<?php
/**
 * Cache manager for Dynamic Pricing.
 *
 * @package AICOSO_Dynamic_Pricing_For_WooCommerce
 */

// Exit if accessed directly.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Cache manager class.
 */
class DP_AICOSO_Cache_Manager {

	/**
	 * Cache group name.
	 *
	 * @var string
	 */
	private $cache_group = 'dp_aicoso_prices';

	/**
	 * Default cache expiry time in seconds.
	 *
	 * @var int
	 */
	private $cache_expiry = 3600; // 1 hour.

	/**
	 * Whether to use database cache.
	 *
	 * @var bool
	 */
	private $use_db_cache = true;

	/**
	 * Constructor.
	 */
	public function __construct() {
		// Load settings.
		$settings = get_option( 'dp_aicoso_settings', array() );

		if ( isset( $settings['cache_expiry'] ) ) {
			$this->cache_expiry = intval( $settings['cache_expiry'] );
		}

		if ( isset( $settings['enable_cache'] ) ) {
			$this->use_db_cache = (bool) $settings['enable_cache'];
		}

		// Schedule cache cleanup.
		add_action( 'dp_aicoso_cleanup_cache', array( $this, 'cleanup_expired_cache' ) );
	}

	/**
	 * Get cached value.
	 *
	 * @param string $key Cache key.
	 * @return mixed|false Cached value or false.
	 */
	public function get( $key ) {
		// Try object cache first.
		$value = wp_cache_get( $key, $this->cache_group );
		if ( false !== $value ) {
			return $value;
		}

		// Try transient cache.
		$value = get_transient( $key );
		if ( false !== $value ) {
			// Also set in object cache for this request.
			wp_cache_set( $key, $value, $this->cache_group, $this->cache_expiry );
			return $value;
		}

		// Try database cache if enabled.
		if ( $this->use_db_cache ) {
			$value = $this->get_from_database( $key );
			if ( false !== $value ) {
				// Set in faster caches.
				wp_cache_set( $key, $value, $this->cache_group, $this->cache_expiry );
				set_transient( $key, $value, $this->cache_expiry );
				return $value;
			}
		}

		return false;
	}

	/**
	 * Set cache value.
	 *
	 * @param string $key    Cache key.
	 * @param mixed  $value  Value to cache.
	 * @param int    $expiry Expiry time in seconds (optional).
	 * @return bool Success.
	 */
	public function set( $key, $value, $expiry = null ) {
		if ( null === $expiry ) {
			$expiry = $this->cache_expiry;
		}

		// Set in object cache.
		wp_cache_set( $key, $value, $this->cache_group, $expiry );

		// Set in transient cache.
		set_transient( $key, $value, $expiry );

		// Set in database cache if enabled.
		if ( $this->use_db_cache ) {
			$this->set_in_database( $key, $value, $expiry );
		}

		return true;
	}

	/**
	 * Delete cached value.
	 *
	 * @param string $key Cache key.
	 * @return bool Success.
	 */
	public function delete( $key ) {
		// Delete from object cache.
		wp_cache_delete( $key, $this->cache_group );

		// Delete transient.
		delete_transient( $key );

		// Delete from database.
		if ( $this->use_db_cache ) {
			$this->delete_from_database( $key );
		}

		return true;
	}

	/**
	 * Flush all cache.
	 */
	public function flush() {
		// Clear object cache for our group.
		wp_cache_flush_group( $this->cache_group );

		// Clear transients.
		global $wpdb;
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Cache clearing operation
		$wpdb->query(
			$wpdb->prepare(
				"DELETE FROM {$wpdb->options}
				WHERE option_name LIKE %s
				OR option_name LIKE %s",
				'_transient_dp_aicoso_%',
				'_transient_timeout_dp_aicoso_%'
			)
		);

		// Clear database cache.
		if ( $this->use_db_cache ) {
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.DirectDatabaseQuery.SchemaChange -- Table truncation operation, table name is hardcoded
			$wpdb->query( 'TRUNCATE TABLE `' . $wpdb->prefix . 'dp_aicoso_price_cache`' );
		}
	}

	/**
	 * Get value from database cache.
	 *
	 * @param string $key Cache key.
	 * @return mixed|false Cached value or false.
	 */
	private function get_from_database( $key ) {
		global $wpdb;

		// Using hardcoded table reference to avoid PHPCS issues.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Cache retrieval operation
		$result = $wpdb->get_row(
			$wpdb->prepare(
				'SELECT calculated_price, expires_at FROM `' . $wpdb->prefix . 'dp_aicoso_price_cache` WHERE cache_key = %s AND expires_at > %s LIMIT 1',
				$key,
				current_time( 'mysql' )
			)
		);

		if ( $result ) {
			return floatval( $result->calculated_price );
		}

		return false;
	}

	/**
	 * Set value in database cache.
	 *
	 * @param string $key    Cache key.
	 * @param mixed  $value  Value to cache.
	 * @param int    $expiry Expiry time in seconds.
	 */
	private function set_in_database( $key, $value, $expiry ) {
		global $wpdb;

		// Calculate expiry time.
		$expires_at = gmdate( 'Y-m-d H:i:s', current_time( 'timestamp' ) + $expiry );

		// Extract context from key if possible.
		$product_id = 0;
		$user_role = 'guest';
		$quantity = 1;

		// Try to parse key for context (simplified).
		if ( preg_match( '/price_(\d+)_(\d+)_([^_]+)/', $key, $matches ) ) {
			$product_id = intval( $matches[1] );
			$quantity = intval( $matches[2] );
			$user_role = sanitize_text_field( $matches[3] );
		}

		// Insert or update cache entry.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Write operation for cache storage
		$wpdb->replace(
			$wpdb->prefix . 'dp_aicoso_price_cache',
			array(
				'cache_key'        => $key,
				'product_id'       => $product_id,
				'user_role'        => $user_role,
				'quantity'         => $quantity,
				'calculated_price' => floatval( $value ),
				'original_price'   => 0, // Would need to be passed in for accuracy.
				'applied_rules'    => '', // Would need to be passed in.
				'expires_at'       => $expires_at,
			),
			array( '%s', '%d', '%s', '%d', '%f', '%f', '%s', '%s' )
		);
	}

	/**
	 * Delete value from database cache.
	 *
	 * @param string $key Cache key.
	 */
	private function delete_from_database( $key ) {
		global $wpdb;

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Write operation for cache deletion
		$wpdb->delete(
			$wpdb->prefix . 'dp_aicoso_price_cache',
			array( 'cache_key' => $key ),
			array( '%s' )
		);
	}

	/**
	 * Cleanup expired cache entries.
	 */
	public function cleanup_expired_cache() {
		if ( ! $this->use_db_cache ) {
			return;
		}

		global $wpdb;

		// Delete expired entries.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Cache maintenance operation
		$wpdb->query(
			$wpdb->prepare(
				'DELETE FROM `' . $wpdb->prefix . 'dp_aicoso_price_cache` WHERE expires_at < %s',
				current_time( 'mysql' )
			)
		);

		// Log cleanup.
		if ( $wpdb->rows_affected > 0 ) {
			// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log -- Debug logging for cache cleanup
			error_log( sprintf( 'DP AICOSO: Cleaned up %d expired cache entries', $wpdb->rows_affected ) );
		}
	}

	/**
	 * Clear cache for specific product.
	 *
	 * @param int $product_id Product ID.
	 */
	public function clear_product_cache( $product_id ) {
		global $wpdb;

		// Clear transients.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Cache clearing operation
		$wpdb->query(
			$wpdb->prepare(
				"DELETE FROM {$wpdb->options}
				WHERE option_name LIKE %s",
				'_transient_dp_aicoso_%_' . $product_id . '_%'
			)
		);

		// Clear database cache.
		if ( $this->use_db_cache ) {
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Write operation for cache clearing
			$wpdb->delete(
				$wpdb->prefix . 'dp_aicoso_price_cache',
				array( 'product_id' => $product_id ),
				array( '%d' )
			);
		}
	}

	/**
	 * Clear cache for specific user role.
	 *
	 * @param string $role User role.
	 */
	public function clear_role_cache( $role ) {
		global $wpdb;

		// Clear transients.
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Cache clearing operation
		$wpdb->query(
			$wpdb->prepare(
				"DELETE FROM {$wpdb->options}
				WHERE option_name LIKE %s",
				'_transient_dp_aicoso_%_' . $role . '_%'
			)
		);

		// Clear database cache.
		if ( $this->use_db_cache ) {
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Write operation for cache clearing
			$wpdb->delete(
				$wpdb->prefix . 'dp_aicoso_price_cache',
				array( 'user_role' => $role ),
				array( '%s' )
			);
		}
	}

	/**
	 * Get cache statistics.
	 *
	 * @return array Cache statistics.
	 */
	public function get_stats() {
		global $wpdb;
		$stats = array(
			'total_entries' => 0,
			'expired_entries' => 0,
			'cache_size' => 0,
			'hit_rate' => 0,
		);

		if ( $this->use_db_cache ) {
			// Total entries.
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Stats query
			$stats['total_entries'] = $wpdb->get_var( 'SELECT COUNT(*) FROM `' . $wpdb->prefix . 'dp_aicoso_price_cache`' );

			// Expired entries.
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Stats query
			$stats['expired_entries'] = $wpdb->get_var(
				$wpdb->prepare(
					'SELECT COUNT(*) FROM `' . $wpdb->prefix . 'dp_aicoso_price_cache` WHERE expires_at < %s',
					current_time( 'mysql' )
				)
			);

			// Cache table size.
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- Stats query for cache information
			$table_status = $wpdb->get_row(
				$wpdb->prepare(
					'SELECT ' .
						'ROUND(((data_length + index_length) / 1024 / 1024), 2) AS size_mb ' .
					'FROM information_schema.TABLES ' .
					'WHERE table_schema = %s ' .
					'AND table_name = %s',
					DB_NAME,
					$wpdb->prefix . 'dp_aicoso_price_cache'
				)
			);

			if ( $table_status ) {
				$stats['cache_size'] = $table_status->size_mb . ' MB';
			}
		}

		return $stats;
	}
}