import { Router, Response } from 'express';
import { z } from 'zod';
import { getDatabase } from '../database';
import { authenticate, AuthRequest } from '../middleware/auth';

const router = Router();

// ─── COLLABORATOR ROUTES ONLY ───
// All project CRUD now goes through WebSocket (see realtime.ts)

// Search users by username (for share modal)
router.get('/collaborators/search', authenticate, (req: AuthRequest, res: Response) => {
  const query = req.query.username as string;
  if (!query || query.length < 2) {
    res.json({ users: [] });
    return;
  }
  const db = getDatabase();
  const users = db.prepare(
    'SELECT id, username FROM users WHERE username LIKE ? AND id != ? LIMIT 20'
  ).all(`%${query}%`, req.userId);
  res.json({ users });
});

// List collaborators for a project
router.get('/:id/collaborators', authenticate, (req: AuthRequest, res: Response) => {
  const db = getDatabase();
  const project = db.prepare(
    'SELECT user_id FROM projects WHERE id = ? AND user_id = ?'
  ).get(req.params.id, req.userId) as any;

  let hasAccess = !!project;
  if (!hasAccess) {
    const collab = db.prepare(
      'SELECT permission FROM project_collaborators WHERE project_id = ? AND user_id = ?'
    ).get(req.params.id, req.userId) as any;
    hasAccess = !!collab;
  }

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

  const owner = db.prepare(
    'SELECT id, username FROM users WHERE id = (SELECT user_id FROM projects WHERE id = ?)'
  ).get(req.params.id) as any;

  const collaborators = db.prepare(`
    SELECT u.id, u.username, c.permission, c.created_at
    FROM project_collaborators c
    JOIN users u ON u.id = c.user_id
    WHERE c.project_id = ?
    ORDER BY c.created_at ASC
  `).all(req.params.id);

  res.json({
    owner: owner ? { id: owner.id, username: owner.username } : null,
    collaborators,
  });
});

// Add collaborator
router.post('/:id/collaborators', authenticate, async (req: AuthRequest, res: Response) => {
  try {
    const schema = z.object({
      username: z.string().min(1),
      permission: z.enum(['view', 'edit', 'admin']).default('edit'),
    });
    const { username, permission } = schema.parse(req.body);
    const db = getDatabase();

    const project = db.prepare(
      'SELECT user_id FROM projects WHERE id = ?'
    ).get(req.params.id) as any;

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

    const isOwner = project.user_id === req.userId;
    let isAdmin = isOwner;
    if (!isOwner) {
      const collab = db.prepare(
        'SELECT permission FROM project_collaborators WHERE project_id = ? AND user_id = ?'
      ).get(req.params.id, req.userId) as any;
      isAdmin = collab?.permission === 'admin';
    }

    if (!isAdmin) {
      res.status(403).json({ error: 'Only the owner or admin can add collaborators' });
      return;
    }

    const targetUser = db.prepare(
      'SELECT id, username FROM users WHERE username = ?'
    ).get(username) as any;

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

    if (targetUser.id === project.user_id) {
      res.status(400).json({ error: 'Cannot add the project owner as a collaborator' });
      return;
    }

    const existing = db.prepare(
      'SELECT permission FROM project_collaborators WHERE project_id = ? AND user_id = ?'
    ).get(req.params.id, targetUser.id) as any;

    if (existing) {
      res.status(400).json({ error: 'User is already a collaborator' });
      return;
    }

    const { v4: uuidv4 } = require('uuid');
    db.prepare(`
      INSERT INTO project_collaborators (project_id, user_id, permission, added_by, created_at)
      VALUES (?, ?, ?, ?, ?)
    `).run(req.params.id, targetUser.id, permission, req.userId, Date.now());

    res.status(201).json({
      collaborator: {
        id: targetUser.id,
        username: targetUser.username,
        permission,
      },
    });
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      res.status(400).json({ error: 'Invalid input', details: error.errors });
      return;
    }
    console.error('Add collaborator error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// Update collaborator permission
router.put('/:id/collaborators/:userId', authenticate, async (req: AuthRequest, res: Response) => {
  try {
    const schema = z.object({
      permission: z.enum(['view', 'edit', 'admin']),
    });
    const { permission } = schema.parse(req.body);
    const db = getDatabase();

    const project = db.prepare(
      'SELECT user_id FROM projects WHERE id = ?'
    ).get(req.params.id) as any;

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

    const isOwner = project.user_id === req.userId;
    let isAdmin = isOwner;
    if (!isOwner) {
      const collab = db.prepare(
        'SELECT permission FROM project_collaborators WHERE project_id = ? AND user_id = ?'
      ).get(req.params.id, req.userId) as any;
      isAdmin = collab?.permission === 'admin';
    }

    if (!isAdmin) {
      res.status(403).json({ error: 'Permission denied' });
      return;
    }

    const result = db.prepare(`
      UPDATE project_collaborators SET permission = ? WHERE project_id = ? AND user_id = ?
    `).run(permission, req.params.id, req.params.userId);

    if (result.changes === 0) {
      res.status(404).json({ error: 'Collaborator not found' });
      return;
    }

    res.json({ message: 'Permission updated', permission });
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      res.status(400).json({ error: 'Invalid input', details: error.errors });
      return;
    }
    console.error('Update collaborator error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// Remove collaborator
router.delete('/:id/collaborators/:userId', authenticate, (req: AuthRequest, res: Response) => {
  const db = getDatabase();

  const project = db.prepare(
    'SELECT user_id FROM projects WHERE id = ?'
  ).get(req.params.id) as any;

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

  const isOwner = project.user_id === req.userId;
  const isSelf = req.userId === req.params.userId;
  let isAdmin = isOwner;
  if (!isOwner && !isSelf) {
    const collab = db.prepare(
      'SELECT permission FROM project_collaborators WHERE project_id = ? AND user_id = ?'
    ).get(req.params.id, req.userId) as any;
    isAdmin = collab?.permission === 'admin';
  }

  if (!isOwner && !isAdmin && !isSelf) {
    res.status(403).json({ error: 'Permission denied' });
    return;
  }

  const result = db.prepare(
    'DELETE FROM project_collaborators WHERE project_id = ? AND user_id = ?'
  ).run(req.params.id, req.userId);

  if (result.changes === 0) {
    res.status(404).json({ error: 'Collaborator not found' });
    return;
  }

  res.json({ message: 'Collaborator removed' });
});

export default router;