<?php

use PR_DHL\lib\PDFMerger\PDFMerger;

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

if (! class_exists('PR_DHL_Libraryloader')) {

    class PR_DHL_Libraryloader
    {
        const CLASS_PDF_MERGER = 'pdf_merger';

        private static $instances = [];

        protected $include_path = null;

        protected $file_path = null;

        protected $loaded = [];

        /**
         * Constructor.
         */
        public function __construct()
        {
            // Set paths
            $this->include_path = PR_DHL_PLUGIN_DIR_PATH.DIRECTORY_SEPARATOR.'lib'.DIRECTORY_SEPARATOR;
            $this->file_path = $this->include_path.'PDFMerger'.DIRECTORY_SEPARATOR.'PDFMerger.php';
            $this->file_path = str_replace(['/', '\\'], DIRECTORY_SEPARATOR, $this->file_path);
        }

        /**
         * Returns a singleton instance of the called class
         *
         * @return static
         */
        public static function instance()
        {

            $class = get_called_class();
            if (! isset(self::$instances[$class])) {
                self::$instances[$class] = new static;
            }

            return self::$instances[$class];

        }

        public function get_pdf_merger()
        {
            if (! class_exists('PR_DHL\lib\PDFMerger\PDFMerger')) {
                $loaded = $this->include_file($this->file_path);

                if (! $loaded) {
                    return null;
                }
                $this->loaded[] = self::CLASS_PDF_MERGER;
            }

            // Something very unexpected happened, return
            if (! class_exists('PR_DHL\lib\PDFMerger\PDFMerger')) {
                return null;
            }

            return new PDFMerger;
        }

        /**
         * Include a file if it exists.
         *
         * @return bool
         */
        protected function include_file($path)
        {

            if (file_exists($path)) {
                // Supress errors of third party libraries
                $status = @include_once $path;
                if ($status !== 1) {
                    return false;
                }

                return true;
            }

            return false;
        }
    }
}