<?php

abstract class Engine {
	
	abstract function run ( $data = array() );
	
	protected static $instances = array();
	
	public static function fromFile ( $file, $root = '', $cache = '', $content = '' ) {
		
		if ( !$file )
			throw new Exception('No file provided !');
		
		// if specified, $root must be an actual directory
		if ( $root && !( $root = realpath($root[0] === DIRECTORY_SEPARATOR ? $root : realpath('.') . DIRECTORY_SEPARATOR . $root) ) )
			throw new Exception(sprintf('Directory "%1$s" for root not found !', $root));
		
		// if specified, $cache must be an actual directory
		if ( $cache && !( $cache = realpath($cache[0] === DIRECTORY_SEPARATOR ? $cache : realpath('.') . DIRECTORY_SEPARATOR . $cache) ) )
			throw new Exception(sprintf('Directory "%1$s" for cache not found !', $cache));
		
		// if $cache is set, then $root too !!
		if ( $cache && !$root )
			throw new Exception(sprintf('Directory cache "%1$" set but empty root directory provided !', $cache));
		
		$file = Path::get($file);
		$filepath = $file->prepend('/', $root);
		$filemirror = $file->prepend($cache);
		$cachepath = Path::get($file . '.php')->prepend($cache);
		$basename = basename($file);
		$dirname = dirname($file);
		
		// Process Level cache : not instantiate the same file twice
		if ( !empty(static::$instances[get_called_class()][$filepath->__toString()]) )
			return static::$instances[get_called_class()][$filepath->__toString()];
		
		// prepare cache dirctories
		if ( $cache ) {
			$cacheDir = dirname($cachepath);
			if ( !file_exists($cacheDir) )
				mkdir($cacheDir, 0777, 1);
		}
		
/*#BEGIN debug#*/
		if ( file_exists($filepath) )
			$m = filemtime($filepath);
		elseif ( $content && ( !file_exists($filemirror) || $content === file_get_contents($filemirror) ) )
			$m = -1;
		else $m = time();
		if ( $cache && !file_exists($cachepath . $m) ) {
			
			if ( file_exists($filemirror) )
				unlink($filemirror);
			if ( file_exists($cachepath) )
				unlink($cachepath);
			
		}
		if ( $cache ) file_put_contents($cachepath . $m, $m);
/*#END debug#*/
		
		if ( $cache && file_exists($cachepath) ) {
			
			$instance = new static($dirname, $root, $cache, $basename);
			$instance->file = $filemirror;
			$instance->include = $cachepath;
			
		} else {
			
			if ( file_exists($filepath) )
				$content = file_get_contents($filepath);
			
			elseif ( !$content )
				throw new Exception(sprintf('File "%1$s" not found and no content provided !', $filepath));
			
			if ( $cache )
				file_put_contents($filemirror, $content);
			
			try {
				
				$instance = static::fromString($content, $dirname, $root, $cache, $basename);
				
			} catch ( Exception $e ) {
				
				throw new Exception(sprintf(
					'Error during compilation of file "%1$s" !',
					$filepath
				), 0, $e);
				
			}
			
			if ( $cache ) {
				
				file_put_contents($cachepath, "<?php\n" . $instance->code . "\n?>");
				
				$instance->include = $cachepath;
				$instance->code = '';
				$instance->file = $filemirror;
				$instance->source = '';
				
			}
			
		}
		
		return static::$instances[get_called_class()][$filepath->__toString()] = $instance;
		
	}
	
	protected
	// Source code
		$source = '',
		$file = '',
	// Compiled code
		$code = '',
		$include = '',
	// Env
		$dir = '',
		$root = '',
		$cache = '',
		$basename = '';
	
	protected function __construct ( $dir, $root = '', $cache = '', $basename = '') {
		
		$this->dir = $dir;
		$this->root = $root;
		$this->cache = $cache;
		$this->basename = $basename;
		
	}
	
	public function getSource () {
		
		if ( $this->file )
			return file_get_contents($this->file);
		
		return $this->source;
		
	}
	
	/*** Runtime API ***/
	
	public function getDir () {
		
		return $this->dir;
		
	}
	
	public function getRoot () {
		
		return $this->root;
		
	}
	
	public function getCache () {
		
		return $this->cache;
		
	}
	
	public function getFile () {
		
		return $this->dir . '/' . $this->basename;
		
	}
	
	public function getBasename () {
		
		return $this->basename;
		
	}
	
}

?>