<?php
namespace Qazana;

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

/**
 * Template class for Qazana.
 *
 * @since 1.0.0
 */
class Page_Template_Manager {

    /**
      * A Unique Identifier.
      */
     protected $plugin_slug;

    /**
     * A reference to an instance of this class.
     */
    private static $instance;

    /**
     * The array of templates that this plugin tracks.
     */
    protected $templates;

    /**
     * Initializes the plugin by setting filters and administration functions.
     */
    private function __construct() {
        
        $this->templates = array();

        $this->page_template_path = apply_filters( 'qazana_view_page_template_path', plugin_dir_path( dirname( dirname( __FILE__ ) ) ) . 'templates/default/' );

        // Add a filter to the attributes metabox to inject template into the cache.
        add_filter( 'page_attributes_dropdown_pages_args', array( $this, 'register_project_templates' ) );

        // 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 your templates to this array.
        $templates = array(
            'qazana.php' => 'Qazana Canvas',
        );

        $this->templates = apply_filters( 'qazana_page_templates', $templates );
    }

    /**
     * Adds our template to the pages cache in order to trick WordPress
     * into thinking the template file exists where it doens't really exist.
     */
    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.
     */
    public function view_project_template( $template ) {

        $page_template = get_post_meta( get_the_ID(), '_wp_page_template', true );

        if ( $page_template == 'qazana.php' ) {
            add_filter( 'qazana_is_qazana_page', '__return_true' );
        }

        if ( ! isset( $this->templates[ get_post_meta( get_the_ID(), '_wp_page_template', true ) ] ) ) {
            return $template;
        }

        $wp_page_template = get_post_meta( get_the_ID(), '_wp_page_template', true );

        // Check child theme first
        if ( file_exists( trailingslashit( $this->page_template_path ) . $wp_page_template ) ) {
            $file = trailingslashit( $this->page_template_path ) . $wp_page_template;

        }

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

        return $template;
    }

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

        return self::$instance;
    }
}
