: f = "a"; break;
        case 1: f = "b"; break;
        case 2: f = "c"; break;
        case 3: f = "d"; break;
        case 4: f = "e"; break;
        case 5: f = "f"; break;
        case 6: f = "g"; break;
        case 7: f = "h"; break;
    }

    return `${f}${r}`;
}

function mirror_y(s: Square): Square {
    let rf = rank_and_file(s);
    rf.rank = 7 - rf.rank;
    return rank_and_file_to_algebraic(rf);
}

const sym_mirror_y: Player = mirror_player(mirror_y);

function mirror_x(s: Square): Square {
    let rf = rank_and_file(s);
    rf.file = 7 - rf.file;
    return rank_and_file_to_algebraic(rf);
}

const sym_mirror_x: Player = mirror_player(mirror_x);

function flip(s: Square): Square {
    let rf = rank_and_file(s);
    rf.rank = 7 - rf.rank;
    rf.file = 7 - rf.file;
    return rank_and_file_to_algebraic(rf);
}

const sym_180: Player = mirror_player(flip);

function find(p: Piece, b: Chess): Square | null {
    for (const square of SQUARES) {
        let got = b.get(square);
        if (typeof got == "boolean") {
            continue;
        }
        if (got.color == p.color && got.type == p.type) {
            return square;
        }
    }
    console.log(`didn't find this :O ${p}`);
    return null;
}

// maybe a find function would be useful Piece -> Board -> Square | null
const suicide_king: Player = board => {
    let distance_between_kings = (b: Chess) =>
        chebyshev_distance(
            find({ color: WHITE, type: KING }, b) ?? "a1",
            find({ color: BLACK, type: KING }, b) ?? "a1"
        );
    return min_move_by(board, distance_between_kings);
};

// cccp and pacifist are basically opposites
// ugh not really

function pieces_of_color(
    b: Chess,
    color: Color
): { square: Square; type: PieceSymbol; color: Color }[] {
    let flat_board = b.board().flat();
    let non_empties: { square: Square; type: PieceSymbol; color: Color }[] = [];
    for (const s of flat_board) {
        if (typeof s == "boolean") {
            continue;
        }
        non_empties.push(s);
    }

    return non_empties.filter(p => p.color == color);
}

function num_pieces_of_color(b: Chess, color: Color): number {
    return pieces_of_color(b, color).length;
}
// see generous in http://tom7.org/chess/weak.pdf
function value_piece(type: PieceSymbol): number {
    switch (type) {
        case "p":
            return 1;
        case "b":
        case "n":
            return 3;
        case "r":
            return 5;
        case "q":
            return 9;
        case "k":
            // impossible (mostly)
            // idk why i said this it's really not impossible lol
            return 413;
    }
}
function value_of_pieces_of_color(b: Chess, color: Color): number {
    return pieces_of_color(b, color)
        .map(p => value_piece(p.type))
        .reduce((a, b) => a + b);
}

// hm
const HUMAN_COLOR: Color = WHITE;
const ROBOT_COLOR: Color = BLACK;

// DONE: I THINK: UGH piece value
const cccp: Player = board => {
    let cccp_score = (b: Chess) => {
        if (b.isCheckmate()) {
            console.log("Found checkmate! :D");
            return 0;
        }
        if (b.isCheck()) {
            console.log("Found check! :T");
            return 1;
        }
        // maximize the difference in value
        let prev_value = value_of_pieces_of_color(board, HUMAN_COLOR);
        let new_value = value_of_pieces_of_color(b, HUMAN_COLOR);
        if (new_value < prev_value) {
            console.log("There's less human-colored pieces now! :)");
            return 10 * (6 - (prev_value - new_value));
        }
        // sum the ranks of the robot pieces (brittle with piece colors changing which uhh just don't do that :))
        // they are zero based oopsie
        return (
            100 *
            pieces_of_color(b, ROBOT_COLOR)
                .map(b => 8 - rank_and_file(b.square).rank)
                .reduce((a, b) => a + b)
        );
    };
    return min_move_by(board, cccp_score);
};

// FIXME: function name is TOO short FIX
function total_chebyshev_distances_of_pieces_of_color_to_square(
    board: Chess,
    color: Color,
    square: Square
): number {
    return pieces_of_color(board, color)
        .map(p => chebyshev_distance(p.square, square))
        .reduce((a, b) => a + b);
}

const huddle: Player = board => {
    return min_move_by(board, b =>
        total_chebyshev_distances_of_pieces_of_color_to_square(
            b,
            ROBOT_COLOR,
            find({ color: ROBOT_COLOR, type: KING }, b) ?? "a1"
        )
    );
};

const swarm: Player = board => {
    return min_move_by(board, b =>
        total_chebyshev_distances_of_pieces_of_color_to_square(
            b,
            ROBOT_COLOR,
            find({ color: HUMAN_COLOR, type: KING }, b) ?? "a1"
        )
    );
};

function sum_of_possible_capture_value(b: Chess): number {
    let prev_value = value_of_pieces_of_color(b, ROBOT_COLOR);

    let sum = 0;
    for (const move of b.moves()) {
        let new_board = with_move(b, move);
        let new_value = value_of_pieces_of_color(new_board, ROBOT_COLOR);
        // value only goes down..... pretty much
        // but the negation is now done by the guys so
        sum += prev_value - new_value;
    }

    return sum;
}

// surprisingly not too difficult
const generous: Player = board => {
    // sum of the difference in ROBOT_COLOR piece value of all moves
    // but like uhh negative
    let generous_score = (b: Chess) => {
        return -sum_of_possible_capture_value(b);
    };

    return min_move_by(board, generous_score);
};

const no_i_insist: Player = board => {
    let no_i_insist_score = (b: Chess) => {
        if (b.isCheckmate()) {
            return 612;
        }
        if (b.isCheck()) {
            return 413;
        }
        let prev_value = value_of_pieces_of_color(b, ROBOT_COLOR);
        return -(sum_of_possible_capture_value(b) / b.moves().length);
    };

    return min_move_by(board, no_i_insist_score);
};

const pacifist: Player = board => {
    let pacifist_score = b => {
        if (b.isCheckmate()) {
            return 612;
        }
        if (b.isCheck()) {
            return 413;
        }

        let prev_value = value_of_pieces_of_color(board, HUMAN_COLOR);
        let new_value = value_of_pieces_of_color(b, HUMAN_COLOR);
        if (new_value < prev_value) {
            return prev_value - new_value;
        }

        return 0;
    };

    return min_move_by(board, pacifist_score);
};

const players = [
    {
        f: random_move,
        name: "random_move",
        description: "Moves randomly, believe it or not.",
    },
    {
        f: same_color,
        name: "same_color",
        description:
            "Makes the move that maximizes the number of pieces on their own color",
    },
    {
        f: opposite_color,
        name: "opposite_color",
        description: "Behavior left as an exercise to the reader",
    },
    {
        f: pacifist,
        name: "pacifist",
        description:
            "Avoids checkmate, then avoids checks, then avoids captures, if forced, captures the lowest value piece it can",
    },
    {
        f: first_move,
        name: "first_move",
        description:
            "Makes the lexicographically first move based on [source_row, source_col, dest_row, dest_col, promotion]",
    },
    {
        f: alphabetical,
        name: "alphabetical",
        description:
            "Makes the first move asciilphabetically (based on algebraic notation)",
    },
    {
        f: huddle,
        name: "huddle",
        description:
            "Makes the move that minimizes the total Chebyshev distances from their pieces to their king",
    },
    {
        f: swarm,
        name: "swarm",
        description:
            "Makes the move that minimizes the total Chebyshev distances from their pieces to YOUR king",
    },
    {
        f: generous,
        name: "generous",
        description:
            "Maximizes the number of YOUR moves that take their pieces, weighting by value",
    },
    {
        f: no_i_insist,
        name: "no_i_insist",
        description:
            "Maximizes the proportion of potential capture value of YOUR moves to the number of YOUR moves; very weird the way i've done it",
    },
    {
        f: reverse_starting,
        name: "reverse_starting",
        description:
            "Makes the move that minimizes the number of moves it takes to move their pieces to the opposite end",
    },
    {
        f: cccp,
        name: "cccp",
        description:
            "First checkmates, then checks, then captures (the best piece it can), then pushes",
    },
    {
        f: suicide_king,
        name: "suicide_king",
        description:
            "Makes the move that minimizes the Chebyshev distance between the two kings",
    },
    {
        f: sym_mirror_y,
        name: "sym_mirror_y",
        description:
            "Tries to make the board as vertically symmetric as possible (basically copies your moves)",
    },
    {
        f: sym_mirror_x,
        name: "sym_mirror_x",
        description:
            "Tries to make the board as horizontally symmetric as possible (basically doesn't copy your moves or do anything useful)",
    },
    {
        f: sym_180,
        name: "sym_180",
        description:
            "Tries to make the board as symmetric as possible when flipped around",
    },
    {
        f: min_oppt_move,
        name: "min_oppt_move",
        description: "Does the move that leaves the least moves for YOU",
    },
    {
        f: equalizer,
        name: "equalizer",
        description:
            "Moves the least moved piece (actually piece type, e.g. moving a pawn counts for all pawns; it sucks, i know), breaking ties by moving to the least visited square",
    },
    // alphabetical is fine i guess, since the checklist order has little to do with the og paper
    // ehhh nvm
]; //.sort((a, b) => a.name.localeCompare(b.name));

// https://stackoverflow.com/questions/12739171/javascript-epoch-time-in-days

function days_since_epoch() {
    var now = new Date().getMilliseconds();
    return Math.floor(now / 8.64e7);
}

function find_specified_in_hash(): null | {
    f: Player;
    name: string;
    description: string;
} {
    return players.find(p => `#${p.name}` == window.location.hash);
}

// bad
// const todays_player = players[days_since_epoch() % players.length];
const todays_player =
    find_specified_in_hash() ??
    players[Math.floor(Math.random() * players.length)];

console.log(`SPOILER: today's player is ${todays_player.name}`);
// const todays_player = min_oppt_move;

const board: any = document.getElementById("board");

const game = new Chess();

function computer_move() {
    num_moves++;
    return todays_player.f(game);
}

// might want to change this when it's more wordly
function show_game_over() {
    let game_over = document.getElementById("game-over");
    game_over.style.display = "block";
    game_over.innerText = `GAME OVER; player was ${todays_player.name}`;

    console.log("GAME OVER");
}

function show_win() {
    let game_over = document.getElementById("game-over");
    game_over.style.display = "block";
    game_over.innerText = "YOU WIN YOU WIN YOU WIN YOU WIN HOLY CRAP";

    let stats = document.getElementById("stats");
    stats.style.display = "block";
    let stats_text = `#elo_worldle\n#ew_${todays_player.name}\nGuesses: ${num_guesses}\nMoves: ${num_moves}`;
    stats.innerText = stats_text;

    let copy_stats = document.getElementById("copy-stats");
    copy_stats.style.display = "block";
    copy_stats.addEventListener("click", _ =>
        navigator.clipboard.writeText(stats_text)
    );

    console.log("PLAYER IS WIN");
}

var num_guesses = 0;
var num_moves = 0;

function append_players_to(n: Node) {
    for (const player of players) {
        let child = document.createElement("div");
        child.classList.add("player");

        let child_name = document.createElement("h1");
        child_name.classList.add("player-name");
        child_name.innerText = player.name;

        let child_desc = document.createElement("p");
        child_desc.classList.add("player-desc");
        child_desc.innerText = player.description;

        let guess_button = document.createElement("button");
        guess_button.innerText = "^ guess ^";

        guess_button.onclick = _ => {
            num_guesses++;
            if (todays_player.name == player.name) {
                show_win();
                child.classList.add("correct");
            } else {
                child.classList.add("wrong");
            }
            guess_button.onclick = () => {};
        };

        child.appendChild(child_name);
        child.appendChild(child_desc);
        child.appendChild(guess_button);
        child_name.addEventListener("click", _ =>
            child.classList.toggle("strikethrough")
        );
        n.appendChild(child);
    }
}

window.addEventListener("DOMContentLoaded", () => {
    board.addEventListener("movestart", (e: any) => {
        console.log(
            `Move started: ${e.detail.from}, ${e.detail.piece.color} ${e.detail.piece.pieceType}`
        );
        e.detail.setTargets(
            // This produces a list like ["e3", "e5"]
            game.moves({ square: e.detail.from, verbose: true }).map(m => m.to)
        );

        if (game.isGameOver()) {
            show_game_over();
        }
    });

    board.addEventListener("moveend", (e: any) => {
        console.log(
            `Move ending: ${e.detail.from} -> ${e.detail.to}, ${e.detail.piece.color} ${e.detail.piece.pieceType}`
        );
        const move = game.move({
            from: e.detail.from,
            to: e.detail.to,
            promotion: "q",
        });
        if (move === null) {
            e.preventDefault();
        }

        if (game.isGameOver()) {
            show_game_over();
        }
    });

    board.addEventListener("movefinished", (e: any) => {
        board.fen = game.fen();
        board.turn = game.turn() === "w" ? "white" : "black";
        board.interactive = game.turn() === "w";

        if (!board.interactive) {
            let move = computer_move();
            if (!move) {
                console.log(
                    "Didn't get a move from the computer (this is fine if the game is over)"
                );
                return;
            }
            console.log(`Computer move: ${move}`);
            game.move(move);
            board.fen = game.fen();
            board.turn = "white";
            board.interactive = true;
        }
    });

    document
        .getElementById("finish")
        .addEventListener("click", _ => show_game_over());

    append_players_to(document.getElementById("players"));
});