const express = require('express');
const { v4: uuidv4 } = require('uuid');
const { readTable, writeTable } = require('../utils/db');
const authMiddleware = require('../middleware/auth');

const router = express.Router();

// POST /api/ai/conversations — 保存一次对话
router.post('/', authMiddleware, (req, res) => {
  const { sceneId, roomId, messages } = req.body || {};
  if (!sceneId || !Array.isArray(messages)) {
    return res.status(400).json({ code: 400, message: 'sceneId 和 messages 不能为空' });
  }

  const conversations = readTable('conversations');
  const now = new Date().toISOString();

  // 统一存为 role/content 格式，兼容旧的 { userId, text } 格式
  const formattedMessages = messages.map((m) => ({
    role: (m.role === 'user' || m.role === 'assistant')
      ? m.role
      : (m.userId === req.user.userId ? 'user' : 'assistant'),
    content: m.content || m.text || '',
    createdAt: m.time || now,
  }));

  // 推断会话开始/结束时间
  const startedAt = formattedMessages[0]?.createdAt || now;
  const endedAt = formattedMessages[formattedMessages.length - 1]?.createdAt || now;

  const session = {
    id: uuidv4(),
    userId: req.user.userId,
    sceneId,
    roomId: roomId || '',
    startedAt,
    endedAt,
    createdAt: now,
    messages: formattedMessages,
  };

  conversations.push(session);
  writeTable('conversations', conversations);

  return res.json({ code: 200, data: { sessionId: session.id } });
});

// GET /api/ai/conversations — 分页列表（仅当前用户）
router.get('/', authMiddleware, (req, res) => {
  const page = Math.max(1, parseInt(req.query.page) || 1);
  const size = Math.max(1, Math.min(100, parseInt(req.query.size) || 20));

  const all = readTable('conversations').filter((c) => c.userId === req.user.userId);
  // 按时间倒序
  all.sort((a, b) => new Date(b.createdAt) - new Date(a.createdAt));

  const total = all.length;
  const list = all.slice((page - 1) * size, page * size).map((c) => ({
    id: c.id,
    sceneId: c.sceneId,
    roomId: c.roomId,
    startedAt: c.startedAt,
    endedAt: c.endedAt,
    messageCount: c.messages.length,
    firstMessage: c.messages.find((m) => m.role === 'user')?.content || '',
  }));

  return res.json({ code: 200, data: { total, page, size, list } });
});

// GET /api/ai/conversations/:id — 详情（含消息）
router.get('/:id', authMiddleware, (req, res) => {
  const conversations = readTable('conversations');
  const conv = conversations.find((c) => c.id === req.params.id);

  if (!conv) {
    return res.status(404).json({ code: 404, message: '对话记录不存在' });
  }
  if (conv.userId !== req.user.userId) {
    return res.status(403).json({ code: 403, message: '无权访问该对话' });
  }

  return res.json({ code: 200, data: conv });
});

// POST /api/ai/conversations/:id/append — 继续对话追加消息
router.post('/:id/append', authMiddleware, (req, res) => {
  const { messages } = req.body || {};
  if (!Array.isArray(messages)) {
    return res.status(400).json({ code: 400, message: 'messages 不能为空' });
  }

  const conversations = readTable('conversations');
  const conv = conversations.find((c) => c.id === req.params.id);

  if (!conv) return res.status(404).json({ code: 404, message: '对话记录不存在' });
  if (conv.userId !== req.user.userId) return res.status(403).json({ code: 403, message: '无权操作该对话' });

  const now = new Date().toISOString();
  const newFormatted = messages.map((m) => ({
    role: m.role === 'user' || m.role === 'assistant' ? m.role : 'assistant',
    content: m.content || '',
    createdAt: m.time || now,
  }));

  conv.messages.push(...newFormatted);
  conv.endedAt = newFormatted[newFormatted.length - 1]?.createdAt || now;

  writeTable('conversations', conversations);
  return res.json({ code: 200, data: { sessionId: conv.id } });
});

// DELETE /api/ai/conversations/:id — 删除（仅本人）
router.delete('/:id', authMiddleware, (req, res) => {
  const conversations = readTable('conversations');
  const idx = conversations.findIndex((c) => c.id === req.params.id);

  if (idx === -1) {
    return res.status(404).json({ code: 404, message: '对话记录不存在' });
  }
  if (conversations[idx].userId !== req.user.userId) {
    return res.status(403).json({ code: 403, message: '无权删除该对话' });
  }

  conversations.splice(idx, 1);
  writeTable('conversations', conversations);

  return res.json({ code: 200, data: null });
});

module.exports = router;