<?php

require_once( dirname(__FILE__).'/Version.php');

/**
 * Utility for handling the generation and caching of css files
 *
 * @package Less
 * @subpackage cache
 *
 */
class Less_Cache{

	// directory less.php can use for storing data
	public static $cache_dir	= false;

	// prefix for the storing data
	public static $prefix		= 'lessphp_';

	// prefix for the storing vars
	public static $prefix_vars	= 'lessphpvars_';

	// specifies the number of seconds after which data created by less.php will be seen as 'garbage' and potentially cleaned up
	public static $gc_lifetime	= 604800;


	/**
	 * Save and reuse the results of compiled less files.
	 * The first call to Get() will generate css and save it.
	 * Subsequent calls to Get() with the same arguments will return the same css filename
	 *
	 * @param array $less_files Array of .less files to compile
	 * @param array $parser_options Array of compiler options
	 * @param array $modify_vars Array of variables
	 * @return string Name of the css file
	 */
	public static function Get( $less_files, $parser_options = array(), $modify_vars = array() ){


		//check $cache_dir
		if( isset($parser_options['cache_dir']) ){
			Less_Cache::$cache_dir = $parser_options['cache_dir'];
		}

		if( empty(Less_Cache::$cache_dir) ){
			throw new Exception('cache_dir not set');
		}

		if( isset($parser_options['prefix']) ){
			Less_Cache::$prefix = $parser_options['prefix'];
		}

		if( empty(Less_Cache::$prefix) ){
			throw new Exception('prefix not set');
		}

		if( isset($parser_options['prefix_vars']) ){
			Less_Cache::$prefix_vars = $parser_options['prefix_vars'];
		}

		if( empty(Less_Cache::$prefix_vars) ){
			throw new Exception('prefix_vars not set');
		}

		self::CheckCacheDir();
		$less_files = (array)$less_files;


		//create a file for variables
		if( !empty($modify_vars) ){
			$lessvars = Less_Parser::serializeVars($modify_vars);
			$vars_file = Less_Cache::$cache_dir . Less_Cache::$prefix_vars . sha1($lessvars) . '.less';

			if( !file_exists($vars_file) ){
				file_put_contents($vars_file, $lessvars);
			}

			$less_files += array($vars_file => '/');
		}


		// generate name for compiled css file
		$hash = md5(json_encode($less_files));
 		$list_file = Less_Cache::$cache_dir . Less_Cache::$prefix . $hash . '.list';


 		// check cached content
 		if( !isset($parser_options['use_cache']) || $parser_options['use_cache'] === true ){
			if( file_exists($list_file) ){

				self::ListFiles($list_file, $list, $cached_name);
				$compiled_name = self::CompiledName($list);

				// if $cached_name is the same as the $compiled name, don't regenerate
				if( !$cached_name || $cached_name === $compiled_name ){

					$output_file = self::OutputFile($compiled_name, $parser_options );

					if( $output_file && file_exists($output_file) ){
						@touch($list_file);
						return basename($output_file); // for backwards compatibility, we just return the name of the file
					}
				}
			}
		}

		$compiled = self::Cache( $less_files, $parser_options );
		if( !$compiled ){
			return false;
		}

		$compiled_name = self::CompiledName( $less_files );
		$output_file = self::OutputFile($compiled_name, $parser_options );


		//save the file list
		$list = $less_files;
		$list[] = $compiled_name;
		$cache = implode("\n",$list);
		file_put_contents( $list_file, $cache );


		//save the css
		file_put_contents( $output_file, $compiled );


		//clean up
		self::CleanCache();

		return basename($output_file);
	}

	/**
	 * Force the compiler to regenerate the cached css file
	 *
	 * @param array $less_files Array of .less files to compile
	 * @param array $parser_options Array of compiler options
	 * @param array $modify_vars Array of variables
	 * @return string Name of the css file
	 */
	public static function Regen( $less_files, $parser_options = array(), $modify_vars = array() ){
		$parser_options['use_cache'] = false;
		return self::Get( $less_files, $parser_options, $modify_vars );
	}

	public static function Cache( &$less_files, $parser_options = array() ){


		// get less.php if it exists
		$file = dirname(__FILE__) . '/Less.php';
		if( file_exists($file) && !class_exists('Less_Parser') ){
			require_once($file);
		}

		$parser_options['cache_dir'] = Less_Cache::$cache_dir;
		$parser = new Less_Parser($parser_options);


		// combine files
		foreach($less_files as $file_path => $uri_or_less ){

			//treat as less markup if there are newline characters
			if( strpos($uri_or_less,"\n") !== false ){
				$parser->Parse( $uri_or_less );
				continue;
			}

			$parser->ParseFile( $file_path, $uri_or_less );
		}

		$compiled = $parser->getCss();


		$less_files = $parser->allParsedFiles();

		return $compiled;
	}


	private static function OutputFile( $compiled_name, $parser_options ){

		//custom output file
		if( !empty($parser_options['output']) ){

			//relative to cache directory?
			if( preg_match('#[\\\\/]#',$parser_options['output']) ){
				return $parser_options['output'];
			}

			return Less_Cache::$cache_dir.$parser_options['output'];
		}

		return Less_Cache::$cache_dir.$compiled_name;
	}


	private static function CompiledName( $files ){

		//save the file list
		$temp = array(Less_Version::cache_version);
		foreach($files as $file){
			$temp[] = filemtime($file)."\t".filesize($file)."\t".$file;
		}

		return Less_Cache::$prefix.sha1(json_encode($temp)).'.css';
	}


	public static function SetCacheDir( $dir ){
		Less_Cache::$cache_dir = $dir;
	}

	public static function CheckCacheDir(){

		Less_Cache::$cache_dir = str_replace('\\','/',Less_Cache::$cache_dir);
		Less_Cache::$cache_dir = rtrim(Less_Cache::$cache_dir,'/').'/';

		if( !file_exists(Less_Cache::$cache_dir) ){
			if( !mkdir(Less_Cache::$cache_dir) ){
				throw new Less_Exception_Parser('Less.php cache directory couldn\'t be created: '.Less_Cache::$cache_dir);
			}

		}elseif( !is_dir(Less_Cache::$cache_dir) ){
			throw new Less_Exception_Parser('Less.php cache directory doesn\'t exist: '.Less_Cache::$cache_dir);

		}elseif( !is_writable(Less_Cache::$cache_dir) ){
			throw new Less_Exception_Parser('Less.php cache directory isn\'t writable: '.Less_Cache::$cache_dir);

		}

	}


	/**
	 * Delete unused less.php files
	 *
	 */
	public static function CleanCache(){
		static $clean = false;

		if( $clean ){
			return;
		}

		$files = scandir(Less_Cache::$cache_dir);
		if( $files ){
			$check_time = time() - self::$gc_lifetime;
			foreach($files as $file){

				// don't delete if the file wasn't created with less.php
				if( strpos($file,Less_Cache::$prefix) !== 0 ){
					continue;
				}

				$full_path = Less_Cache::$cache_dir . $file;

				// make sure the file still exists
				// css files may have already been deleted
				if( !file_exists($full_path) ){
					continue;
				}
				$mtime = filemtime($full_path);

				// don't delete if it's a relatively new file
				if( $mtime > $check_time ){
					continue;
				}

				$parts = explode('.',$file);
				$type = array_pop($parts);


				// delete css files based on the list files
				if( $type === 'css' ){
					continue;
				}


				// delete the list file and associated css file
				if( $type === 'list' ){
					self::ListFiles($full_path, $list, $css_file_name);
					if( $css_file_name ){
						$css_file = Less_Cache::$cache_dir . $css_file_name;
						if( file_exists($css_file) ){
							unlink($css_file);
						}
					}
				}

				unlink($full_path);
			}
		}

		$clean = true;
	}


	/**
	 * Get the list of less files and generated css file from a list file
	 *
	 */
	static function ListFiles($list_file, &$list, &$css_file_name ){

		$list = explode("\n",file_get_contents($list_file));

		//pop the cached name that should match $compiled_name
		$css_file_name = array_pop($list);

		if( !preg_match('/^' . Less_Cache::$prefix . '[a-f0-9]+\.css$/',$css_file_name) ){
			$list[] = $css_file_name;
			$css_file_name = false;
		}

	}

}
