import { Request, Response } from 'express';
import Event from '../model/event.model';
import User from '../model/user.model';
import { Parser } from 'json2csv';

interface IAnalyticsRequest extends Request {
  userId?: string;
}

// ==================== GET EVENT MAP DATA ====================
export const getEventMapData = async (req: IAnalyticsRequest, res: Response) => {
  try {
    const {
      theme,
      organization,
      startDate,
      endDate,
      status = 'published'
    } = req.query;

    const filter: any = {
      status,
      location: { $exists: true } // Only events with location
    };

    if (theme) filter.theme = theme;
    if (organization) filter.organization = organization;

    if (startDate || endDate) {
      filter.startDate = {};
      if (startDate) filter.startDate.$gte = new Date(startDate as string);
      if (endDate) filter.startDate.$lte = new Date(endDate as string);
    }

    const events = await Event.find(filter)
      .populate('organization', 'username organizationType')
      .populate('createdBy', 'username')
      .select('title code theme location startDate endDate type participantCount venue');

    // Format for map markers
    const mapData = events.map(event => ({
      id: event._id,
      title: event.title,
      code: event.code,
      theme: event.theme,
      organization: (event.organization as any).username,
      coordinates: event.location?.coordinates,
      latitude: event.location?.coordinates[1],
      longitude: event.location?.coordinates[0],
      startDate: event.startDate,
      endDate: event.endDate,
      type: event.type,
      venue: event.venue,
      participantCount: event.participants.length,
      capacity: event.capacity
    }));

    return res.json({
      totalEvents: mapData.length,
      events: mapData
    });
  } catch (err: any) {
    console.error(err);
    return res.status(500).json({ message: 'Server error', error: err.message });
  }
};

// ==================== GET COVERAGE HEATMAP DATA ====================
export const getHeatmapData = async (req: IAnalyticsRequest, res: Response) => {
  try {
    const { theme, startDate, endDate } = req.query;

    const filter: any = {
      status: { $in: ['published', 'completed'] },
      location: { $exists: true }
    };

    if (theme) filter.theme = theme;
    if (startDate || endDate) {
      filter.startDate = {};
      if (startDate) filter.startDate.$gte = new Date(startDate as string);
      if (endDate) filter.startDate.$lte = new Date(endDate as string);
    }

    const events = await Event.find(filter)
      .select('location participants');

    // Create heatmap points (lat, lng, weight)
    const heatmapPoints = events.map(event => ({
      lat: event.location?.coordinates[1],
      lng: event.location?.coordinates[0],
      weight: event.participants.length // Weight by attendance
    }));

    return res.json({ points: heatmapPoints });
  } catch (err: any) {
    console.error(err);
    return res.status(500).json({ message: 'Server error', error: err.message });
  }
};

// ==================== GET THEME COVERAGE STATISTICS ====================
export const getThemeCoverage = async (req: IAnalyticsRequest, res: Response) => {
  try {
    const { startDate, endDate, organization } = req.query;

    const filter: any = {
      status: { $in: ['published', 'completed'] }
    };

    if (organization) filter.organization = organization;
    if (startDate || endDate) {
      filter.startDate = {};
      if (startDate) filter.startDate.$gte = new Date(startDate as string);
      if (endDate) filter.startDate.$lte = new Date(endDate as string);
    }

    // Aggregate by theme
    const themeCoverage = await Event.aggregate([
      { $match: filter },
      {
        $group: {
          _id: '$theme',
          eventCount: { $sum: 1 },
          totalParticipants: { $sum: { $size: '$participants' } },
          totalCapacity: { $sum: '$capacity' },
          avgAttendance: { $avg: { $size: '$participants' } }
        }
      },
      { $sort: { eventCount: -1 } }
    ]);

    return res.json({ themeCoverage });
  } catch (err: any) {
    console.error(err);
    return res.status(500).json({ message: 'Server error', error: err.message });
  }
};

// ==================== GET ORGANIZATION STATISTICS ====================
export const getOrganizationStats = async (req: IAnalyticsRequest, res: Response) => {
  try {
    const { startDate, endDate } = req.query;

    const filter: any = {
      status: { $in: ['published', 'completed'] }
    };

    if (startDate || endDate) {
      filter.startDate = {};
      if (startDate) filter.startDate.$gte = new Date(startDate as string);
      if (endDate) filter.startDate.$lte = new Date(endDate as string);
    }

    const orgStats = await Event.aggregate([
      { $match: filter },
      {
        $group: {
          _id: '$organization',
          eventCount: { $sum: 1 },
          totalParticipants: { $sum: { $size: '$participants' } },
          totalCapacity: { $sum: '$capacity' },
          themes: { $addToSet: '$theme' }
        }
      },
      {
        $lookup: {
          from: 'users',
          localField: '_id',
          foreignField: '_id',
          as: 'orgDetails'
        }
      },
      {
        $project: {
          organization: { $arrayElemAt: ['$orgDetails.username', 0] },
          organizationType: { $arrayElemAt: ['$orgDetails.organizationType', 0] },
          eventCount: 1,
          totalParticipants: 1,
          totalCapacity: 1,
          themeCount: { $size: '$themes' },
          utilizationRate: {
            $multiply: [
              { $divide: ['$totalParticipants', '$totalCapacity'] },
              100
            ]
          }
        }
      },
      { $sort: { eventCount: -1 } }
    ]);

    return res.json({ organizationStats: orgStats });
  } catch (err: any) {
    console.error(err);
    return res.status(500).json({ message: 'Server error', error: err.message });
  }
};

// ==================== GET TRAINER ACTIVITY ====================
export const getTrainerActivity = async (req: IAnalyticsRequest, res: Response) => {
  try {
    const { organization, startDate, endDate } = req.query;

    const filter: any = {
      status: { $in: ['published', 'completed'] }
    };

    if (organization) filter.organization = organization;
    if (startDate || endDate) {
      filter.startDate = {};
      if (startDate) filter.startDate.$gte = new Date(startDate as string);
      if (endDate) filter.startDate.$lte = new Date(endDate as string);
    }

    const trainerStats = await Event.aggregate([
      { $match: filter },
      {
        $group: {
          _id: '$createdBy',
          eventCount: { $sum: 1 },
          totalParticipants: { $sum: { $size: '$participants' } },
          themes: { $addToSet: '$theme' }
        }
      },
      {
        $lookup: {
          from: 'users',
          localField: '_id',
          foreignField: '_id',
          as: 'trainerDetails'
        }
      },
      {
        $project: {
          trainer: { $arrayElemAt: ['$trainerDetails.username', 0] },
          email: { $arrayElemAt: ['$trainerDetails.email', 0] },
          workDesignation: { $arrayElemAt: ['$trainerDetails.workDesignation', 0] },
          eventCount: 1,
          totalParticipants: 1,
          themeCount: { $size: '$themes' },
          avgParticipantsPerEvent: {
            $divide: ['$totalParticipants', '$eventCount']
          }
        }
      },
      { $sort: { eventCount: -1 } }
    ]);

    return res.json({ trainerActivity: trainerStats });
  } catch (err: any) {
    console.error(err);
    return res.status(500).json({ message: 'Server error', error: err.message });
  }
};

// ==================== GET DISTRICT COVERAGE ====================
export const getDistrictCoverage = async (req: IAnalyticsRequest, res: Response) => {
  try {
    // This would require reverse geocoding to get district from coordinates
    // For now, returning placeholder structure
    // You'd integrate with a geocoding service (Google Maps, Mapbox, etc.)

    const { state } = req.query;

    // Placeholder - implement reverse geocoding
    return res.json({
      message: 'District coverage requires geocoding integration',
      placeholder: {
        state: state || 'Maharashtra',
        districts: [
          { name: 'Mumbai', eventCount: 45, participantCount: 1200 },
          { name: 'Pune', eventCount: 32, participantCount: 890 },
          { name: 'Nagpur', eventCount: 18, participantCount: 450 }
        ]
      }
    });
  } catch (err: any) {
    console.error(err);
    return res.status(500).json({ message: 'Server error', error: err.message });
  }
};

// ==================== EXPORT ANALYTICS TO CSV ====================
export const exportAnalyticsToCsv = async (req: IAnalyticsRequest, res: Response) => {
  try {
    const { startDate, endDate, organization, theme } = req.query;

    const filter: any = {
      status: { $in: ['published', 'completed'] }
    };

    if (organization) filter.organization = organization;
    if (theme) filter.theme = theme;
    if (startDate || endDate) {
      filter.startDate = {};
      if (startDate) filter.startDate.$gte = new Date(startDate as string);
      if (endDate) filter.startDate.$lte = new Date(endDate as string);
    }

    const events = await Event.find(filter)
      .populate('organization', 'username organizationType')
      .populate('createdBy', 'username email')
      .lean();

    // Format data for CSV
    const csvData = events.map(event => ({
      'Event Code': event.code,
      'Title': event.title,
      'Theme': event.theme,
      'Organization': (event.organization as any).username,
      'Organization Type': (event.organization as any).organizationType,
      'Trainer': (event.createdBy as any).username,
      'Trainer Email': (event.createdBy as any).email,
      'Type': event.type,
      'Venue': event.venue || 'N/A',
      'Start Date': new Date(event.startDate).toLocaleDateString(),
      'End Date': new Date(event.endDate).toLocaleDateString(),
      'Capacity': event.capacity,
      'Registered': event.participants.length,
      'Attendance': event.participants.filter((p: any) => p.attendance?.checkInTime).length,
      'Utilization %': ((event.participants.length / event.capacity) * 100).toFixed(2),
      'Status': event.status
    }));

    const parser = new Parser();
    const csv = parser.parse(csvData);

    res.setHeader('Content-Type', 'text/csv');
    res.setHeader('Content-Disposition', 'attachment; filename=training_analytics.csv');

    return res.send(csv);
  } catch (err: any) {
    console.error(err);
    return res.status(500).json({ message: 'Server error', error: err.message });
  }
};

// ==================== GET DASHBOARD OVERVIEW ====================
export const getDashboardOverview = async (req: IAnalyticsRequest, res: Response) => {
  try {
    const { startDate, endDate, organization } = req.query;

    const filter: any = {};
    if (organization) filter.organization = organization;
    if (startDate || endDate) {
      filter.startDate = {};
      if (startDate) filter.startDate.$gte = new Date(startDate as string);
      if (endDate) filter.startDate.$lte = new Date(endDate as string);
    }

    const now = new Date();

    // Total events
    const totalEvents = await Event.countDocuments(filter);

    // Upcoming events
    const upcomingEvents = await Event.countDocuments({
      ...filter,
      startDate: { $gt: now },
      status: 'published'
    });

    // Completed events
    const completedEvents = await Event.countDocuments({
      ...filter,
      endDate: { $lt: now },
      status: { $in: ['completed', 'published'] }
    });

    // Pending Verifications (Trainers + Organizations)
    // Note: This is global unless filtered by organization (for trainers)
    const verificationFilter: any = { role: 'organization', verificationStatus: 'pending' };
    const pendingOrgVerifications = await User.countDocuments(verificationFilter);

    const pendingTrainerFilter: any = { role: 'trainer', organizationVerificationStatus: 'pending' };
    if (organization) pendingTrainerFilter.organization = organization;
    const pendingTrainerVerifications = await User.countDocuments(pendingTrainerFilter);

    const totalPendingVerifications = pendingOrgVerifications + pendingTrainerVerifications;

    // Active Trainers
    const trainerFilter: any = { role: 'trainer', isActive: true };
    if (organization) trainerFilter.organization = organization;
    const activeTrainers = await User.countDocuments(trainerFilter);

    // Active Organizations
    const activeOrganizations = await User.countDocuments({ role: 'organization', verificationStatus: 'approved' });

    // Total participants across all events
    const participantStats = await Event.aggregate([
      { $match: filter },
      {
        $group: {
          _id: null,
          totalParticipants: { $sum: { $size: '$participants' } },
          totalCapacity: { $sum: '$capacity' },
          totalAttended: {
            $sum: {
              $size: {
                $filter: {
                  input: '$participants',
                  as: 'p',
                  cond: { $ne: ['$$p.attendance.checkInTime', null] }
                }
              }
            }
          }
        }
      }
    ]);

    const stats = participantStats[0] || {
      totalParticipants: 0,
      totalCapacity: 0,
      totalAttended: 0
    };

    // Unique themes
    const themes = await Event.distinct('theme', filter);

    return res.json({
      overview: {
        totalEvents,
        upcomingEvents,
        completedEvents,
        totalParticipants: stats.totalParticipants,
        totalCapacity: stats.totalCapacity,
        totalAttended: stats.totalAttended,
        utilizationRate: stats.totalCapacity > 0
          ? ((stats.totalParticipants / stats.totalCapacity) * 100).toFixed(2)
          : 0,
        attendanceRate: stats.totalParticipants > 0
          ? ((stats.totalAttended / stats.totalParticipants) * 100).toFixed(2)
          : 0,
        uniqueThemes: themes.length,
        activeOrganizations,
        activeTrainers,
        pendingVerifications: totalPendingVerifications,
        pendingOrgVerifications,
        pendingTrainerVerifications
      }
    });
  } catch (err: any) {
    console.error(err);
    return res.status(500).json({ message: 'Server error', error: err.message });
  }
};