<?php
	/**
	 * @package   Freemius
	 * @copyright Copyright (c) 2015, Freemius, Inc.
	 * @license   https://www.gnu.org/licenses/gpl-3.0.html GNU General Public License Version 3
	 * @since     2.6.0
	 */

	if ( ! defined( 'ABSPATH' ) ) {
		exit;
	}

	interface FS_I_Garbage_Collector {
		function clean();
	}

	class FS_Product_Garbage_Collector implements FS_I_Garbage_Collector {
		/**
		 * @var FS_Options
		 */
		private $_accounts;

		/**
		 * @var string[]
		 */
		private $_options_names;

		/**
		 * @var string
		 */
		private $_type;

		/**
		 * @var string
		 */
		private $_plural_type;

		/**
		 * @var array<string, int> Map of product slugs to their last load timestamp, only for products that are not active.
		 */
		private $_gc_timestamp;

		/**
		 * @var array<string, array<string, mixed>> Map of product slugs to their data, as stored by the primary storage of `Freemius` class.
		 */
		private $_storage_data;

		function __construct( FS_Options $_accounts, $option_names, $type ) {
			$this->_accounts      = $_accounts;
			$this->_options_names = $option_names;
			$this->_type          = $type;
			$this->_plural_type   = ( $type . 's' );
		}

		function clean() {
			$this->_gc_timestamp  = $this->_accounts->get_option( 'gc_timestamp', array() );
			$this->_storage_data  = $this->_accounts->get_option( $this->_type . '_data', array() );

			$options            = $this->load_options();
			$has_updated_option = false;

			$filtered_products         = $this->get_filtered_products();
			$products_to_clean         = $filtered_products['products_to_clean'];
			$active_products_by_id_map = $filtered_products['active_products_by_id_map'];

			foreach( $products_to_clean as $product ) {
				$slug = $product->slug;

				// Clear the product's data.
				foreach( $options as $option_name => $option ) {
					$updated = false;

					/**
					 * We expect to deal with only array like options here.
					 * @todo - Refactor this to create dedicated GC classes for every option, then we can make the code mode predictable.
					 *       For example, depending on data integrity of `plugins` we can still miss something entirely in the `plugin_data` or vice-versa.
					 *       A better algorithm is to iterate over all options individually in separate classes and check against primary storage to see if those can be garbage collected.
					 *       But given the chance of data integrity issue is very low, we let this run for now and gather feedback.
					 */
					if ( ! is_array( $option ) ) {
						continue;
					}

					if ( array_key_exists( $slug, $option ) ) {
						unset( $option[ $slug ] );
						$updated = true;
					} else if ( array_key_exists( "{$slug}:{$this->_type}", $option ) ) { /* admin_notices */
						unset( $option[ "{$slug}:{$this->_type}" ] );
						$updated = true;
					} else if ( isset( $product->id ) && array_key_exists( $product->id, $option ) ) { /* all_licenses, add-ons, and id_slug_type_path_map */
						$is_inactive_by_id   = ! isset( $active_products_by_id_map[ $product->id ] );
						$is_inactive_by_slug = (
							'id_slug_type_path_map' === $option_name &&
							(
								! isset( $option[ $product->id ]['slug'] ) ||
								$slug === $option[ $product->id ]['slug']
							)
						);

						if ( $is_inactive_by_id || $is_inactive_by_slug ) {
							unset( $option[ $product->id ] );
							$updated = true;
						}
					} else if ( /* file_slug_map */
						isset( $product->file ) &&
						array_key_exists( $product->file, $option ) &&
						$slug === $option[ $product->file ]
					) {
						unset( $option[ $product->file ] );
						$updated = true;
					}

					if ( $updated ) {
						$this->_accounts->set_option( $option_name, $option );

						$options[ $option_name ] = $option;

						$has_updated_option = true;
					}
				}

				// Clear the product's data from the primary storage.
				if ( isset( $this->_storage_data[ $slug ] ) ) {
					unset( $this->_storage_data[ $slug ] );
					$has_updated_option = true;
				}

				// Clear from GC timestamp.
				// @todo - This perhaps needs a separate garbage collector for all expired products. But the chance of left-over is very slim.
				if ( isset( $this->_gc_timestamp[ $slug ] ) ) {
					unset( $this->_gc_timestamp[ $slug ] );
					$has_updated_option = true;
				}
			}

			$this->_accounts->set_option( 'gc_timestamp', $this->_gc_timestamp );
			$this->_accounts->set_option( $this->_type . '_data', $this->_storage_data );

			return $has_updated_option;
		}

		private function get_all_option_names() {
			return array_merge(
				array(
					'admin_notices',
					'updates',
					'all_licenses',
					'addons',
					'id_slug_type_path_map',
					'file_slug_map',
				),
				$this->_options_names
			);
		}

		private function get_products() {
			$products = $this->_accounts->get_option( $this->_plural_type, array() );

			// Fill any missing product found in the primary storage.
			// @todo - This wouldn't be needed if we use dedicated GC design for every options. The options themselves would provide such information.
			foreach( $this->_storage_data as $slug => $product_data ) {
				if ( ! isset( $products[ $slug ] ) ) {
					$products[ $slug ] = (object) $product_data;
				}

				// This is needed to handle a scenario in which there are duplicate sets of data for the same product, but one of them needs to be removed.
				$products[ $slug ] = clone $products[ $slug ];

				// The reason for having the line above. This also handles a scenario in which the slug is either empty or not empty but incorrect.
				$products[ $slug ]->slug = $slug;
			}

			$this->update_gc_timestamp( $products );

			return $products;
		}

		private function get_filtered_products() {
			$products_to_clean         = array();
			$active_products_by_id_map = array();

			$products = $this->get_products();

			foreach ( $products as $slug => $product_data ) {
				if ( ! is_object( $product_data ) ) {
					continue;
				}

				if ( $this->is_product_active( $slug ) ) {
					$active_products_by_id_map[ $product_data->id ] = true;
					continue;
				}

				$is_addon = ( ! empty( $product_data->parent_plugin_id ) );

				if ( ! $is_addon ) {
					$products_to_clean[] = $product_data;
				} else {
					/**
					 * If add-on, add to the beginning of the array so that add-ons are removed before their parent. This is to prevent an unexpected issue when an add-on exists but its parent was already removed.
					 */
					array_unshift( $products_to_clean, $product_data );
				}
			}

			return array(
				'products_to_clean'         => $products_to_clean,
				'active_products_by_id_map' => $active_products_by_id_map,
			);
		}

		/**
		 * @param string $slug
		 *
		 * @return bool
		 */
		private function is_product_active( $slug ) {
			$instances = Freemius::_get_all_instances();

			foreach ( $instances as $instance ) {
				if ( $instance->get_slug() === $slug ) {
					return true;
				}
			}

			$expiration_time = fs_get_optional_constant( 'WP_FS__GARBAGE_COLLECTOR_EXPIRATION_TIME_SECS', ( WP_FS__TIME_WEEK_IN_SEC * 4 ) );

			if ( $this->get_last_load_timestamp( $slug ) > ( time() - $expiration_time ) ) {
				// Last activation was within the last 4 weeks.
				return true;
			}

			return false;
		}

		private function load_options() {
			$options      = array();
			$option_names = $this->get_all_option_names();

			foreach ( $option_names as $option_name ) {
				$options[ $option_name ] = $this->_accounts->get_option( $option_name, array() );
			}

			return $options;
		}

		/**
		 * Updates the garbage collector timestamp, only if it was not already set by the product's primary storage.
		 *
		 * @param array $products
		 *
		 * @return void
		 */
		private function update_gc_timestamp( $products ) {
			foreach ($products as $slug => $product_data) {
				if ( ! is_object( $product_data ) && ! is_array( $product_data ) ) {
					continue;
				}


				// If the product is active, we don't need to update the gc_timestamp.
				if ( isset( $this->_storage_data[ $slug ]['last_load_timestamp'] ) ) {
					continue;
				}

				// First try to check if the product is present in the primary storage. If so update that.
				if ( isset( $this->_storage_data[ $slug ] ) ) {
					$this->_storage_data[ $slug ]['last_load_timestamp'] = time();
				} else if ( ! isset( $this->_gc_timestamp[ $slug ] ) ) {
					// If not, fallback to the gc_timestamp, but we don't want to update it more than once.
					$this->_gc_timestamp[ $slug ] = time();
				}
			}
		}

		private function get_last_load_timestamp( $slug ) {
			if ( isset( $this->_storage_data[ $slug ]['last_load_timestamp'] ) ) {
				return $this->_storage_data[ $slug ]['last_load_timestamp'];
			}

			return isset( $this->_gc_timestamp[ $slug ] ) ?
				$this->_gc_timestamp[ $slug ] :
				// This should never happen, but if it does, let's assume the product is not expired.
				time();
		}
	}

	class FS_User_Garbage_Collector implements FS_I_Garbage_Collector {
		private $_accounts;

		private $_types;

		function __construct( FS_Options $_accounts, array $types ) {
			$this->_accounts = $_accounts;
			$this->_types    = $types;
		}

		function clean() {
			$users = Freemius::get_all_users();

			$user_has_install_map = $this->get_user_has_install_map();

			if ( count( $users ) === count( $user_has_install_map ) ) {
				return false;
			}

			$products_user_id_license_ids_map = $this->_accounts->get_option( 'user_id_license_ids_map', array() );

			$has_updated_option = false;

			foreach ( $users as $user_id => $user ) {
				if ( ! isset( $user_has_install_map[ $user_id ] ) ) {
					unset( $users[ $user_id ] );

					foreach( $products_user_id_license_ids_map as $product_id => $user_id_license_ids_map ) {
						unset( $user_id_license_ids_map[ $user_id ] );

						if ( empty( $user_id_license_ids_map ) ) {
							unset( $products_user_id_license_ids_map[ $product_id ] );
						} else {
							$products_user_id_license_ids_map[ $product_id ] = $user_id_license_ids_map;
						}
					}

					$this->_accounts->set_option( 'users', $users );
					$this->_accounts->set_option( 'user_id_license_ids_map', $products_user_id_license_ids_map );

					$has_updated_option = true;
				}
			}

			return $has_updated_option;
		}

		private function get_user_has_install_map() {
			$user_has_install_map = array();

			foreach ( $this->_types as $product_type ) {
				$option_name = ( WP_FS__MODULE_TYPE_PLUGIN !== $product_type ) ?
					"{$product_type}_sites" :
					'sites';

				$installs = $this->_accounts->get_option( $option_name, array() );

				foreach ( $installs as $install ) {
					$user_has_install_map[ $install->user_id ] = true;
				}
			}

			return $user_has_install_map;
		}
	}

	// Main entry-level class.
	class FS_Garbage_Collector implements FS_I_Garbage_Collector {
		/**
		 * @var FS_Garbage_Collector
		 * @since 2.6.0
		 */
		private static $_instance;

		/**
		 * @return FS_Garbage_Collector
		 */
		static function instance() {
			if ( ! isset( self::$_instance ) ) {
				self::$_instance = new self();
			}

			return self::$_instance;
		}

		#endregion

		private function __construct() {
		}

		function clean() {
			$_accounts = FS_Options::instance( WP_FS__ACCOUNTS_OPTION_NAME, true );

			$products_cleaners = $this->get_product_cleaners( $_accounts );

			$has_cleaned = false;

			foreach ( $products_cleaners as $products_cleaner ) {
				if ( $products_cleaner->clean() ) {
					$has_cleaned = true;
				}
			}

			if ( $has_cleaned ) {
				$user_cleaner = new FS_User_Garbage_Collector(
					$_accounts,
					array_keys( $products_cleaners )
				);

				$user_cleaner->clean();
			}

			// @todo - We need a garbage collector for `all_plugins` and `active_plugins` (and variants of themes).

			// Always store regardless of whether there were cleaned products or not since during the process, the logic may set the last load timestamp of some products.
			$_accounts->store();
		}

		/**
		 * @param FS_Options $_accounts
		 *
		 * @return FS_I_Garbage_Collector[]
		 */
		private function get_product_cleaners( FS_Options $_accounts ) {
			/**
			 * @var FS_I_Garbage_Collector[] $products_cleaners
			 */
			$products_cleaners = array();

			$products_cleaners[ WP_FS__MODULE_TYPE_PLUGIN ] = new FS_Product_Garbage_Collector(
				$_accounts,
				array(
					'sites',
					'plans',
					'plugins',
				),
				WP_FS__MODULE_TYPE_PLUGIN
			);

			$products_cleaners[ WP_FS__MODULE_TYPE_THEME ] = new FS_Product_Garbage_Collector(
				$_accounts,
				array(
					'theme_sites',
					'theme_plans',
					'themes',
				),
				WP_FS__MODULE_TYPE_THEME
			);

			return $products_cleaners;
		}
	}