import { Request, Response } from 'express';
import Event, { IEvent } from '../models/Event';
import mongoose from 'mongoose';

/**
 * Get all events with optional filtering
 */
export const getEvents = async (req: Request, res: Response) => {
  try {
    const { 
      status, 
      category, 
      search, 
      startDate, 
      endDate,
      page = 1, 
      limit = 10 
    } = req.query;

    // Build query
    const query: any = {};

    // Filter by status if provided
    if (status && status !== 'all') {
      query.status = status;
    }

    // Filter by category if provided
    if (category && category !== 'all') {
      query.category = category;
    }

    // Filter by date range if provided
    if (startDate || endDate) {
      query.date = {};
      if (startDate) {
        query.date.$gte = new Date(startDate as string);
      }
      if (endDate) {
        query.date.$lte = new Date(endDate as string);
      }
    }

    // Text search if provided
    if (search) {
      query.$text = { $search: search as string };
    }

    // Calculate pagination
    const skip = ((Number(page) || 1) - 1) * (Number(limit) || 10);

    // Execute query with pagination
    const events = await Event.find(query)
      .sort({ date: 1 }) // Sort by date ascending
      .skip(skip)
      .limit(Number(limit));

    // Get total count for pagination
    const total = await Event.countDocuments(query);

    return res.status(200).json({
      events,
      pagination: {
        total,
        page: Number(page),
        limit: Number(limit),
        pages: Math.ceil(total / Number(limit))
      }
    });
  } catch (error) {
    console.error('Error fetching events:', error);
    return res.status(500).json({
      error: {
        message: 'Failed to fetch events'
      }
    });
  }
};

/**
 * Get a single event by ID
 */
export const getEventById = async (req: Request, res: Response) => {
  try {
    const { id } = req.params;

    // Validate ID format
    if (!mongoose.Types.ObjectId.isValid(id)) {
      return res.status(400).json({
        error: {
          message: 'Invalid event ID format'
        }
      });
    }

    // Find event
    const event = await Event.findById(id);

    // Check if event exists
    if (!event) {
      return res.status(404).json({
        error: {
          message: 'Event not found'
        }
      });
    }

    return res.status(200).json({ event });
  } catch (error) {
    console.error('Error fetching event:', error);
    return res.status(500).json({
      error: {
        message: 'Failed to fetch event'
      }
    });
  }
};

/**
 * Create a new event
 */
export const createEvent = async (req: Request, res: Response) => {
  try {
    const {
      title,
      description,
      date,
      time,
      location,
      category,
      status,
      registrationRequired,
      maxAttendees,
      recurring,
      recurrencePattern,
      tags
    } = req.body;

    // Create new event
    const event = new Event({
      title,
      description,
      date,
      time,
      location,
      category,
      status: status || 'draft',
      registrationRequired: registrationRequired || false,
      registeredCount: 0,
      maxAttendees,
      recurring: recurring || false,
      recurrencePattern,
      tags
    });

    // Save event to database
    await event.save();

    return res.status(201).json({
      message: 'Event created successfully',
      event
    });
  } catch (error) {
    console.error('Error creating event:', error);
    
    // Handle validation errors
    if (error instanceof mongoose.Error.ValidationError) {
      return res.status(400).json({
        error: {
          message: 'Validation error',
          details: error.errors
        }
      });
    }

    return res.status(500).json({
      error: {
        message: 'Failed to create event'
      }
    });
  }
};

/**
 * Update an existing event
 */
export const updateEvent = async (req: Request, res: Response) => {
  try {
    const { id } = req.params;
    const updateData = req.body;

    // Validate ID format
    if (!mongoose.Types.ObjectId.isValid(id)) {
      return res.status(400).json({
        error: {
          message: 'Invalid event ID format'
        }
      });
    }

    // Find and update event
    const event = await Event.findByIdAndUpdate(
      id,
      updateData,
      { new: true, runValidators: true }
    );

    // Check if event exists
    if (!event) {
      return res.status(404).json({
        error: {
          message: 'Event not found'
        }
      });
    }

    return res.status(200).json({
      message: 'Event updated successfully',
      event
    });
  } catch (error) {
    console.error('Error updating event:', error);
    
    // Handle validation errors
    if (error instanceof mongoose.Error.ValidationError) {
      return res.status(400).json({
        error: {
          message: 'Validation error',
          details: error.errors
        }
      });
    }

    return res.status(500).json({
      error: {
        message: 'Failed to update event'
      }
    });
  }
};

/**
 * Delete an event
 */
export const deleteEvent = async (req: Request, res: Response) => {
  try {
    const { id } = req.params;

    // Validate ID format
    if (!mongoose.Types.ObjectId.isValid(id)) {
      return res.status(400).json({
        error: {
          message: 'Invalid event ID format'
        }
      });
    }

    // Find and delete event
    const event = await Event.findByIdAndDelete(id);

    // Check if event exists
    if (!event) {
      return res.status(404).json({
        error: {
          message: 'Event not found'
        }
      });
    }

    return res.status(200).json({
      message: 'Event deleted successfully'
    });
  } catch (error) {
    console.error('Error deleting event:', error);
    return res.status(500).json({
      error: {
        message: 'Failed to delete event'
      }
    });
  }
};

/**
 * Register for an event
 */
export const registerForEvent = async (req: Request, res: Response) => {
  try {
    const { id } = req.params;
    const { userId } = req.body;

    // Validate ID format
    if (!mongoose.Types.ObjectId.isValid(id)) {
      return res.status(400).json({
        error: {
          message: 'Invalid event ID format'
        }
      });
    }

    // Find event
    const event = await Event.findById(id);

    // Check if event exists
    if (!event) {
      return res.status(404).json({
        error: {
          message: 'Event not found'
        }
      });
    }

    // Check if registration is required
    if (!event.registrationRequired) {
      return res.status(400).json({
        error: {
          message: 'Registration is not required for this event'
        }
      });
    }

    // Check if event is at capacity
    if (event.maxAttendees && event.registeredCount >= event.maxAttendees) {
      return res.status(400).json({
        error: {
          message: 'Event is at full capacity'
        }
      });
    }

    // Increment registered count
    event.registeredCount += 1;
    await event.save();

    // TODO: In a real implementation, we would also save the user's registration
    // in a separate EventRegistration collection

    return res.status(200).json({
      message: 'Successfully registered for event',
      event
    });
  } catch (error) {
    console.error('Error registering for event:', error);
    return res.status(500).json({
      error: {
        message: 'Failed to register for event'
      }
    });
  }
};

/**
 * Cancel registration for an event
 */
export const cancelRegistration = async (req: Request, res: Response) => {
  try {
    const { id } = req.params;
    const { userId } = req.body;

    // Validate ID format
    if (!mongoose.Types.ObjectId.isValid(id)) {
      return res.status(400).json({
        error: {
          message: 'Invalid event ID format'
        }
      });
    }

    // Find event
    const event = await Event.findById(id);

    // Check if event exists
    if (!event) {
      return res.status(404).json({
        error: {
          message: 'Event not found'
        }
      });
    }

    // Check if registration is required
    if (!event.registrationRequired) {
      return res.status(400).json({
        error: {
          message: 'Registration is not required for this event'
        }
      });
    }

    // Decrement registered count (ensure it doesn't go below 0)
    if (event.registeredCount > 0) {
      event.registeredCount -= 1;
      await event.save();
    }

    // TODO: In a real implementation, we would also remove the user's registration
    // from a separate EventRegistration collection

    return res.status(200).json({
      message: 'Successfully cancelled registration',
      event
    });
  } catch (error) {
    console.error('Error cancelling registration:', error);
    return res.status(500).json({
      error: {
        message: 'Failed to cancel registration'
      }
    });
  }
};