(function () {
    "use strict";

    // ===== State =====
    let boardWidth = 5;
    let boardHeight = 5;
    // colConstraints[c] = number of cells that should be filled in column c
    let colConstraints = [];
    // rowConstraints[r] = number of cells that should be filled in row r
    let rowConstraints = [];
    // blocked[r][c] = true if that cell is blocked
    let blocked = [];
    // pieces: array of 3x3 boolean grids  e.g. [[false,true,false],[true,true,true],[false,false,false]]
    let pieces = [];
    // piece designer state (3x3)
    let pieceDesign = [
        [false, false, false],
        [false, false, false],
        [false, false, false]
    ];

    // ===== DOM refs =====
    const boardWidthInput = document.getElementById("boardWidth");
    const boardHeightInput = document.getElementById("boardHeight");
    const generateBtn = document.getElementById("generateBtn");
    const boardArea = document.getElementById("boardArea");
    const pieceDesignerGrid = document.getElementById("pieceDesignerGrid");
    const addPieceBtn = document.getElementById("addPieceBtn");
    const pieceInventory = document.getElementById("pieceInventory");
    const exportBtn = document.getElementById("exportBtn");
    const exportOutput = document.getElementById("exportOutput");

    // ===== Board generation =====
    function initBoard() {
        boardWidth = parseInt(boardWidthInput.value) || 5;
        boardHeight = parseInt(boardHeightInput.value) || 5;

        colConstraints = new Array(boardWidth).fill(0);
        rowConstraints = new Array(boardHeight).fill(0);
        blocked = [];
        for (let r = 0; r < boardHeight; r++) {
            blocked.push(new Array(boardWidth).fill(false));
        }
        renderBoard();
    }

    function renderBoard() {
        // Build table:  top-left empty | col spinboxes
        //               row spinbox    | cells
        let html = '<table class="board-table">';

        // Header row: empty corner + column spinboxes
        html += "<tr>";
        html += '<td></td>'; // top-left corner
        for (let c = 0; c < boardWidth; c++) {
            html += '<td class="constraint-label">';
            html += `<input type="number" min="0" class="col-constraint" data-col="${c}" value="${colConstraints[c]}">`;
            html += "</td>";
        }
        html += "</tr>";

        // Board rows
        for (let r = 0; r < boardHeight; r++) {
            html += "<tr>";
            // Row spinbox
            html += '<td class="constraint-label">';
            html += `<input type="number" min="0" class="row-constraint" data-row="${r}" value="${rowConstraints[r]}">`;
            html += "</td>";
            for (let c = 0; c < boardWidth; c++) {
                const blockedClass = blocked[r][c] ? " blocked" : "";
                html += `<td class="board-cell${blockedClass}" data-row="${r}" data-col="${c}"></td>`;
            }
            html += "</tr>";
        }

        html += "</table>";
        boardArea.innerHTML = html;

        // Attach events
        boardArea.querySelectorAll(".board-cell").forEach(cell => {
            cell.addEventListener("click", function () {
                const r = parseInt(this.dataset.row);
                const c = parseInt(this.dataset.col);
                blocked[r][c] = !blocked[r][c];
                this.classList.toggle("blocked");
            });
        });

        boardArea.querySelectorAll(".col-constraint").forEach(input => {
            input.addEventListener("change", function () {
                colConstraints[parseInt(this.dataset.col)] = parseInt(this.value) || 0;
            });
        });

        boardArea.querySelectorAll(".row-constraint").forEach(input => {
            input.addEventListener("change", function () {
                rowConstraints[parseInt(this.dataset.row)] = parseInt(this.value) || 0;
            });
        });
    }

    // ===== Piece designer =====
    function renderPieceDesigner() {
        pieceDesignerGrid.innerHTML = "";
        for (let r = 0; r < 3; r++) {
            for (let c = 0; c < 3; c++) {
                const cell = document.createElement("div");
                cell.className = "piece-designer-cell" + (pieceDesign[r][c] ? " active" : "");
                cell.dataset.row = r;
                cell.dataset.col = c;
                cell.addEventListener("click", function () {
                    const pr = parseInt(this.dataset.row);
                    const pc = parseInt(this.dataset.col);
                    pieceDesign[pr][pc] = !pieceDesign[pr][pc];
                    this.classList.toggle("active");
                });
                pieceDesignerGrid.appendChild(cell);
            }
        }
    }

    function addPiece() {
        // Check that at least one cell is active
        const hasCell = pieceDesign.some(row => row.some(v => v));
        if (!hasCell) return;

        // Deep-copy the design
        const copy = pieceDesign.map(row => row.slice());
        pieces.push(copy);

        // Reset designer
        pieceDesign = [
            [false, false, false],
            [false, false, false],
            [false, false, false]
        ];
        renderPieceDesigner();
        renderInventory();
    }

    function renderInventory() {
        pieceInventory.innerHTML = "";
        pieces.forEach((piece, index) => {
            const wrapper = document.createElement("div");
            wrapper.className = "inventory-piece";

            for (let r = 0; r < 3; r++) {
                for (let c = 0; c < 3; c++) {
                    const cell = document.createElement("div");
                    cell.className = "inventory-piece-cell" + (piece[r][c] ? " active" : "");
                    wrapper.appendChild(cell);
                }
            }

            // Delete button
            const delBtn = document.createElement("button");
            delBtn.className = "delete-piece-btn";
            delBtn.textContent = "×";
            delBtn.title = "Delete piece";
            delBtn.addEventListener("click", function (e) {
                e.stopPropagation();
                pieces.splice(index, 1);
                renderInventory();
            });
            wrapper.appendChild(delBtn);

            pieceInventory.appendChild(wrapper);
        });
    }

    // ===== Export =====
    function exportPuzzle() {
        const data = {
            width: boardWidth,
            height: boardHeight,
            colConstraints: colConstraints,
            rowConstraints: rowConstraints,
            blocked: blocked,
            pieces: pieces
        };
        const json = JSON.stringify(data);
        const encoded = btoa(json);
        exportOutput.style.display = "block";
        exportOutput.value = encoded;
        exportOutput.select();
    }

    // ===== Event bindings =====
    generateBtn.addEventListener("click", initBoard);
    addPieceBtn.addEventListener("click", addPiece);
    exportBtn.addEventListener("click", exportPuzzle);

    // Also auto-update board on input change
    boardWidthInput.addEventListener("change", initBoard);
    boardHeightInput.addEventListener("change", initBoard);

    // ===== Init =====
    initBoard();
    renderPieceDesigner();
})();