document.addEventListener("DOMContentLoaded", () => {
    // --- Get all necessary elements ---
    const chatForm = document.getElementById("chat-form");
    const messageInput = document.getElementById("message-input");
    const chatMessages = document.getElementById("chat-messages");
    const themeToggle = document.getElementById("theme-toggle");
    const sendButton = chatForm.querySelector("button[type='submit']");
    const leftColumn = document.getElementById("left-column");
    const uploadResumeButton = document.getElementById("upload-resume-button");
    const resumeFileInput = document.getElementById("resume-file-input");
    const refreshChatButton = document.getElementById("refresh-chat-button");
    const menuToggle = document.getElementById("menu-toggle");
    
    // --- Elements for mobile menu ---
    const closeMenuButton = document.getElementById("close-menu-button");
    const pageOverlay = document.getElementById("page-overlay");

    let conversationState = {};

    // --- Functions to open and close the mobile menu ---
    const openMenu = () => {
        leftColumn.classList.add('active');
        pageOverlay.classList.add('active');
        document.body.classList.add('menu-open'); // Prevents background scroll
    };

    const closeMenu = () => {
        leftColumn.classList.remove('active');
        pageOverlay.classList.remove('active');
        document.body.classList.remove('menu-open');
    };

    // --- Event Listeners for menu control ---
    menuToggle.addEventListener('click', openMenu);
    closeMenuButton.addEventListener('click', closeMenu);
    pageOverlay.addEventListener('click', closeMenu);

    const sendMessage = (messageText) => {
        messageInput.value = messageText;
        const submitEvent = new Event('submit', { bubbles: true, cancelable: true });
        chatForm.dispatchEvent(submitEvent);
    };

    const uploadResumeFile = async (file) => {
        if (!file) return;
        if (file.size > 5 * 1024 * 1024) { // 5MB limit
            addMessage("bot", "The selected file is too large. Please upload a file smaller than 5MB.");
            return;
        }

        addMessage("user", `Uploading Resume: <i>${file.name}</i>`);
        showTypingIndicator();

        const formData = new FormData();
        formData.append("resume_file", file);

        try {
            const response = await fetch("/upload_resume", {
                method: "POST",
                body: formData,
            });

            if (!response.ok) throw new Error(`HTTP error! status: ${response.status}`);
            const data = await response.json();

            removeTypingIndicator();

            if (data.response) {
                let finalResponse = data.response;
                finalResponse += "<div class='quick-reply-container'><div class='quick-reply-button clickable-card' data-action='quick_reply' data-value='Resume Analyser'>📄 Analyze Another Resume</div><div class='quick-reply-button clickable-card' data-action='quick_reply' data-value='End Chat'>🚪 End Chat</div></div>";
                addMessage("bot", finalResponse);
                
                conversationState.state = 'awaiting_initial_action';

            } else if (data.error) {
                addMessage("bot", `Error: ${data.error}`);
                conversationState.state = 'awaiting_initial_action';
            }
            updatePlaceholder();

        } catch (error) {
            removeTypingIndicator();
            console.error("Upload error:", error);
            addMessage("bot", "Sorry, I encountered an error while uploading your resume.");
            conversationState.state = 'awaiting_initial_action';
            updatePlaceholder();
        }
        resumeFileInput.value = '';
    };

    chatMessages.addEventListener('click', (event) => {
        const card = event.target.closest('.clickable-card');
        if (!card) return;
        const action = card.dataset.action;
        const value = card.dataset.value;
        if (action === 'details' || action === 'compare' || action === 'quick_reply') {
            sendMessage(value);
            const buttonContainer = card.closest('.quick-reply-container');
            if (buttonContainer) buttonContainer.remove();
        } else if (action === 'restart') {
            location.reload();
        }
    });

    leftColumn.addEventListener('click', (event) => {
        const featureCard = event.target.closest('[data-action="feature_select"]');
        if (!featureCard || conversationState.state === 'asking_questions') {
            if (conversationState.state === 'asking_questions') {
                const card = document.querySelector('.card');
                card.style.transition = 'outline 0.1s ease-out';
                card.style.outline = '2px solid #DB2777';
                setTimeout(() => { card.style.outline = 'none'; }, 500);
            }
            return;
        }
        const featureName = featureCard.dataset.value;
        sendMessage(featureName);
        closeMenu(); // Close menu after selection
    });

    const updatePlaceholder = () => {
        const currentState = conversationState.state;
        let shouldBeEnabled = true;
        let placeholderText = "Send a message...";

        if (currentState === 'session_ended') {
            placeholderText = "Click 'Start Over' to begin a new session.";
            shouldBeEnabled = false;
        } else if (currentState === 'awaiting_initial_action') {
            placeholderText = "Type 'start' or select a feature...";
        } else if (currentState === 'awaiting_resume_upload') {
            placeholderText = "Upload your resume using the upload button...";
            shouldBeEnabled = false;
        } else {
             placeholderText = "Send a message...";
        }

        messageInput.placeholder = placeholderText;
        messageInput.disabled = !shouldBeEnabled;
        sendButton.disabled = !shouldBeEnabled;
        uploadResumeButton.style.display = (currentState === 'awaiting_resume_upload') ? 'block' : 'none';

        if (shouldBeEnabled) {
            messageInput.focus();
        }
    };

    const addMessage = (sender, message) => {
        const messageElement = document.createElement("div");
        messageElement.classList.add("message", `${sender}-message`);
        if (sender === "bot") {
            const avatarImg = document.createElement("img");
            avatarImg.src = "/static/bot_avatar.png";
            avatarImg.alt = "Bot Avatar";
            avatarImg.className = "bot-avatar";
            messageElement.appendChild(avatarImg);
        }
        const paragraph = document.createElement("p");
        paragraph.innerHTML = message;
        messageElement.appendChild(paragraph);
        chatMessages.appendChild(messageElement);
        // Removed automatic scrolling for bot messages
    };

    const showTypingIndicator = () => {
        messageInput.disabled = true;
        sendButton.disabled = true;
        if (document.getElementById("typing-indicator")) return;
        const indicatorElement = document.createElement("div");
        indicatorElement.id = "typing-indicator";
        indicatorElement.classList.add("message", "bot-message");
        indicatorElement.innerHTML = `<img src="/static/bot_avatar.png" alt="Bot Avatar" class="bot-avatar"><div class="typing-indicator"><span></span><span></span><span></span></div>`;
        chatMessages.appendChild(indicatorElement);
        chatMessages.scrollTop = chatMessages.scrollHeight; // Scroll only for typing indicator
    };

    const removeTypingIndicator = () => {
        const indicator = document.getElementById("typing-indicator");
        if (indicator) indicator.remove();
    };
    
    const handleFormSubmit = async (event) => {
        event.preventDefault();
        const message = messageInput.value.trim();
        if (!message) return;

        addMessage("user", message);
        chatMessages.scrollTop = chatMessages.scrollHeight;
        
        messageInput.value = "";
        showTypingIndicator();

        try {
            const response = await fetch("/chat", {
                method: "POST",
                headers: { "Content-Type": "application/json" },
                body: JSON.stringify({ message: message, conversation: conversationState }),
            });

            if (!response.ok) throw new Error(`HTTP error! status: ${response.status}`);
            const data = await response.json();

            setTimeout(() => {
                removeTypingIndicator();
                conversationState = data.conversation;
                if (data.response) {
                    addMessage("bot", data.response);
                }
                updatePlaceholder();
            }, 500);

        } catch (error) {
            removeTypingIndicator();
            console.error("Fetch error:", error);
            addMessage("bot", "Sorry, I'm having trouble connecting.");
            updatePlaceholder();
        }
    };

    const initializeChat = async () => {
        try {
            const response = await fetch("/chat", {
                method: "POST",
                headers: { "Content-Type": "application/json" },
                body: JSON.stringify({ message: "", conversation: {} }),
            });
            const data = await response.json();
            conversationState = data.conversation;
            addMessage("bot", data.response);
            updatePlaceholder();
        } catch (error) {
            console.error("Initialization error:", error);
            addMessage("bot", "Sorry, I'm having trouble connecting.");
        }
    };

    const handleThemeChange = () => {
        document.body.className = themeToggle.checked ? 'dark' : 'light';
    };

    refreshChatButton.addEventListener('click', (event) => {
        event.preventDefault();
        location.reload();
    });

    chatForm.addEventListener("submit", handleFormSubmit);
    themeToggle.addEventListener("change", handleThemeChange);
    uploadResumeButton.addEventListener('click', () => resumeFileInput.click());
    resumeFileInput.addEventListener('change', (event) => uploadResumeFile(event.target.files[0]));

    document.body.className = 'light';
    initializeChat();
});