<?php if( !defined('__ROOT__') ) define('__ROOT__', dirname(dirname(__FILE__)) );


	class Exporter{

		private $modules; // will contain modules (config)

		public static function config_path(){ return __ROOT__.'/exporter/modules.json'; }

		/* CONSTRUCTOR -> LOADS CONFIG
		*
		*/
		public function __construct(){

			$this->modules = json_decode( file_get_contents(self::config_path()), true);

		}


		/* RETURNS AVAILABLE MODULE LIST
		*
		* @return modules<Array> 							Set containing modules and their versions
		*
		*/
		public function available(){
			$modules = [];

			foreach($this->modules['available'] as $module=>$versions){
				$modules[$module] = [];

				foreach($versions as $version=>$dependencies)
					$modules[$module][] = $version;
			}

			return $modules;
		}


		/* ENABLES A MODULE'S VERSION
		*
		* @pModule<String> 										Module's name
		* @pVersion<String> 									Module's version
		* @pDep<Boolean> 										TRUE if dependency
		*
		* @return err_msg<String>								Error message | TRUE (if all is ok)
		*
		*/
		public function enable($pModule=null, $pVersion=null, $pDep=false){

			/* [1] Module management
			=========================================================*/
			/* (1) If @module not given, exit */
			if( is_null($pModule) )
				return "Missing @moduleName.\n";

			/* (2) Checking module existence */
			if( !isset($this->modules['available'][$pModule]) )
				return "Module `$pModule` unknown.\n";

			/* (3) Set module name & content */
			$mname   = $pModule;
			$module  = $this->modules['available'][$mname];


			/* [2] Version management
			=========================================================*/
			/* (1) Set default version name & content */
			$vname   = array_slice(array_keys($module), -1)[0];
			$version = $module[$vname];

			/* (2) If wrong version given, set to default */
			if( is_null($pVersion) || !isset($module[$pVersion]) )
				echo "chosing latest $vname version.\n";

			/* (2) Else, we get given @version */
			else
				$version = $module[( $vname = $pVersion )];


			/* [3] Enables module & version
			=========================================================*/
			/* (1) If module disabled -> enables it */
			if( !isset($this->modules['enabled'][$mname]) )
				$this->modules['enabled'][$mname] = '0';

			/* (2) If not dependency or version lower -> Set version */
			if( !$pDep || $this->lower($module, $this->modules['enabled'][$mname], $vname) ){

				if( $pDep ) echo "- $mname-$vname   ($vname+ required)\n";

				$this->modules['enabled'][$mname] = $vname;

			} else if( $pDep ) echo "- $mname-".$this->modules['enabled'][$mname]."   ($vname+ required)\n";


			/* [4] Loading dependencies
			=========================================================*/
			/* (1) Loading each dependency */
			if( count($version) > 0 ){

				echo "dependencies:\n";

				foreach($version as $depMod=>$depVer)
					$enabled = $this->enable($depMod, $depVer, true);
			}


			/* [5] Storing data
			=========================================================*/
			$this->store();

			return true;
		}


		/* DISABLES A MODULE'S VERSION
		*
		* @pModule<String> 									Module's name
		*
		* @return err_msg<String> 							Error message || TRUE if success
		*
		*/
		public function disable($pModule=null){
			/* [1] Module management (existence)
			=========================================================*/
			/* (1) If @module not given, exit */
			if( is_null($pModule) )
				return "Missing @moduleName.\n";

			/* (2) Checking if module is enabled */
			$enabled_modules = array_keys($this->modules['enabled']);
			if( !in_array($pModule, $enabled_modules) )
				return "Module `$pModule` not enabled.\n";

			/* (3) Set module name & content */
			$mname  = $pModule;
			$module = $this->modules['enabled'][$mname];


			/* [2] Dependency verification (not needed)
			=========================================================*/
			$dependency = false; // if it's a dependency of another enabled module
			$callers = [];       // list of enabled modules that needs current one

			/* (1) For each enabled module (excepted itself) */
			foreach($enabled_modules as $module){

				// except current module
				if( $module == $mname ) continue;

				/* (2) For each version of its module (and its dependencies) */
				foreach($this->modules['available'][$module] as $version=>$dependencies){

					// if not the current enabled module's version
					if( $version != $this->modules['enabled'][$module] )
						continue;

					/* (3) If current module in dependencies -> can't disable */
					isset($dependencies[$mname]) && ($dependency = true) && ($callers[] = "`$module`");

				}

			}

			/* (4) If a dependency, explain */
			if( $dependency )
				return "Cannot disable module $mname because ".implode(',',$callers)." needs it.\n";


			/* [3] Disabling module
			=========================================================*/
			/* (1) Disabling module */
			unset($this->modules['enabled'][$mname]);

			/* (2) Storing changes */
			$this->store();

			/* (3) Return success */
			return true;
		}


		/* CHECKS IF @pFirst IS LOWER THAN @pSecond VERSION
		*
		* @pModule<Array> 										Module's content
		* @pFirst<String>										First version
		* @pSecond<String>										Second version
		*
		* @return lower<Boolean> 								Returns if @pFirst is lower
		*
		* Note: Supposing that @pFirst and @pSecond are keys of @pModule (no check)
		*
		*/
		public function lower($pModule, $pFirst, $pSecond){
			/* (1) Get @pModule keys  */
			$keys = array_keys($pModule);

			/* (1) Get @pFirst index */
			$pf_index = array_search($pFirst, $keys);

			/* (2) Get @pSecond index */
			$ps_index = array_search($pSecond, $keys);

			return $pf_index < $ps_index;
		}


		/* STORES DATA
		*
		*/
		public function store(){
			file_put_contents(self::config_path(), json_encode($this->modules, JSON_PRETTY_PRINT));
		}

	}

?>