const express = require('express');
const { body, validationResult } = require('express-validator');
const { protect, authorize } = require('../middleware/auth');
const database = require('../config/database');
const alertService = require('../services/alertService');
const logger = require('../utils/logger');

const router = express.Router();

// Get all alerts
router.get('/', protect, async (req, res) => {
  try {
    const { page = 1, limit = 50, status, severity, device_id } = req.query;
    const offset = (page - 1) * limit;
    
    let query = 'SELECT * FROM alerts WHERE 1=1';
    const params = [];
    
    if (status) {
      query += ' AND status = ?';
      params.push(status);
    }
    
    if (severity) {
      query += ' AND severity = ?';
      params.push(severity);
    }
    
    if (device_id) {
      query += ' AND device_id = ?';
      params.push(device_id);
    }
    
    query += ' ORDER BY created_at DESC LIMIT ? OFFSET ?';
    params.push(parseInt(limit), offset);
    
    const alerts = await database.query(query, params);
    
    // Get total count
    let countQuery = 'SELECT COUNT(*) as total FROM alerts WHERE 1=1';
    const countParams = [];
    
    if (status) {
      countQuery += ' AND status = ?';
      countParams.push(status);
    }
    
    if (severity) {
      countQuery += ' AND severity = ?';
      countParams.push(severity);
    }
    
    if (device_id) {
      countQuery += ' AND device_id = ?';
      countParams.push(device_id);
    }
    
    const [countResult] = await database.query(countQuery, countParams);
    const total = countResult.total;
    
    res.json({
      success: true,
      data: alerts,
      pagination: {
        page: parseInt(page),
        limit: parseInt(limit),
        total,
        pages: Math.ceil(total / limit)
      }
    });
  } catch (error) {
    logger.error('Get alerts error:', error);
    res.status(500).json({
      success: false,
      message: 'Failed to get alerts'
    });
  }
});

// Get alert by ID
router.get('/:alertId', protect, async (req, res) => {
  try {
    const { alertId } = req.params;
    
    const alerts = await database.query(
      'SELECT * FROM alerts WHERE id = ?',
      [alertId]
    );
    
    if (alerts.length === 0) {
      return res.status(404).json({
        success: false,
        message: 'Alert not found'
      });
    }
    
    res.json({
      success: true,
      data: alerts[0]
    });
  } catch (error) {
    logger.error('Get alert error:', error);
    res.status(500).json({
      success: false,
      message: 'Failed to get alert'
    });
  }
});

// Acknowledge alert
router.post('/:alertId/acknowledge', protect, async (req, res) => {
  try {
    const { alertId } = req.params;
    
    await alertService.acknowledgeAlert(alertId, req.user.id);
    
    res.json({
      success: true,
      message: 'Alert acknowledged successfully'
    });
  } catch (error) {
    logger.error('Acknowledge alert error:', error);
    res.status(500).json({
      success: false,
      message: 'Failed to acknowledge alert'
    });
  }
});

// Resolve alert
router.post('/:alertId/resolve', protect, [
  body('resolution').optional().isString().withMessage('Resolution must be a string')
], async (req, res) => {
  try {
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
      return res.status(400).json({
        success: false,
        errors: errors.array()
      });
    }
    
    const { alertId } = req.params;
    const { resolution } = req.body;
    
    await alertService.resolveAlert(alertId, req.user.id, resolution);
    
    res.json({
      success: true,
      message: 'Alert resolved successfully'
    });
  } catch (error) {
    logger.error('Resolve alert error:', error);
    res.status(500).json({
      success: false,
      message: 'Failed to resolve alert'
    });
  }
});

// Get alert statistics
router.get('/stats/overview', protect, async (req, res) => {
  try {
    const { period = '24h' } = req.query;
    
    let timeFilter;
    switch (period) {
      case '1h':
        timeFilter = 'DATE_SUB(NOW(), INTERVAL 1 HOUR)';
        break;
      case '24h':
        timeFilter = 'DATE_SUB(NOW(), INTERVAL 24 HOUR)';
        break;
      case '7d':
        timeFilter = 'DATE_SUB(NOW(), INTERVAL 7 DAY)';
        break;
      case '30d':
        timeFilter = 'DATE_SUB(NOW(), INTERVAL 30 DAY)';
        break;
      default:
        timeFilter = 'DATE_SUB(NOW(), INTERVAL 24 HOUR)';
    }
    
    // Get total alerts
    const [totalAlerts] = await database.query(
      `SELECT COUNT(*) as count FROM alerts WHERE created_at >= ${timeFilter}`
    );
    
    // Get alerts by severity
    const severityStats = await database.query(
      `SELECT severity, COUNT(*) as count FROM alerts WHERE created_at >= ${timeFilter} GROUP BY severity`
    );
    
    // Get alerts by status
    const statusStats = await database.query(
      `SELECT status, COUNT(*) as count FROM alerts WHERE created_at >= ${timeFilter} GROUP BY status`
    );
    
    // Get alerts by type
    const typeStats = await database.query(
      `SELECT type, COUNT(*) as count FROM alerts WHERE created_at >= ${timeFilter} GROUP BY type ORDER BY count DESC LIMIT 10`
    );
    
    const stats = {
      period,
      total_alerts: totalAlerts.count,
      by_severity: severityStats,
      by_status: statusStats,
      by_type: typeStats
    };
    
    res.json({
      success: true,
      data: stats
    });
  } catch (error) {
    logger.error('Get alert stats error:', error);
    res.status(500).json({
      success: false,
      message: 'Failed to get alert statistics'
    });
  }
});

module.exports = router;