<?php
/**
 * Joomla! Content Management System
 *
 * @copyright  Copyright (C) 2005 - 2018 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE.txt
 */

namespace Joomla\CMS\Installer;

defined('JPATH_PLATFORM') or die;

use Joomla\CMS\Application\ApplicationHelper;
use Joomla\CMS\Plugin\PluginHelper;
use Joomla\CMS\Table\Extension;
use Joomla\CMS\Table\Table;

\JLoader::import('joomla.filesystem.file');
\JLoader::import('joomla.filesystem.folder');
\JLoader::import('joomla.filesystem.path');
\JLoader::import('joomla.base.adapter');

/**
 * Joomla base installer class
 *
 * @since  3.1
 */
class Installer extends \JAdapter
{
	/**
	 * Array of paths needed by the installer
	 *
	 * @var    array
	 * @since  3.1
	 */
	protected $paths = array();

	/**
	 * True if package is an upgrade
	 *
	 * @var    boolean
	 * @since  3.1
	 */
	protected $upgrade = null;

	/**
	 * The manifest trigger class
	 *
	 * @var    object
	 * @since  3.1
	 */
	public $manifestClass = null;

	/**
	 * True if existing files can be overwritten
	 *
	 * @var    boolean
	 * @since  12.1
	 */
	protected $overwrite = false;

	/**
	 * Stack of installation steps
	 * - Used for installation rollback
	 *
	 * @var    array
	 * @since  3.1
	 */
	protected $stepStack = array();

	/**
	 * Extension Table Entry
	 *
	 * @var    Extension
	 * @since  3.1
	 */
	public $extension = null;

	/**
	 * The output from the install/uninstall scripts
	 *
	 * @var    string
	 * @since  3.1
	 * */
	public $message = null;

	/**
	 * The installation manifest XML object
	 *
	 * @var    object
	 * @since  3.1
	 */
	public $manifest = null;

	/**
	 * The extension message that appears
	 *
	 * @var    string
	 * @since  3.1
	 */
	protected $extension_message = null;

	/**
	 * The redirect URL if this extension (can be null if no redirect)
	 *
	 * @var    string
	 * @since  3.1
	 */
	protected $redirect_url = null;

	/**
	 * Flag if the uninstall process was triggered by uninstalling a package
	 *
	 * @var    boolean
	 * @since  3.7.0
	 */
	protected $packageUninstall = false;

	/**
	 * Installer instance container.
	 *
	 * @var    Installer
	 * @since  3.1
	 * @deprecated  4.0
	 */
	protected static $instance;

	/**
	 * Installer instances container.
	 *
	 * @var    Installer[]
	 * @since  3.4
	 */
	protected static $instances;

	/**
	 * Constructor
	 *
	 * @param   string  $basepath       Base Path of the adapters
	 * @param   string  $classprefix    Class prefix of adapters
	 * @param   string  $adapterfolder  Name of folder to append to base path
	 *
	 * @since   3.1
	 */
	public function __construct($basepath = __DIR__, $classprefix = '\\Joomla\\CMS\\Installer\\Adapter', $adapterfolder = 'Adapter')
	{
		parent::__construct($basepath, $classprefix, $adapterfolder);

		$this->extension = Table::getInstance('extension');
	}

	/**
	 * Returns the global Installer object, only creating it if it doesn't already exist.
	 *
	 * @param   string  $basepath       Base Path of the adapters
	 * @param   string  $classprefix    Class prefix of adapters
	 * @param   string  $adapterfolder  Name of folder to append to base path
	 *
	 * @return  Installer  An installer object
	 *
	 * @since   3.1
	 */
	public static function getInstance($basepath = __DIR__, $classprefix = '\\Joomla\\CMS\\Installer\\Adapter', $adapterfolder = 'Adapter')
	{
		if (!isset(self::$instances[$basepath]))
		{
			self::$instances[$basepath] = new Installer($basepath, $classprefix, $adapterfolder);

			// For B/C, we load the first instance into the static $instance container, remove at 4.0
			if (!isset(self::$instance))
			{
				self::$instance = self::$instances[$basepath];
			}
		}

		return self::$instances[$basepath];
	}

	/**
	 * Get the allow overwrite switch
	 *
	 * @return  boolean  Allow overwrite switch
	 *
	 * @since   3.1
	 */
	public function isOverwrite()
	{
		return $this->overwrite;
	}

	/**
	 * Set the allow overwrite switch
	 *
	 * @param   boolean  $state  Overwrite switch state
	 *
	 * @return  boolean  True it state is set, false if it is not
	 *
	 * @since   3.1
	 */
	public function setOverwrite($state = false)
	{
		$tmp = $this->overwrite;

		if ($state)
		{
			$this->overwrite = true;
		}
		else
		{
			$this->overwrite = false;
		}

		return $tmp;
	}

	/**
	 * Get the redirect location
	 *
	 * @return  string  Redirect location (or null)
	 *
	 * @since   3.1
	 */
	public function getRedirectUrl()
	{
		return $this->redirect_url;
	}

	/**
	 * Set the redirect location
	 *
	 * @param   string  $newurl  New redirect location
	 *
	 * @return  void
	 *
	 * @since   3.1
	 */
	public function setRedirectUrl($newurl)
	{
		$this->redirect_url = $newurl;
	}

	/**
	 * Get whether this installer is uninstalling extensions which are part of a package
	 *
	 * @return  boolean
	 *
	 * @since   3.7.0
	 */
	public function isPackageUninstall()
	{
		return $this->packageUninstall;
	}

	/**
	 * Set whether this installer is uninstalling extensions which are part of a package
	 *
	 * @param   boolean  $uninstall  True if a package triggered the uninstall, false otherwise
	 *
	 * @return  void
	 *
	 * @since   3.7.0
	 */
	public function setPackageUninstall($uninstall)
	{
		$this->packageUninstall = $uninstall;
	}

	/**
	 * Get the upgrade switch
	 *
	 * @return  boolean
	 *
	 * @since   3.1
	 */
	public function isUpgrade()
	{
		return $this->upgrade;
	}

	/**
	 * Set the upgrade switch
	 *
	 * @param   boolean  $state  Upgrade switch state
	 *
	 * @return  boolean  True if upgrade, false otherwise
	 *
	 * @since   3.1
	 */
	public function setUpgrade($state = false)
	{
		$tmp = $this->upgrade;

		if ($state)
		{
			$this->upgrade = true;
		}
		else
		{
			$this->upgrade = false;
		}

		return $tmp;
	}

	/**
	 * Get the installation manifest object
	 *
	 * @return  \SimpleXMLElement  Manifest object
	 *
	 * @since   3.1
	 */
	public function getManifest()
	{
		if (!is_object($this->manifest))
		{
			$this->findManifest();
		}

		return $this->manifest;
	}

	/**
	 * Get an installer path by name
	 *
	 * @param   string  $name     Path name
	 * @param   string  $default  Default value
	 *
	 * @return  string  Path
	 *
	 * @since   3.1
	 */
	public function getPath($name, $default = null)
	{
		return (!empty($this->paths[$name])) ? $this->paths[$name] : $default;
	}

	/**
	 * Sets an installer path by name
	 *
	 * @param   string  $name   Path name
	 * @param   string  $value  Path
	 *
	 * @return  void
	 *
	 * @since   3.1
	 */
	public function setPath($name, $value)
	{
		$this->paths[$name] = $value;
	}

	/**
	 * Pushes a step onto the installer stack for rolling back steps
	 *
	 * @param   array  $step  Installer step
	 *
	 * @return  void
	 *
	 * @since   3.1
	 */
	public function pushStep($step)
	{
		$this->stepStack[] = $step;
	}

	/**
	 * Installation abort method
	 *
	 * @param   string  $msg   Abort message from the installer
	 * @param   string  $type  Package type if defined
	 *
	 * @return  boolean  True if successful
	 *
	 * @since   3.1
	 */
	public function abort($msg = null, $type = null)
	{
		$retval = true;
		$step = array_pop($this->stepStack);

		// Raise abort warning
		if ($msg)
		{
			\JLog::add($msg, \JLog::WARNING, 'jerror');
		}

		while ($step != null)
		{
			switch ($step['type'])
			{
				case 'file':
					// Remove the file
					$stepval = \JFile::delete($step['path']);
					break;

				case 'folder':
					// Remove the folder
					$stepval = \JFolder::delete($step['path']);
					break;

				case 'query':
					// Execute the query.
					$stepval = $this->parseSQLFiles($step['script']);
					break;

				case 'extension':
					// Get database connector object
					$db = $this->getDbo();
					$query = $db->getQuery(true);

					// Remove the entry from the #__extensions table
					$query->delete($db->quoteName('#__extensions'))
						->where($db->quoteName('extension_id') . ' = ' . (int) $step['id']);
					$db->setQuery($query);

					try
					{
						$db->execute();

						$stepval = true;
					}
					catch (\JDatabaseExceptionExecuting $e)
					{
						// The database API will have already logged the error it caught, we just need to alert the user to the issue
						\JLog::add(\JText::_('JLIB_INSTALLER_ABORT_ERROR_DELETING_EXTENSIONS_RECORD'), \JLog::WARNING, 'jerror');

						$stepval = false;
					}

					break;

				default:
					if ($type && is_object($this->_adapters[$type]))
					{
						// Build the name of the custom rollback method for the type
						$method = '_rollback_' . $step['type'];

						// Custom rollback method handler
						if (method_exists($this->_adapters[$type], $method))
						{
							$stepval = $this->_adapters[$type]->$method($step);
						}
					}
					else
					{
						// Set it to false
						$stepval = false;
					}
					break;
			}

			// Only set the return value if it is false
			if ($stepval === false)
			{
				$retval = false;
			}

			// Get the next step and continue
			$step = array_pop($this->stepStack);
		}

		return $retval;
	}

	// Adapter functions

	/**
	 * Package installation method
	 *
	 * @param   string  $path  Path to package source folder
	 *
	 * @return  boolean  True if successful
	 *
	 * @since   3.1
	 */
	public function install($path = null)
	{
		if ($path && \JFolder::exists($path))
		{
			$this->setPath('source', $path);
		}
		else
		{
			$this->abort(\JText::_('JLIB_INSTALLER_ABORT_NOINSTALLPATH'));

			return false;
		}

		if (!$adapter = $this->setupInstall('install', true))
		{
			$this->abort(\JText::_('JLIB_INSTALLER_ABORT_DETECTMANIFEST'));

			return false;
		}

		if (!is_object($adapter))
		{
			return false;
		}

		// Add the languages from the package itself
		if (method_exists($adapter, 'loadLanguage'))
		{
			$adapter->loadLanguage($path);
		}

		// Fire the onExtensionBeforeInstall event.
		PluginHelper::importPlugin('extension');
		$dispatcher = \JEventDispatcher::getInstance();
		$dispatcher->trigger(
			'onExtensionBeforeInstall',
			array(
				'method' => 'install',
				'type' => $this->manifest->attributes()->type,
				'manifest' => $this->manifest,
				'extension' => 0,
			)
		);

		// Run the install
		$result = $adapter->install();

		// Fire the onExtensionAfterInstall
		$dispatcher->trigger(
			'onExtensionAfterInstall',
			array('installer' => clone $this, 'eid' => $result)
		);

		if ($result !== false)
		{
			// Refresh versionable assets cache
			\JFactory::getApplication()->flushAssets();

			return true;
		}

		return false;
	}

	/**
	 * Discovered package installation method
	 *
	 * @param   integer  $eid  Extension ID
	 *
	 * @return  boolean  True if successful
	 *
	 * @since   3.1
	 */
	public function discover_install($eid = null)
	{
		if (!$eid)
		{
			$this->abort(\JText::_('JLIB_INSTALLER_ABORT_EXTENSIONNOTVALID'));

			return false;
		}

		if (!$this->extension->load($eid))
		{
			$this->abort(\JText::_('JLIB_INSTALLER_ABORT_LOAD_DETAILS'));

			return false;
		}

		if ($this->extension->state != -1)
		{
			$this->abort(\JText::_('JLIB_INSTALLER_ABORT_ALREADYINSTALLED'));

			return false;
		}

		// Load the adapter(s) for the install manifest
		$type   = $this->extension->type;
		$params = array('extension' => $this->extension, 'route' => 'discover_install');

		$adapter = $this->getAdapter($type, $params);

		if (!is_object($adapter))
		{
			return false;
		}

		if (!method_exists($adapter, 'discover_install') || !$adapter->getDiscoverInstallSupported())
		{
			$this->abort(\JText::sprintf('JLIB_INSTALLER_ERROR_DISCOVER_INSTALL_UNSUPPORTED', $type));

			return false;
		}

		// The adapter needs to prepare itself
		if (method_exists($adapter, 'prepareDiscoverInstall'))
		{
			try
			{
				$adapter->prepareDiscoverInstall();
			}
			catch (\RuntimeException $e)
			{
				$this->abort($e->getMessage());

				return false;
			}
		}

		// Add the languages from the package itself
		if (method_exists($adapter, 'loadLanguage'))
		{
			$adapter->loadLanguage();
		}

		// Fire the onExtensionBeforeInstall event.
		PluginHelper::importPlugin('extension');
		$dispatcher = \JEventDispatcher::getInstance();
		$dispatcher->trigger(
			'onExtensionBeforeInstall',
			array(
				'method' => 'discover_install',
				'type' => $this->extension->get('type'),
				'manifest' => null,
				'extension' => $this->extension->get('extension_id'),
			)
		);

		// Run the install
		$result = $adapter->discover_install();

		// Fire the onExtensionAfterInstall
		$dispatcher->trigger(
			'onExtensionAfterInstall',
			array('installer' => clone $this, 'eid' => $result)
		);

		if ($result !== false)
		{
			// Refresh versionable assets cache
			\JFactory::getApplication()->flushAssets();

			return true;
		}

		return false;
	}

	/**
	 * Extension discover method
	 *
	 * Asks each adapter to find extensions
	 *
	 * @return  InstallerExtension[]
	 *
	 * @since   3.1
	 */
	public function discover()
	{
		$this->loadAllAdapters();
		$results = array();

		foreach ($this->_adapters as $adapter)
		{
			// Joomla! 1.5 installation adapter legacy support
			if (method_exists($adapter, 'discover'))
			{
				$tmp = $adapter->discover();

				// If its an array and has entries
				if (is_array($tmp) && count($tmp))
				{
					// Merge it into the system
					$results = array_merge($results, $tmp);
				}
			}
		}

		return $results;
	}

	/**
	 * Package update method
	 *
	 * @param   string  $path  Path to package source folder
	 *
	 * @return  boolean  True if successful
	 *
	 * @since   3.1
	 */
	public function update($path = null)
	{
		if ($path && \JFolder::exists($path))
		{
			$this->setPath('source', $path);
		}
		else
		{
			$this->abort(\JText::_('JLIB_INSTALLER_ABORT_NOUPDATEPATH'));

			return false;
		}

		if (!$adapter = $this->setupInstall('update', true))
		{
			$this->abort(\JText::_('JLIB_INSTALLER_ABORT_DETECTMANIFEST'));

			return false;
		}

		if (!is_object($adapter))
		{
			return false;
		}

		// Add the languages from the package itself
		if (method_exists($adapter, 'loadLanguage'))
		{
			$adapter->loadLanguage($path);
		}

		// Fire the onExtensionBeforeUpdate event.
		PluginHelper::importPlugin('extension');
		$dispatcher = \JEventDispatcher::getInstance();
		$dispatcher->trigger('onExtensionBeforeUpdate', array('type' => $this->manifest->attributes()->type, 'manifest' => $this->manifest));

		// Run the update
		$result = $adapter->update();

		// Fire the onExtensionAfterUpdate
		$dispatcher->trigger(
			'onExtensionAfterUpdate',
			array('installer' => clone $this, 'eid' => $result)
		);

		if ($result !== false)
		{
			return true;
		}

		return false;
	}

	/**
	 * Package uninstallation method
	 *
	 * @param   string   $type        Package type
	 * @param   mixed    $identifier  Package identifier for adapter
	 * @param   integer  $cid         Application ID; deprecated in 1.6
	 *
	 * @return  boolean  True if successful
	 *
	 * @since   3.1
	 */
	public function uninstall($type, $identifier, $cid = 0)
	{
		$params = array('extension' => $this->extension, 'route' => 'uninstall');

		$adapter = $this->getAdapter($type, $params);

		if (!is_object($adapter))
		{
			return false;
		}

		// We don't load languages here, we get the extension adapter to work it out
		// Fire the onExtensionBeforeUninstall event.
		PluginHelper::importPlugin('extension');
		$dispatcher = \JEventDispatcher::getInstance();
		$dispatcher->trigger('onExtensionBeforeUninstall', array('eid' => $identifier));

		// Run the uninstall
		$result = $adapter->uninstall($identifier);

		// Fire the onExtensionAfterInstall
		$dispatcher->trigger(
			'onExtensionAfterUninstall',
			array('installer' => clone $this, 'eid' => $identifier, 'result' => $result)
		);

		// Refresh versionable assets cache
		\JFactory::getApplication()->flushAssets();

		return $result;
	}

	/**
	 * Refreshes the manifest cache stored in #__extensions
	 *
	 * @param   integer  $eid  Extension ID
	 *
	 * @return  boolean
	 *
	 * @since   3.1
	 */
	public function refreshManifestCache($eid)
	{
		if ($eid)
		{
			if (!$this->extension->load($eid))
			{
				$this->abort(\JText::_('JLIB_INSTALLER_ABORT_LOAD_DETAILS'));

				return false;
			}

			if ($this->extension->state == -1)
			{
				$this->abort(\JText::sprintf('JLIB_INSTALLER_ABORT_REFRESH_MANIFEST_CACHE', $this->extension->name));

				return false;
			}

			// Fetch the adapter
			$adapter = $this->getAdapter($this->extension->type);

			if (!is_object($adapter))
			{
				return false;
			}

			if (!method_exists($adapter, 'refreshManifestCache'))
			{
				$this->abort(\JText::sprintf('JLIB_INSTALLER_ABORT_METHODNOTSUPPORTED_TYPE', $this->extension->type));

				return false;
			}

			$result = $adapter->refreshManifestCache();

			if ($result !== false)
			{
				return true;
			}
			else
			{
				return false;
			}
		}

		$this->abort(\JText::_('JLIB_INSTALLER_ABORT_REFRESH_MANIFEST_CACHE_VALID'));

		return false;
	}

	// Utility functions

	/**
	 * Prepare for installation: this method sets the installation directory, finds
	 * and checks the installation file and verifies the installation type.
	 *
	 * @param   string   $route          The install route being followed
	 * @param   boolean  $returnAdapter  Flag to return the instantiated adapter
	 *
	 * @return  boolean|InstallerAdapter  InstallerAdapter object if explicitly requested otherwise boolean
	 *
	 * @since   3.1
	 */
	public function setupInstall($route = 'install', $returnAdapter = false)
	{
		// We need to find the installation manifest file
		if (!$this->findManifest())
		{
			return false;
		}

		// Load the adapter(s) for the install manifest
		$type   = (string) $this->manifest->attributes()->type;
		$params = array('route' => $route, 'manifest' => $this->getManifest());

		// Load the adapter
		$adapter = $this->getAdapter($type, $params);

		if ($returnAdapter)
		{
			return $adapter;
		}

		return true;
	}

	/**
	 * Backward compatible method to parse through a queries element of the
	 * installation manifest file and take appropriate action.
	 *
	 * @param   \SimpleXMLElement  $element  The XML node to process
	 *
	 * @return  mixed  Number of queries processed or False on error
	 *
	 * @since   3.1
	 */
	public function parseQueries(\SimpleXMLElement $element)
	{
		// Get the database connector object
		$db = & $this->_db;

		if (!$element || !count($element->children()))
		{
			// Either the tag does not exist or has no children therefore we return zero files processed.
			return 0;
		}

		// Get the array of query nodes to process
		$queries = $element->children();

		if (count($queries) === 0)
		{
			// No queries to process
			return 0;
		}

		$update_count = 0;

		// Process each query in the $queries array (children of $tagName).
		foreach ($queries as $query)
		{
			$db->setQuery($db->convertUtf8mb4QueryToUtf8($query));

			try
			{
				$db->execute();
			}
			catch (\JDatabaseExceptionExecuting $e)
			{
				\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_SQL_ERROR', $e->getMessage()), \JLog::WARNING, 'jerror');

				return false;
			}

			$update_count++;
		}

		return $update_count;
	}

	/**
	 * Method to extract the name of a discreet installation sql file from the installation manifest file.
	 *
	 * @param   object  $element  The XML node to process
	 *
	 * @return  mixed  Number of queries processed or False on error
	 *
	 * @since   3.1
	 */
	public function parseSQLFiles($element)
	{
		if (!$element || !count($element->children()))
		{
			// The tag does not exist.
			return 0;
		}

		$db = & $this->_db;

		// TODO - At 4.0 we can change this to use `getServerType()` since SQL Server will not be supported
		$dbDriver = strtolower($db->name);

		if ($db->getServerType() === 'mysql')
		{
			$dbDriver = 'mysql';
		}

		$update_count = 0;

		// Get the name of the sql file to process
		foreach ($element->children() as $file)
		{
			$fCharset = strtolower($file->attributes()->charset) === 'utf8' ? 'utf8' : '';
			$fDriver  = strtolower($file->attributes()->driver);

			if ($fDriver === 'mysqli' || $fDriver === 'pdomysql')
			{
				$fDriver = 'mysql';
			}

			if ($fCharset === 'utf8' && $fDriver == $dbDriver)
			{
				$sqlfile = $this->getPath('extension_root') . '/' . trim($file);

				// Check that sql files exists before reading. Otherwise raise error for rollback
				if (!file_exists($sqlfile))
				{
					\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_SQL_FILENOTFOUND', $sqlfile), \JLog::WARNING, 'jerror');

					return false;
				}

				$buffer = file_get_contents($sqlfile);

				// Graceful exit and rollback if read not successful
				if ($buffer === false)
				{
					\JLog::add(\JText::_('JLIB_INSTALLER_ERROR_SQL_READBUFFER'), \JLog::WARNING, 'jerror');

					return false;
				}

				// Create an array of queries from the sql file
				$queries = \JDatabaseDriver::splitSql($buffer);

				if (count($queries) === 0)
				{
					// No queries to process
					continue;
				}

				// Process each query in the $queries array (split out of sql file).
				foreach ($queries as $query)
				{
					$db->setQuery($db->convertUtf8mb4QueryToUtf8($query));

					try
					{
						$db->execute();
					}
					catch (\JDatabaseExceptionExecuting $e)
					{
						\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_SQL_ERROR', $e->getMessage()), \JLog::WARNING, 'jerror');

						return false;
					}

					$update_count++;
				}
			}
		}

		return $update_count;
	}

	/**
	 * Set the schema version for an extension by looking at its latest update
	 *
	 * @param   \SimpleXMLElement  $schema  Schema Tag
	 * @param   integer            $eid     Extension ID
	 *
	 * @return  void
	 *
	 * @since   3.1
	 */
	public function setSchemaVersion(\SimpleXMLElement $schema, $eid)
	{
		if ($eid && $schema)
		{
			$db = \JFactory::getDbo();
			$schemapaths = $schema->children();

			if (!$schemapaths)
			{
				return;
			}

			if (count($schemapaths))
			{
				$dbDriver = strtolower($db->name);

				if ($db->getServerType() === 'mysql')
				{
					$dbDriver = 'mysql';
				}

				$schemapath = '';

				foreach ($schemapaths as $entry)
				{
					$attrs = $entry->attributes();

					if ($attrs['type'] == $dbDriver)
					{
						$schemapath = $entry;
						break;
					}
				}

				if ($schemapath !== '')
				{
					$files = str_replace('.sql', '', \JFolder::files($this->getPath('extension_root') . '/' . $schemapath, '\.sql$'));
					usort($files, 'version_compare');

					// Update the database
					$query = $db->getQuery(true)
						->delete('#__schemas')
						->where('extension_id = ' . $eid);
					$db->setQuery($query);

					if ($db->execute())
					{
						$query->clear()
							->insert($db->quoteName('#__schemas'))
							->columns(array($db->quoteName('extension_id'), $db->quoteName('version_id')))
							->values($eid . ', ' . $db->quote(end($files)));
						$db->setQuery($query);
						$db->execute();
					}
				}
			}
		}
	}

	/**
	 * Method to process the updates for an item
	 *
	 * @param   \SimpleXMLElement  $schema  The XML node to process
	 * @param   integer            $eid     Extension Identifier
	 *
	 * @return  boolean           Result of the operations
	 *
	 * @since   3.1
	 */
	public function parseSchemaUpdates(\SimpleXMLElement $schema, $eid)
	{
		$update_count = 0;

		// Ensure we have an XML element and a valid extension id
		if ($eid && $schema)
		{
			$db = \JFactory::getDbo();
			$schemapaths = $schema->children();

			if (count($schemapaths))
			{
				// TODO - At 4.0 we can change this to use `getServerType()` since SQL Server will not be supported
				$dbDriver = strtolower($db->name);

				if ($db->getServerType() === 'mysql')
				{
					$dbDriver = 'mysql';
				}

				$schemapath = '';

				foreach ($schemapaths as $entry)
				{
					$attrs = $entry->attributes();

					// Assuming that the type is a mandatory attribute but if it is not mandatory then there should be a discussion for it.
					$uDriver = strtolower($attrs['type']);

					if ($uDriver === 'mysqli' || $uDriver === 'pdomysql')
					{
						$uDriver = 'mysql';
					}

					if ($uDriver == $dbDriver)
					{
						$schemapath = $entry;
						break;
					}
				}

				if ($schemapath !== '')
				{
					$files = \JFolder::files($this->getPath('extension_root') . '/' . $schemapath, '\.sql$');

					if (empty($files))
					{
						return $update_count;
					}

					$files = str_replace('.sql', '', $files);
					usort($files, 'version_compare');

					$query = $db->getQuery(true)
						->select('version_id')
						->from('#__schemas')
						->where('extension_id = ' . $eid);
					$db->setQuery($query);
					$version = $db->loadResult();

					// No version - use initial version.
					if (!$version)
					{
						$version = '0.0.0';
					}

					foreach ($files as $file)
					{
						if (version_compare($file, $version) > 0)
						{
							$buffer = file_get_contents($this->getPath('extension_root') . '/' . $schemapath . '/' . $file . '.sql');

							// Graceful exit and rollback if read not successful
							if ($buffer === false)
							{
								\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_SQL_READBUFFER'), \JLog::WARNING, 'jerror');

								return false;
							}

							// Create an array of queries from the sql file
							$queries = \JDatabaseDriver::splitSql($buffer);

							if (count($queries) === 0)
							{
								// No queries to process
								continue;
							}

							// Process each query in the $queries array (split out of sql file).
							foreach ($queries as $query)
							{
								$db->setQuery($db->convertUtf8mb4QueryToUtf8($query));

								try
								{
									$db->execute();
								}
								catch (\JDatabaseExceptionExecuting $e)
								{
									\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_SQL_ERROR', $e->getMessage()), \JLog::WARNING, 'jerror');

									return false;
								}

								$queryString = (string) $query;
								$queryString = str_replace(array("\r", "\n"), array('', ' '), substr($queryString, 0, 80));
								\JLog::add(\JText::sprintf('JLIB_INSTALLER_UPDATE_LOG_QUERY', $file, $queryString), \JLog::INFO, 'Update');

								$update_count++;
							}
						}
					}

					// Update the database
					$query = $db->getQuery(true)
						->delete('#__schemas')
						->where('extension_id = ' . $eid);
					$db->setQuery($query);

					if ($db->execute())
					{
						$query->clear()
							->insert($db->quoteName('#__schemas'))
							->columns(array($db->quoteName('extension_id'), $db->quoteName('version_id')))
							->values($eid . ', ' . $db->quote(end($files)));
						$db->setQuery($query);
						$db->execute();
					}
				}
			}
		}

		return $update_count;
	}

	/**
	 * Method to parse through a files element of the installation manifest and take appropriate
	 * action.
	 *
	 * @param   \SimpleXMLElement  $element   The XML node to process
	 * @param   integer            $cid       Application ID of application to install to
	 * @param   array              $oldFiles  List of old files (SimpleXMLElement's)
	 * @param   array              $oldMD5    List of old MD5 sums (indexed by filename with value as MD5)
	 *
	 * @return  boolean      True on success
	 *
	 * @since   3.1
	 */
	public function parseFiles(\SimpleXMLElement $element, $cid = 0, $oldFiles = null, $oldMD5 = null)
	{
		// Get the array of file nodes to process; we checked whether this had children above.
		if (!$element || !count($element->children()))
		{
			// Either the tag does not exist or has no children (hence no files to process) therefore we return zero files processed.
			return 0;
		}

		$copyfiles = array();

		// Get the client info
		$client = ApplicationHelper::getClientInfo($cid);

		/*
		 * Here we set the folder we are going to remove the files from.
		 */
		if ($client)
		{
			$pathname = 'extension_' . $client->name;
			$destination = $this->getPath($pathname);
		}
		else
		{
			$pathname = 'extension_root';
			$destination = $this->getPath($pathname);
		}

		/*
		 * Here we set the folder we are going to copy the files from.
		 *
		 * Does the element have a folder attribute?
		 *
		 * If so this indicates that the files are in a subdirectory of the source
		 * folder and we should append the folder attribute to the source path when
		 * copying files.
		 */

		$folder = (string) $element->attributes()->folder;

		if ($folder && file_exists($this->getPath('source') . '/' . $folder))
		{
			$source = $this->getPath('source') . '/' . $folder;
		}
		else
		{
			$source = $this->getPath('source');
		}

		// Work out what files have been deleted
		if ($oldFiles && ($oldFiles instanceof \SimpleXMLElement))
		{
			$oldEntries = $oldFiles->children();

			if (count($oldEntries))
			{
				$deletions = $this->findDeletedFiles($oldEntries, $element->children());

				foreach ($deletions['folders'] as $deleted_folder)
				{
					\JFolder::delete($destination . '/' . $deleted_folder);
				}

				foreach ($deletions['files'] as $deleted_file)
				{
					\JFile::delete($destination . '/' . $deleted_file);
				}
			}
		}

		$path = array();

		// Copy the MD5SUMS file if it exists
		if (file_exists($source . '/MD5SUMS'))
		{
			$path['src'] = $source . '/MD5SUMS';
			$path['dest'] = $destination . '/MD5SUMS';
			$path['type'] = 'file';
			$copyfiles[] = $path;
		}

		// Process each file in the $files array (children of $tagName).
		foreach ($element->children() as $file)
		{
			$path['src'] = $source . '/' . $file;
			$path['dest'] = $destination . '/' . $file;

			// Is this path a file or folder?
			$path['type'] = $file->getName() === 'folder' ? 'folder' : 'file';

			/*
			 * Before we can add a file to the copyfiles array we need to ensure
			 * that the folder we are copying our file to exits and if it doesn't,
			 * we need to create it.
			 */

			if (basename($path['dest']) !== $path['dest'])
			{
				$newdir = dirname($path['dest']);

				if (!\JFolder::create($newdir))
				{
					\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_CREATE_DIRECTORY', $newdir), \JLog::WARNING, 'jerror');

					return false;
				}
			}

			// Add the file to the copyfiles array
			$copyfiles[] = $path;
		}

		return $this->copyFiles($copyfiles);
	}

	/**
	 * Method to parse through a languages element of the installation manifest and take appropriate
	 * action.
	 *
	 * @param   \SimpleXMLElement  $element  The XML node to process
	 * @param   integer            $cid      Application ID of application to install to
	 *
	 * @return  boolean  True on success
	 *
	 * @since   3.1
	 */
	public function parseLanguages(\SimpleXMLElement $element, $cid = 0)
	{
		// TODO: work out why the below line triggers 'node no longer exists' errors with files
		if (!$element || !count($element->children()))
		{
			// Either the tag does not exist or has no children therefore we return zero files processed.
			return 0;
		}

		$copyfiles = array();

		// Get the client info
		$client = ApplicationHelper::getClientInfo($cid);

		// Here we set the folder we are going to copy the files to.
		// 'languages' Files are copied to JPATH_BASE/language/ folder

		$destination = $client->path . '/language';

		/*
		 * Here we set the folder we are going to copy the files from.
		 *
		 * Does the element have a folder attribute?
		 *
		 * If so this indicates that the files are in a subdirectory of the source
		 * folder and we should append the folder attribute to the source path when
		 * copying files.
		 */

		$folder = (string) $element->attributes()->folder;

		if ($folder && file_exists($this->getPath('source') . '/' . $folder))
		{
			$source = $this->getPath('source') . '/' . $folder;
		}
		else
		{
			$source = $this->getPath('source');
		}

		// Process each file in the $files array (children of $tagName).
		foreach ($element->children() as $file)
		{
			/*
			 * Language files go in a subfolder based on the language code, ie.
			 * <language tag="en-US">en-US.mycomponent.ini</language>
			 * would go in the en-US subdirectory of the language folder.
			 */

			// We will only install language files where a core language pack
			// already exists.

			if ((string) $file->attributes()->tag !== '')
			{
				$path['src'] = $source . '/' . $file;

				if ((string) $file->attributes()->client !== '')
				{
					// Override the client
					$langclient = ApplicationHelper::getClientInfo((string) $file->attributes()->client, true);
					$path['dest'] = $langclient->path . '/language/' . $file->attributes()->tag . '/' . basename((string) $file);
				}
				else
				{
					// Use the default client
					$path['dest'] = $destination . '/' . $file->attributes()->tag . '/' . basename((string) $file);
				}

				// If the language folder is not present, then the core pack hasn't been installed... ignore
				if (!\JFolder::exists(dirname($path['dest'])))
				{
					continue;
				}
			}
			else
			{
				$path['src'] = $source . '/' . $file;
				$path['dest'] = $destination . '/' . $file;
			}

			/*
			 * Before we can add a file to the copyfiles array we need to ensure
			 * that the folder we are copying our file to exits and if it doesn't,
			 * we need to create it.
			 */

			if (basename($path['dest']) !== $path['dest'])
			{
				$newdir = dirname($path['dest']);

				if (!\JFolder::create($newdir))
				{
					\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_CREATE_DIRECTORY', $newdir), \JLog::WARNING, 'jerror');

					return false;
				}
			}

			// Add the file to the copyfiles array
			$copyfiles[] = $path;
		}

		return $this->copyFiles($copyfiles);
	}

	/**
	 * Method to parse through a media element of the installation manifest and take appropriate
	 * action.
	 *
	 * @param   \SimpleXMLElement  $element  The XML node to process
	 * @param   integer            $cid      Application ID of application to install to
	 *
	 * @return  boolean     True on success
	 *
	 * @since   3.1
	 */
	public function parseMedia(\SimpleXMLElement $element, $cid = 0)
	{
		if (!$element || !count($element->children()))
		{
			// Either the tag does not exist or has no children therefore we return zero files processed.
			return 0;
		}

		$copyfiles = array();

		// Here we set the folder we are going to copy the files to.
		// Default 'media' Files are copied to the JPATH_BASE/media folder

		$folder = ((string) $element->attributes()->destination) ? '/' . $element->attributes()->destination : null;
		$destination = \JPath::clean(JPATH_ROOT . '/media' . $folder);

		// Here we set the folder we are going to copy the files from.

		/*
		 * Does the element have a folder attribute?
		 * If so this indicates that the files are in a subdirectory of the source
		 * folder and we should append the folder attribute to the source path when
		 * copying files.
		 */

		$folder = (string) $element->attributes()->folder;

		if ($folder && file_exists($this->getPath('source') . '/' . $folder))
		{
			$source = $this->getPath('source') . '/' . $folder;
		}
		else
		{
			$source = $this->getPath('source');
		}

		// Process each file in the $files array (children of $tagName).
		foreach ($element->children() as $file)
		{
			$path['src'] = $source . '/' . $file;
			$path['dest'] = $destination . '/' . $file;

			// Is this path a file or folder?
			$path['type'] = $file->getName() === 'folder' ? 'folder' : 'file';

			/*
			 * Before we can add a file to the copyfiles array we need to ensure
			 * that the folder we are copying our file to exits and if it doesn't,
			 * we need to create it.
			 */

			if (basename($path['dest']) !== $path['dest'])
			{
				$newdir = dirname($path['dest']);

				if (!\JFolder::create($newdir))
				{
					\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_CREATE_DIRECTORY', $newdir), \JLog::WARNING, 'jerror');

					return false;
				}
			}

			// Add the file to the copyfiles array
			$copyfiles[] = $path;
		}

		return $this->copyFiles($copyfiles);
	}

	/**
	 * Method to parse the parameters of an extension, build the JSON string for its default parameters, and return the JSON string.
	 *
	 * @return  string  JSON string of parameter values
	 *
	 * @since   3.1
	 * @note    This method must always return a JSON compliant string
	 */
	public function getParams()
	{
		// Validate that we have a fieldset to use
		if (!isset($this->manifest->config->fields->fieldset))
		{
			return '{}';
		}

		// Getting the fieldset tags
		$fieldsets = $this->manifest->config->fields->fieldset;

		// Creating the data collection variable:
		$ini = array();

		// Iterating through the fieldsets:
		foreach ($fieldsets as $fieldset)
		{
			if (!count($fieldset->children()))
			{
				// Either the tag does not exist or has no children therefore we return zero files processed.
				return '{}';
			}

			// Iterating through the fields and collecting the name/default values:
			foreach ($fieldset as $field)
			{
				// Check against the null value since otherwise default values like "0"
				// cause entire parameters to be skipped.

				if (($name = $field->attributes()->name) === null)
				{
					continue;
				}

				if (($value = $field->attributes()->default) === null)
				{
					continue;
				}

				$ini[(string) $name] = (string) $value;
			}
		}

		return json_encode($ini);
	}

	/**
	 * Copyfiles
	 *
	 * Copy files from source directory to the target directory
	 *
	 * @param   array    $files      Array with filenames
	 * @param   boolean  $overwrite  True if existing files can be replaced
	 *
	 * @return  boolean  True on success
	 *
	 * @since   3.1
	 */
	public function copyFiles($files, $overwrite = null)
	{
		/*
		 * To allow for manual override on the overwriting flag, we check to see if
		 * the $overwrite flag was set and is a boolean value.  If not, use the object
		 * allowOverwrite flag.
		 */

		if ($overwrite === null || !is_bool($overwrite))
		{
			$overwrite = $this->overwrite;
		}

		/*
		 * $files must be an array of filenames.  Verify that it is an array with
		 * at least one file to copy.
		 */
		if (is_array($files) && count($files) > 0)
		{
			foreach ($files as $file)
			{
				// Get the source and destination paths
				$filesource = \JPath::clean($file['src']);
				$filedest = \JPath::clean($file['dest']);
				$filetype = array_key_exists('type', $file) ? $file['type'] : 'file';

				if (!file_exists($filesource))
				{
					/*
					 * The source file does not exist.  Nothing to copy so set an error
					 * and return false.
					 */
					\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_NO_FILE', $filesource), \JLog::WARNING, 'jerror');

					return false;
				}
				elseif (($exists = file_exists($filedest)) && !$overwrite)
				{
					// It's okay if the manifest already exists
					if ($this->getPath('manifest') === $filesource)
					{
						continue;
					}

					// The destination file already exists and the overwrite flag is false.
					// Set an error and return false.
					\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_FILE_EXISTS', $filedest), \JLog::WARNING, 'jerror');

					return false;
				}
				else
				{
					// Copy the folder or file to the new location.
					if ($filetype === 'folder')
					{
						if (!\JFolder::copy($filesource, $filedest, null, $overwrite))
						{
							\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_FAIL_COPY_FOLDER', $filesource, $filedest), \JLog::WARNING, 'jerror');

							return false;
						}

						$step = array('type' => 'folder', 'path' => $filedest);
					}
					else
					{
						if (!\JFile::copy($filesource, $filedest, null))
						{
							\JLog::add(\JText::sprintf('JLIB_INSTALLER_ERROR_FAIL_COPY_FILE', $filesource, $filedest), \JLog::WARNING, 'jerror');

							// In 3.2, TinyMCE language handling changed.  Display a special notice in case an older language pack is installed.
							if (strpos($filedest, 'media/editors/tinymce/jscripts/tiny_mce/langs'))
							{
								\JLog::add(\JText::_('JLIB_INSTALLER_NOT_ERROR'), \JLog::WARNING, 'jerror');
							}

							return false;
						}

						$step = array('type' => 'file', 'path' => $filedest);
					}

					/*
					 * Since we copied a file/folder, we want to add it to the installation step stack so that
					 * in case we have to roll back the installation we can remove the files copied.
					 */
					if (!$exists)
					{
						$this->stepStack[] = $step;
					}
				}
			}
		}
		else
		{
			// The $files variable was either not an array or an empty array
			return false;
		}

		return count($files);
	}

	/**
	 * Method to parse through a files element of the installation manifest and remove
	 * the files that were installed
	 *
	 * @param   object   $element  The XML node to process
	 * @param   integer  $cid      Application ID of application to remove from
	 *
	 * @return  boolean  True on success
	 *
	 * @since   3.1
	 */
	public function removeFiles($element, $cid = 0)
	{
		if (!$element || !count($element->children()))
		{
			// Either the tag does not exist or has no children therefore we return zero files processed.
			return true;
		}

		$retval = true;

		// Get the client info if we're using a specific client
		if ($cid > -1)
		{
			$client = ApplicationHelper::getClientInfo($cid);
		}
		else
		{
			$client = null;
		}

		// Get the array of file nodes to process
		$files = $element->children();

		if (count($files) === 0)
		{
			// No files to process
			return true;
		}

		$folder = '';

		/*
		 * Here we set the folder we are going to remove the files from.  There are a few
		 * special cases that need to be considered for certain reserved tags.
		 */
		switch ($element->getName())
		{
			case 'media':
				if ((string) $element->attributes()->destination)
				{
					$folder = (string) $element->attributes()->destination;
				}
				else
				{
					$folder = '';
				}

				$source = $client->path . '/media/' . $folder;

				break;

			case 'languages':
				$lang_client = (string) $element->attributes()->client;

				if ($lang_client)
				{
					$client = ApplicationHelper::getClientInfo($lang_client, true);
					$source = $client->path . '/language';
				}
				else
				{
					if ($client)
					{
						$source = $client->path . '/language';
					}
					else
					{
						$source = '';
					}
				}

				break;

			default:
				if ($client)
				{
					$pathname = 'extension_' . $client->name;
					$source = $this->getPath($pathname);
				}
				else
				{
					$pathname = 'extension_root';
					$source = $this->getPath($pathname);
				}

				break;
		}

		// Process each file in the $files array (children of $tagName).
		foreach ($files as $file)
		{
			/*
			 * If the file is a language, we must handle it differently.  Language files
			 * go in a subdirectory based on the language code, ie.
			 * <language tag="en_US">en_US.mycomponent.ini</language>
			 * would go in the en_US subdirectory of the languages directory.
			 */

			if ($file->getName() === 'language' && (string) $file->attributes()->tag !== '')
			{
				if ($source)
				{
					$path = $source . '/' . $file->attributes()->tag . '/' . basename((string) $file);
				}
				else
				{
					$target_client = ApplicationHelper::getClientInfo((string) $file->attributes()->client, true);
					$path = $target_client->path . '/language/' . $file->attributes()->tag . '/' . basename((string) $file);
				}

				// If the language folder is not present, then the core pack hasn't been installed... ignore
				if (!\JFolder::exists(dirname($path)))
				{
					continue;
				}
			}
			else
			{
				$path = $source . '/' . $file;
			}

			// Actually delete the files/folders

			if (is_dir($path))
			{
				$val = \JFolder::delete($path);
			}
			else
			{
				$val = \JFile::delete($path);
			}

			if ($val === false)
			{
				\JLog::add('Failed to delete ' . $path, \JLog::WARNING, 'jerror');
				$retval = false;
			}
		}

		if (!empty($folder))
		{
			\JFolder::delete($source);
		}

		return $retval;
	}

	/**
	 * Copies the installation manifest file to the extension folder in the given client
	 *
	 * @param   integer  $cid  Where to copy the installfile [optional: defaults to 1 (admin)]
	 *
	 * @return  boolean  True on success, False on error
	 *
	 * @since   3.1
	 */
	public function copyManifest($cid = 1)
	{
		// Get the client info
		$client = ApplicationHelper::getClientInfo($cid);

		$path['src'] = $this->getPath('manifest');

		if ($client)
		{
			$pathname = 'extension_' . $client->name;
			$path['dest'] = $this->getPath($pathname) . '/' . basename($this->getPath('manifest'));
		}
		else
		{
			$pathname = 'extension_root';
			$path['dest'] = $this->getPath($pathname) . '/' . basename($this->getPath('manifest'));
		}

		return $this->copyFiles(array($path), true);
	}

	/**
	 * Tries to find the package manifest file
	 *
	 * @return  boolean  True on success, False on error
	 *
	 * @since   3.1
	 */
	public function findManifest()
	{
		// Do nothing if folder does not exist for some reason
		if (!\JFolder::exists($this->getPath('source')))
		{
			return false;
		}

		// Main folder manifests (higher priority)
		$parentXmlfiles = \JFolder::files($this->getPath('source'), '.xml$', false, true);

		// Search for children manifests (lower priority)
		$allXmlFiles    = \JFolder::files($this->getPath('source'), '.xml$', 1, true);

		// Create an unique array of files ordered by priority
		$xmlfiles = array_unique(array_merge($parentXmlfiles, $allXmlFiles));

		// If at least one XML file exists
		if (!empty($xmlfiles))
		{
			foreach ($xmlfiles as $file)
			{
				// Is it a valid Joomla installation manifest file?
				$manifest = $this->isManifest($file);

				if ($manifest !== null)
				{
					// If the root method attribute is set to upgrade, allow file overwrite
					if ((string) $manifest->attributes()->method === 'upgrade')
					{
						$this->upgrade = true;
						$this->overwrite = true;
					}

					// If the overwrite option is set, allow file overwriting
					if ((string) $manifest->attributes()->overwrite === 'true')
					{
						$this->overwrite = true;
					}

					// Set the manifest object and path
					$this->manifest = $manifest;
					$this->setPath('manifest', $file);

					// Set the installation source path to that of the manifest file
					$this->setPath('source', dirname($file));

					return true;
				}
			}

			// None of the XML files found were valid install files
			\JLog::add(\JText::_('JLIB_INSTALLER_ERROR_NOTFINDJOOMLAXMLSETUPFILE'), \JLog::WARNING, 'jerror');

			return false;
		}
		else
		{
			// No XML files were found in the install folder
			\JLog::add(\JText::_('JLIB_INSTALLER_ERROR_NOTFINDXMLSETUPFILE'), \JLog::WARNING, 'jerror');

			return false;
		}
	}

	/**
	 * Is the XML file a valid Joomla installation manifest file.
	 *
	 * @param   string  $file  An xmlfile path to check
	 *
	 * @return  \SimpleXMLElement|null  A \SimpleXMLElement, or null if the file failed to parse
	 *
	 * @since   3.1
	 */
	public function isManifest($file)
	{
		$xml = simplexml_load_file($file);

		// If we cannot load the XML file return null
		if (!$xml)
		{
			return;
		}

		// Check for a valid XML root tag.
		if ($xml->getName() !== 'extension')
		{
			return;
		}

		// Valid manifest file return the object
		return $xml;
	}

	/**
	 * Generates a manifest cache
	 *
	 * @return string serialised manifest data
	 *
	 * @since   3.1
	 */
	public function generateManifestCache()
	{
		return json_encode(self::parseXMLInstallFile($this->getPath('manifest')));
	}

	/**
	 * Cleans up discovered extensions if they're being installed some other way
	 *
	 * @param   string   $type     The type of extension (component, etc)
	 * @param   string   $element  Unique element identifier (e.g. com_content)
	 * @param   string   $folder   The folder of the extension (plugins; e.g. system)
	 * @param   integer  $client   The client application (administrator or site)
	 *
	 * @return  object    Result of query
	 *
	 * @since   3.1
	 */
	public function cleanDiscoveredExtension($type, $element, $folder = '', $client = 0)
	{
		$db = \JFactory::getDbo();
		$query = $db->getQuery(true)
			->delete($db->quoteName('#__extensions'))
			->where('type = ' . $db->quote($type))
			->where('element = ' . $db->quote($element))
			->where('folder = ' . $db->quote($folder))
			->where('client_id = ' . (int) $client)
			->where('state = -1');
		$db->setQuery($query);

		return $db->execute();
	}

	/**
	 * Compares two "files" entries to find deleted files/folders
	 *
	 * @param   array  $old_files  An array of \SimpleXMLElement objects that are the old files
	 * @param   array  $new_files  An array of \SimpleXMLElement objects that are the new files
	 *
	 * @return  array  An array with the delete files and folders in findDeletedFiles[files] and findDeletedFiles[folders] respectively
	 *
	 * @since   3.1
	 */
	public function findDeletedFiles($old_files, $new_files)
	{
		// The magic find deleted files function!
		// The files that are new
		$files = array();

		// The folders that are new
		$folders = array();

		// The folders of the files that are new
		$containers = array();

		// A list of files to delete
		$files_deleted = array();

		// A list of folders to delete
		$folders_deleted = array();

		foreach ($new_files as $file)
		{
			switch ($file->getName())
			{
				case 'folder':
					// Add any folders to the list
					$folders[] = (string) $file; // add any folders to the list
					break;

				case 'file':
				default:
					// Add any files to the list
					$files[] = (string) $file;

					// Now handle the folder part of the file to ensure we get any containers
					// Break up the parts of the directory
					$container_parts = explode('/', dirname((string) $file));

					// Make sure this is clean and empty
					$container = '';

					foreach ($container_parts as $part)
					{
						// Iterate through each part
						// Add a slash if its not empty
						if (!empty($container))
						{
							$container .= '/';
						}

						// Aappend the folder part
						$container .= $part;

						if (!in_array($container, $containers))
						{
							// Add the container if it doesn't already exist
							$containers[] = $container;
						}
					}
					break;
			}
		}

		foreach ($old_files as $file)
		{
			switch ($file->getName())
			{
				case 'folder':
					if (!in_array((string) $file, $folders))
					{
						// See whether the folder exists in the new list
						if (!in_array((string) $file, $containers))
						{
							// Check if the folder exists as a container in the new list
							// If it's not in the new list or a container then delete it
							$folders_deleted[] = (string) $file;
						}
					}
					break;

				case 'file':
				default:
					if (!in_array((string) $file, $files))
					{
						// Look if the file exists in the new list
						if (!in_array(dirname((string) $file), $folders))
						{
							// Look if the file is now potentially in a folder
							$files_deleted[] = (string) $file; // not in a folder, doesn't exist, wipe it out!
						}
					}
					break;
			}
		}

		return array('files' => $files_deleted, 'folders' => $folders_deleted);
	}

	/**
	 * Loads an MD5SUMS file into an associative array
	 *
	 * @param   string  $filename  Filename to load
	 *
	 * @return  array  Associative array with filenames as the index and the MD5 as the value
	 *
	 * @since   3.1
	 */
	public function loadMD5Sum($filename)
	{
		if (!file_exists($filename))
		{
			// Bail if the file doesn't exist
			return false;
		}

		$data = file($filename, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
		$retval = array();

		foreach ($data as $row)
		{
			// Split up the data
			$results = explode('  ', $row);

			// Cull any potential prefix
			$results[1] = str_replace('./', '', $results[1]);

			// Throw into the array
			$retval[$results[1]] = $results[0];
		}

		return $retval;
	}

	/**
	 * Parse a XML install manifest file.
	 *
	 * XML Root tag should be 'install' except for languages which use meta file.
	 *
	 * @param   string  $path  Full path to XML file.
	 *
	 * @return  array  XML metadata.
	 *
	 * @since   12.1
	 */
	public static function parseXMLInstallFile($path)
	{
		// Check if xml file exists.
		if (!file_exists($path))
		{
			return false;
		}

		// Read the file to see if it's a valid component XML file
		$xml = simplexml_load_file($path);

		if (!$xml)
		{
			return false;
		}

		// Check for a valid XML root tag.

		// Extensions use 'extension' as the root tag.  Languages use 'metafile' instead

		$name = $xml->getName();

		if ($name !== 'extension' && $name !== 'metafile')
		{
			unset($xml);

			return false;
		}

		$data = array();

		$data['name'] = (string) $xml->name;

		// Check if we're a language. If so use metafile.
		$data['type'] = $xml->getName() === 'metafile' ? 'language' : (string) $xml->attributes()->type;

		$data['creationDate'] = ((string) $xml->creationDate) ?: \JText::_('JLIB_UNKNOWN');
		$data['author'] = ((string) $xml->author) ?: \JText::_('JLIB_UNKNOWN');

		$data['copyright'] = (string) $xml->copyright;
		$data['authorEmail'] = (string) $xml->authorEmail;
		$data['authorUrl'] = (string) $xml->authorUrl;
		$data['version'] = (string) $xml->version;
		$data['description'] = (string) $xml->description;
		$data['group'] = (string) $xml->group;

		if ($xml->files && count($xml->files->children()))
		{
			$filename = \JFile::getName($path);
			$data['filename'] = \JFile::stripExt($filename);

			foreach ($xml->files->children() as $oneFile)
			{
				if ((string) $oneFile->attributes()->plugin)
				{
					$data['filename'] = (string) $oneFile->attributes()->plugin;
					break;
				}
			}
		}

		return $data;
	}

	/**
	 * Fetches an adapter and adds it to the internal storage if an instance is not set
	 * while also ensuring its a valid adapter name
	 *
	 * @param   string  $name     Name of adapter to return
	 * @param   array   $options  Adapter options
	 *
	 * @return  InstallerAdapter
	 *
	 * @since       3.4
	 * @deprecated  4.0  The internal adapter cache will no longer be supported,
	 *                   use loadAdapter() to fetch an adapter instance
	 */
	public function getAdapter($name, $options = array())
	{
		$this->getAdapters($options);

		if (!$this->setAdapter($name, $this->_adapters[$name]))
		{
			return false;
		}

		return $this->_adapters[$name];
	}

	/**
	 * Gets a list of available install adapters.
	 *
	 * @param   array  $options  An array of options to inject into the adapter
	 * @param   array  $custom   Array of custom install adapters
	 *
	 * @return  array  An array of available install adapters.
	 *
	 * @since   3.4
	 * @note    As of 4.0, this method will only return the names of available adapters and will not
	 *          instantiate them and store to the $_adapters class var.
	 */
	public function getAdapters($options = array(), array $custom = array())
	{
		$files = new \DirectoryIterator($this->_basepath . '/' . $this->_adapterfolder);

		// Process the core adapters
		foreach ($files as $file)
		{
			$fileName = $file->getFilename();

			// Only load for php files.
			if (!$file->isFile() || $file->getExtension() !== 'php')
			{
				continue;
			}

			// Derive the class name from the filename.
			$name  = str_ireplace('.php', '', trim($fileName));
			$name  = str_ireplace('adapter', '', trim($name));
			$class = rtrim($this->_classprefix, '\\') . '\\' . ucfirst($name) . 'Adapter';

			if (!class_exists($class))
			{
				// Not namespaced
				$class = $this->_classprefix . ucfirst($name);
			}

			// Core adapters should autoload based on classname, keep this fallback just in case
			if (!class_exists($class))
			{
				// Try to load the adapter object
				\JLoader::register($class, $this->_basepath . '/' . $this->_adapterfolder . '/' . $fileName);

				if (!class_exists($class))
				{
					// Skip to next one
					continue;
				}
			}

			$this->_adapters[strtolower($name)] = $this->loadAdapter($name, $options);
		}

		// Add any custom adapters if specified
		if (count($custom) >= 1)
		{
			foreach ($custom as $adapter)
			{
				// Setup the class name
				// TODO - Can we abstract this to not depend on the Joomla class namespace without PHP namespaces?
				$class = $this->_classprefix . ucfirst(trim($adapter));

				// If the class doesn't exist we have nothing left to do but look at the next type. We did our best.
				if (!class_exists($class))
				{
					continue;
				}

				$this->_adapters[$name] = $this->loadAdapter($name, $options);
			}
		}

		return $this->_adapters;
	}

	/**
	 * Method to load an adapter instance
	 *
	 * @param   string  $adapter  Adapter name
	 * @param   array   $options  Adapter options
	 *
	 * @return  InstallerAdapter
	 *
	 * @since   3.4
	 * @throws  \InvalidArgumentException
	 */
	public function loadAdapter($adapter, $options = array())
	{
		$class = rtrim($this->_classprefix, '\\') . '\\' . ucfirst($adapter) . 'Adapter';

		if (!class_exists($class))
		{
			// Not namespaced
			$class = $this->_classprefix . ucfirst($adapter);
		}

		if (!class_exists($class))
		{
			// @deprecated 4.0 - The adapter should be autoloaded or manually included by the caller
			$path = $this->_basepath . '/' . $this->_adapterfolder . '/' . $adapter . '.php';

			// Try to load the adapter object
			if (!file_exists($path))
			{
				throw new \InvalidArgumentException(sprintf('The %s install adapter does not exist.', $adapter));
			}

			// Try once more to find the class
			\JLoader::register($class, $path);

			if (!class_exists($class))
			{
				throw new \InvalidArgumentException(sprintf('The %s install adapter does not exist.', $adapter));
			}
		}

		// Ensure the adapter type is part of the options array
		$options['type'] = $adapter;

		return new $class($this, $this->getDbo(), $options);
	}

	/**
	 * Loads all adapters.
	 *
	 * @param   array  $options  Adapter options
	 *
	 * @return  void
	 *
	 * @since       3.4
	 * @deprecated  4.0  Individual adapters should be instantiated as needed
	 * @note        This method is serving as a proxy of the legacy \JAdapter API into the preferred API
	 */
	public function loadAllAdapters($options = array())
	{
		$this->getAdapters($options);
	}
}
