import express from 'express';
import Todo from '../models/Todo.js';
import User from '../models/User.js';
import { requireAdmin } from '../middleware/auth.js';

const router = express.Router();

// Get todos - different behavior for admin vs user
router.get('/', async (req, res) => {
  try {
    const { date, userId } = req.query;
    let query = {};

    if (req.user.role === 'admin') {
      // Admin can see all todos or filter by userId
      if (userId) {
        query.userId = userId;
      }
    } else {
      // Regular users only see their assigned tasks
      query.userId = req.user._id;
    }

    if (date) {
      const startDate = new Date(date);
      const endDate = new Date(date);
      endDate.setDate(endDate.getDate() + 1);
      
      query.dueDate = {
        $gte: startDate,
        $lt: endDate
      };
    }

    const todos = await Todo.find(query)
      .populate('userId', 'username email')
      .populate('assignedBy', 'username email')
      .sort({ createdAt: -1 });
    
    res.json(todos);
  } catch (error) {
    res.status(500).json({ message: 'Server error', error: error.message });
  }
});

// Create new todo - only admins can assign tasks to others
router.post('/', async (req, res) => {
  try {
    const { title, description, priority, dueDate, userId } = req.body;

    let todoData = {
      title,
      description,
      priority,
      dueDate: new Date(dueDate)
    };

    if (req.user.role === 'admin') {
      // Admin can assign tasks to any user
      todoData.userId = userId || req.user._id;
      todoData.assignedBy = req.user._id;
    } else {
      // Regular users can only create tasks for themselves
      todoData.userId = req.user._id;
    }

    const todo = new Todo(todoData);
    await todo.save();
    
    const populatedTodo = await Todo.findById(todo._id)
      .populate('userId', 'username email')
      .populate('assignedBy', 'username email');
    
    res.status(201).json(populatedTodo);
  } catch (error) {
    res.status(500).json({ message: 'Server error', error: error.message });
  }
});

// Update todo - different permissions for admin vs user
router.put('/:id', async (req, res) => {
  try {
    const { id } = req.params;
    const updates = req.body;

    console.log('Update request:', { id, updates, userRole: req.user.role });

    let query = { _id: id };
    let finalUpdates = { ...updates };
    
    if (req.user.role === 'admin') {
      // Admin can update any todo
      console.log('Admin updating todo');
    } else {
      // Regular users can only update their own todos
      query.userId = req.user._id;
      console.log('User updating own todo');
      
      // Users can only update status and submit tasks
      const allowedUpdates = ['status'];
      const filteredUpdates = {};
      
      allowedUpdates.forEach(field => {
        if (updates[field] !== undefined) {
          filteredUpdates[field] = updates[field];
        }
      });
      
      // Handle task submission
      if (updates.status === 'submitted') {
        filteredUpdates.submittedAt = new Date();
      }
      
      finalUpdates = filteredUpdates;
      console.log('Filtered updates for user:', finalUpdates);
    }

    const todo = await Todo.findOneAndUpdate(query, finalUpdates, { new: true })
      .populate('userId', 'username email')
      .populate('assignedBy', 'username email');

    if (!todo) {
      console.log('Todo not found with query:', query);
      return res.status(404).json({ message: 'Todo not found or access denied' });
    }

    console.log('Todo updated successfully:', todo);
    res.json(todo);
  } catch (error) {
    console.error('Update todo error:', error);
    res.status(500).json({ message: 'Server error', error: error.message });
  }
});

// Delete todo - only admins can delete
router.delete('/:id', requireAdmin, async (req, res) => {
  try {
    const { id } = req.params;

    const todo = await Todo.findByIdAndDelete(id);

    if (!todo) {
      return res.status(404).json({ message: 'Todo not found' });
    }

    res.json({ message: 'Todo deleted successfully' });
  } catch (error) {
    res.status(500).json({ message: 'Server error', error: error.message });
  }
});

// Admin routes for user management
router.get('/admin/users', requireAdmin, async (req, res) => {
  try {
    const users = await User.find({ role: 'user' }).select('-password');
    res.json(users);
  } catch (error) {
    res.status(500).json({ message: 'Server error', error: error.message });
  }
});

// Admin route to get all todos with user details
router.get('/admin/all-todos', requireAdmin, async (req, res) => {
  try {
    const todos = await Todo.find()
      .populate('userId', 'username email')
      .populate('assignedBy', 'username email')
      .sort({ createdAt: -1 });
    
    res.json(todos);
  } catch (error) {
    res.status(500).json({ message: 'Server error', error: error.message });
  }
});

// Admin route to assign task to user
router.post('/admin/assign', requireAdmin, async (req, res) => {
  try {
    const { title, description, priority, dueDate, userId } = req.body;

    const todo = new Todo({
      title,
      description,
      priority,
      dueDate: new Date(dueDate),
      userId,
      assignedBy: req.user._id
    });

    await todo.save();
    
    const populatedTodo = await Todo.findById(todo._id)
      .populate('userId', 'username email')
      .populate('assignedBy', 'username email');
    
    res.status(201).json(populatedTodo);
  } catch (error) {
    res.status(500).json({ message: 'Server error', error: error.message });
  }
});

// Admin route to mark task as completed
router.put('/admin/complete/:id', requireAdmin, async (req, res) => {
  try {
    const { id } = req.params;

    const todo = await Todo.findByIdAndUpdate(
      id,
      { 
        status: 'completed',
        completedAt: new Date()
      },
      { new: true }
    ).populate('userId', 'username email')
     .populate('assignedBy', 'username email');

    if (!todo) {
      return res.status(404).json({ message: 'Todo not found' });
    }

    res.json(todo);
  } catch (error) {
    res.status(500).json({ message: 'Server error', error: error.message });
  }
});



export default router;