(function () {
    "use strict";

    let gameState = null;
    let timerInterval = null;
    let selectedCells = [];

    // DOM refs
    const setupDiv = document.getElementById("game-setup");
    const boardDiv = document.getElementById("game-board");
    const categorySelect = document.getElementById("category-select");
    const boardSizeInput = document.getElementById("board-size");
    const sizeDisplay = document.getElementById("size-display");
    const newGameBtn = document.getElementById("new-game-btn");
    const gridTable = document.getElementById("grid-table");
    const wordList = document.getElementById("word-list");
    const wordInput = document.getElementById("word-input");
    const guessBtn = document.getElementById("guess-btn");
    const submitSelectionBtn = document.getElementById("submit-selection-btn");
    const clearSelectionBtn = document.getElementById("clear-selection-btn");
    const guessFeedback = document.getElementById("guess-feedback");
    const timerEl = document.getElementById("timer");
    const completionBanner = document.getElementById("completion-banner");
    const finalTime = document.getElementById("final-time");
    const playAgainBtn = document.getElementById("play-again-btn");
    const inputArea = document.getElementById("input-area");

    // Load categories
    async function loadCategories() {
        const resp = await fetch("/api/categories");
        const categories = await resp.json();
        categorySelect.innerHTML = "";
        categories.forEach(function (cat) {
            const opt = document.createElement("option");
            opt.value = cat.id;
            opt.textContent = cat.name.charAt(0).toUpperCase() + cat.name.slice(1);
            categorySelect.appendChild(opt);
        });
    }

    boardSizeInput.addEventListener("input", function () {
        sizeDisplay.textContent = this.value;
    });

    // New game
    newGameBtn.addEventListener("click", async function () {
        const categoryId = parseInt(categorySelect.value);
        const boardSize = parseInt(boardSizeInput.value);
        const resp = await fetch("/api/game/new", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({ category_id: categoryId, board_size: boardSize }),
        });
        gameState = await resp.json();
        showBoard();
    });

    function showBoard() {
        setupDiv.classList.add("d-none");
        boardDiv.classList.remove("d-none");
        completionBanner.classList.add("d-none");
        playAgainBtn.classList.add("d-none");
        inputArea.classList.remove("d-none");
        selectedCells = [];
        renderGrid();
        renderWordList();
        startTimer();
    }

    function renderGrid() {
        gridTable.innerHTML = "";
        gameState.grid.forEach(function (row, r) {
            const tr = document.createElement("tr");
            row.forEach(function (letter, c) {
                const td = document.createElement("td");
                td.textContent = letter;
                td.dataset.row = r;
                td.dataset.col = c;
                td.addEventListener("click", function () {
                    onCellClick(r, c, td);
                });
                tr.appendChild(td);
            });
            gridTable.appendChild(tr);
        });
    }

    function renderWordList() {
        wordList.innerHTML = "";
        gameState.words.forEach(function (w) {
            const li = document.createElement("li");
            li.className = "list-group-item";
            li.textContent = w.text;
            li.dataset.word = w.text;
            if (w.found) {
                li.classList.add("word-found");
            }
            wordList.appendChild(li);
        });
    }

    // Timer
    function startTimer() {
        if (timerInterval) clearInterval(timerInterval);
        const startedAt = new Date(gameState.started_at);
        function tick() {
            const elapsed = Math.floor((Date.now() - startedAt.getTime()) / 1000);
            const mins = Math.floor(elapsed / 60);
            const secs = elapsed % 60;
            timerEl.textContent = mins + ":" + (secs < 10 ? "0" : "") + secs;
        }
        tick();
        timerInterval = setInterval(tick, 1000);
    }

    function stopTimer() {
        if (timerInterval) {
            clearInterval(timerInterval);
            timerInterval = null;
        }
    }

    // Text guess
    guessBtn.addEventListener("click", submitTextGuess);
    wordInput.addEventListener("keydown", function (e) {
        if (e.key === "Enter") submitTextGuess();
    });

    async function submitTextGuess() {
        const word = wordInput.value.trim();
        if (!word) return;
        wordInput.value = "";
        await sendGuess({ word: word });
    }

    // Click selection
    function onCellClick(row, col, td) {
        if (gameState.status === "completed") return;

        // Check if already selected — deselect
        const idx = selectedCells.findIndex(
            function (c) { return c.row === row && c.col === col; }
        );
        if (idx !== -1) {
            selectedCells.splice(idx, 1);
            td.classList.remove("cell-selected");
            updateSelectionButtons();
            return;
        }

        // Validate straight line
        if (selectedCells.length >= 2) {
            if (!isValidExtension(row, col)) {
                showFeedback("Selection must form a straight line.", "text-warning");
                return;
            }
        }

        selectedCells.push({ row: row, col: col });
        td.classList.add("cell-selected");
        updateSelectionButtons();
    }

    function isValidExtension(row, col) {
        if (selectedCells.length < 2) return true;
        const dr = selectedCells[1].row - selectedCells[0].row;
        const dc = selectedCells[1].col - selectedCells[0].col;
        const len = selectedCells.length;
        const expectedRow = selectedCells[0].row + dr * len;
        const expectedCol = selectedCells[0].col + dc * len;
        return row === expectedRow && col === expectedCol;
    }

    function updateSelectionButtons() {
        if (selectedCells.length > 0) {
            submitSelectionBtn.classList.remove("d-none");
            clearSelectionBtn.classList.remove("d-none");
        } else {
            submitSelectionBtn.classList.add("d-none");
            clearSelectionBtn.classList.add("d-none");
        }
    }

    submitSelectionBtn.addEventListener("click", async function () {
        if (selectedCells.length === 0) return;
        await sendGuess({ cells: selectedCells });
        clearSelection();
    });

    clearSelectionBtn.addEventListener("click", clearSelection);

    function clearSelection() {
        selectedCells = [];
        document.querySelectorAll(".cell-selected").forEach(function (td) {
            td.classList.remove("cell-selected");
        });
        updateSelectionButtons();
    }

    // Send guess to server
    async function sendGuess(payload) {
        const resp = await fetch("/api/game/" + gameState.id + "/guess", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify(payload),
        });
        const result = await resp.json();
        gameState.words = result.words;
        gameState.status = result.status;

        if (result.correct) {
            highlightFoundCells(result.cells);
            renderWordList();
            showFeedback("Found: " + result.word + "!", "text-success");
        } else {
            showFeedback("Not a match.", "text-danger");
        }

        if (result.status === "completed") {
            onGameComplete(result.completed_at);
        }
    }

    function highlightFoundCells(cells) {
        cells.forEach(function (c) {
            const td = gridTable.querySelector(
                'td[data-row="' + c.row + '"][data-col="' + c.col + '"]'
            );
            if (td) td.classList.add("cell-found");
        });
    }

    function showFeedback(msg, cls) {
        guessFeedback.textContent = msg;
        guessFeedback.className = "mt-2 " + cls;
        setTimeout(function () {
            guessFeedback.textContent = "";
            guessFeedback.className = "mt-2";
        }, 2000);
    }

    function onGameComplete(completedAt) {
        stopTimer();
        completionBanner.classList.remove("d-none");
        finalTime.textContent = timerEl.textContent;
        playAgainBtn.classList.remove("d-none");
        inputArea.classList.add("d-none");
    }

    playAgainBtn.addEventListener("click", function () {
        boardDiv.classList.add("d-none");
        setupDiv.classList.remove("d-none");
    });

    // Init
    loadCategories();
})();