// 駒の定義と初期配置


const initialBoard = [
    ["l", "n", "s", "g", "k", "g", "s", "n", "l"],
    [null, "r", null, null, null, null, null, "b", null],
    ["p", "p", "p", "p", "p", "p", "p", "p", "p"],
    [null, null, null, null, null, null, null, null, null],
    [null, null, null, null, null, null, null, null, null],
    [null, null, null, null, null, null, null, null, null],
    ["P", "P", "P", "P", "P", "P", "P", "P", "P"],
    [null, "B", null, null, null, null, null, "R", null],
    ["L", "N", "S", "G", "K", "G", "S", "N", "L"]
];

const pieceNames = {
    P: "歩", L: "香", N: "桂", S: "銀", G: "金", K: "王", B: "角", R: "飛",
    p: "歩", l: "香", n: "桂", s: "銀", g: "金", k: "玉", b: "角", r: "飛"
};

const directions = {
    P: [[-1, 0]], p: [[1, 0]],
    L: Array.from({length: 8}, (_, i) => [-i - 1, 0]),
    l: Array.from({length: 8}, (_, i) => [i + 1, 0]),
    N: [[-2, -1], [-2, 1]], n: [[2, -1], [2, 1]],
    S: [[-1, -1], [-1, 0], [-1, 1], [1, -1], [1, 1]], s: [[1, -1], [1, 0], [1, 1], [-1, -1], [-1, 1]],
    G: [[-1, -1], [-1, 0], [-1, 1], [0, -1], [0, 1], [1, 0]],
    g: [[1, -1], [1, 0], [1, 1], [0, -1], [0, 1], [-1, 0]],
    K: [[-1, -1], [-1, 0], [-1, 1], [0, -1], [0, 1], [1, -1], [1, 0], [1, 1]],
    k: [[-1, -1], [-1, 0], [-1, 1], [0, -1], [0, 1], [1, -1], [1, 0], [1, 1]],
    B: "diagonal", b: "diagonal",
    R: "orthogonal", r: "orthogonal"
};

let board = JSON.parse(JSON.stringify(initialBoard));
let selected = null;
let currentTurn = "upper";
let hands = { upper: {}, lower: {} };
let lastMove = null; // {from: [i, j], to: [i, j]}

function createBoard() {
    const container = document.getElementById("board-container");
    container.innerHTML = "";
    const table = document.createElement("table");

    for (let i = 0; i < 9; i++) {
        const tr = document.createElement("tr");
        for (let j = 0; j < 9; j++) {
            const td = document.createElement("td");
            const piece = board[i][j];
            if (piece) {
                td.textContent = pieceNames[piece];
                if (piece === piece.toLowerCase()) {
                    td.style.transform = "rotate(180deg)";
                }
            }

            td.addEventListener("click", () => handleClick(i, j));
            if (selected && Array.isArray(selected) && isLegalMove(selected, [i, j])) {
                td.classList.add("highlight");
            }
            if (selected && Array.isArray(selected) && selected[0] === i && selected[1] === j) {
                td.classList.add("selected");
            }
            if (
                lastMove &&
                ((lastMove.from[0] === i && lastMove.from[1] === j) ||
                 (lastMove.to[0] === i && lastMove.to[1] === j))
            ) {
                td.style.backgroundColor = "#ffdddd"; // 最後に動いた駒のマス
            }
            tr.appendChild(td);
        }
        table.appendChild(tr);
    }


    container.appendChild(table);
    updateHands();

    const status = document.getElementById("status");
    status.textContent = currentTurn === "upper" ? "先手の番です" : "後手（AI）の番です";

    // ✅ AIのターンだったら自動で1手指す（少し待機）
    if (currentTurn === "lower") {
        setTimeout(() => {
            aiMove();
        }, 500);
    }
}


function isInside(i, j) {
    return i >= 0 && i < 9 && j >= 0 && j < 9;
}

function isOwnPiece(piece) {
    return currentTurn === "upper" ? piece && piece === piece.toUpperCase() : piece && piece === piece.toLowerCase();
}

function handleClick(i, j) {
    const cell = board[i][j];

    if (selected && selected.drop) {
        // ✅ 打ち処理（持ち駒から打つ）
        const piece = selected.drop;

        if (cell === null) {
            // 最低限の合法判定（例：歩は1段目に打てない）
            if (piece === "P" && i === 0) return;

            board[i][j] = piece;
            lastMove = { from: null, to: [i, j] };

            hands.upper[piece]--;
            if (hands.upper[piece] === 0) delete hands.upper[piece];

            selected = null;
            currentTurn = "lower";
            createBoard();
            return;
        }
    }

    if (selected && Array.isArray(selected)) {
        const [si, sj] = selected;
        if (isLegalMove([si, sj], [i, j])) {
            const movingPiece = board[si][sj];
            const destPiece = board[i][j];

            if (destPiece && !isOwnPiece(destPiece)) {
                const captured = destPiece.toUpperCase();
                hands.upper[captured] = (hands.upper[captured] || 0) + 1;
            }

            board[i][j] = movingPiece;
            lastMove = { from: [si, sj], to: [i, j] };  // 通常移動の時
            board[si][sj] = null;

            if (movingPiece === "P" && i === 0) {
                board[i][j] = "+P";
            }

            selected = null;
            checkVictory();
            currentTurn = "lower";
            createBoard();
        } else {
            selected = null;
            createBoard();
        }
    } else if (cell && isOwnPiece(cell)) {
        selected = [i, j];
        createBoard();
    }
}


function isLegalMove(from, to) {
    const [fi, fj] = from;
    const [ti, tj] = to;
    const piece = board[fi][fj];
    if (!piece) return false;

    const dir = directions[piece];
    const di = ti - fi;
    const dj = tj - fj;

    if (dir === "diagonal") {
        if (Math.abs(di) !== Math.abs(dj)) return false;
        const stepI = di / Math.abs(di);
        const stepJ = dj / Math.abs(dj);
        for (let k = 1; k < Math.abs(di); k++) {
            if (board[fi + stepI * k][fj + stepJ * k]) return false;
        }
        return true;
    }

    if (dir === "orthogonal") {
        if (di !== 0 && dj !== 0) return false;
        const stepI = di === 0 ? 0 : di / Math.abs(di);
        const stepJ = dj === 0 ? 0 : dj / Math.abs(dj);
        for (let k = 1; k < Math.max(Math.abs(di), Math.abs(dj)); k++) {
            if (board[fi + stepI * k][fj + stepJ * k]) return false;
        }
        return true;
    }

    for (const [dx, dy] of dir || []) {
        if (dx === di && dy === dj) return true;
    }

    return false;
}

function updateHands() {
    const sente = document.getElementById("sente-hand");
    const gote = document.getElementById("gote-hand");
    sente.innerHTML = "";
    gote.innerHTML = "";

    for (const piece in hands.upper) {
        const span = document.createElement("span");
        span.textContent = pieceNames[piece] + "×" + hands.upper[piece];

        // ✅ プレイヤーの持ち駒はクリック可能
        span.style.cursor = "pointer";
        span.addEventListener("click", () => {
            selected = { drop: piece };
            createBoard();
        });

        sente.appendChild(span);
    }

    for (const piece in hands.lower) {
        const span = document.createElement("span");
        span.textContent = pieceNames[piece] + "×" + hands.lower[piece];
        gote.appendChild(span);
    }
}


function checkVictory() {
    let kings = { K: false, k: false };
    for (const row of board) {
        for (const cell of row) {
            if (cell === "K") kings.K = true;
            if (cell === "k") kings.k = true;
        }
    }
    if (!kings.K) alert("後手の勝ち（王取り）！");
    if (!kings.k) alert("先手の勝ち（玉取り）！");
}

window.onload = createBoard;

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