import { Router } from 'express';
import { query } from '../config/db.js';
import { requireAuth } from '../middleware/auth.js';

const router = Router();
router.use(requireAuth);

async function isMember(conversationId, userId) {
  const { rows } = await query(
    'SELECT 1 FROM conversation_members WHERE conversation_id = $1 AND user_id = $2',
    [conversationId, userId],
  );
  return !!rows[0];
}

async function withReactions(type, messages) {
  if (!messages.length) return messages;
  const ids = messages.map((m) => m.id);
  const { rows } = await query(
    `SELECT target_id, emoji, COUNT(*)::int AS count,
       array_agg(user_id) AS users
     FROM reactions WHERE target_type = $1 AND target_id = ANY($2)
     GROUP BY target_id, emoji`,
    [type, ids],
  );
  const byMsg = {};
  for (const r of rows) {
    if (!byMsg[r.target_id]) byMsg[r.target_id] = [];
    byMsg[r.target_id].push({ emoji: r.emoji, count: r.count, users: r.users });
  }
  return messages.map((m) => ({ ...m, reactions: byMsg[m.id] || [] }));
}

// GET /api/dm — my conversations (peer, last message, unread)
router.get('/', async (req, res) => {
  const { rows } = await query(
    `SELECT c.id, c.created_at,
       (SELECT json_build_object('id', u.id, 'name', u.name, 'email', u.email, 'avatar', COALESCE(u.avatar,''))
        FROM conversation_members cm2 JOIN users u ON u.id = cm2.user_id
        WHERE cm2.conversation_id = c.id AND cm2.user_id <> $1 LIMIT 1) AS peer,
       (SELECT json_build_object('body', m.body, 'created_at', m.created_at, 'user_id', m.user_id)
        FROM dm_messages m WHERE m.conversation_id = c.id
        ORDER BY m.created_at DESC LIMIT 1) AS last_message,
       (SELECT COUNT(*)::int FROM dm_messages m
        JOIN conversation_members me ON me.conversation_id = c.id AND me.user_id = $1
        WHERE m.conversation_id = c.id AND m.created_at > me.last_read_at AND m.user_id <> $1) AS unread
     FROM conversations c
     JOIN conversation_members me ON me.conversation_id = c.id AND me.user_id = $1
     ORDER BY COALESCE((SELECT MAX(created_at) FROM dm_messages WHERE conversation_id = c.id), c.created_at) DESC`,
    [req.user.id],
  );
  return res.json({ conversations: rows });
});

// POST /api/dm { user_id } — find-or-create 1:1 conversation
router.post('/', async (req, res) => {
  const { user_id } = req.body ?? {};
  if (!user_id || user_id === req.user.id) return res.status(400).json({ error: 'Valid user_id required' });
  const { rows: target } = await query('SELECT id, name, email, avatar FROM users WHERE id = $1', [user_id]);
  if (!target[0]) return res.status(404).json({ error: 'User not found' });
  const { rows: existing } = await query(
    `SELECT c.id FROM conversations c
     JOIN conversation_members a ON a.conversation_id = c.id AND a.user_id = $1
     JOIN conversation_members b ON b.conversation_id = c.id AND b.user_id = $2
     WHERE (SELECT COUNT(*) FROM conversation_members WHERE conversation_id = c.id) = 2
     LIMIT 1`,
    [req.user.id, user_id],
  );
  if (existing[0]) return res.json({ conversation: { id: existing[0].id } });
  const { rows } = await query('INSERT INTO conversations (created_by) VALUES ($1) RETURNING id', [req.user.id]);
  await query('INSERT INTO conversation_members (conversation_id, user_id) VALUES ($1,$2),($1,$3)', [
    rows[0].id, req.user.id, user_id,
  ]);
  return res.status(201).json({ conversation: { id: rows[0].id } });
});

// GET /api/dm/:id/messages?limit=100 — marks as read
router.get('/:id/messages', async (req, res) => {
  if (!(await isMember(req.params.id, req.user.id))) return res.status(403).json({ error: 'Forbidden' });
  const limit = Math.min(Number(req.query.limit) || 100, 200);
  const { rows } = await query(
    `SELECT m.*, u.name AS author_name, u.avatar AS author_avatar
     FROM dm_messages m LEFT JOIN users u ON u.id = m.user_id
     WHERE m.conversation_id = $1 ORDER BY m.created_at DESC LIMIT $2`,
    [req.params.id, limit],
  );
  const messages = (await withReactions('dm', rows)).reverse();
  await query(
    'UPDATE conversation_members SET last_read_at = now() WHERE conversation_id = $1 AND user_id = $2',
    [req.params.id, req.user.id],
  );
  return res.json({ messages });
});

// GET /api/dm/:id/search?q=
router.get('/:id/search', async (req, res) => {
  if (!(await isMember(req.params.id, req.user.id))) return res.status(403).json({ error: 'Forbidden' });
  const q = String(req.query.q || '').slice(0, 100);
  if (q.length < 2) return res.json({ messages: [] });
  const { rows } = await query(
    `SELECT m.*, u.name AS author_name FROM dm_messages m
     LEFT JOIN users u ON u.id = m.user_id
     WHERE m.conversation_id = $1 AND m.body ILIKE $2
     ORDER BY m.created_at DESC LIMIT 30`,
    [req.params.id, `%${q}%`],
  );
  return res.json({ messages: rows });
});

// POST /api/dm/:id/messages { body, attachment? }
router.post('/:id/messages', async (req, res) => {
  if (!(await isMember(req.params.id, req.user.id))) return res.status(403).json({ error: 'Forbidden' });
  const { body = '', attachment = '' } = req.body ?? {};
  if (String(body).trim().length < 1 || String(body).length > 2000) {
    return res.status(400).json({ error: 'Body must be 1-2000 chars' });
  }
  const { rows } = await query(
    'INSERT INTO dm_messages (conversation_id, user_id, body, attachment) VALUES ($1,$2,$3,$4) RETURNING *',
    [req.params.id, req.user.id, String(body).trim(), String(attachment).slice(0, 2000)],
  );
  const { rows: author } = await query('SELECT name, avatar FROM users WHERE id = $1', [req.user.id]);
  const msg = { ...rows[0], author_name: author[0]?.name, author_avatar: author[0]?.avatar, reactions: [] };
  const io = req.app.get('io');
  io?.to(`dm:${req.params.id}`).emit('dm:message', { message: msg });
  // Notify the other member
  const { rows: others } = await query(
    'SELECT user_id FROM conversation_members WHERE conversation_id = $1 AND user_id <> $2',
    [req.params.id, req.user.id],
  );
  for (const o of others) {
    await query(
      `INSERT INTO notifications (user_id, type, title, body, link)
       VALUES ($1,'chat',$2,$3,$4)`,
      [o.user_id, `✉️ ${author[0]?.name || 'Someone'}`, String(body).trim().slice(0, 140), '/chat'],
    );
    io?.to(`user:${o.user_id}`).emit('notification:new', { type: 'dm' });
  }
  return res.status(201).json({ message: msg });
});

// PATCH /api/dm/message/:mid { body } (own)
router.patch('/message/:mid', async (req, res) => {
  const { rows } = await query('SELECT * FROM dm_messages WHERE id = $1', [req.params.mid]);
  const msg = rows[0];
  if (!msg) return res.status(404).json({ error: 'Not found' });
  if (msg.user_id !== req.user.id) return res.status(403).json({ error: 'Forbidden' });
  const { body = '' } = req.body ?? {};
  if (String(body).trim().length < 1 || String(body).length > 2000) {
    return res.status(400).json({ error: 'Body must be 1-2000 chars' });
  }
  const { rows: updated } = await query(
    'UPDATE dm_messages SET body = $1, edited_at = now() WHERE id = $2 RETURNING *',
    [String(body).trim(), msg.id],
  );
  req.app.get('io')?.to(`dm:${msg.conversation_id}`).emit('dm:edited', { message: updated[0] });
  return res.json({ message: updated[0] });
});

// DELETE /api/dm/message/:mid (own or admin)
router.delete('/message/:mid', async (req, res) => {
  const { rows } = await query('SELECT * FROM dm_messages WHERE id = $1', [req.params.mid]);
  const msg = rows[0];
  if (!msg) return res.status(404).json({ error: 'Not found' });
  const { rows: me } = await query('SELECT is_admin FROM users WHERE id = $1', [req.user.id]);
  if (msg.user_id !== req.user.id && !me[0]?.is_admin) return res.status(403).json({ error: 'Forbidden' });
  await query('DELETE FROM dm_messages WHERE id = $1', [msg.id]);
  req.app.get('io')?.to(`dm:${msg.conversation_id}`).emit('dm:deleted', { id: msg.id });
  return res.status(204).end();
});

export default router;