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<!-- static/index.html -->
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
    <title>AI Chat with Gemini</title>
    <style>
        :root {
            --background-color: #212121;
            --input-area-color: #212121;
            --user-bubble-color: #303030;
            --ai-bubble-color: #2a2a2a;
            --text-color: #e0e0e0;
            --placeholder-color: #888888;
            --icon-color: #b0b0b0;
            --send-button-color: #4CAF50;
            --border-color: #333333;
            --code-bg-color: #1e1e1e;
            --code-text-color: #f8f8f2;
            --link-color: #64b5f6;
            --quote-color: #4CAF50;
        }

        /* Reset and Base Styles */
        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }

        html, body {
            height: 100%;
            overflow: hidden; /* Prevent scrolling on main body */
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
            background-color: var(--background-color);
            color: var(--text-color);
            display: flex;
            flex-direction: column;
            height: 100%;
            line-height: 1.6;
        }

        .chat-container {
            display: flex;
            flex-direction: column;
            height: 100%;
            width: 100%;
            max-width: 800px; /* Max width for larger screens */
            margin: 0 auto; /* Center the container */
            border-left: 1px solid var(--border-color); /* Optional: add subtle borders */
            border-right: 1px solid var(--border-color);
        }

        .chat-area {
            flex-grow: 1; /* Takes remaining vertical space */
            overflow-y: auto; /* Enable scrolling for chat messages */
            padding: 20px 16px;
            display: flex;
            flex-direction: column;
        }

        /* Welcome Screen */
        .welcome-screen {
            text-align: center;
            margin: auto; /* Center content vertically and horizontally */
            color: var(--placeholder-color);
            padding: 20px;
        }

        .welcome-screen h2 {
            font-size: 1.8rem;
            font-weight: 400;
            margin-bottom: 10px;
        }
        
        .welcome-screen p {
            font-size: 1rem;
            line-height: 1.5;
        }

        .welcome-screen.hidden {
            display: none; /* Hide when chat starts */
        }

        /* Message Bubbles */
        .message {
            max-width: 85%; /* Limit bubble width */
            padding: 12px 16px;
            border-radius: 18px;
            margin-bottom: 12px;
            word-wrap: break-word; /* Ensure long words wrap */
            line-height: 1.6;
            font-size: 1rem;
            position: relative; /* For audio button positioning */
            animation: fadeIn 0.3s ease-out; /* Fade in animation for new messages */
        }

        .user-message {
            background-color: var(--user-bubble-color);
            align-self: flex-end; /* Align user messages to the right */
            border-bottom-right-radius: 4px; /* Slight variation for visual appeal */
        }

        .ai-message {
            background-color: var(--ai-bubble-color);
            align-self: flex-start; /* Align AI messages to the left */
            border-bottom-left-radius: 4px; /* Slight variation for visual appeal */
            padding-bottom: 30px; /* Space for audio button at the bottom */
        }

        /* AI Message Content Styling (for markdown-converted HTML) */
        .ai-message-content {
            overflow: hidden; /* Contains floats/margins */
        }
        .ai-message-content p { margin-bottom: 12px; }
        .ai-message-content p:last-child { margin-bottom: 0; } /* No bottom margin on last paragraph */
        .ai-message-content strong { color: #ffffff; font-weight: 600; }
        .ai-message-content em { color: #d1d1d1; font-style: italic; }
        .ai-message-content a { color: var(--link-color); text-decoration: none; word-break: break-all; }
        .ai-message-content a:hover { text-decoration: underline; }
        .ai-message-content ul, .ai-message-content ol { padding-left: 24px; margin-bottom: 12px; }
        .ai-message-content li { margin-bottom: 6px; }
        .ai-message-content blockquote {
            border-left: 3px solid var(--quote-color);
            padding-left: 12px;
            margin-left: 0;
            color: #bdbdbd;
            margin-bottom: 12px;
        }
        /* Code Blocks */
        .ai-message-content pre {
            background-color: var(--code-bg-color);
            border-radius: 6px;
            padding: 12px;
            overflow-x: auto; /* Enable horizontal scrolling for long code lines */
            margin-bottom: 12px;
        }
        .ai-message-content code {
            font-family: 'Courier New', Courier, monospace;
            background-color: var(--code-bg-color);
            padding: 2px 4px;
            border-radius: 3px;
            color: var(--code-text-color);
            font-size: 0.9em;
            white-space: pre-wrap; /* Preserve whitespace and wrap long lines */
        }
        /* Inline code styling specific for the `code-block` class which is on `pre` */
        .ai-message-content .code-block code {
            padding: 0; /* Code inside pre shouldn't have extra padding */
            background-color: transparent; /* No background for code inside pre */
            color: inherit; /* Inherit color from pre */
        }

        /* Audio Button Styling */
        .audio-button {
            position: absolute;
            bottom: 6px;
            right: 8px;
            background: rgba(255, 255, 255, 0.1); /* Semi-transparent background */
            border: none;
            border-radius: 50%;
            width: 30px;
            height: 30px;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            transition: background-color 0.2s;
            z-index: 10; /* Ensure it's above message content */
        }
        .audio-button:hover {
            background: rgba(255, 255, 255, 0.2);
        }
        .audio-button svg {
            width: 18px;
            height: 18px;
            fill: var(--icon-color);
            transition: fill 0.2s;
        }
        .audio-button:hover svg {
            fill: white; /* Icon brighter on hover */
        }
        /* Loading spinner for audio button */
        .audio-button.loading .speaker-icon {
            display: none; /* Hide speaker icon when loading */
        }
        .audio-button .loader {
            display: none; /* Hidden by default */
            width: 18px;
            height: 18px;
            border: 2px solid #f3f3f3; /* Light grey border */
            border-top: 2px solid var(--send-button-color); /* Green top border for spinner */
            border-radius: 50%;
            animation: spin 1s linear infinite; /* Spin animation */
        }
        .audio-button.loading .loader {
            display: block; /* Show spinner when loading */
        }
        @keyframes spin {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
        }

        /* Typing Indicator */
        .typing-indicator {
            display: flex;
            align-items: center;
            padding: 12px 16px;
        }
        .typing-indicator span {
            height: 8px; width: 8px; background-color: var(--icon-color); border-radius: 50%; display: inline-block; margin: 0 2px;
            animation: bounce 1.4s infinite both;
        }
        .typing-indicator span:nth-child(2) { animation-delay: 0.2s; }
        .typing-indicator span:nth-child(3) { animation-delay: 0.4s; }

        @keyframes bounce {
            0%, 80%, 100% { transform: scale(0); }
            40% { transform: scale(1.0); }
        }

        /* Input Area */
        .input-area {
            display: flex;
            align-items: flex-end; /* Align items to the bottom (textarea can grow) */
            padding: 10px 16px;
            border-top: 1px solid var(--border-color);
            background-color: var(--input-area-color);
            flex-shrink: 0; /* Prevent shrinking */
        }
        .input-wrapper {
            display: flex;
            align-items: center;
            width: 100%;
            background-color: var(--user-bubble-color);
            border-radius: 24px; /* Pill-shaped input */
            padding: 4px;
        }
        .input-area textarea {
            flex-grow: 1; /* Takes up available space */
            border: none;
            background: transparent;
            color: var(--text-color);
            resize: none; /* Disable manual resize */
            font-size: 1rem;
            line-height: 1.5;
            max-height: 120px; /* Max height for textarea */
            overflow-y: auto; /* Scroll if content exceeds max height */
            padding: 8px 12px;
            font-family: inherit; /* Inherit font from body */
            outline: none; /* Remove focus outline */
        }
        .input-area textarea::placeholder { color: var(--placeholder-color); }

        /* Icon Buttons (Attach, Send) */
        .input-area .icon-button {
            background: none;
            border: none;
            padding: 8px;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            transition: opacity 0.2s;
        }
        .input-area .icon-button:hover {
            opacity: 0.8;
        }
        .input-area .icon-button svg { width: 24px; height: 24px; fill: var(--icon-color); }
        
        .send-button {
            background-color: var(--send-button-color);
            border-radius: 50%;
            padding: 8px;
            transition: background-color 0.2s, opacity 0.2s;
        }
        .send-button.disabled {
            background-color: #555;
            cursor: not-allowed;
            opacity: 0.6;
        }
        .send-button.disabled svg {
            fill: #888;
        }
        .send-button svg { fill: white; width: 24px; height: 24px; }

        /* Animation for new messages */
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(10px); }
            to { opacity: 1; transform: translateY(0); }
        }
    </style>
</head>
<body>
    <div class="chat-container">
        <main class="chat-area">
            <div class="welcome-screen">
                <h2>Welcome to AstroChat!</h2>
                <p>Hello! I'm your AI assistant powered by Gemini. Ask me anything - I can explain concepts, generate ideas, or help with coding!</p>
                <p>Try asking me something like: <em>"Explain quantum computing in simple terms"</em> or <em>"Help me debug this Python code"</em></p>
            </div>
        </main>

        <footer class="input-area">
            <form id="chat-form" class="input-wrapper">
                <button type="button" class="icon-button" id="attach-button">
                    <svg viewBox="0 0 24 24"><path d="M16.5 6v11.5c0 2.21-1.79 4-4 4s-4-1.79-4-4V5a2.5 2.5 0 0 1 5 0v10.5c0 .83-.67 1.5-1.5 1.5s-1.5-.67-1.5-1.5V6H10v9.5a2.5 2.5 0 0 0 5 0V5c-1.38 0-2.5 1.12-2.5 2.5v10.5c0 1.38-1.12 2.5-2.5 2.5s-2.5-1.12-2.5-2.5V5a4 4 0 0 1 8 0v11.5c-1.1 0-2-.9-2-2V6h-1.5z"></path></svg>
                </button>
                <textarea id="message-input" placeholder="Ask anything..." rows="1"></textarea>
                <button type="submit" id="send-button" class="icon-button send-button disabled">
                    <svg viewBox="0 0 24 24"><path d="M2 21l21-9L2 3v7l15 2-15 2v7z"></path></svg>
                </button>
            </form>
        </footer>
    </div>

    <script>
        document.addEventListener('DOMContentLoaded', () => {
            const chatForm = document.getElementById('chat-form');
            const messageInput = document.getElementById('message-input');
            const chatArea = document.querySelector('.chat-area');
            const welcomeScreen = document.querySelector('.welcome-screen');
            const sendButton = document.getElementById('send-button');
            const attachButton = document.getElementById('attach-button');

            // Global variable to hold the currently playing audio object
            let currentAudio = null;

            // Adjusts the height of the textarea based on content
            const adjustTextareaHeight = () => {
                messageInput.style.height = 'auto'; // Reset height
                messageInput.style.height = `${messageInput.scrollHeight}px`; // Set to scroll height
                updateSendButtonState(); // Update send button state after height adjustment
            };

            // Updates the disabled state of the send button
            const updateSendButtonState = () => {
                const isDisabled = messageInput.value.trim() === '';
                sendButton.classList.toggle('disabled', isDisabled);
                sendButton.disabled = isDisabled;
            };
            
            // Scrolls the chat area to the bottom
            const scrollToBottom = () => {
                chatArea.scrollTop = chatArea.scrollHeight;
            };

            // Adds a message to the chat area
            // `plainText` is used specifically for audio generation, keeping original text without HTML
            const addMessage = (content, sender, isHTML = false, plainText = '') => {
                welcomeScreen.classList.add('hidden'); // Hide welcome screen once chat begins
                
                const messageElement = document.createElement('div');
                messageElement.classList.add('message', `${sender}-message`);
                
                const contentDiv = document.createElement('div');
                if (isHTML) {
                    contentDiv.classList.add(`${sender}-message-content`);
                    contentDiv.innerHTML = content; // Set innerHTML for HTML content
                } else {
                    contentDiv.textContent = content; // Set textContent for plain text
                }
                messageElement.appendChild(contentDiv);

                // Add audio button for AI messages
                if (sender === 'ai' && plainText) {
                    const audioButton = document.createElement('button');
                    audioButton.classList.add('audio-button');
                    // Store the plain text directly on the button for easy retrieval
                    audioButton.dataset.plainText = plainText; 
                    audioButton.innerHTML = `
                        <svg class="speaker-icon" viewBox="0 0 24 24">
                            <path d="M3 10v4c0 .55.45 1 1 1h3.5l5.5 5V5L7.5 9H4c-.55 0-1 .45-1 1zm14 0h-1.5c-2.31 0-4.22-1.74-4.47-4H10v12h1.5v-2.22c.25-2.26 2.16-4.22 4.47-4.22H17c1.1 0 2 .9 2 2s-.9 2-2 2h-1.5v2H17c2.21 0 4-1.79 4-4s-1.79-4-4-4z"/>
                        </svg>
                        <div class="loader"></div>
                    `;
                    audioButton.title = "Listen to response"; // Add tooltip
                    audioButton.addEventListener('click', () => playAudio(audioButton, plainText));
                    messageElement.appendChild(audioButton);
                }
                
                chatArea.appendChild(messageElement);
                scrollToBottom();
                return messageElement;
            };
            
            // Displays a typing indicator for the AI
            const showTypingIndicator = () => {
                const indicatorElement = document.createElement('div');
                indicatorElement.classList.add('message', 'ai-message', 'typing-indicator');
                indicatorElement.innerHTML = '<span></span><span></span><span></span>';
                chatArea.appendChild(indicatorElement);
                scrollToBottom();
                return indicatorElement; // Return element to remove it later
            };

            // Plays audio for a given text
            const playAudio = async (buttonElement, text) => {
                // Stop any currently playing audio
                if (currentAudio) {
                    currentAudio.pause();
                    currentAudio.currentTime = 0;
                    currentAudio = null;
                }

                buttonElement.classList.add('loading'); // Show loading spinner
                buttonElement.disabled = true; // Disable button during loading

                try {
                    const response = await fetch('/generate-audio', {
                        method: 'POST',
                        headers: { 'Content-Type': 'application/json' },
                        body: JSON.stringify({ text: text })
                    });
                    
                    const data = await response.json();
                    
                    if (data.error) {
                        throw new Error(data.error);
                    }
                    
                    currentAudio = new Audio(data.audio_url);
                    currentAudio.play();

                    // Remove loading state when audio ends
                    currentAudio.onended = () => {
                        buttonElement.classList.remove('loading');
                        buttonElement.disabled = false;
                        currentAudio = null;
                    };

                    // Handle audio playback errors
                    currentAudio.onerror = () => {
                        console.error("Error playing audio.");
                        alert("Could not play audio. Please try again.");
                        buttonElement.classList.remove('loading');
                        buttonElement.disabled = false;
                        currentAudio = null;
                    };
                    
                } catch (error) {
                    console.error("Error generating audio:", error);
                    alert("Failed to generate audio. " + (error.message || "Please try again."));
                    buttonElement.classList.remove('loading');
                    buttonElement.disabled = false;
                }
            };


            // Fetches AI response from the backend
            const getAIResponse = async (userMessage) => {
                const indicator = showTypingIndicator(); // Show typing indicator
                
                try {
                    const response = await fetch('/chat', {
                        method: 'POST',
                        headers: {
                            'Content-Type': 'application/json',
                        },
                        body: JSON.stringify({ message: userMessage })
                    });
                    
                    const data = await response.json();
                    
                    if (data.error) {
                        throw new Error(data.error);
                    }
                    
                    // Remove typing indicator before adding the actual message
                    chatArea.removeChild(indicator);
                    // Add AI message with both HTML and plain text
                    addMessage(data.response_html, 'ai', true, data.response_text);
                    
                } catch (error) {
                    chatArea.removeChild(indicator); // Remove indicator on error too
                    addMessage("Sorry, I encountered an error. Please try again.", 'ai');
                    console.error("Error:", error);
                }
            };

            // Event listener for form submission
            chatForm.addEventListener('submit', async (e) => {
                e.preventDefault(); // Prevent default form submission behavior (page reload)
                const message = messageInput.value.trim();
                
                if (message) {
                    addMessage(message, 'user'); // Add user message to chat
                    messageInput.value = ''; // Clear input field
                    adjustTextareaHeight(); // Reset textarea height
                    
                    await getAIResponse(message); // Get AI response
                }
            });

            // Event listener for Enter key (send message) and Shift+Enter (new line)
            messageInput.addEventListener('keydown', (e) => {
                if (e.key === 'Enter' && !e.shiftKey) {
                    e.preventDefault(); // Prevent new line
                    chatForm.dispatchEvent(new Event('submit')); // Trigger form submission
                }
            });

            // Event listener for input changes to adjust textarea height and send button state
            messageInput.addEventListener('input', adjustTextareaHeight);
            
            // Attach button (placeholder functionality)
            attachButton.addEventListener('click', () => {
                // In a real app, this would open a file dialog
                alert("Attachment feature not implemented yet!");
                messageInput.focus(); // Keep focus on message input
            });
            
            // Initial setup on page load
            updateSendButtonState(); // Set initial state of send button
            messageInput.focus(); // Focus on the input field

            // Optional: Initial welcome message from AI on first visit
            const isFirstVisit = !localStorage.getItem('chatVisited');
            if (isFirstVisit) {
                localStorage.setItem('chatVisited', 'true');
                // Use a timeout to allow page to load fully before first message appears
                setTimeout(() => {
                    // The welcome screen now has content, so we just let it display initially.
                    // If you want an AI message to appear *after* the welcome screen and replace it,
                    // you'd use addMessage here instead of directly rendering text in welcome-screen div.
                    // For now, the welcome screen itself has the initial greeting.
                }, 500);
            }
        });
    </script>
</body>
</html>