<?php
/**
 * APL Core Class
 *
 * Core object to Advanced Post List
 *
 * @link https://github.com/Advanced-Post-List/advanced-post-list/
 *
 * @package advanced-post-list
 * @since 0.1.0
 */

/**
 * APL Core
 *
 * Main Properties & Methods for Advanced Post List plugin.
 *
 * @since 0.1.0
 * @since 0.2.0
 * @since 0.3.0
 * @since 0.4.0 - Removed Admin functions and added into APL_Admin class.
 */
class APL_Core {

	/**
	 * APL Options Name
	 *
	 * @since 0.1.0
	 * @since 0.4.0 Changed name $_APL_OPTION_NAME to $_option_name
	 * @deprecated 0.4.0 Recommend manual param.
	 * @access public
	 * @var string
	 */
	private $_option_name = 'apl_options';

	/**
	 * Remove/Prevent Duplicate Posts
	 *
	 * @since 0.3.0
	 * @access public
	 * @var array
	 */
	private $_remove_duplicates = array();

	/**
	 * Core Constructor
	 *
	 * Constructor for APL_Core functionality.
	 *
	 * STEP 1: Set plugin file data/properties.
	 * STEP 2: Add Hooks.
	 * STEP 3: Add Admin Hooks.
	 *
	 * @since 0.1.0
	 * @since 0.2.0 - Refined how version checking was performed.
	 * @since 0.4.0 - Added hook for loading the textdomain to enable
	 *                internalization support.
	 *                Changed check version to hook method.
	 * @since 0.5.4 - Encapsulated operation in hook `action__init()`.
	 */
	public function __construct() {
		add_action( 'plugins_loaded', array( $this, 'action__init' ), 3 );
	}

	/**
	 * Initialization Action
	 *
	 * @since 0.5.4 - Move from constructor.
	 */
	public function action__init() {
		// Set plugin file data/properties.
		$this->_define_constants();
		$this->_requires();

		/* **** ACTION & FILTERS HOOKS **** */
		add_action( 'plugins_loaded', array( $this, 'action_check_version' ), 9 );
		add_action( 'plugins_loaded', array( $this, 'action_load_plugin_textdomain' ) );
		add_action( 'init', array( $this, 'action_register_post_type_post_list' ), 6 );
		add_action( 'init', array( $this, 'action_register_post_type_design' ), 6 );

		// Public Hooks.
		add_shortcode( 'post_list', array( $this, 'shortcode_post_list' ) );
		add_action( 'widgets_init', array( $this, 'action_widget_init' ) );

		/* **** ADMIN ACTION & FILTERS HOOKS **** */
		if ( is_admin() ) {
			// Admin Class.
			add_action( 'init', array( 'APL_Admin', 'get_instance' ) );

			/* **** ACTIVATE/DE-ACTIVATE/UNINSTALL HOOKS **** */
			$file_dir = APL_DIR . 'advanced-post-list.php';
			register_activation_hook( $file_dir, array( 'APL_Core', 'activation' ) );
			register_deactivation_hook( $file_dir, array( 'APL_Core', 'deactivation' ) );
			register_uninstall_hook( $file_dir, array( 'APL_Core', 'uninstall' ) );
		}
	}

	/**
	 * Define APL Constants
	 *
	 * Defines all the constants for APL.
	 *
	 * @ignore
	 * @since 0.3.2
	 * @access private
	 *
	 * @see get_file_data()
	 * @link https://hitchhackerguide.com/2011/02/12/get_plugin_data/
	 *
	 * @param string $plugin_file Main plugin file.
	 */
	private function _define_constants() {
		/*
		 * Get plugin-file-data from advanced-post-list.php, and grab
		 * the plugin's meta default_headers.
		 */
		$default_headers = array(
			'Name'    => 'Plugin Name',
			'Slug'    => 'Text Domain',
			'Version' => 'Version',
		);
		$plugin_data = get_file_data( __FILE__, $default_headers );

		/**
		 * APL Display Name.
		 *
		 * @since 0.1.0
		 * @since 0.3.2 - Moved from advanced-post-list.php to class-apl-core
		 *                APL_Core::_define_constants().
		 * @var string $APL_NAME Contains 'Advanced Post List'.
		 */
		define( 'APL_NAME', $plugin_data['Name'] );

		/**
		 * APL Slug.
		 *
		 * @since 0.3.2
		 * @var string $APL_SLUG Contains 'advanced-post-list'.
		 */
		define( 'APL_SLUG', $plugin_data['Slug'] );

		/**
		 * Version Number.
		 *
		 * @since 0.1.0
		 * @since 0.3.2 - Moved from advanced-post-list.php to class-apl-core
		 *                APL_Core::_define_constants().
		 * @var string $APL_VERSION Ex. '1.2.3'.
		 */
		define( 'APL_VERSION', $plugin_data['Version'] );

		/**
		 * URL Location.
		 *
		 * @since 0.1.0
		 * @since 0.3.2 - Moved from advanced-post-list.php to class-apl-core
		 *                APL_Core::_define_constants().
		 * @var string $APL_URL Contains 'http://localhost/wordpress/wp-content/plugins/advanced-post-list/'.
		 */
		define( 'APL_URL', plugin_dir_url( __FILE__ ) );

		/**
		 * Directory Path.
		 *
		 * @since 0.1.0
		 * @since 0.3.2 - Moved from advanced-post-list.php to class-apl-core
		 *                APL_Core::_define_constants().
		 * @var string $APL_DIR Contains 'C:\xampp\htdocs\wordpress\wp-content\plugins\advanced-post-list/'.
		 */
		define( 'APL_DIR', plugin_dir_path( __FILE__ ) );

		if ( ! defined( 'APL_TEMPLATE_DEBUG_MODE' ) ) {
			/**
			 * APL Template Debug
			 *
			 * @since 0.4.4.1
			 * @var boolean $APL_TEMPLATE_DEBUG_MODE Used for bypassing child theme customizations when debugging.
			 */
			define( 'APL_TEMPLATE_DEBUG_MODE', false );
		}
	}

	/**
	 * Add Required Files
	 *
	 * Adds the required files to include.
	 *
	 * @ignore
	 * @since 0.3.0
	 * @access private
	 *
	 * @see Function/method/class relied on
	 * @global string APL_DIR APL file path.
	 */
	private function _requires() {
		// PUBLIC.
		// Class Objects.
		require_once APL_DIR . 'includes/class/class-apl-post-list.php';
		require_once APL_DIR . 'includes/class/class-apl-design.php';
		require_once APL_DIR . 'includes/class/class-apl-widget.php';
		require_once APL_DIR . 'includes/class/class-apl-query.php';
		require_once APL_DIR . 'includes/class/class-apl-updater.php';
		// OLD - Remove between 0.4 - 0.6.
		require_once APL_DIR . 'includes/class/dep-class-apl-preset-db.php';
		require_once APL_DIR . 'includes/class/dep-class-apl-preset.php';
		require_once APL_DIR . 'includes/class/old-APLPresetDbObj.php';
		require_once APL_DIR . 'includes/class/old-APLPresetObj.php';

		// Functions.
		require_once APL_DIR . 'includes/functions.php';

		// ADMIN.
		require_once APL_DIR . 'admin/class-apl-admin.php';
	}

	/**
	 * Register the Design Post Type
	 *
	 * Hook for loading the textdomain location.
	 *
	 * @since 0.4.0
	 *
	 * @link https://codex.wordpress.org/Function_Reference/register_post_type WP Codex.
	 */
	public function action_register_post_type_post_list() {

		$args = array(
			'labels'              => array(
				'name'                  => __( 'APL Post Lists', 'advanced-post-list' ),
				'singular_name'         => __( 'Post List', 'advanced-post-list' ),
				'add_new'               => _x( 'Add New', 'List', 'advanced-post-list' ),
				'add_new_item'          => __( 'Add New Post List', 'advanced-post-list' ),
				'edit_item'             => __( 'Edit Post List', 'advanced-post-list' ),
				'new_item'              => __( 'New Post List', 'advanced-post-list' ),
				'view_item'             => __( 'View Post List', 'advanced-post-list' ),
				'view_items'            => __( 'View Post Lists', 'advanced-post-list' ),
				'search_items'          => __( 'Search Post Lists', 'advanced-post-list' ),
				'not_found'             => __( 'No Post Lists found', 'advanced-post-list' ),
				'not_found_in_trash'    => __( 'No Post Lists found in Trash', 'advanced-post-list' ),
				'parent_item_colon'     => __( ':', 'advanced-post-list' ),
				'all_items'             => __( 'All Post Lists', 'advanced-post-list' ),
				'archives'              => __( 'Post List Archives', 'advanced-post-list' ),
				'attributes'            => __( 'Post List Attributes', 'advanced-post-list' ),
				'insert_into_item'      => __( 'Insert into Post List', 'advanced-post-list' ),
				'uploaded_to_this_item' => __( 'Upload to this Post List', 'advanced-post-list' ),
				'menu_name'             => __( 'APL Post List', 'advanced-post-list' ),
			),
			'description'         => __( 'APL Preset Post Lists.', 'advanced-post-list' ),
			'public'              => true,
			'exclude_from_search' => true,
			'publicly_queryable'  => false,
			// Shows up in admin menu bar.
			'show_ui'             => true,
			'show_in_menu'        => 'advanced_post_list',
			'show_in_nav_menus'   => false,
			'show_in_admin_bar'   => true,
			'menu_position'       => 58,
			'menu_icon'           => 'dashicons-welcome-widgets-menus',
			'hierarchical'        => true,
			'supports'            => array(
				'title',
			),
			'has_archive'         => false,
			// Disables the URL query /?{query_var}={single_post_slug}.
			'query_var'           => false,
			// 'can_export'            => true, // Default true.
			'delete_with_user'    => false,
		);

		$args = apply_filters( 'apl_register_post_type_post_list', $args );
		register_post_type( 'apl_post_list', $args );
	}

	/**
	 * Register the Design Post Type
	 *
	 * Hook for loading the textdomain location.
	 *
	 * @since 0.4.0
	 *
	 * @link https://codex.wordpress.org/Function_Reference/register_post_type WP Codex.
	 */
	public function action_register_post_type_design() {
		$args = array(
			'labels'              => array(
				'name'                  => __( 'APL Designs', 'advanced-post-list' ),
				'singular_name'         => __( 'Design', 'advanced-post-list' ),
				'add_new'               => _x( 'Add New', 'design', 'advanced-post-list' ),
				'add_new_item'          => __( 'Add New Design', 'advanced-post-list' ),
				'edit_item'             => __( 'Edit Design', 'advanced-post-list' ),
				'new_item'              => __( 'New Design', 'advanced-post-list' ),
				'view_item'             => __( 'View Design', 'advanced-post-list' ),
				'view_items'            => __( 'View Designs', 'advanced-post-list' ),
				'search_items'          => __( 'Search Designs', 'advanced-post-list' ),
				'not_found'             => __( 'No Design found', 'advanced-post-list' ),
				'not_found_in_trash'    => __( 'No Design found in Trash', 'advanced-post-list' ),
				'parent_item_colon'     => __( ':', 'advanced-post-list' ),
				'all_items'             => __( 'All Designs', 'advanced-post-list' ),
				'archives'              => __( 'Design Archives', 'advanced-post-list' ),
				'attributes'            => __( 'Design Attributes', 'advanced-post-list' ),
				'insert_into_item'      => __( 'Insert into Design', 'advanced-post-list' ),
				'uploaded_to_this_item' => __( 'Upload to this Design', 'advanced-post-list' ),
				'menu_name'             => __( 'APL Design', 'advanced-post-list' ),
			),
			'description'         => __( 'APL Designs for Preset Post Lists.', 'advanced-post-list' ),
			'public'              => true,
			'exclude_from_search' => true,
			'publicly_queryable'  => false,
			// Shows up in admin area.
			'show_ui'             => false,
			'show_in_menu'        => false,
			'show_in_nav_menus'   => false,
			'show_in_admin_bar'   => false,
			'menu_icon'           => 'dashicons-admin-generic',
			'hierarchical'        => true,
			'supports'            => array(
				'title',
			),
			'has_archive'         => false,
			// Disables the URL query /?{query_var}={single_post_slug}.
			'query_var'           => false,
			// 'can_export'            => true, // Default true.
			'delete_with_user'    => false,
		);

		if ( defined( 'ICL_SITEPRESS_VERSION' ) ) {
			$args['show_ui'] = true;
		}

		$args = apply_filters( 'apl_register_post_type_design', $args );
		register_post_type( 'apl_design', $args );
	}

	/**
	 * Hook for APL check version
	 *
	 * Update method for handling the Upgrader Class.
	 *
	 * @since 0.3.0
	 * @since 0.4.0 - Changed to action hook.
	 * @since 0.4.4 Handle 0.3 and 0.4 database types separately, and stricter updating with APL_Post_Lists and APL_Designs.
	 * @access public
	 *
	 * @see 'plugins_loaded' action hook.
	 * @link https://codex.wordpress.org/Plugin_API/Action_Reference/plugins_loaded
	 * @link https://developer.wordpress.org/reference/hooks/plugins_loaded/
	 */
	public function action_check_version() {
		$options = apl_options_load();
		if ( isset( $options['version'] ) ) {
			if ( version_compare( $options['version'], APL_VERSION, '<' ) ) {
				$update_items = array();

				if ( version_compare( '0.3.0', $options['version'], '<' ) && version_compare( '0.4.0', $options['version'], '>' ) ) {
					// 0.3 Database.
					$preset_db = new APL_Preset_Db( 'default' );

					$update_items = array(
						'options'   => $options,
						'preset_db' => $preset_db,
					);
				} elseif ( version_compare( '0.4.0', $options['version'], '<' ) ) {
					// 0.4+ Database.
					$post_lists = apl_get_post_lists( array(), 'apl_post_list' );
					$designs    = apl_get_designs( array(), 'apl_design' );

					$update_items = array(
						'options'           => $options,
						'apl_post_list_arr' => $post_lists,
						'apl_design_arr'    => $designs,
					);
				}

				$updater = new APL_Updater( $options['version'], $update_items, 'APL' );
				// If update occurred, save post lists and designs associated with the post list, and then
				// save the remaining designs. When completed, save apl_options to finalize version update.
				if ( $updater->update_occurred ) {
					$apl_post_list_arr = $updater->apl_post_list_arr;
					$apl_design_arr    = $updater->apl_design_arr;

					// APL_Post_List and APL_Designs.
					foreach ( $apl_post_list_arr as $k1_ => &$apl_post_list ) {
						foreach ( $apl_design_arr as $k2_design_key => $apl_design ) {
							if ( $apl_design->slug === $apl_post_list->pl_apl_design || $apl_design->slug === $apl_post_list->pl_apl_design_slug ) {
								$apl_design->save_design();

								$apl_post_list->pl_apl_design_id = $apl_design->id;

								unset( $apl_design_arr[ $k2_design_key ] );
								array_values( $apl_design_arr );
								break;
							}
						}
						$apl_post_list->save_post_list();
					}

					// Remaining APL Designs.
					foreach ( $apl_design_arr as $apl_design ) {
						$apl_design->save_design();
					}

					// Update and save plugin options.
					$options = $updater->options;
					apl_options_save( $options );
				}
			}
		}
	}

	/**
	 * Update Post List Database
	 *
	 * Updates or adds to database via APL_Post_List object.
	 *
	 * @deprecated 0.4.4 Was used in version update, but needed to be updated with APL_Designs.
	 *
	 * @since 0.4.0
	 * @access private
	 *
	 * @param array $apl_post_list_arr Array of Post Lists.
	 */
	public function update_post_list_database( $apl_post_list_arr ) {
		foreach ( $apl_post_list_arr as $k1_ => $apl_post_list ) {
			$apl_post_list->save_post_list();
		}
	}

	/**
	 * Update Design Database
	 *
	 * Updates or adds to database via APL_Design object.
	 *
	 * @deprecated 0.4.4
	 *
	 * @ignore
	 * @since 0.4.0
	 * @access private
	 *
	 * @param array $apl_design_arr Array of Designs.
	 */
	private function update_design_database( $apl_design_arr ) {
		foreach ( $apl_design_arr as $apl_design ) {
			$apl_design->save_design();
		}
	}

	/**
	 * Load APL's Textdomain
	 *
	 * Hook for loading the textdomain location.
	 *
	 * @since 0.4.0
	 *
	 * @link https://developer.wordpress.org/plugins/internationalization/how-to-internationalize-your-plugin/
	 */
	public function action_load_plugin_textdomain() {
		$lang_dir = 'advanced-post-list/languages/';
		load_plugin_textdomain( APL_SLUG, false, $lang_dir );
	}

	/**
	 * WP Plugin Activation
	 *
	 * Handles the activation method when the plugin is first activated.
	 *
	 * @since 0.1.0
	 * @access public
	 */
	public static function activation() {
		// Step 1.
		$options = apl_options_load();

		require_once APL_DIR . 'admin/class-apl-notices.php';
		require_once APL_DIR . 'admin/class-apl-admin.php';
		apl_notice_set_activation_review_plugin( false, true );

		$args = array(
			'post_status' => array(
				'draft',
				'pending',
				'publish',
				'future',
				'private',
			),
		);

		// If there are no presets/post_lists, then add defaults for initial presets.
		$apl_post_lists = apl_get_post_lists( $args );
		if ( 1 > count( $apl_post_lists ) ) {
			$apl_admin = APL_Admin::get_instance();
			$apl_admin->restore_default_presets();
		}

		// Any Need? apl_options_load() already sets defaults if no data is found.
		apl_options_save( $options );
	}

	/**
	 * WP Plugin De-activation
	 *
	 * Handles the deactivation method when plugin is deactivated
	 *
	 * STEP 1 - Load Options from database.
	 * STEP 2 - If user has delete database set to true OR APLOption exists but
	 *          delete_core_db is not set, then delete all options.
	 *
	 * @since 0.1.0
	 * @since 0.2.0 - Added delete_option('APL_preset_db-default') for deleting
	 *                preset database data.
	 * @since 0.4.0 - Change database to Post Data to uninstall.
	 * @since 0.4.4 Added stricter APL_Design object referencing.
	 *
	 * @link https://developer.wordpress.org/reference/functions/unregister_post_type/
	 * @access public
	 */
	public static function deactivation() {
		// STEP 1.
		$options = get_option( 'apl_options' );
		// STEP 2.
		if ( true === $options['delete_core_db'] || ( false !== $options && ! isset( $options['delete_core_db'] ) ) ) {
			delete_option( 'apl_options' );

			// POST LIST POST DATA.
			$pl_args = array(
				'post_type'      => 'apl_post_list',
				'posts_per_page' => -1,
				'post_status'    => array(
					'draft',
					'pending',
					'publish',
					'future',
					'private',
					'trash',
				),
			);

			$pl_query       = new WP_Query( $pl_args );
			$post_list_data = $pl_query->posts;

			foreach ( $post_list_data as $v1_pl_post ) {
				$apl_post_list = new APL_Post_List( $v1_pl_post->post_name );

				$apl_post_list->delete_post_list();
			}
			unregister_post_type( 'apl_post_list' );

			// DESIGN POST DATA.
			$d_args = array(
				'post_type'      => 'apl_design',
				'posts_per_page' => -1,
				'post_status'    => array(
					'draft',
					'pending',
					'publish',
					'future',
					'private',
					'trash',
				),
			);

			$d_query     = new WP_Query( $d_args );
			$design_data = $d_query->posts;

			foreach ( $design_data as $v1_d_post ) {
				$apl_design = new APL_Design( intval( $v1_d_post->ID ) );

				$apl_design->delete_design();
			}
			unregister_post_type( 'apl_design' );
		}// End if().
	}

	/**
	 * WP Plugin Uninstall
	 *
	 * Handles the uninstall method when plugin is uninstalled.
	 *
	 * @since 0.1.0
	 * @since 0.2.0 - Changed to delete all plugin data, whether 'delete plugin
	 *                data upon deactivation' is set or not.
	 * @since 0.4.0 - Changed to delete Post Data.
	 * @since 0.4.4 Added stricter APL_Design object referencing.
	 * @access public
	 */
	public static function uninstall() {
		delete_option( 'apl_options' );

		// POST LIST POST DATA.
		$pl_args = array(
			'post_type'      => 'apl_post_list',
			'posts_per_page' => -1,
			'post_status'    => array(
				'draft',
				'pending',
				'publish',
				'future',
				'private',
				'trash',
			),
		);

		$pl_query       = new WP_Query( $pl_args );
		$post_list_data = $pl_query->posts;

		foreach ( $post_list_data as $v1_pl_post ) {
			$apl_post_list = new APL_Post_List( $v1_pl_post->post_name );

			$apl_post_list->delete_post_list();
		}
		unregister_post_type( 'apl_post_list' );

		// DESIGN POST DATA.
		$d_args = array(
			'post_type'      => 'apl_design',
			'posts_per_page' => -1,
			'post_status'    => array(
				'draft',
				'pending',
				'publish',
				'future',
				'private',
				'trash',
			),
		);

		$d_query     = new WP_Query( $d_args );
		$design_data = $d_query->posts;

		foreach ( $design_data as $v1_d_post ) {
			$apl_design = new APL_Design( intval( $v1_d_post->ID ) );

			$apl_design->delete_design();
		}
		unregister_post_type( 'apl_design' );
	}

	/**
	 * (DEPRECATED) Option Defaults
	 *
	 * Sets options to default values. Deprecated.
	 *
	 * STEP 1 - Set options as an array.
	 * STEP 2 - Add default values to options.
	 * STEP 3 - Return Options.
	 *
	 * @since 0.1.0
	 * @deprecated 0.4.0 Use apl_options_default()
	 * @see apl_options_default()
	 * @access private
	 *
	 * @return array Core option settings
	 */
	private function apl_options_default() {
		// New name ( default_options ).
		// Step 1.
		$options = array();
		// Step 2.
		$options['version']              = APL_VERSION;
		$options['delete_core_db']       = false;
		$options['default_empty_enable'] = false;
		$options['default_empty_output'] = '<p>' . __( 'Sorry, but no content is available at this time.', 'advanced-post-list' ) . '</p>';

		// Step 3.
		return $options;
	}

	/**
	 * (DEPRECATED) APL Load Option
	 *
	 * Gets APLOptions from WordPress database and send the option data back
	 * if any. Deprecated.
	 *
	 * STEP 1 - Get APLOptions from WordPress Database or get false if options
	 *          doesn't exist.
	 * STEP 2 - If Options exists, then return object. Otherwise return false.
	 *
	 * @since 0.1.0
	 * @deprecated 0.4.0 Use apl_options_load()
	 * @see apl_options_load()
	 * @access private
	 *
	 * @see Function/method/class relied on
	 * @link URL
	 *
	 * @return array APL option settings.
	 */
	private function apl_options_load() {
		// New Name ( get_options ).
		// Step 1.
		$options = get_option( $this->_option_name );

		// Step 2.
		if ( false !== $options ) {
			return $options;
		} else {
			$defaults = $this->apl_options_default();
			$this->apl_options_save( $defaults );
			return $defaults;
		}
	}

	/**
	 * (DEPRECATED) Save Options
	 *
	 * Deprecated.
	 *
	 * STEP 1 - If option data (param) exists, save option data to
	 *               WordPress database.
	 *
	 * @since 0.1.0
	 * @deprecated 0.4.0 Use apl_options_save()
	 * @see apl_options_save()
	 * @access private
	 *
	 * @see Function/method/class relied on
	 * @link URL
	 *
	 * @param array $options Core option settings.
	 */
	private function apl_options_save( $options ) {
		// New name ( set_options ).
		// STEP 1.
		if ( isset( $options ) ) {
			update_option( $this->_option_name, $options );
		}
	}

	/**
	 * Widget Initialization
	 *
	 * Registers the Plugin's Widget to WordPress.
	 *
	 * @since 0.1.0
	 *
	 * @see APL_Widget class 'advanced-post-list/includes/class/class-apl-widget.php
	 * @link https://developer.wordpress.org/themes/functionality/widgets/
	 * @link https://codex.wordpress.org/Function_Reference/register_widget
	 */
	public function action_widget_init() {
		register_widget( 'APL_Widget' );
	}

	/**
	 * Shortcode [Post_List]
	 *
	 * Method handler for 'post_list' shortcode and displaying the target post list.
	 *
	 * STEP 1 - If a value is not set, do STEP 3.
	 * STEP 2 - Return $this->display($preset_name).
	 * STEP 3 - Otherwise return an empty string.
	 *
	 * @since 0.1.0
	 *
	 * @param array $att Carries the preset name.
	 * @return string HTML content, if param is set. Otherwise return an empty string.
	 */
	public function shortcode_post_list( $att ) {
		// STEP 1.
		if ( isset( $att['name'] ) ) {
			// STEP 2.
			return $this->display_post_list( $att['name'] );
		} elseif ( current_user_can( 'manage_options' ) ) {
			return esc_html__( 'NOTICE: Shortcode name is missing. Ex [post_list name=\'example\']', 'advanced-post-list' );
		} else {
			// STEP 3.
			return '';
		}
	}

	/**
	 * Public Hard-code Display Post List
	 *
	 * Public function for displaying Post Lists.
	 *
	 * @since 0.3.0
	 * @since 0.4.0 - Added slug sanitization.
	 *
	 * @param string $preset_name Preset slug/name.
	 * @return string HTML content.
	 */
	public function display_post_list( $preset_name ) {
		$preset_name = sanitize_key( $preset_name );
		return $this->post_list_loop( $preset_name );
	}

	/**
	 * DEPRECATED Public Hard-code Display
	 *
	 * Public function for displaying Post Lists.
	 *
	 * @deprecated 0.4
	 * @since 0.1.0
	 *
	 * @param string $preset_name Slug of the preset post list.
	 * @return string
	 */
	public function APL_Display( $preset_name ) {
		return $this->display_post_list( $preset_name );
	}
	/**
	 * Post List Looper
	 *
	 * Method used for executing the frontend loop. Currently uses an output
	 * string (HTML) to return.
	 *
	 * @ignore
	 * @since 0.1.0
	 * @since 0.2.0  - Corrected a typo in the if statement for _postExcludeCurrent.
	 * @since 0.3.b8 - Complete overhaul. Moved dynamic settings to APLQuery,
	 *                 implemented WP's loop.
	 * @since 0.4.0  - Changed 'Preset' database objects to APL_Post_List
	 *                 and APL_Design database objects.
	 * @since 0.4.4  - Added compatability with WPML.
	 * @access private
	 *
	 * @see APL_Post_List class
	 * @see APL_Design class
	 * @see APL_Query class
	 * @see APL_Internal_Shortcodes class
	 * @uses `wpml_object_id`
	 * @link https://wpml.org/wpml-hook/wpml_object_id/
	 *
	 * @param string $post_list_slug Preset slug/name.
	 * @return string HTML string.
	 */
	private function post_list_loop( $post_list_slug ) {
		// STEP 1 - Get Post List data, and if valid, do initilization.
		// Otherwise, for Admin show an alert message, and nothing to viewers.
		$apl_post_list = new APL_Post_List( $post_list_slug );
		if ( $apl_post_list->id ) {
			// Get APL Design.
			$design_id = $apl_post_list->pl_apl_design_id;
			if ( defined( 'ICL_SITEPRESS_VERSION' ) ) {
				$design_id = apply_filters( 'wpml_object_id', $apl_post_list->pl_apl_design_id, 'apl_design', true );
			}
			$apl_design = new APL_Design( $design_id );
		} elseif ( current_user_can( 'manage_options' ) ) {
			// Admin Message.
			return esc_html__( 'NOTICE: Post list \'name\' does not exist or is invalid.', 'advanced-post-list' );
		} else {
			// Users/Visitors.
			return '';
		}

		// INIT.
		require_once APL_DIR . 'includes/class/class-apl-shortcodes.php';

		// If Exclude Duplicates is checked (w/ multiple post lists),
		// then add any post IDs collected to the preset post list object's
		// exclude post array to be filter out.
		if ( $apl_post_list->pl_exclude_dupes ) {
			foreach ( $this->_remove_duplicates as $v1_post_id ) {
				$apl_post_list->post__not_in[] = $v1_post_id;
			}
		}

		// Init APL_Query object (sets the query strings).
		// The constructor will process and produce a final array of query_args.
		// Then APL_Query will need to query_wp and return a final WP_Query class.
		// NOTE: Look into class inheritance, or change the class name to match the concept; APL_Process, *_Factory.
		$apl_query = new APL_Query( $apl_post_list );

		// STEP - Query the posts to retrieve the final WP_Query class.
		// NOTE: There's got to be a better concept to produce a final WP_Query.
		$wp_query_class = $apl_query->query_wp( $apl_query->query_args_arr );

		/*
		 * ******************************************************************
		 * * The Loop (APL/WP Concept) **************************************
		 * ******************************************************************
		 */
		// STEP 5 - If there are posts, the use the loop to display posts.
		// Otherwise return an exit message if no posts are found.
		$output = '';
		$count  = 0;
		if ( $wp_query_class->have_posts() ) {
			// BEFORE.
			$output .= apply_filters( 'apl_core_loop_before', $apl_design->before );

			$output .= $this->display_preset_list_content( $wp_query_class, $post_list_slug, $apl_design );

			// AFTER.
			$output .= apply_filters( 'apl_core_loop_after', $apl_design->after );
		} else {
			// EMPTY.
			$apl_options = apl_options_load();

			if ( ! empty( $apl_design->empty ) ) {
				$output .= $apl_design->empty;
			} elseif ( true === $apl_options['default_empty_enable'] && ! empty( $apl_options['default_empty_output'] ) ) {
				$output .= $apl_options['default_empty_output'];
			}
		}// End if().

		wp_reset_postdata();

		// STEP - Return output string.
		return $output;
	}

	/**
	 * Display Preset List Content
	 *
	 * @since 0.5
	 *
	 * @param WP_Query   $wp_query_class The query class from WP.
	 * @param string     $apl_preset     APL's Preset Object.
	 * @param APL_Design $apl_design     APL Design to render.
	 * @return mixed|string|void
	 */
	private function display_preset_list_content( &$wp_query_class, $apl_preset, $apl_design ) {
		// Initial Internal Shortcodes since there's posts.
		$internal_shortcodes = new APL_Internal_Shortcodes();

		$count  = 0;
		$output = '';

		$output = apply_filters( 'apl_core_loop_before_content', $output, $count, $wp_query_class );

		// LIST CONTENT.
		while ( $wp_query_class->have_posts() ) {
			$wp_query_class->the_post();

			$this->_remove_duplicates[] = $wp_query_class->post->ID;
			$output                    .= $internal_shortcodes->replace( $apl_design->content, $wp_query_class->post );
			$count++;
		}

		// [final_end] internal shortcode.
		if ( strrpos( $output, 'final_end' ) ) {
			$output = $internal_shortcodes->final_end( $output );
		}

		$output = apply_filters( 'apl_core_loop_after_content', $output, $count, $wp_query_class );

		// Exit method for apl-shortcodes class; __destroy magic method wasn't working as intended.
		$internal_shortcodes->remove();

		return $output;
	}
}