<?php
/**
 * LoginPress Theme Template Class.
 *
 * LoginPress template functions.
 *
 * @package LoginPress
 * @since 1.1.3
 */

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

if ( ! class_exists( 'LoginPress_Theme_Template' ) ) :

	/**
	 * LoginPress Theme Template Class.
	 *
	 * Add LoginPress Templates to use in the theme.
	 *
	 * @since 1.1.3
	 */
	class LoginPress_Theme_Template {

		/**
		 * A reference to an instance of this class.
		 *
		 * @var LoginPress_Theme_Template|null
		 */
		private static $instance;

		/**
		 * The array of templates that this plugin tracks.
		 *
		 * @var array<string, string>
		 */
		protected $templates;

		/**
		 * Returns an instance of this class.
		 *
		 * @since 1.1.3
		 * @return LoginPress_Theme_Template
		 */
		public static function get_instance() {
			if ( null === self::$instance ) {
				self::$instance = new LoginPress_Theme_Template();
			}

			return self::$instance;
		}

		/**
		 * Initializes the plugin by setting filters and administration functions.
		 *
		 * @since 1.1.3
		 * @return void
		 */
		private function __construct() {

			$this->templates = array();

			// Add a filter to the attributes metabox to inject template into the cache.
			if ( version_compare( (string) get_bloginfo( 'version' ), '4.7', '<' ) ) {
				// 4.6 and older.
				add_filter( 'page_attributes_dropdown_pages_args', array( $this, 'register_project_templates' ) );
			} else {
				// Add a filter to the wp 4.7 version attributes metabox.
				add_filter( 'theme_page_templates', array( $this, 'add_new_template' ) );
			}

			// Add a filter to the save post to inject out template into the page cache.
			add_filter( 'wp_insert_post_data', array( $this, 'register_project_templates' ) );

			// Add a filter to the template include to determine if the page has our template assigned and return it's path.
			add_filter( 'template_include', array( $this, 'view_project_template' ) );

			// Add templates.
			$this->templates = array(
				'template-loginpress.php' => 'LoginPress',
			);
		}

		/**
		 * Adds our template to the page dropdown for v4.7+.
		 *
		 * @param array<string, string> $posts_templates The templates array.
		 * @return array<string, string>
		 */
		public function add_new_template( $posts_templates ) {

			$posts_templates = array_merge( $posts_templates, $this->templates );
			return $posts_templates;
		}

		/**
		 * Adds our template to the pages cache in order to trick WordPress.
		 * into thinking the template file exists where it doesn't really exist.
		 *
		 * @param array<string, mixed> $atts The attributes array.
		 * @return array<string, mixed>
		 */
		public function register_project_templates( $atts ) {

			// Create the key used for the themes cache.
			$cache_key = 'page_templates-' . md5( get_theme_root() . '/' . get_stylesheet() );

			// Retrieve the cache list.
			// If it doesn't exist, or it's empty prepare an array.
			$templates = wp_get_theme()->get_page_templates();
			if ( empty( $templates ) ) {
				$templates = array();
			}

			// New cache, therefore remove the old one.
			wp_cache_delete( $cache_key, 'themes' );

			// Now add our template to the list of templates by merging our templates
			// with the existing templates array from the cache.
			$templates = array_merge( $templates, $this->templates );

			// Add the modified cache to allow WordPress to pick it up for listing
			// available templates.
			wp_cache_add( $cache_key, $templates, 'themes', 1800 );

			return $atts;
		}

		/**
		 * Checks if the template is assigned to the page.
		 *
		 * @param string $template The template path.
		 * @return string
		 */
		public function view_project_template( $template ) {

			// Get global post.
			global $post;

			// Return template if post is empty.
			if ( ! $post ) {
				return $template;
			}

			// Return default template if we don't have a custom one defined.
			if ( ! isset( $this->templates[ get_post_meta( $post->ID, '_wp_page_template', true ) ] ) ) {
				return $template;
			}

			$file = plugin_dir_path( __FILE__ ) . get_post_meta( $post->ID, '_wp_page_template', true );

			// Just to be safe, we check if the file exist first.
			if ( file_exists( $file ) ) {
				return $file;
			} else {
				echo esc_html( $file );
			}

			// Return template.
			return $template;
		}
	}
endif;
add_action(
	'plugins_loaded',
	function () {
		LoginPress_Theme_Template::get_instance();
	}
);
