<?php
/**
 * @package   AkeebaBackup
 * @copyright Copyright (c)2009-2014 Nicholas K. Dionysopoulos
 * @license   GNU General Public License version 3, or later
 *
 * @since     3.0
 */

// Protect from unauthorized access
defined('_JEXEC') or die();

// JSON API version number
define('AKEEBA_JSON_API_VERSION', '320');

use Akeeba\Engine\Factory;
use Akeeba\Engine\Platform;
use Akeeba\Engine\Util\Encrypt;

/*
 * Short API version history:
 * 300	First draft. Basic backup working. Encryption semi-broken.
 * 316	Fixed download feature.
 */

if (!defined('AKEEBA_BACKUP_ORIGIN'))
{
	define('AKEEBA_BACKUP_ORIGIN', 'json');
}

class AkeebaModelJsons extends F0FModel
{
	const    STATUS_OK = 200; // Normal reply
	const    STATUS_NOT_AUTH = 401; // Invalid credentials
	const    STATUS_NOT_ALLOWED = 403; // Not enough privileges
	const    STATUS_NOT_FOUND = 404; // Requested resource not found
	const    STATUS_INVALID_METHOD = 405; // Unknown JSON method
	const    STATUS_ERROR = 500; // An error occurred
	const    STATUS_NOT_IMPLEMENTED = 501; // Not implemented feature
	const    STATUS_NOT_AVAILABLE = 503; // Remote service not activated

	const    ENCAPSULATION_RAW = 1; // Data in plain-text JSON
	const    ENCAPSULATION_AESCTR128 = 2; // Data in AES-128 stream (CTR) mode encrypted JSON
	const    ENCAPSULATION_AESCTR256 = 3; // Data in AES-256 stream (CTR) mode encrypted JSON
	const    ENCAPSULATION_AESCBC128 = 4; // Data in AES-128 standard (CBC) mode encrypted JSON
	const    ENCAPSULATION_AESCBC256 = 5; // Data in AES-256 standard (CBC) mode encrypted JSON

	private $json_errors = array(
		'JSON_ERROR_NONE'      => 'No error has occurred (probably emtpy data passed)',
		'JSON_ERROR_DEPTH'     => 'The maximum stack depth has been exceeded',
		'JSON_ERROR_CTRL_CHAR' => 'Control character error, possibly incorrectly encoded',
		'JSON_ERROR_SYNTAX'    => 'Syntax error'
	);

	/** @var int The status code */
	private $status = 200;

	/** @var int Data encapsulation format */
	private $encapsulation = 1;

	/** @var mixed Any data to be returned to the caller */
	private $data = '';

	/** @var string A password passed to us by the caller */
	private $password = null;

	/** @var string The method called by the client */
	private $method_name = null;

	public function execute($json)
	{
		// Check if we're activated
		$enabled = Platform::getInstance()->get_platform_configuration_option('frontend_enable', 0);
		if (!$enabled)
		{
			$this->data = 'Access denied';
			$this->status = self::STATUS_NOT_AVAILABLE;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return $this->getResponse();
		}

		// Try to JSON-decode the request's input first
		$request = @$this->json_decode($json, false);
		if (is_null($request))
		{
			// Could not decode JSON
			$this->data = 'JSON decoding error';
			$this->status = self::STATUS_ERROR;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return $this->getResponse();
		}

		// Decode the request body
		// Request format: {encapsulation, body{ [key], [challenge], method, [data] }} or {[challenge], method, [data]}
		if (isset($request->encapsulation) && isset($request->body))
		{
			if (!class_exists('\\Akeeba\\Engine\\Util\\Encrypt') && !($request->encapsulation == self::ENCAPSULATION_RAW))
			{
				// Encrypted request found, but there is no encryption class available!
				$this->data = 'This server does not support encrypted requests';
				$this->status = self::STATUS_NOT_AVAILABLE;
				$this->encapsulation = self::ENCAPSULATION_RAW;

				return $this->getResponse();
			}

			// Fully specified request
			switch ($request->encapsulation)
			{
				case self::ENCAPSULATION_AESCBC128:
					if (!isset($body))
					{
						$request->body = base64_decode($request->body);
						$body = Factory::getEncryption()->AESDecryptCBC($request->body, $this->serverKey(), 128);
					}
					break;

				case self::ENCAPSULATION_AESCBC256:
					if (!isset($body))
					{
						$request->body = base64_decode($request->body);
						$body = Factory::getEncryption()->AESDecryptCBC($request->body, $this->serverKey(), 256);
					}
					break;

				case self::ENCAPSULATION_AESCTR128:
					if (!isset($body))
					{
						$body = Factory::getEncryption()->AESDecryptCtr($request->body, $this->serverKey(), 128);
					}
					break;

				case self::ENCAPSULATION_AESCTR256:
					if (!isset($body))
					{
						$body = Factory::getEncryption()->AESDecryptCtr($request->body, $this->serverKey(), 256);
					}
					break;

				case self::ENCAPSULATION_RAW:
					$body = $request->body;
					break;
			}

			if (!empty($request->body))
			{
				$authorised = true;
				$body = rtrim($body, chr(0));

				// Make sure it looks like a valid JSON string and is at least 12 characters (minimum valid message length)
				if ((strlen($body) < 12) || (substr($body, 0, 1) != '{') || (substr($body, -1) != '}'))
				{
					$authorised = false;
				}

				// Try to JSON decode the body
				if ($authorised)
				{
					$request->body = $this->json_decode($body);

					if (is_null($request->body))
					{
						$authorised = false;
					}
					elseif (!is_object($request->body))
					{
						$authorised = false;
					}
				}

				// Make sure there is a requested method
				if ($authorised)
				{
					if (!isset($request->body->method) || empty($request->body->method))
					{
						$authorised = false;
					}
				}

				if (!$authorised)
				{
					// Decryption failed. The user is an impostor! Go away, hacker!
					$this->data = 'Authentication failed';
					$this->status = self::STATUS_NOT_AUTH;
					$this->encapsulation = self::ENCAPSULATION_RAW;

					return $this->getResponse();
				}
			}
		}
		elseif (isset($request->body))
		{
			// Partially specified request, assume RAW encapsulation
			$request->encapsulation = self::ENCAPSULATION_RAW;
			$request->body = $this->json_decode($request->body);
		}
		else
		{
			// Legacy request
			$legacyRequest = clone $request;
			$request = (object)array('encapsulation' => self::ENCAPSULATION_RAW, 'body' => null);
			$request->body = $this->json_decode($legacyRequest);
			unset($legacyRequest);
		}

		// Authenticate the user. Do note that if an encrypted request was made, we can safely assume that
		// the user is authenticated (he already knows the server key!)
		if ($request->encapsulation == self::ENCAPSULATION_RAW)
		{
			$authenticated = false;
			if (isset($request->body->challenge))
			{
				list($challenge, $check) = explode(':', $request->body->challenge);
				$crosscheck = strtolower(md5($challenge . $this->serverKey()));
				$authenticated = ($crosscheck == $check);
			}
			if (!$authenticated)
			{
				// If the challenge was missing or it was wrong, don't let him go any further
				$this->data = 'Invalid login credentials';
				$this->status = self::STATUS_NOT_AUTH;
				$this->encapsulation = self::ENCAPSULATION_RAW;

				return $this->getResponse();
			}
		}

		// Replicate the encapsulation preferences of the client for our own output
		$this->encapsulation = $request->encapsulation;

		// Store the client-specified key, or use the server key if none specified and the request
		// came encrypted.
		$this->password = isset($request->body->key) ? $request->body->key : null;
		$hasKey = (isset($request->body->key) || property_exists($request->body, 'key')) ? !is_null($request->body->key) : false;
		if (!$hasKey && ($request->encapsulation != self::ENCAPSULATION_RAW))
		{
			$this->password = $this->serverKey();
		}

		// Does the specified method exist?
		$method_exists = false;
		$method_name = '';
		if (isset($request->body->method))
		{
			$method_name = ucfirst($request->body->method);
			$this->method_name = $method_name;
			$method_exists = method_exists($this, '_api' . $method_name);
		}
		if (!$method_exists)
		{
			// The requested method doesn't exist. Oops!
			$this->data = "Invalid method $method_name";
			$this->status = self::STATUS_INVALID_METHOD;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return $this->getResponse();
		}

		// Run the method
		$params = array();
		if (isset($request->body->data))
		{
			$params = (array)$request->body->data;
		}
		$this->data = call_user_func(array($this, '_api' . $method_name), $params);

		return $this->getResponse();
	}

	/**
	 * Packages the response to a JSON-encoded object, optionally encrypting the
	 * data part with a caller-supplied password.
	 *
	 * @return string The JSON-encoded response
	 */
	private function getResponse()
	{
		// Initialize the response
		$response = array(
			'encapsulation' => $this->encapsulation,
			'body'          => array(
				'status' => $this->status,
				'data'   => null
			)
		);

		switch ($this->method_name)
		{
			case 'Download':
				$data = json_encode($this->data);
				break;
			default:
				$data = $this->json_encode($this->data);
				break;
		}

		if (empty($this->password))
		{
			$this->encapsulation = self::ENCAPSULATION_RAW;
		}

		switch ($this->encapsulation)
		{
			case self::ENCAPSULATION_RAW:
				break;

			case self::ENCAPSULATION_AESCTR128:
				$data = Factory::getEncryption()->AESEncryptCtr($data, $this->password, 128);
				break;

			case self::ENCAPSULATION_AESCTR256:
				$data = Factory::getEncryption()->AESEncryptCtr($data, $this->password, 256);
				break;

			case self::ENCAPSULATION_AESCBC128:
				$data = base64_encode(Factory::getEncryption()->AESEncryptCBC($data, $this->password, 128));
				break;

			case self::ENCAPSULATION_AESCBC256:
				$data = base64_encode(Factory::getEncryption()->AESEncryptCBC($data, $this->password, 256));
				break;
		}

		$response['body']['data'] = $data;

		switch ($this->method_name)
		{
			case 'Download':
				return '###' . json_encode($response) . '###';
				break;
			default:
				return '###' . $this->json_encode($response) . '###';
				break;
		}
	}

	private function serverKey()
	{
		static $key = null;

		if (is_null($key))
		{
			$key = Platform::getInstance()->get_platform_configuration_option('frontend_secret_word', '');
		}

		return $key;
	}

	private function _apiGetVersion()
	{
		$edition = AKEEBA_PRO ? 'pro' : 'core';

		return (object)array(
			'api'       => AKEEBA_JSON_API_VERSION,
			'component' => AKEEBA_VERSION,
			'date'      => AKEEBA_DATE,
			'edition'   => $edition,
		);
	}

	private function _apiGetProfiles()
	{
		require_once JPATH_SITE . '/administrator/components/com_akeeba/models/profiles.php';
		$model = new AkeebaModelProfiles();
		$profiles = $model->getProfilesList(true);
		$ret = array();

		if (count($profiles))
		{
			foreach ($profiles as $profile)
			{
				$temp = new stdClass();
				$temp->id = $profile->id;
				$temp->name = $profile->description;
				$ret[] = $temp;
			}
		}

		return $ret;
	}

	private function _apiStartBackup($config)
	{
		// Get the passed configuration values
		$defConfig = array(
			'profile'     => 1,
			'description' => '',
			'comment'     => '',
			'backupid'    => null,
		);
		$config = array_merge($defConfig, $config);

		foreach ($config as $key => $value)
		{
			if (!array_key_exists($key, $defConfig))
			{
				unset($config[$key]);
			}
		}

		extract($config);

		// Nuke the factory
		Factory::nuke();

		// Set the profile
		$profile = (int)$profile;

		if (!is_numeric($profile))
		{
			$profile = 1;
		}

		if (strtoupper($backupid) == '[DEFAULT]')
		{
			$db = JFactory::getDbo();
			$query = $db->getQuery(true)
						->select('MAX(' . $db->qn('id') . ')')
						->from($db->qn('#__ak_stats'));

			try
			{
				$maxId = $db->setQuery($query)->loadResult();
			}
			catch (Exception $e)
			{
				$maxId = 0;
			}

			$backupid = 'id' . ($maxId + 1);
		}
		elseif (empty($backupid))
		{
			$backupid = null;
		}

		$session = JFactory::getSession();
		$session->set('profile', $profile, 'akeeba');
		Platform::getInstance()->load_configuration($profile);

		// Use the default description if none specified
		if (empty($description))
		{
			JLoader::import('joomla.utilities.date');
			$dateNow = new JDate();
			/*
			$user = JFactory::getUser();
			$userTZ = $user->getParam('timezone',0);
			$dateNow->setOffset($userTZ);
			*/
			$description = JText::_('BACKUP_DEFAULT_DESCRIPTION') . ' ' . $dateNow->format(JText::_('DATE_FORMAT_LC2'), true);
		}

		// Start the backup
		Factory::resetState(array(
			'maxrun' => 0
		));

		Factory::getTempFiles()->deleteTempFiles();

		$tempVarsTag = AKEEBA_BACKUP_ORIGIN;
		$tempVarsTag .= empty($$backupid) ? '' : ('.' . $$backupid);

		Factory::getFactoryStorage()->reset($tempVarsTag);

		Factory::loadState(AKEEBA_BACKUP_ORIGIN, $backupid);
		$kettenrad = Factory::getKettenrad();
		$kettenrad->setBackupId($backupid);

		$options = array(
			'description' => $description,
			'comment'     => $comment,
			'tag'         => AKEEBA_BACKUP_ORIGIN
		);
		$kettenrad->setup($options); // Setting up the engine
		$array = $kettenrad->tick(); // Initializes the init domain
		Factory::saveState(AKEEBA_BACKUP_ORIGIN, $backupid);

		$array = $kettenrad->getStatusArray();
		if ($array['Error'] != '')
		{
			// A backup error had occurred. Why are we here?!
			$this->status = self::STATUS_ERROR;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return 'A backup error had occurred: ' . $array['Error'];
		}
		else
		{
			$statistics = Factory::getStatistics();
			$array['BackupID'] = $statistics->getId();
			$array['HasRun'] = 1; // Force the backup to go on.
			return $array;
		}
	}

	private function _apiStartSRPBackup($config)
	{
		// Get the passed configuration values
		$defConfig = array(
			'tag'           => 'restorepoint',
			'type'          => 'component',
			'name'          => 'akeeba',
			'group'         => '',
			'customdirs'    => array(),
			'extraprefixes' => array(),
			'customtables'  => array(),
			'skiptables'    => array(),
			'xmlname'       => '',
		);
		$config = array_merge($defConfig, $config);
		foreach ($config as $key => $value)
		{
			if (!array_key_exists($key, $defConfig))
			{
				unset($config[$key]);
			}
		}

		// Fetch the extension's version information
		require_once JPATH_ADMINISTRATOR . '/components/com_akeeba/assets/xmlslurp/xmlslurp.php';
		$slurp = new LiveUpdateXMLSlurp();
		$exttype = $config['type'];
		switch ($exttype)
		{
			case 'component':
				$extname = 'com_';
				break;
			case 'module':
				$extname = 'mod_';
				break;
			case 'plugin':
				$extname = 'plg_';
				break;
			case 'template':
				$extname = 'tpl_';
				break;
		}
		$extname .= $config['name'];
		$info = $slurp->getInfo($extname, '');

		$configOverrides = array(
			'akeeba.basic.archive_name'                   => 'restore-point-[DATE]-[TIME]',
			'akeeba.basic.backup_type'                    => 'full',
			'akeeba.basic.backup_type'                    => 'full',
			'akeeba.advanced.archiver_engine'             => 'jpa',
			'akeeba.advanced.postproc_engine'             => 'none',
			'akeeba.advanced.embedded_installer'          => 'none',
			'engine.archiver.common.dereference_symlinks' => true, // hopefully no extension has symlinks inside its own directories...
			'core.filters.srp.type'                       => $config['type'],
			'core.filters.srp.group'                      => $config['group'],
			'core.filters.srp.name'                       => $config['name'],
			'core.filters.srp.customdirs'                 => $config['customdirs'],
			'core.filters.srp.customfiles'                => $config['customfiles'],
			'core.filters.srp.extraprefixes'              => $config['extraprefixes'],
			'core.filters.srp.customtables'               => $config['customtables'],
			'core.filters.srp.skiptables'                 => $config['skiptables'],
			'core.filters.srp.langfiles'                  => $config['langfiles']
		);

		// Parse a local file stored in (backend)/assets/srpdefs/$extname.xml
		JLoader::import('joomla.filesystem.file');
		$filename = JPATH_COMPONENT_ADMINISTRATOR . '/assets/srpdefs/' . $extname . '.xml';
		if (JFile::exists($filename))
		{
			$xml = JFactory::getXMLParser('simple');
			if ($xml->loadFile($filename))
			{
				$extraConfig = $this->parseRestorePointXML($xml->document);
				if ($extraConfig !== false)
				{
					$this->mergeSRPConfig($configOverrides, $extraConfig);
				}
			}
			unset($xml);
		}

		// Parse the extension's manifest file and look for a <restorepoint> tag
		if (!empty($info['xmlfile']))
		{
			$xml = JFactory::getXMLParser('simple');
			if ($xml->loadFile($info['xmlfile']))
			{
				$restorepoint = $xml->document->getElementByPath('restorepoint');
				if ($restorepoint)
				{
					$extraConfig = $this->parseRestorePointXML($restorepoint);
					if ($extraConfig !== false)
					{
						$this->mergeSRPConfig($configOverrides, $extraConfig);
					}
				}
			}
			unset($restorepoint);
			unset($xml);
		}

		// Create an SRP descriptor
		$srpdescriptor = array(
			'type'    => $config['type'],
			'name'    => $config['name'],
			'group'   => $config['group'],
			'version' => $info['version'],
			'date'    => $info['date']
		);

		// Set the description and comment
		$description = "System Restore Point - " . JText::_($exttype) . ": $extname";
		$comment = "---BEGIN SRP---\n" . json_encode($srpdescriptor) . "\n---END SRP---";
		$jpskey = '';
		$angiekey = '';

		// Set a custom finalization action queue
		$configOverrides['volatile.core.finalization.action_handlers'] = array(
			new \Akeeba\Engine\Finalization\Srpquotas()
		);
		$configOverrides['volatile.core.finalization.action_queue'] = array(
			'remove_temp_files',
			'update_statistics',
			'update_filesizes',
			'apply_srp_quotas'
		);

		// Apply the configuration overrides, please
		$platform = Platform::getInstance();
		$platform->configOverrides = $configOverrides;

		// Nuke the factory
		Factory::nuke();

		$profile = 1;
		$session = JFactory::getSession();
		$session->set('profile', $profile, 'akeeba');
		Platform::getInstance()->load_configuration($profile);

		Factory::getFactoryStorage()->reset('restorepoint');

		Factory::loadState('restorepoint');
		$kettenrad = Factory::getKettenrad();
		$options = array(
			'description' => $description,
			'comment'     => $comment,
			'tag'         => 'restorepoint'
		);
		$kettenrad->setup($options); // Setting up the engine
		$kettenrad->tick();
		if (($kettenrad->getState() != 'running') && ($tag == 'restorepoint'))
		{
			$kettenrad->tick();
		}
		$kettenrad->resetWarnings(); // So as not to have duplicate warnings reports
		Factory::saveState($tag);

		$array = $kettenrad->getStatusArray();
		if ($array['Error'] != '')
		{
			// A backup error had occurred. Why are we here?!
			$this->status = self::STATUS_ERROR;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return 'A backup error had occurred: ' . $array['Error'];
		}
		else
		{
			$statistics = Factory::getStatistics();
			$array['BackupID'] = $statistics->getId();
			$array['HasRun'] = 1; // Force the backup to go on.
			return $array;
		}
	}

	private function _apiStepBackup($config)
	{
		$defConfig = array(
			'profile'  => null,
			'tag'      => AKEEBA_BACKUP_ORIGIN,
			'backupid' => null,
		);
		$config = array_merge($defConfig, $config);
		extract($config);

		// Try to set the profile from the setup parameters
		if (!empty($profile))
		{
			$registry = Factory::getConfiguration();
			$session = JFactory::getSession();
			$session->set('profile', $profile, 'akeeba');
		}

		Factory::loadState($tag, $backupid);
		$kettenrad = Factory::getKettenrad();
		$kettenrad->setBackupId($backupid);

		$registry = Factory::getConfiguration();
		$session = JFactory::getSession();
		$session->set('profile', $registry->activeProfile, 'akeeba');

		$array = $kettenrad->tick();
		$ret_array = $kettenrad->getStatusArray();
		$array['Progress'] = $ret_array['Progress'];
		Factory::saveState($tag, $backupid);

		if ($array['Error'] != '')
		{
			// A backup error had occurred. Why are we here?!
			$this->status = self::STATUS_ERROR;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return 'A backup error had occurred: ' . $array['Error'];
		}
		elseif ($array['HasRun'] == false)
		{
			Factory::nuke();
			Factory::getFactoryStorage()->reset();
		}

		return $array;
	}

	private function _apiListBackups($config)
	{
		$defConfig = array(
			'from'  => 0,
			'limit' => 50
		);
		$config = array_merge($defConfig, $config);
		extract($config);

		require_once JPATH_COMPONENT_ADMINISTRATOR . '/models/statistics.php';

		$model = new AkeebaModelStatistics();
		$model->setState('limitstart', $from);
		$model->setState('limit', $limit);

		return $model->getStatisticsListWithMeta(false);
	}

	private function _apiGetBackupInfo($config)
	{
		$defConfig = array(
			'backup_id' => '0'
		);
		$config = array_merge($defConfig, $config);
		extract($config);

		// Get the basic statistics
		$record = Platform::getInstance()->get_statistics($backup_id);

		// Get a list of filenames
		$backup_stats = Platform::getInstance()->get_statistics($backup_id);

		// Backup record doesn't exist
		if (empty($backup_stats))
		{
			$this->status = self::STATUS_NOT_FOUND;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return 'Invalid backup record identifier';
		}

		$filenames = Factory::getStatistics()->get_all_filenames($record);

		if (empty($filenames))
		{
			// Archives are not stored on the server or no files produced
			$record['filenames'] = array();
		}
		else
		{
			$filedata = array();
			$i = 0;

			// Get file sizes per part
			foreach ($filenames as $file)
			{
				$i++;
				$size = @filesize($file);
				$size = is_numeric($size) ? $size : 0;
				$filedata[] = array(
					'part' => $i,
					'name' => basename($file),
					'size' => $size
				);
			}

			// Add the file info to $record['filenames']
			$record['filenames'] = $filedata;
		}

		return $record;
	}

	private function _apiDownload($config)
	{
		$defConfig = array(
			'backup_id'  => 0,
			'part_id'    => 1,
			'segment'    => 1,
			'chunk_size' => 1
		);
		$config = array_merge($defConfig, $config);
		extract($config);

		$backup_stats = Platform::getInstance()->get_statistics($backup_id);
		if (empty($backup_stats))
		{
			// Backup record doesn't exist
			$this->status = self::STATUS_NOT_FOUND;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return 'Invalid backup record identifier';
		}
		$files = Factory::getStatistics()->get_all_filenames($backup_stats);

		if ((count($files) < $part_id) || ($part_id <= 0))
		{
			// Invalid part
			$this->status = self::STATUS_NOT_FOUND;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return 'Invalid backup part';
		}

		$file = $files[$part_id - 1];

		$filesize = @filesize($file);
		$seekPos = $chunk_size * 1048756 * ($segment - 1);

		if ($seekPos > $filesize)
		{
			// Trying to seek past end of file
			$this->status = self::STATUS_NOT_FOUND;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return 'Invalid segment';
		}

		$fp = fopen($file, 'rb');

		if ($fp === false)
		{
			// Could not read file
			$this->status = self::STATUS_ERROR;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return 'Error reading backup archive';
		}

		rewind($fp);
		if (fseek($fp, $seekPos, SEEK_SET) === -1)
		{
			// Could not seek to position
			$this->status = self::STATUS_ERROR;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return 'Error reading specified segment';
		}

		$buffer = fread($fp, 1048756);

		if ($buffer === false)
		{
			// Could not read
			$this->status = self::STATUS_ERROR;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return 'Error reading specified segment';
		}

		fclose($fp);

		switch ($this->encapsulation)
		{
			case self::ENCAPSULATION_RAW:
				return base64_encode($buffer);
				break;

			case self::ENCAPSULATION_AESCTR128:
				$this->encapsulation = self::ENCAPSULATION_AESCBC128;

				return $buffer;
				break;

			case self::ENCAPSULATION_AESCTR256:
				$this->encapsulation = self::ENCAPSULATION_AESCBC256;

				return $buffer;
				break;

			default:
				// On encrypted comms the encryption will take care of transport encoding
				return $buffer;
				break;
		}
	}

	private function _apiDelete($config)
	{
		$defConfig = array(
			'backup_id' => 0
		);
		$config = array_merge($defConfig, $config);
		extract($config);

		require_once JPATH_COMPONENT_ADMINISTRATOR . '/models/statistics.php';

		$model = new AkeebaModelStatistics();
		$model->setState('id', (int)$backup_id);
		$result = $model->delete();
		if (!$result)
		{
			$this->status = self::STATUS_ERROR;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return $model->getError();
		}
		else
		{
			return true;
		}
	}

	private function _apiDeleteFiles($config)
	{
		$defConfig = array(
			'backup_id' => 0
		);
		$config = array_merge($defConfig, $config);
		extract($config);

		require_once JPATH_COMPONENT_ADMINISTRATOR . '/models/statistics.php';

		$model = new AkeebaModelStatistics();
		$model->setState('id', (int)$backup_id);
		$result = $model->deleteFile();
		if (!$result)
		{
			$this->status = self::STATUS_ERROR;
			$this->encapsulation = self::ENCAPSULATION_RAW;

			return $model->getError();
		}
		else
		{
			return true;
		}
	}

	private function _apiGetLog($config)
	{
		$defConfig = array(
			'tag' => 'remote'
		);
		$config = array_merge($defConfig, $config);
		extract($config);

		$filename = Factory::getLog()->getLogFilename($tag);
		$buffer = file_get_contents($filename);

		switch ($this->encapsulation)
		{
			case self::ENCAPSULATION_RAW:
				return base64_encode($buffer);
				break;

			case self::ENCAPSULATION_AESCTR128:
				$this->encapsulation = self::ENCAPSULATION_AESCBC128;

				return $buffer;
				break;

			case self::ENCAPSULATION_AESCTR256:
				$this->encapsulation = self::ENCAPSULATION_AESCBC256;

				return $buffer;
				break;

			default:
				// On encrypted comms the encryption will take care of transport encoding
				return $buffer;
				break;
		}
	}

	private function _apiDownloadDirect($config)
	{
		$defConfig = array(
			'backup_id' => 0,
			'part_id'   => 1
		);
		$config = array_merge($defConfig, $config);
		extract($config);

		$backup_stats = Platform::getInstance()->get_statistics($backup_id);
		if (empty($backup_stats))
		{
			// Backup record doesn't exist
			$this->status = self::STATUS_NOT_FOUND;
			$this->encapsulation = self::ENCAPSULATION_RAW;
			@ob_end_clean();
			header('HTTP/1.1 500 Invalid backup record identifier');
			flush();
			JFactory::getApplication()->close();
		}
		$files = Factory::getStatistics()->get_all_filenames($backup_stats);

		if ((count($files) < $part_id) || ($part_id <= 0))
		{
			// Invalid part
			$this->status = self::STATUS_NOT_FOUND;
			$this->encapsulation = self::ENCAPSULATION_RAW;
			@ob_end_clean();
			header('HTTP/1.1 500 Invalid backup part');
			flush();
			JFactory::getApplication()->close();
		}

		$filename = $files[$part_id - 1];
		@clearstatcache();

		// For a certain unmentionable browser -- Thank you, Nooku, for the tip
		if (function_exists('ini_get') && function_exists('ini_set'))
		{
			if (ini_get('zlib.output_compression'))
			{
				ini_set('zlib.output_compression', 'Off');
			}
		}

		// Remove php's time limit -- Thank you, Nooku, for the tip
		if (function_exists('ini_get') && function_exists('set_time_limit'))
		{
			if (!ini_get('safe_mode'))
			{
				@set_time_limit(0);
			}
		}

		$basename = @basename($filename);
		$filesize = @filesize($filename);
		$extension = strtolower(str_replace(".", "", strrchr($filename, ".")));

		while (@ob_end_clean())
		{
			;
		}
		@clearstatcache();
		// Send MIME headers
		header('MIME-Version: 1.0');
		header('Content-Disposition: attachment; filename="' . $basename . '"');
		header('Content-Transfer-Encoding: binary');
		header('Accept-Ranges: bytes');

		switch ($extension)
		{
			case 'zip':
				// ZIP MIME type
				header('Content-Type: application/zip');
				break;

			default:
				// Generic binary data MIME type
				header('Content-Type: application/octet-stream');
				break;
		}
		// Notify of filesize, if this info is available
		if ($filesize > 0)
		{
			header('Content-Length: ' . @filesize($filename));
		}
		// Disable caching
		header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
		header("Expires: 0");
		header('Pragma: no-cache');
		flush();
		if ($filesize > 0)
		{
			// If the filesize is reported, use 1M chunks for echoing the data to the browser
			$blocksize = 1048756; //1M chunks
			$handle = @fopen($filename, "r");
			// Now we need to loop through the file and echo out chunks of file data
			if ($handle !== false)
			{
				while (!@feof($handle))
				{
					echo @fread($handle, $blocksize);
					@ob_flush();
					flush();
				}
			}
			if ($handle !== false)
			{
				@fclose($handle);
			}
		}
		else
		{
			// If the filesize is not reported, hope that readfile works
			@readfile($filename);
		}
		flush();
		JFactory::getApplication()->close();
	}

	/**
	 * Encodes a variable to JSON using PEAR's Services_JSON
	 *
	 * @param mixed $value   The value to encode
	 * @param int   $options Encoding preferences flags
	 *
	 * @return string The JSON-encoded string
	 */
	private function json_encode($value, $options = 0)
	{
		$flags = SERVICES_JSON_LOOSE_TYPE;
		if ($options & JSON_FORCE_OBJECT)
		{
			$flags = 0;
		}
		$encoder = new Akeeba_Services_JSON($flags);

		return $encoder->encode($value);
	}

	/**
	 * Decodes a JSON string to a variable using PEAR's Services_JSON
	 *
	 * @param string $value The JSON-encoded string
	 * @param bool   $assoc True to return an associative array instead of an object
	 *
	 * @return mixed The decoded variable
	 */
	private function json_decode($value, $assoc = false)
	{
		$flags = 0;
		if ($assoc)
		{
			$flags = SERVICES_JSON_LOOSE_TYPE;
		}
		$decoder = new Akeeba_Services_JSON($flags);

		return $decoder->decode($value);
	}

	private function parseRestorePointXML($xml)
	{
		if (!count($xml->children()))
		{
			return false;
		}

		$ret = array();

		// 1. Group name -- core.filters.srp.group
		$group = $xml->getElementByPath('group');
		if ($group)
		{
			$ret['core.filters.srp.group'] = $group->data();
		}

		// 2. Custom dirs -- core.filters.srp.customdirs
		$customdirs = $xml->getElementByPath('customdirs');
		if ($customdirs)
		{
			$stack = array();
			if (count($customdirs->children()))
			{
				$children = $customdirs->children();
				foreach ($children as $child)
				{
					if ($child->name() == 'dir')
					{
						$stack[] = $child->data();
					}
				}
			}
			if (!empty($stack))
			{
				$ret['core.filters.srp.customdirs'] = $stack;
			}
		}

		// 3. Extra prefixes -- core.filters.srp.extraprefixes
		$extraprefixes = $xml->getElementByPath('extraprefixes');
		if ($extraprefixes)
		{
			$stack = array();
			if (count($extraprefixes->children()))
			{
				$children = $extraprefixes->children();
				foreach ($children as $child)
				{
					if ($child->name() == 'prefix')
					{
						$stack[] = $child->data();
					}
				}
			}
			if (!empty($stack))
			{
				$ret['core.filters.srp.extraprefixes'] = $stack;
			}
		}

		// 4. Custom tables -- core.filters.srp.customtables
		$customtables = $xml->getElementByPath('customtables');
		if ($customtables)
		{
			$stack = array();
			if (count($customtables->children()))
			{
				$children = $customtables->children();
				foreach ($children as $child)
				{
					if ($child->name() == 'table')
					{
						$stack[] = $child->data();
					}
				}
			}
			if (!empty($stack))
			{
				$ret['core.filters.srp.customtables'] = $stack;
			}
		}

		// 5. Skip tables -- core.filters.srp.skiptables
		$skiptables = $xml->getElementByPath('skiptables');
		if ($skiptables)
		{
			$stack = array();
			if (count($skiptables->children()))
			{
				$children = $skiptables->children();
				foreach ($children as $child)
				{
					if ($child->name() == 'table')
					{
						$stack[] = $child->data();
					}
				}
			}
			if (!empty($stack))
			{
				$ret['core.filters.srp.skiptables'] = $stack;
			}
		}

		// 6. Language files -- core.filters.srp.langfiles
		$langfiles = $xml->getElementByPath('langfiles');
		if ($langfiles)
		{
			$stack = array();
			if (count($langfiles->children()))
			{
				$children = $langfiles->children();
				foreach ($children as $child)
				{
					if ($child->name() == 'lang')
					{
						$stack[] = $child->data();
					}
				}
			}
			if (!empty($stack))
			{
				$ret['core.filters.srp.langfiles'] = $stack;
			}
		}

		// 7. Custom files -- core.filters.srp.customfiles
		$customfiles = $xml->getElementByPath('customfiles');
		if ($customfiles)
		{
			$stack = array();
			if (count($customfiles->children()))
			{
				$children = $customfiles->children();
				foreach ($children as $child)
				{
					if ($child->name() == 'file')
					{
						$stack[] = $child->data();
					}
				}
			}
			if (!empty($stack))
			{
				$ret['core.filters.srp.customfiles'] = $stack;
			}
		}

		if (empty($ret))
		{
			return false;
		}

		return $ret;
	}

	private function mergeSRPConfig(&$config, $extraConfig)
	{
		foreach ($config as $key => $value)
		{
			if (array_key_exists($key, $extraConfig))
			{
				if (is_array($value) && is_array($extraConfig[$key]))
				{
					$config[$key] = array_merge($extraConfig[$key], $value);
				}
			}
		}
	}
}