stock-management-demo/src-server/routes/chat.js

import { Router } from 'express';
import prisma from '../database.js';
import { requireAuth } from '../middlewares/authMiddleware.js'; // Import the middleware

import { askGeminiChat } from '../utils/gemini.js';

import { getUserById } from './auth.js';

const router = Router();

// Apply the authentication middleware to all chat routes
router.use(requireAuth);

// POST /api/chat/threads - Create a new chat thread (optionally with a first message)
router.post('/threads', async(req, res) =>
{
  const { content } = req.body; // Content is now optional

  // If content is provided, validate it
  if (content && (typeof content !== 'string' || content.trim().length === 0))
  {
    return res.status(400).json({ error: 'Message content cannot be empty if provided.' });
  }

  try
  {
    const createData = {};
    if (content)
    {
      // If content exists, create the thread with the first message
      createData.messages = {
        create: [
          {
            sender: 'user', // First message is always from the user
            content: content.trim(),
          },
        ],
      };
    }
    // If content is null/undefined, createData remains empty, creating just the thread

    const newThread = await prisma.chatThread.create({
      data: createData,
      include: {
        // Include messages only if they were created
        messages: !!content,
      },
    });

    if(content)
    {
      const user = await getUserById(req.session.loggedInUserId);
      if (!user)
      {
        req.session.destroy(err =>
        {});
        return res.status(401).json({ status: 'unauthenticated' });
      }
      await askGeminiChat(newThread.id, `[${user.fullName || user.username}] ${content}`);
    }

    // Respond with the new thread ID and messages (if any)
    res.status(201).json({
      threadId: newThread.id,
      // Ensure messages array is empty if no content was provided
      messages: newThread.messages ? newThread.messages.map(msg => ({ ...msg, createdAt: msg.createdAt.toISOString() })) : []
    });
  }
  catch (error)
  {
    console.error('Error creating chat thread:', error);
    res.status(500).json({ error: 'Failed to create chat thread.' });
  }
});

// GET /api/chat/threads/:threadId/messages - Get messages for a specific thread
router.get('/threads/:threadId/messages', async(req, res) =>
{
  const { threadId } = req.params;

  try
  {
    const messages = await prisma.chatMessage.findMany({
      where: {
        threadId: threadId,
      },
      orderBy: {
        createdAt: 'asc', // Get messages in chronological order
      },
    });

    if (!messages)
    { // Check if thread exists indirectly
      // If findMany returns empty, the thread might not exist or has no messages.
      // Check if thread exists explicitly
      const thread = await prisma.chatThread.findUnique({ where: { id: threadId } });
      if (!thread)
      {
        return res.status(404).json({ error: 'Chat thread not found.' });
      }
    }

    res.status(200).json(messages.map(msg => ({ ...msg, createdAt: msg.createdAt.toISOString() })));
  }
  catch (error)
  {
    console.error(`Error fetching messages for thread ${threadId}:`, error);
    // Basic error handling, check for specific Prisma errors if needed
    if (error.code === 'P2023' || error.message.includes('Malformed UUID'))
    { // Example: Invalid UUID format
      return res.status(400).json({ error: 'Invalid thread ID format.' });
    }
    res.status(500).json({ error: 'Failed to fetch messages.' });
  }
});

// POST /api/chat/threads/:threadId/messages - Add a message to an existing thread
router.post('/threads/:threadId/messages', async(req, res) =>
{
  const { threadId } = req.params;
  const { content, sender = 'user' } = req.body; // Default sender to 'user'

  if (!content || typeof content !== 'string' || content.trim().length === 0)
  {
    return res.status(400).json({ error: 'Message content cannot be empty.' });
  }
  if (sender !== 'user' && sender !== 'bot')
  {
    return res.status(400).json({ error: 'Invalid sender type.' });
  }

  try
  {
    // Verify thread exists first
    const thread = await prisma.chatThread.findUnique({
      where: { id: threadId },
    });

    if (!thread)
    {
      return res.status(404).json({ error: 'Chat thread not found.' });
    }

    const newMessage = await prisma.chatMessage.create({
      data: {
        threadId: threadId,
        sender: sender,
        content: content.trim(),
      },
    });

    // Optionally: Update the thread's updatedAt timestamp
    await prisma.chatThread.update({
      where: { id: threadId },
      data: { updatedAt: new Date() }
    });

    const user = await getUserById(req.session.loggedInUserId);
    if (!user)
    {
      req.session.destroy(err =>
      {});
      return res.status(401).json({ status: 'unauthenticated' });
    }
    await askGeminiChat(threadId, `[${user.fullName || user.username}] ${content}`);

    res.status(201).json({ ...newMessage, createdAt: newMessage.createdAt.toISOString() });
  }
  catch (error)
  {
    console.error(`Error adding message to thread ${threadId}:`, error);
    if (error.code === 'P2023' || error.message.includes('Malformed UUID'))
    { // Example: Invalid UUID format
      return res.status(400).json({ error: 'Invalid thread ID format.' });
    }
    res.status(500).json({ error: 'Failed to add message.' });
  }
});

export default router;