const chatMessages = document.getElementById('chatMessages');
const messageInput = document.getElementById('messageInput');
const sendBtn = document.getElementById('sendBtn');
const uploadBtn = document.getElementById('uploadBtn');
const fileInput = document.getElementById('fileInput');
const documentList = document.getElementById('documentList');
const ragToggle = document.getElementById('ragToggle');

let sessionId = generateSessionId();

function generateSessionId() {
    return 'session_' + Date.now() + '_' + Math.random().toString(36).substr(2, 9);
}

function addMessage(content, isUser = false) {
    const messageDiv = document.createElement('div');
    messageDiv.className = `message ${isUser ? 'user' : 'assistant'}`;
    messageDiv.textContent = content;
    chatMessages.appendChild(messageDiv);
    chatMessages.scrollTop = chatMessages.scrollHeight;
    return messageDiv;
}

function addLoadingMessage() {
    const messageDiv = document.createElement('div');
    messageDiv.className = 'message loading';
    messageDiv.textContent = 'Thinking...';
    chatMessages.appendChild(messageDiv);
    chatMessages.scrollTop = chatMessages.scrollHeight;
    return messageDiv;
}

async function sendMessage() {
    const message = messageInput.value.trim();
    if (!message) return;

    addMessage(message, true);
    messageInput.value = '';
    sendBtn.disabled = true;

    const loadingMsg = addLoadingMessage();

    try {
        const response = await fetch('/chat/stream', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
            },
            body: JSON.stringify({
                message: message,
                session_id: sessionId,
                use_rag: ragToggle.checked
            })
        });

        const reader = response.body.getReader();
        const decoder = new TextDecoder();
        
        loadingMsg.remove();
        const assistantMsg = addMessage('', false);
        let fullResponse = '';

        while (true) {
            const { done, value } = await reader.read();
            if (done) break;

            const chunk = decoder.decode(value);
            const lines = chunk.split('\n');

            for (const line of lines) {
                if (line.startsWith('data: ')) {
                    const data = JSON.parse(line.slice(6));
                    
                    if (data.chunk) {
                        fullResponse += data.chunk;
                        assistantMsg.textContent = fullResponse;
                        chatMessages.scrollTop = chatMessages.scrollHeight;
                    }
                    
                    if (data.error) {
                        assistantMsg.textContent = 'Error: ' + data.error;
                        assistantMsg.style.color = '#dc3545';
                    }
                }
            }
        }

    } catch (error) {
        loadingMsg.remove();
        addMessage('Error: ' + error.message, false);
    } finally {
        sendBtn.disabled = false;
        messageInput.focus();
    }
}

messageInput.addEventListener('keypress', (e) => {
    if (e.key === 'Enter') {
        sendMessage();
    }
});

sendBtn.addEventListener('click', sendMessage);

uploadBtn.addEventListener('click', () => {
    fileInput.click();
});

fileInput.addEventListener('change', async (e) => {
    const file = e.target.files[0];
    if (!file) return;

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

    uploadBtn.disabled = true;
    uploadBtn.textContent = 'Uploading...';

    try {
        const response = await fetch('/documents/upload', {
            method: 'POST',
            body: formData
        });

        if (response.ok) {
            const data = await response.json();
            addMessage(`Document "${data.filename}" uploaded successfully! (${data.chunk_count} chunks)`, false);
            loadDocuments();
        } else {
            const error = await response.json();
            addMessage('Upload failed: ' + error.detail, false);
        }
    } catch (error) {
        addMessage('Upload error: ' + error.message, false);
    } finally {
        uploadBtn.disabled = false;
        uploadBtn.textContent = 'Upload Document';
        fileInput.value = '';
    }
});

async function loadDocuments() {
    try {
        const response = await fetch('/documents/');
        const documents = await response.json();

        documentList.innerHTML = '';

        documents.forEach(doc => {
            const docDiv = document.createElement('div');
            docDiv.className = 'document-item';
            
            const nameSpan = document.createElement('span');
            nameSpan.className = 'document-name';
            nameSpan.textContent = doc.filename;
            
            const deleteBtn = document.createElement('button');
            deleteBtn.className = 'btn-delete';
            deleteBtn.textContent = 'Delete';
            deleteBtn.onclick = () => deleteDocument(doc.id);
            
            docDiv.appendChild(nameSpan);
            docDiv.appendChild(deleteBtn);
            documentList.appendChild(docDiv);
        });
    } catch (error) {
        console.error('Failed to load documents:', error);
    }
}

async function deleteDocument(docId) {
    if (!confirm('Are you sure you want to delete this document?')) return;

    try {
        const response = await fetch(`/documents/${docId}`, {
            method: 'DELETE'
        });

        if (response.ok) {
            loadDocuments();
            addMessage('Document deleted successfully', false);
        }
    } catch (error) {
        addMessage('Delete failed: ' + error.message, false);
    }
}

loadDocuments();