<?php
	/**
	 * Elgg filestore.
	 * This file contains classes, interfaces and functions for saving and retrieving data to various file 
	 * stores.
	 * 
	 * @package Elgg
	 * @subpackage API
	 * @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
	 * @author Marcus Povey
	 * @copyright Curverider Ltd 2008
	 * @link http://elgg.org/
	 */

	include_once("objects.php");
	
	/**
	 * @class ElggFilestore
	 * This class defines the interface for all elgg data repositories.
	 * @author Marcus Povey
	 */
	abstract class ElggFilestore
	{
		/**
		 * Attempt to open the file $file for storage or writing.
		 *
		 * @param ElggFile $file
		 * @param string $mode "read", "write", "append"
		 * @return mixed A handle to the opened file or false on error.
		 */
		abstract public function open(ElggFile $file, $mode);
		
		/**
		 * Write data to a given file handle.
		 *
		 * @param mixed $f The file handle - exactly what this is depends on the file system
		 * @param string $data The binary string of data to write
		 * @return int Number of bytes written.
		 */
		abstract public function write($f, $data);
		
		/**
		 * Read data from a filestore.
		 *
		 * @param mixed $f The file handle
		 * @param int $length Length in bytes to read.
		 * @param int $offset The optional offset.
		 * @return mixed String of data or false on error.
		 */
		abstract public function read($f, $length, $offset = 0);
		
		/**
		 * Seek a given position within a file handle.
		 * 
		 * @param mixed $f The file handle.
		 * @param int $position The position.
		 */
		abstract public function seek($f, $position);
		
		/**
		 * Close a given file handle.
		 *
		 * @param mixed $f
		 */
		abstract public function close($f);
		
		/**
		 * Delete the file associated with a given file handle.
		 *
		 * @param ElggFile $file
		 */
		abstract public function delete(ElggFile $file);
		
		/**
		 * Get the filestore's creation parameters as an associative array.
		 * Used for serialisation and for storing the creation details along side a file object.
		 * 
		 * @return array
		 */
		abstract public function getParameters();
		
		/**
		 * Set the parameters from the associative array produced by $this->getParameters().
		 */
		abstract public function setParameters(array $parameters);

	}
	
	/**
	 * @class ElggDiskFilestore
	 * This class uses disk storage to save data.
	 * @author Marcus Povey
	 */
	class ElggDiskFilestore extends ElggFilestore
	{
		/**
		 * Directory root.
		 */
		private $dir_root;
		
		/**
		 * Default depth of file directory matrix
		 */
		private $matrix_depth = 5;
		
		/**
		 * Construct a disk filestore using the given directory root.
		 *
		 * @param string $directory_root Root directory, must end in "/"
		 */
		public function __construct($directory_root)
		{
			$this->dir_root = $directory_root;
		}
		
		public function open(ElggFile $file, $mode)
		{
			$name = $file->getFilename();
			$matrix = $this->make_file_matrix($name);
			
			// Try and create the directory
			try { $this->make_directory_root($this->dir_root . $matrix); } catch (Exception $e){}
			
			switch ($mode)
			{
				case "read" : $mode = "r+b"; break;
				case "write" : $mode = "w+b"; break;
				case "append" : $mode = "a+b"; break;
				default: throw new InvalidParameterException("Unrecognised file mode '$mode'");
			}
			
			return fopen($this->dir_root . $matrix . $name, $mode);
		}
		
		public function write($f, $data)
		{
			return fwrite($f, $data);
		}
		
		public function read($f, $length, $offset = 0)
		{
			if ($offset)
				$this->seek($f, $offset);
				
			return fread($f, $length);
		}
		
		public function close($f)
		{
			return fclose($f);
		}
		
		public function delete(ElggFile $file)
		{
			$name = $file->getFilename();
			$matrix = $this->make_file_matrix($name);
			
			$unlink = unlink($this->dir_root . $matrix . $name);
			if ($unlink)
				return $file->delete();
	
			return false;
		}
		
		public function seek($f, $position)
		{
			return fseek($f, $position);
		}
		
		/**
		 * Make the directory root.
		 *
		 * @param string $dirroot
		 */
		protected function make_directory_root($dirroot)
		{
			if (!@mkdir($dirroot, 0700, true)) 
				throw new IOException("Could not make $dirroot");
				
			return true;
		}
		
		/**
		 * Construct the filename matrix.
		 *
		 * @param string $filename
		 */
		protected function make_file_matrix($filename)
		{
			$matrix = "";
			
			$len = strlen($filename);
			if ($len>$this->matrix_depth)
				$len = $this->matrix_depth;
			
			for ($n = 0; $n < $len; $n++)
				$matrix .= $filename[$n] . "/";	
	
			return $matrix;
		}
		
		public function getParameters()
		{
			return array("dir_root" => $this->dir_root);
		}
		
		public function setParameters(array $parameters)
		{
			if (isset($parameters['dir_root']))
			{
				$this->dir_root = $parameters['dir_root'];
				return true;
			}
			
			return false;
		}
	}
	
	/**
	 * @class ElggFile
	 * This class represents a physical file.
	 * @author Marcus Povey
	 */
	class ElggFile extends ElggObject
	{
		/** Filestore */
		private $filestore;
		
		/** File handle used to identify this file in a filestore. Created by open. */
		private $handle;
		
		protected function initialise_attributes()
		{
			parent::initialise_attributes();
			
			$this->attributes['subtype'] = "file";
		}
		
		public function __construct($guid = null) 
		{			
			parent::__construct($guid);
			
			// Set default filestore
			$this->filestore = $this->getFilestore();
		}
		
		/**
		 * Set the filename of this file.
		 * 
		 * @param string $name The filename.
		 */
		public function setFilename($name) { $this->title = $name; }
		
		/**
		 * Return the filename.
		 */
		public function getFilename() { return $this->title; }
		
		/**
		 * Set the optional file description.
		 * 
		 * @param string $description The description.
		 */
		public function setDescription($description) { $this->description = $description; }
		
		/**
		 * Open the file with the given mode
		 * 
		 * @param string $mode Either read/write/append
		 */
		public function open($mode)
		{
			if (!$this->title)
				throw new IOException("You must specify a name before opening a file.");
				
			// See if file has already been saved
				// seek on datastore, parameters and name
			
			// Sanity check
			if (
				($mode!="read") &&
				($mode!="write") &&
				($mode!="append")
			)
				throw new InvalidParameterException("Unrecognised file mode '$mode'");
			
			// Get the filestore
			$fs = $this->getFilestore();
			
			// Ensure that we save the file details to object store
			//$this->save();
			
			// Open the file handle
			$this->handle = $fs->open($this, $mode);
			
			return $this->handle;
		}
		
		/**
		 * Write some data.
		 * 
		 * @param string $data The data
		 */
		public function write($data)
		{
			$fs = $this->getFilestore();
			
			return $fs->write($this->handle, $data);
		}
		
		/**
		 * Read some data.
		 * 
		 * @param int $length Amount to read.
		 * @param int $offset The offset to start from.
		 */
		public function read($length, $offset = 0)
		{
			$fs = $this->getFilestore();
			
			return $fs->read($this->handle, $length, $offset);
		}
		
		/**
		 * Close the file and commit changes
		 */
		public function close()
		{
			$fs = $this->getFilestore();
			
			if ($fs->close($this->handle))
			{
				$this->handle = NULL;
				
				return true;
			}
			
			return false;
		}
		
		/**
		 * Delete this file.
		 */
		public function delete()
		{
			$fs = $this->getFilestore();
			
			return $fs->delete($this);
		}
		
		/**
		 * Seek a position in the file.
		 * 
		 * @param int $position
		 */
		public function seek($position)
		{
			$fs = $this->getFilestore();
			
			return $fs->seek($this->handle, $position);
		}
	
		/**
		 * Set a filestore.
		 * 
		 * @param ElggFilestore $filestore The file store.
		 */
		public function setFilestore(ElggFilestore $filestore)
		{
			$this->filestore = $filestore;	
		}
		
		/**
		 * Return a filestore suitable for saving this file.
		 * This filestore is either a pre-registered filestore, a filestore loaded from metatags saved
		 * along side this file, or the system default.
		 */
		protected function getFilestore()
		{
			// Short circuit if already set.
			if ($this->filestore)
				return $this->filestore;
				
			
			// If filestore meta set then retrieve filestore TODO: Better way of doing this?
			$metas = get_metadata_for_entity($this->guid);
			$parameters = array();
			foreach ($metas as $meta)
			{
				if (strpos($meta->name, "filestore::")!==false)
				{
					// Filestore parameter tag
					$comp = explode("::", $meta->name);
					$name = $comp[1]; 
			
					$parameters[$name] = $meta->value;
				}
			}
		
			// If parameters loaded then create new filestore
			if (count($parameters)!=0)
			{
				// Create new filestore object
				if ((!isset($parameters['filestore'])) || (!class_exists($parameters['filestore'])))
					throw new ClassNotFoundException("Filestore not found or class not saved with file!");
					
				$this->filestore = new $parameters['filestore']();

				// Set parameters
				$this->filestore->setParameters($parameters);
			}
			

			// if still nothing then set filestore to default
			if (!$this->filestore)
				$this->filestore = get_default_filestore();

			return $this->filestore;
		}
		
		public function save()
		{
			if (!parent::save())
				return false;
				
			// Get filestore if necessary
				
			// Save datastore metadata
			$params = $this->filestore->getParameters();
			foreach ($params as $k => $v)
				$this->setMetaData("filestore::$k", $v);
			
			// Now make a note of the filestore class
			$this->setMetaData("filestore::filestore", get_class($this->filestore));
			
			return true;
		}
		
	}
	

	/// Variable holding the default datastore
	$DEFAULT_FILE_STORE = NULL;
	
	/**
	 * Return the default filestore.
	 *
	 * @return ElggFilestore
	 */
	function get_default_filestore()
	{
		global $DEFAULT_FILE_STORE;
		
		return $DEFAULT_FILE_STORE;
	}
	
	/**
	 * Set the default filestore for the system.
	 */
	function set_default_filestore(ElggFilestore $filestore)
	{
		global $DEFAULT_FILE_STORE;
		
		$DEFAULT_FILE_STORE = $filestore;
		
		return true;
	}
	
	
	// Now register a default filestore
	set_default_filestore(new ElggDiskFilestore($CONFIG->dataroot));
?>