<?php
/**
 * Push Notification Handler
 * 
 * Handles browser push notifications for PWA.
 * 
 * @package WooNooW\Core\Notifications
 */

namespace WooNooW\Core\Notifications;

class PushNotificationHandler {
	
	/**
	 * Option key for storing subscriptions
	 */
	const SUBSCRIPTIONS_KEY = 'woonoow_push_subscriptions';
	
	/**
	 * Option key for VAPID keys
	 */
	const VAPID_KEYS_KEY = 'woonoow_push_vapid_keys';
	
	/**
	 * Initialize push notifications
	 */
	public static function init() {
		// Generate VAPID keys if not exists
		self::ensure_vapid_keys();
	}
	
	/**
	 * Ensure VAPID keys exist
	 * 
	 * @return array
	 */
	public static function ensure_vapid_keys() {
		$keys = get_option(self::VAPID_KEYS_KEY);
		
		if (!$keys || !isset($keys['public_key']) || !isset($keys['private_key'])) {
			// Generate new VAPID keys
			$keys = self::generate_vapid_keys();
			update_option(self::VAPID_KEYS_KEY, $keys);
		}
		
		return $keys;
	}
	
	/**
	 * Generate VAPID keys
	 * 
	 * @return array
	 */
	private static function generate_vapid_keys() {
		// For now, use placeholder keys
		// In production, use web-push library or external service
		return [
			'public_key' => base64_encode(random_bytes(65)),
			'private_key' => base64_encode(random_bytes(32)),
			'generated_at' => current_time('mysql'),
		];
	}
	
	/**
	 * Get VAPID public key
	 * 
	 * @return string
	 */
	public static function get_public_key() {
		$keys = self::ensure_vapid_keys();
		return $keys['public_key'];
	}
	
	/**
	 * Subscribe to push notifications
	 * 
	 * @param array $subscription Subscription data
	 * @param int $user_id User ID
	 * @return bool
	 */
	public static function subscribe($subscription, $user_id = 0) {
		$subscriptions = get_option(self::SUBSCRIPTIONS_KEY, []);
		
		$subscription_id = md5(json_encode($subscription));
		
		$subscriptions[$subscription_id] = [
			'subscription' => $subscription,
			'user_id' => $user_id,
			'subscribed_at' => current_time('mysql'),
		];
		
		return update_option(self::SUBSCRIPTIONS_KEY, $subscriptions);
	}
	
	/**
	 * Unsubscribe from push notifications
	 * 
	 * @param string $subscription_id Subscription ID
	 * @return bool
	 */
	public static function unsubscribe($subscription_id) {
		$subscriptions = get_option(self::SUBSCRIPTIONS_KEY, []);
		
		if (isset($subscriptions[$subscription_id])) {
			unset($subscriptions[$subscription_id]);
			return update_option(self::SUBSCRIPTIONS_KEY, $subscriptions);
		}
		
		return false;
	}
	
	/**
	 * Get all subscriptions
	 * 
	 * @param int $user_id Optional user ID filter
	 * @return array
	 */
	public static function get_subscriptions($user_id = null) {
		$subscriptions = get_option(self::SUBSCRIPTIONS_KEY, []);
		
		if ($user_id !== null) {
			return array_filter($subscriptions, function($sub) use ($user_id) {
				return $sub['user_id'] == $user_id;
			});
		}
		
		return $subscriptions;
	}
	
	/**
	 * Send push notification
	 * 
	 * @param string $title Notification title
	 * @param string $body Notification body
	 * @param array $options Additional options
	 * @param int $user_id Optional user ID to target
	 * @return int Number of notifications sent
	 */
	public static function send($title, $body, $options = [], $user_id = null) {
		$subscriptions = self::get_subscriptions($user_id);
		
		if (empty($subscriptions)) {
			return 0;
		}
		
		$payload = [
			'title' => $title,
			'body' => $body,
			'icon' => $options['icon'] ?? get_site_icon_url(),
			'badge' => $options['badge'] ?? get_site_icon_url(),
			'data' => $options['data'] ?? [],
			'actions' => $options['actions'] ?? [],
		];
		
		$sent = 0;
		
		foreach ($subscriptions as $subscription_id => $sub) {
			try {
				// In production, use web-push library
				// For now, store in queue for service worker to fetch
				self::queue_notification($subscription_id, $payload);
				$sent++;
			} catch (\Exception $e) {
				error_log('Push notification error: ' . $e->getMessage());
			}
		}
		
		return $sent;
	}
	
	/**
	 * Queue notification for delivery
	 * 
	 * @param string $subscription_id Subscription ID
	 * @param array $payload Notification payload
	 */
	private static function queue_notification($subscription_id, $payload) {
		$queue = get_option('woonoow_push_queue', []);
		
		$queue[] = [
			'subscription_id' => $subscription_id,
			'payload' => $payload,
			'queued_at' => current_time('mysql'),
		];
		
		update_option('woonoow_push_queue', $queue);
	}
	
	/**
	 * Get queued notifications for user
	 * 
	 * @param int $user_id User ID
	 * @return array
	 */
	public static function get_queued_notifications($user_id) {
		$queue = get_option('woonoow_push_queue', []);
		$subscriptions = self::get_subscriptions($user_id);
		$subscription_ids = array_keys($subscriptions);
		
		$user_notifications = array_filter($queue, function($item) use ($subscription_ids) {
			return in_array($item['subscription_id'], $subscription_ids);
		});
		
		// Clear delivered notifications
		$remaining = array_filter($queue, function($item) use ($subscription_ids) {
			return !in_array($item['subscription_id'], $subscription_ids);
		});
		
		update_option('woonoow_push_queue', $remaining);
		
		return array_values($user_notifications);
	}
}