<?php

	namespace api\core;

	use \error\core\Error;
	use \error\core\Err;


	class Config{

		/* (1) Attributes
		---------------------------------------------------------*/
		/* (1) Static */

		/** @var Config?  */
		private static $inst = null; // singleton instance

		private static function config_path() : String { return __ROOT__.'/config/modules.json'; }

		/** @var array[String]  */
		public  static $allowed_http_methods = [ "GET", "POST", "PUT", "DELETE" ];

		/* (2) Instance */

		/** @var array  */
		private $raw;

		/** @var array  */
		public  $index;

		/** @var Error */
		public  $error;


		/** (2) Private constructor
		*
		* @param	String|null		$path		Configuration path
		*
		---------------------------------------------------------*/
		private function __construct(?String $path=null){

			// Set default error
			$this->error = new Error(Err::Success);


			/* (1) Access file content
			---------------------------------------------------------*/ {

				/* (1) Vérification existence fichier config */
				if( !file_exists($path) ) {
					$this->error->set(Err::UnreachableResource);
					return;
				}

				/* (2) Lecture fichier config */
				$conf = @file_get_contents($path);

				/* (3) Si erreur lecture */
				if( $conf === false ) {
					$this->error->set(Err::UnreachableResource);
					return;
				}

				/* (4) Parsage json */
				$this->raw = json_decode( $conf, true );

				/* (5) Gestion de l'erreur de parsage */
				if( $this->raw == null ) {
					$this->error->set(Err::ParsingFailed, 'json');
					return;
				}

			}


			/* (2) Construction de l'index des chemins
			---------------------------------------------------------*/ {

				/* (1) Initialisation */
				$this->index = [];
				$ref = [ '/' => $this->raw ];


				/* (2) Tant qu'il reste des @ref à traiter */
				while( count($ref) > 0 ){

					/* (2.1) For each ref */
					foreach($ref as $ref_path=>$ref_children){

						/* (2.2) For each children */
						foreach($ref_children as $path=>$method_or_subpath){

							/* (2.2.1) If is an HTTP method -> add to index */
							if( in_array($path, self::$allowed_http_methods) ){

								/* (2.2.1.1) If no index for this path -> add it */
								if( !isset($this->index[$ref_path]) )
									$this->index[$ref_path] = [];

								/* (2.2.1.2) Add the HTTP method definition */
								$this->index[$ref_path][$path] = $method_or_subpath;


							/* (2.2.2) If a sub path -> add it to next refs to process */
							}else{

								if( $ref_path == '/' )
									$ref["$ref_path$path"] = $method_or_subpath;
								else
									$ref["$ref_path/$path"] = $method_or_subpath;

							}

						}

						/* (2.3) In all cases -> remove current from ref */
						unset($ref[$ref_path]);

					}

				}

			}

		}


		/** (3) Static singleton 'get-or-create'
		*
		* @return Config						Configuration singleton
		*
		---------------------------------------------------------*/
		public static function get() : Config{

			/* (1) If @inst already exists -> return singleton */
			if( self::$inst instanceof Config )
				return self::$inst;

			/* (2) If @inst not set -> create singleton and return it */
			self::$inst = new self( self::config_path() );

			return self::$inst;

		}


	}