document.addEventListener('DOMContentLoaded', function() {
    const chatForm = document.getElementById('chat-form');
    const messageInput = document.getElementById('message-input');
    const chatMessages = document.getElementById('chat-messages');
    const sendButton = document.getElementById('send-button');
    const loadingIndicator = document.getElementById('loading');
    const suggestionButtons = document.querySelectorAll('.suggestion-btn');
    const clearButton = document.getElementById('clear-chat');
    const exportButton = document.getElementById('export-chat');

    let conversationHistory = [];

    // Character counter for message input
    const maxChars = 1000;
    const charCounter = document.createElement('div');
    charCounter.className = 'char-counter';
    charCounter.textContent = `0/${maxChars}`;
    messageInput.parentNode.appendChild(charCounter);

    messageInput.addEventListener('input', function() {
        const currentLength = this.value.length;
        charCounter.textContent = `${currentLength}/${maxChars}`;
        charCounter.style.color = currentLength > maxChars * 0.9 ? '#e74c3c' : '#666';

        // Enable/disable send button based on input
        sendButton.disabled = currentLength === 0 || currentLength > maxChars;
    });

    // Handle suggestion button clicks
    suggestionButtons.forEach(button => {
        button.addEventListener('click', function() {
            const suggestion = this.textContent;
            messageInput.value = suggestion;
            messageInput.focus();
            messageInput.dispatchEvent(new Event('input'));
        });
    });

    // Handle form submission
    chatForm.addEventListener('submit', function(e) {
        e.preventDefault();
        const message = messageInput.value.trim();

        if (message && message.length <= maxChars) {
            sendMessage(message);
        }
    });

    // Clear chat functionality
    if (clearButton) {
        clearButton.addEventListener('click', function() {
            if (confirm('Are you sure you want to clear the chat history?')) {
                chatMessages.innerHTML = '';
                conversationHistory = [];
                addSystemMessage('Chat cleared. How can I help you with company policies?');
            }
        });
    }

    // Export chat functionality
    if (exportButton) {
        exportButton.addEventListener('click', function() {
            exportChatHistory();
        });
    }

    function sendMessage(message) {
        // Add user message to chat
        addMessage(message, 'user');

        // Clear input and show loading
        messageInput.value = '';
        charCounter.textContent = `0/${maxChars}`;
        sendButton.disabled = true;
        showLoading(true);

        // Send to backend
        fetch('/chat', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
            },
            body: JSON.stringify({
                message: message,
                conversation_history: conversationHistory
            })
        })
        .then(response => {
            if (!response.ok) {
                throw new Error(`HTTP error! status: ${response.status}`);
            }
            return response.json();
        })
        .then(data => {
            showLoading(false);

            if (data.response) {
                addMessage(data.response, 'assistant', data.sources);

                // Update conversation history
                conversationHistory.push({
                    user: message,
                    assistant: data.response
                });

                // Limit conversation history to last 10 exchanges
                if (conversationHistory.length > 10) {
                    conversationHistory = conversationHistory.slice(-10);
                }
            } else {
                addSystemMessage('Sorry, I encountered an error processing your request. Please try again.');
            }
        })
        .catch(error => {
            console.error('Error:', error);
            showLoading(false);
            addSystemMessage('Sorry, there was a connection error. Please check your internet connection and try again.');
        });
    }

    function addMessage(content, sender, sources = null) {
        const messageDiv = document.createElement('div');
        messageDiv.className = `message ${sender}-message`;

        const messageContent = document.createElement('div');
        messageContent.className = 'message-content';
        messageContent.textContent = content;

        const timestamp = document.createElement('div');
        timestamp.className = 'message-timestamp';
        timestamp.textContent = new Date().toLocaleTimeString();

        messageDiv.appendChild(messageContent);
        messageDiv.appendChild(timestamp);

        // Add sources if provided
        if (sources && sources.length > 0) {
            const sourcesDiv = document.createElement('div');
            sourcesDiv.className = 'message-sources';
            sourcesDiv.innerHTML = '<strong>Sources:</strong>';

            sources.forEach((source, index) => {
                const sourceSpan = document.createElement('span');
                sourceSpan.className = 'source-tag';
                sourceSpan.textContent = `${source.filename} (${Math.round(source.score * 100)}% relevant)`;
                sourceSpan.title = `Chunk: ${source.chunk_id}\nScore: ${source.score.toFixed(3)}`;
                sourcesDiv.appendChild(sourceSpan);
            });

            messageDiv.appendChild(sourcesDiv);
        }

        chatMessages.appendChild(messageDiv);
        chatMessages.scrollTop = chatMessages.scrollHeight;
    }

    function addSystemMessage(content) {
        const messageDiv = document.createElement('div');
        messageDiv.className = 'message system-message';

        const messageContent = document.createElement('div');
        messageContent.className = 'message-content';
        messageContent.textContent = content;

        messageDiv.appendChild(messageContent);
        chatMessages.appendChild(messageDiv);
        chatMessages.scrollTop = chatMessages.scrollHeight;
    }

    function showLoading(show) {
        if (loadingIndicator) {
            loadingIndicator.style.display = show ? 'block' : 'none';
        }
        sendButton.disabled = show;
    }

    function exportChatHistory() {
        if (conversationHistory.length === 0) {
            alert('No conversation history to export.');
            return;
        }

        let exportText = 'PolicyWise Chat Export\n';
        exportText += '======================\n';
        exportText += `Exported on: ${new Date().toLocaleString()}\n\n`;

        conversationHistory.forEach((exchange, index) => {
            exportText += `--- Exchange ${index + 1} ---\n`;
            exportText += `User: ${exchange.user}\n`;
            exportText += `Assistant: ${exchange.assistant}\n\n`;
        });

        const blob = new Blob([exportText], { type: 'text/plain' });
        const url = URL.createObjectURL(blob);
        const a = document.createElement('a');
        a.href = url;
        a.download = `policywise-chat-${new Date().toISOString().split('T')[0]}.txt`;
        document.body.appendChild(a);
        a.click();
        document.body.removeChild(a);
        URL.revokeObjectURL(url);
    }

    // Initialize with welcome message
    addSystemMessage('Hello! I\'m PolicyWise, your intelligent policy assistant. I can help you find information from our company policy documents. What would you like to know?');

    // Focus on input field
    messageInput.focus();

    // Handle keyboard shortcuts
    document.addEventListener('keydown', function(e) {
        // Ctrl/Cmd + Enter to send message
        if ((e.ctrlKey || e.metaKey) && e.key === 'Enter') {
            if (messageInput.value.trim()) {
                chatForm.dispatchEvent(new Event('submit'));
            }
        }

        // Escape to clear input
        if (e.key === 'Escape') {
            messageInput.value = '';
            messageInput.dispatchEvent(new Event('input'));
            messageInput.focus();
        }
    });
});