document.addEventListener("DOMContentLoaded", () => {
    // DOM Elements - Navigation
    const btnSimulator = document.getElementById("btn-simulator");
    const btnDeveloper = document.getElementById("btn-developer");
    const btnHistory = document.getElementById("btn-history");

    const sectionSimulator = document.getElementById("section-simulator-view");
    const sectionDeveloper = document.getElementById("section-developer-view");
    const sectionHistory = document.getElementById("section-history-view");

    const pageTitle = document.getElementById("page-title");
    const pageDesc = document.getElementById("page-desc");

    // DOM Elements - Chat Simulator
    const chatInput = document.getElementById("chat-input");
    const btnSendMessage = document.getElementById("btn-send-message");
    const chatMessagesContainer = document.getElementById("chat-messages-container");

    // DOM Elements - Inspector Panel (Phase 1)
    const previewEmptyState = document.getElementById("preview-empty-state");
    const previewLoadingState = document.getElementById("preview-loading-state");
    const previewImage = document.getElementById("preview-image");
    const previewMetadataPanel = document.getElementById("preview-metadata-panel");
    const loadingStepText = document.getElementById("loading-step-text");
    const loadingFunnyQuote = document.getElementById("loading-funny-quote");

    const metaQuery = document.getElementById("meta-query");
    const metaGreeting = document.getElementById("meta-greeting");
    const metaPrompt = document.getElementById("meta-prompt");
    const btnDownload = document.getElementById("btn-download");
    const btnShowApiDetails = document.getElementById("btn-show-api-details");

    // DOM Elements - Settings Modal
    const settingsModal = document.getElementById("settings-modal");
    const btnOpenSettings = document.getElementById("btn-open-settings");
    const btnCloseSettings = document.getElementById("btn-close-settings");
    const btnSaveSettings = document.getElementById("btn-save-settings");
    const btnResetSettings = document.getElementById("btn-reset-settings");

    const inputApiKey = document.getElementById("input-api-key");
    const inputCustomGreeting = document.getElementById("input-custom-greeting");
    const selectHeaderPreset = document.getElementById("select-header-preset");

    // DOM Elements - Developer Hub
    const urlLatest = document.getElementById("url-latest");
    const urlGenerate = document.getElementById("url-generate");
    const btnCopies = document.querySelectorAll(".btn-copy");
    const tabBtns = document.querySelectorAll(".tab-btn");
    const tabContents = document.querySelectorAll(".tab-content");

    // DOM Elements - History
    const historyGridContainer = document.getElementById("history-grid-container");
    const historyCountText = document.getElementById("history-count-text");

    // Configuration / Local State
    let config = {
        apiKey: localStorage.getItem("GOOGLE_API_KEY") || "",
        customGreeting: localStorage.getItem("CUSTOM_GREETING") || "",
        headerPreset: localStorage.getItem("HEADER_PRESET") || "random"
    };

    // Initialize Settings Inputs
    inputApiKey.value = config.apiKey;
    inputCustomGreeting.value = config.customGreeting;
    selectHeaderPreset.value = config.headerPreset;

    // Set Dynamic host URLs based on window.location
    const host = window.location.origin;
    urlLatest.value = `${host}/api/latest`;
    urlGenerate.value = `${host}/api/generate`;

    // Funny quotes to rotate during loading
    const loadingQuotes = [
        "「正在池塘裡培育第一朵金蓮花...」",
        "「正在將太陽緩緩拉出地平線...」",
        "「正在調配紅、橙、黃、綠、藍、靛、紫飽和度...」",
        "「正在使用 90 年代頂級繪圖軟體套用漸層濾鏡...」",
        "「正在祈求大慈大悲觀世音菩薩加持...」",
        "「正在用微軟正黑體與標楷體在畫布邊緣雕琢...」",
        "「正在呼叫隊友串接的通訊軟體 API Webhook...」",
        "「健康就是福，請稍候，認同請分享...」"
    ];

    let loadingInterval = null;

    // Navigation Click Handlers
    btnSimulator.addEventListener("click", () => {
        switchTab(btnSimulator, sectionSimulator, "聊天指令模擬器", "在這裡模擬通訊軟體的對話，即時檢視生成的「早安圖」效果。");
    });

    btnDeveloper.addEventListener("click", () => {
        switchTab(btnDeveloper, sectionDeveloper, "FastAPI 串接中心", "隊友 (成員 A) 可以直接呼叫以下 FastAPI 端點，將同一張早安圖回傳至通訊軟體群組。");
    });

    btnHistory.addEventListener("click", () => {
        switchTab(btnHistory, sectionHistory, "歷史生成紀錄", "瀏覽過去所有生成且包含文字浮水印的早安長輩圖。");
        fetchHistory();
    });

    function switchTab(activeBtn, activeSection, title, description) {
        // Toggle Nav Buttons
        [btnSimulator, btnDeveloper, btnHistory].forEach(btn => btn.classList.remove("active"));
        activeBtn.classList.add("active");

        // Toggle Sections
        [sectionSimulator, sectionDeveloper, sectionHistory].forEach(sec => sec.classList.add("hidden"));
        activeSection.classList.remove("hidden");

        // Update Title & Desc
        pageTitle.textContent = title;
        pageDesc.textContent = description;
    }

    // Modal Operations
    btnOpenSettings.addEventListener("click", () => settingsModal.classList.remove("hidden"));
    btnCloseSettings.addEventListener("click", () => settingsModal.classList.add("hidden"));
    settingsModal.addEventListener("click", (e) => {
        if (e.target === settingsModal) settingsModal.classList.add("hidden");
    });

    btnSaveSettings.addEventListener("click", () => {
        config.apiKey = inputApiKey.value.trim();
        config.customGreeting = inputCustomGreeting.value.trim();
        config.headerPreset = selectHeaderPreset.value;

        localStorage.setItem("GOOGLE_API_KEY", config.apiKey);
        localStorage.setItem("CUSTOM_GREETING", config.customGreeting);
        localStorage.setItem("HEADER_PRESET", config.headerPreset);

        settingsModal.classList.add("hidden");
        showToast("🌸 設定已成功儲存！");
    });

    btnResetSettings.addEventListener("click", () => {
        inputApiKey.value = "";
        inputCustomGreeting.value = "";
        selectHeaderPreset.value = "random";
    });

    // Copy to clipboard helper
    btnCopies.forEach(btn => {
        btn.addEventListener("click", () => {
            const targetId = btn.getAttribute("data-target");
            const targetInput = document.getElementById(targetId);
            targetInput.select();
            document.execCommand("copy");
            
            btn.classList.add("copied");
            btn.innerHTML = `<i class="fa-solid fa-check"></i> 已複製`;
            
            setTimeout(() => {
                btn.classList.remove("copied");
                btn.innerHTML = `<i class="fa-regular fa-copy"></i> 複製`;
            }, 2000);
        });
    });

    // Developer Code Tabs
    tabBtns.forEach(btn => {
        btn.addEventListener("click", () => {
            tabBtns.forEach(b => b.classList.remove("active"));
            btn.classList.add("active");
            
            const tabId = btn.getAttribute("data-tab");
            tabContents.forEach(c => {
                if (c.id === tabId) {
                    c.classList.remove("hidden");
                } else {
                    c.classList.add("hidden");
                }
            });
        });
    });

    // Send Message / Simulate command
    btnSendMessage.addEventListener("click", sendSimulatedMessage);
    chatInput.addEventListener("keydown", (e) => {
        if (e.key === "Enter") sendSimulatedMessage();
    });

    btnShowApiDetails.addEventListener("click", () => {
        btnDeveloper.click();
    });

    function getFormattedTime() {
        const now = new Date();
        return now.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' });
    }

    function addMessageToChat(avatar, text, isUser = false, imageUrl = null) {
        const msgDiv = document.createElement("div");
        msgDiv.className = `message ${isUser ? 'user-message' : 'bot-message'}`;
        
        let content = `<p>${text}</p>`;
        if (imageUrl) {
            content += `<img src="${imageUrl}" class="chat-result-img" alt="Good Morning Image">`;
        }
        
        msgDiv.innerHTML = `
            <div class="avatar">${avatar}</div>
            <div class="msg-bubble">
                ${content}
                <span class="time">${getFormattedTime()}</span>
            </div>
        `;
        
        chatMessagesContainer.appendChild(msgDiv);
        chatMessagesContainer.scrollTop = chatMessagesContainer.scrollHeight;
    }

    function startLoadingAnimation() {
        previewEmptyState.classList.add("hidden");
        previewImage.classList.add("hidden");
        previewMetadataPanel.classList.add("hidden");
        previewLoadingState.classList.remove("hidden");

        let quoteIndex = 0;
        loadingStepText.textContent = "正在聯絡擴散模型伺服器...";
        loadingFunnyQuote.textContent = loadingQuotes[quoteIndex];

        loadingInterval = setInterval(() => {
            quoteIndex = (quoteIndex + 1) % loadingQuotes.length;
            loadingFunnyQuote.textContent = loadingQuotes[quoteIndex];
            
            if (quoteIndex === 2) {
                loadingStepText.textContent = "正在將提示詞轉譯為大自然蓮花之氣...";
            } else if (quoteIndex === 4) {
                loadingStepText.textContent = "Stable Diffusion 3.5 努力生圖中...";
            } else if (quoteIndex === 6) {
                loadingStepText.textContent = "Pillow 正在雕琢霓虹漸層大字...";
            }
        }, 3000);
    }

    function stopLoadingAnimation() {
        if (loadingInterval) {
            clearInterval(loadingInterval);
            loadingInterval = null;
        }
        previewLoadingState.classList.add("hidden");
    }

    function sendSimulatedMessage() {
        let text = chatInput.value.trim();
        if (!text) return;

        // Auto format command prefix if not typed
        if (!text.startsWith("@create image")) {
            text = `@create image ${text}`;
        }

        // Add user message to chat
        addMessageToChat("👤", text, true);
        chatInput.value = "";

        // Add a placeholder bot typing message
        const botTypingDiv = document.createElement("div");
        botTypingDiv.className = "message bot-message";
        botTypingDiv.id = "bot-typing-placeholder";
        botTypingDiv.innerHTML = `
            <div class="avatar">🤖</div>
            <div class="msg-bubble">
                <p><i class="fa-solid fa-spinner fa-spin"></i> 正在吸收指令能量，著手繪製早安圖...</p>
                <span class="time">${getFormattedTime()}</span>
            </div>
        `;
        chatMessagesContainer.appendChild(botTypingDiv);
        chatMessagesContainer.scrollTop = chatMessagesContainer.scrollHeight;

        // Start Inspector Loader
        startLoadingAnimation();

        // Prepare request payload
        const payload = {
            message: text,
            api_key: config.apiKey || null,
            custom_greeting: config.customGreeting || null
        };

        // Call FastAPI generate endpoint
        fetch("/api/generate", {
            method: "POST",
            headers: {
                "Content-Type": "application/json"
            },
            body: JSON.stringify(payload)
        })
        .then(response => {
            if (!response.ok) {
                throw new Error("HTTP error " + response.status);
            }
            return response.json();
        })
        .then(data => {
            // Remove typing placeholder
            const placeholder = document.getElementById("bot-typing-placeholder");
            if (placeholder) placeholder.remove();

            stopLoadingAnimation();

            if (data.success) {
                // Display result in chat simulator
                addMessageToChat("🤖", `早安圖製作完成！祝您健康快樂，認同請分享！`, false, data.image_base64);

                // Update Inspector Panel (Phase 1 Preview)
                previewImage.src = data.image_base64;
                previewImage.classList.remove("hidden");

                metaQuery.textContent = data.query;
                metaGreeting.textContent = data.greeting_text;
                metaPrompt.textContent = data.expanded_prompt;
                
                // Set download link
                btnDownload.href = data.image_base64;
                btnDownload.download = `morning_card_${data.id}.jpg`;

                previewMetadataPanel.classList.remove("hidden");
                showToast("🌸 早安圖生成成功！");
            } else {
                throw new Error(data.error || "未知錯誤");
            }
        })
        .catch(err => {
            // Remove typing placeholder
            const placeholder = document.getElementById("bot-typing-placeholder");
            if (placeholder) placeholder.remove();

            stopLoadingAnimation();
            previewEmptyState.classList.remove("hidden");

            addMessageToChat("🤖", `❌ 生成失敗：${err.message}。請確認您的網路連線或 API Key 設定。`, false);
            showToast("❌ 生成失敗，請檢查設定", "error");
        });
    }

    // Fetch History List
    function fetchHistory() {
        historyGridContainer.innerHTML = `
            <div class="empty-state">
                <i class="fa-solid fa-circle-notch fa-spin"></i>
                <p>載入生成紀錄中...</p>
            </div>
        `;

        fetch("/api/history")
        .then(res => res.json())
        .then(data => {
            historyGridContainer.innerHTML = "";
            historyCountText.textContent = `共 ${data.length} 張早安圖`;

            if (data.length === 0) {
                historyGridContainer.innerHTML = `
                    <div class="empty-state">
                        <i class="fa-regular fa-folder-open"></i>
                        <p>尚無歷史生成紀錄</p>
                    </div>
                `;
                return;
            }

            data.forEach(item => {
                const date = new Date(item.created_at).toLocaleString();
                const card = document.createElement("div");
                card.className = "history-item";
                card.innerHTML = `
                    <div class="history-img-wrapper">
                        <img src="/api/image/${item.id}" alt="長輩圖" loading="lazy">
                    </div>
                    <div class="history-info">
                        <div class="history-title">主題: ${item.query}</div>
                        <div class="history-text">${item.greeting_text}</div>
                        <div class="history-footer">
                            <span>ID: ${item.id.slice(0, 8)}...</span>
                            <span>${date}</span>
                        </div>
                    </div>
                `;
                
                card.addEventListener("click", () => {
                    // Switch to simulator view to inspect this historical image
                    switchTab(btnSimulator, sectionSimulator, "聊天指令模擬器", "檢視歷史長輩圖的詳細提示詞與大字配置。");
                    
                    // Show in preview canvas
                    previewEmptyState.classList.add("hidden");
                    previewImage.src = `/api/image/${item.id}`;
                    previewImage.classList.remove("hidden");

                    metaQuery.textContent = item.query;
                    metaGreeting.textContent = item.greeting_text;
                    metaPrompt.textContent = item.expanded_prompt;

                    btnDownload.href = `/api/image/${item.id}`;
                    btnDownload.download = `morning_card_${item.id}.jpg`;
                    previewMetadataPanel.classList.remove("hidden");
                });

                historyGridContainer.appendChild(card);
            });
        })
        .catch(err => {
            historyGridContainer.innerHTML = `
                <div class="empty-state">
                    <i class="fa-solid fa-triangle-exclamation"></i>
                    <p>載入失敗: ${err.message}</p>
                </div>
            `;
        });
    }

    // Helper: Toast message
    function showToast(message, type = "success") {
        const toast = document.createElement("div");
        toast.className = `toast-notification ${type}`;
        toast.style.position = "fixed";
        toast.style.bottom = "20px";
        toast.style.right = "20px";
        toast.style.background = type === "success" ? "rgba(16, 185, 129, 0.95)" : "rgba(239, 68, 68, 0.95)";
        toast.style.color = "white";
        toast.style.padding = "12px 24px";
        toast.style.borderRadius = "8px";
        toast.style.zIndex = "1000";
        toast.style.boxShadow = "0 4px 15px rgba(0, 0, 0, 0.2)";
        toast.style.fontFamily = "inherit";
        toast.style.fontSize = "14px";
        toast.style.fontWeight = "600";
        toast.style.backdropFilter = "blur(8px)";
        toast.style.transition = "all 0.3s ease";
        toast.style.transform = "translateY(50px)";
        toast.style.opacity = "0";
        toast.textContent = message;

        document.body.appendChild(toast);
        
        // Trigger reflow
        toast.offsetHeight;
        
        toast.style.transform = "translateY(0)";
        toast.style.opacity = "1";

        setTimeout(() => {
            toast.style.transform = "translateY(50px)";
            toast.style.opacity = "0";
            setTimeout(() => toast.remove(), 300);
        }, 3000);
    }
});