<?php
/**
 * LocationIntelligenceEngine.php
 * Core engine for processing passenger location updates from various sources
 * (App Usage, Geofencing, Silent Push) and making automated decisions.
 */

class LocationIntelligenceEngine {
    private $db;
    
    public function __construct($dbConnection) {
        $this->db = $dbConnection;
    }

    /**
     * Process a location update from any source.
     * 
     * @param int|string $passengerId
     * @param float $lat
     * @param float $lng
     * @param string $source Enum: 'app_usage', 'geofence', 'silent_push'
     * @return array Optional new geofence regions to register on user's device
     */
    public function processLocationUpdate($passengerId, $lat, $lng, $source = 'app_usage', $batteryLevel = null) {
        // 1. Update Database
        $this->updateLocationDatabase($passengerId, $lat, $lng, $source, $batteryLevel);
        
        $zone = null;
        // 2. Check for Geofence intersections (always evaluate what zone they are in)
        $zone = $this->checkGeofenceZone($lat, $lng);
        
        if ($zone) {
            // 3. Trigger Campaigns / Notifications
            $this->evaluateCampaignOpportunity($passengerId, $zone, $source);
        }
        
        // 4. Update Driver Demand Map
        $this->updateDemandMap($passengerId, $lat, $lng);
        
        // 5. Get Geofencing regions for the user's device (closest ones)
        // iOS allows 20, Android 100. We'll return top 20 by default.
        return $this->getUpdatedGeofencesForUser($lat, $lng);
    }
    
    private function updateLocationDatabase($passengerId, $lat, $lng, $source, $batteryLevel) {
        try {
            $sql = "INSERT INTO passenger_opening_locations (passenger_id, latitude, longitude, source, battery_level) 
                    VALUES (:pid, :lat, :lng, :source, :battery)";
            $stmt = $this->db->prepare($sql);
            $stmt->execute([
                ':pid' => $passengerId,
                ':lat' => $lat,
                ':lng' => $lng,
                ':source' => $source,
                ':battery' => $batteryLevel
            ]);
        } catch (Exception $e) {
            error_log("[LocationIntelligenceEngine] DB Error: " . $e->getMessage());
        }
    }
    
    private function checkGeofenceZone($lat, $lng) {
        // Find if the user's lat/lng is within the radius of any active geofence zone
        // Using Haversine formula
        $sql = "SELECT id, zone_name, country_code, radius_meters, 
                (6371000 * acos(cos(radians(:lat)) * cos(radians(latitude)) * cos(radians(longitude) - radians(:lng)) + sin(radians(:lat)) * sin(radians(latitude)))) AS distance 
                FROM geofence_zones 
                WHERE is_active = 1 
                HAVING distance <= radius_meters 
                ORDER BY distance ASC LIMIT 1";
        $stmt = $this->db->prepare($sql);
        $stmt->execute([':lat' => $lat, ':lng' => $lng]);
        return $stmt->fetch(PDO::FETCH_ASSOC);
    }
    
    private function evaluateCampaignOpportunity($passengerId, $zone, $source) {
        // Avoid spamming if source is silent_push, maybe only do it for geofence or app_usage
        if ($source === 'silent_push') {
            return; // Don't trigger active campaigns on silent push to save battery and avoid weird timing
        }

        // 1. Check if passenger received a campaign recently (Anti-Spam)
        $sqlSpamCheck = "SELECT COUNT(*) FROM marketing_campaigns_log 
                         WHERE passenger_id = :pid 
                         AND message_type = 'push' 
                         AND sent_at > DATE_SUB(NOW(), INTERVAL 24 HOUR)";
        $stmtSpam = $this->db->prepare($sqlSpamCheck);
        $stmtSpam->execute([':pid' => $passengerId]);
        $spamCount = intval($stmtSpam->fetchColumn());

        if ($spamCount == 0) {
            // 2. Check if there is an ACTIVE marketing campaign for this specific zone or country
            // TODO: Link this to your promos/campaigns table to see if an offer is currently running.
            // DO NOT send a generic "Welcome" notification as it is annoying to users.
            // We only send a push if there's a real incentive (e.g. discount code).
            
            // Example of what will be here:
            // $campaign = $this->getActiveCampaignForZone($zone['id']);
            // if ($campaign) {
            //     $this->sendCampaignNotification($passengerId, $campaign);
            // }
        }
    }
    
    private function updateDemandMap($passengerId, $lat, $lng) {
        // Broadcast this location to drivers or update a demand heat map cache
        // Here we insert into passengerlocation to log the hotspot.
        try {
            $sql = "INSERT INTO passengerlocation (passengerId, lat, lng, rideId) VALUES (:pid, :lat, :lng, '0')";
            $stmt = $this->db->prepare($sql);
            // $stmt->execute([':pid' => $passengerId, ':lat' => $lat, ':lng' => $lng]); // Suppressed for now to avoid db constraints errors
        } catch (Exception $e) {
            error_log("[LocationIntelligenceEngine] Demand Map Error: " . $e->getMessage());
        }
    }

    private function getUpdatedGeofencesForUser($lat, $lng, $limit = 20) {
        // Return top nearest geofences to update on the user's device
        $sql = "SELECT id, zone_name, latitude, longitude, radius_meters, 
                (6371000 * acos(cos(radians(:lat)) * cos(radians(latitude)) * cos(radians(longitude) - radians(:lng)) + sin(radians(:lat)) * sin(radians(latitude)))) AS distance 
                FROM geofence_zones 
                WHERE is_active = 1 
                ORDER BY distance ASC LIMIT :limit";
        
        $stmt = $this->db->prepare($sql);
        $stmt->bindParam(':lat', $lat);
        $stmt->bindParam(':lng', $lng);
        $stmt->bindValue(':limit', (int) $limit, PDO::PARAM_INT);
        $stmt->execute();
        
        return $stmt->fetchAll(PDO::FETCH_ASSOC);
    }
}
?>