<?php
/**
 * @package    Octoleo CMS
 *
 * Joomla! Content Management System
 *
 * @source    https://github.com/joomla/joomla-cms/blob/4.1-dev/libraries/loader.php
 * @adapted   Llewellyn van der Merwe <https://git.vdm.dev/Llewellyn>
 *
 * @copyright (C) 2005 Open Source Matters, Inc. <https://www.joomla.org>
 * @license   GNU General Public License version 2 or later; see LICENSE.txt
 **/

defined('LPATH_PLATFORM') or die;

/**
 * Static class to handle loading of libraries.
 *
 * @since    1.0.0
 */
abstract class LLoader
{
	/**
	 * Container for already imported library paths.
	 *
	 * @var    array
	 * @since  1.7.0
	 */
	protected static $classes = array();

	/**
	 * Container for already imported library paths.
	 *
	 * @var    array
	 * @since  1.7.0
	 */
	protected static $imported = array();

	/**
	 * Container for registered library class prefixes and path lookups.
	 *
	 * @var    array
	 * @since  3.0.0
	 */
	protected static $prefixes = array();

	/**
	 * Holds proxy classes and the class names the proxy.
	 *
	 * @var    array
	 * @since  3.2
	 */
	protected static $classAliases = array();

	/**
	 * Holds the inverse lookup for proxy classes and the class names the proxy.
	 *
	 * @var    array
	 * @since  3.4
	 */
	protected static $classAliasesInverse = array();

	/**
	 * Container for namespace => path map.
	 *
	 * @var    array
	 * @since  3.1.4
	 */
	protected static $namespaces = array();

	/**
	 * Holds a reference for all deprecated aliases (mainly for use by a logging platform).
	 *
	 * @var    array
	 * @since  3.6.3
	 */
	protected static $deprecatedAliases = array();

	/**
	 * The root folders where extensions can be found.
	 *
	 * @var    array
	 * @since  4.0.0
	 */
	protected static $extensionRootFolders = array();

	/**
	 * Method to get the list of registered classes and their respective file paths for the autoloader.
	 *
	 * @return  array  The array of class => path values for the autoloader.
	 *
	 * @since   1.7.0
	 */
	public static function getClassList()
	{
		return self::$classes;
	}

	/**
	 * Method to get the list of deprecated class aliases.
	 *
	 * @return  array  An associative array with deprecated class alias data.
	 *
	 * @since   3.6.3
	 */
	public static function getDeprecatedAliases()
	{
		return self::$deprecatedAliases;
	}

	/**
	 * Method to get the list of registered namespaces.
	 *
	 * @return  array  The array of namespace => path values for the autoloader.
	 *
	 * @since   3.1.4
	 */
	public static function getNamespaces()
	{
		return self::$namespaces;
	}

	/**
	 * Load the file for a class.
	 *
	 * @param   string  $class  The class to be loaded.
	 *
	 * @return  boolean  True on success
	 *
	 * @since   1.7.0
	 */
	public static function load($class)
	{
		// Sanitize class name.
		$key = strtolower($class);

		// If the class already exists do nothing.
		if (class_exists($class, false))
		{
			return true;
		}

		// If the class is registered include the file.
		if (isset(self::$classes[$key]))
		{
			$found = (bool) include_once self::$classes[$key];

			if ($found)
			{
				self::loadAliasFor($class);
			}

			// If the class doesn't exists, we probably have a class alias available
			if (!class_exists($class, false))
			{
				// Search the alias class, first none namespaced and then namespaced
				$original = array_search($class, self::$classAliases) ? : array_search('\\' . $class, self::$classAliases);

				// When we have an original and the class exists an alias should be created
				if ($original && class_exists($original, false))
				{
					class_alias($original, $class);
				}
			}

			return true;
		}

		return false;
	}

	/**
	 * Register a class prefix with lookup path.  This will allow developers to register library
	 * packages with different class prefixes to the system autoloader.  More than one lookup path
	 * may be registered for the same class prefix, but if this method is called with the reset flag
	 * set to true then any registered lookups for the given prefix will be overwritten with the current
	 * lookup path. When loaded, prefix paths are searched in a "last in, first out" order.
	 *
	 * @param   string   $prefix   The class prefix to register.
	 * @param   string   $path     Absolute file path to the library root where classes with the given prefix can be found.
	 * @param   boolean  $reset    True to reset the prefix with only the given lookup path.
	 * @param   boolean  $prepend  If true, push the path to the beginning of the prefix lookup paths array.
	 *
	 * @return  void
	 *
	 * @throws  RuntimeException
	 *
	 * @since   3.0.0
	 */
	public static function registerPrefix($prefix, $path, $reset = false, $prepend = false)
	{
		// Verify the library path exists.
		if (!is_dir($path))
		{
			$path = (str_replace(LPATH_ROOT, '', $path) == $path) ? basename($path) : str_replace(LPATH_ROOT, '', $path);

			throw new RuntimeException('Library path ' . $path . ' cannot be found.', 500);
		}

		// If the prefix is not yet registered or we have an explicit reset flag then set set the path.
		if ($reset || !isset(self::$prefixes[$prefix]))
		{
			self::$prefixes[$prefix] = array($path);
		}
		// Otherwise we want to simply add the path to the prefix.
		else
		{
			if ($prepend)
			{
				array_unshift(self::$prefixes[$prefix], $path);
			}
			else
			{
				self::$prefixes[$prefix][] = $path;
			}
		}
	}

	/**
	 * Offers the ability for "just in time" usage of `class_alias()`.
	 * You cannot overwrite an existing alias.
	 *
	 * @param   string          $alias     The alias name to register.
	 * @param   string          $original  The original class to alias.
	 * @param   string|boolean  $version   The version in which the alias will no longer be present.
	 *
	 * @return  boolean  True if registration was successful. False if the alias already exists.
	 *
	 * @since   3.2
	 */
	public static function registerAlias($alias, $original, $version = false)
	{
		// PHP is case insensitive so support all kind of alias combination
		$lowercasedAlias = strtolower($alias);

		if (!isset(self::$classAliases[$lowercasedAlias]))
		{
			self::$classAliases[$lowercasedAlias] = $original;

			$original = self::stripFirstBackslash($original);

			if (!isset(self::$classAliasesInverse[$original]))
			{
				self::$classAliasesInverse[$original] = array($lowercasedAlias);
			}
			else
			{
				self::$classAliasesInverse[$original][] = $lowercasedAlias;
			}

			// If given a version, log this alias as deprecated
			if ($version)
			{
				self::$deprecatedAliases[] = array('old' => $alias, 'new' => $original, 'version' => $version);
			}

			return true;
		}

		return false;
	}

	/**
	 * Register a namespace to the autoloader. When loaded, namespace paths are searched in a "last in, first out" order.
	 *
	 * @param   string   $namespace  A case sensitive Namespace to register.
	 * @param   string   $path       A case sensitive absolute file path to the library root where classes of the given namespace can be found.
	 * @param   boolean  $reset      True to reset the namespace with only the given lookup path.
	 * @param   boolean  $prepend    If true, push the path to the beginning of the namespace lookup paths array.
	 *
	 * @return  void
	 *
	 * @throws  RuntimeException
	 *
	 * @since   3.1.4
	 */
	public static function registerNamespace($namespace, $path, $reset = false, $prepend = false)
	{
		// Verify the library path exists.
		if (!is_dir($path))
		{
			$path = (str_replace(LPATH_ROOT, '', $path) == $path) ? basename($path) : str_replace(LPATH_ROOT, '', $path);

			throw new RuntimeException('Library path ' . $path . ' cannot be found.', 500);
		}

		// Trim leading and trailing backslashes from namespace, allowing "\Parent\Child", "Parent\Child\" and "\Parent\Child\" to be treated the same way.
		$namespace = trim($namespace, '\\');

		// If the namespace is not yet registered or we have an explicit reset flag then set the path.
		if ($reset || !isset(self::$namespaces[$namespace]))
		{
			self::$namespaces[$namespace] = array($path);
		}

		// Otherwise we want to simply add the path to the namespace.
		else
		{
			if ($prepend)
			{
				array_unshift(self::$namespaces[$namespace], $path);
			}
			else
			{
				self::$namespaces[$namespace][] = $path;
			}
		}
	}

	/**
	 * Method to setup the autoloaders for the Octoleo Platform.
	 * Since the SPL autoloaders are called in a queue we will add our explicit
	 * class-registration based loader first, then fall back on the autoloader based on conventions.
	 * This will allow people to register a class in a specific location and override platform libraries
	 * as was previously possible.
	 *
	 * @param   boolean  $enablePsr       True to enable autoloading based on PSR-0.
	 * @param   boolean  $enablePrefixes  True to enable prefix based class loading (needed to auto load the Octoleo core).
	 * @param   boolean  $enableClasses   True to enable class map based class loading (needed to auto load the Octoleo core).
	 *
	 * @return  void
	 *
	 * @since   3.1.4
	 */
	public static function setup($enablePsr = true, $enablePrefixes = true, $enableClasses = true)
	{
		if ($enableClasses)
		{
			// Register the class map based autoloader.
			spl_autoload_register(array('LLoader', 'load'));
		}

		if ($enablePrefixes)
		{
			// Register the prefix autoloader.
			spl_autoload_register(array('LLoader', '_autoload'));
		}

		if ($enablePsr)
		{
			// Register the PSR based autoloader.
			spl_autoload_register(array('LLoader', 'loadByPsr'));
			spl_autoload_register(array('LLoader', 'loadByAlias'));
		}
	}

	/**
	 * Method to autoload classes that are namespaced to the PSR-4 standard.
	 *
	 * @param   string  $class  The fully qualified class name to autoload.
	 *
	 * @return  boolean  True on success, false otherwise.
	 *
	 * @since       3.7.0
	 * @deprecated  5.0 Use LLoader::loadByPsr instead
	 */
	public static function loadByPsr4($class)
	{
		return self::loadByPsr($class);
	}

	/**
	 * Method to autoload classes that are namespaced to the PSR-4 standard.
	 *
	 * @param   string  $class  The fully qualified class name to autoload.
	 *
	 * @return  boolean  True on success, false otherwise.
	 *
	 * @since   4.0.0
	 */
	public static function loadByPsr($class)
	{
		$class = self::stripFirstBackslash($class);

		// Find the location of the last NS separator.
		$pos = strrpos($class, '\\');

		// If one is found, we're dealing with a NS'd class.
		if ($pos !== false)
		{
			$classPath = str_replace('\\', DIRECTORY_SEPARATOR, substr($class, 0, $pos)) . DIRECTORY_SEPARATOR;
			$className = substr($class, $pos + 1);
		}
		// If not, no need to parse path.
		else
		{
			$classPath = null;
			$className = $class;
		}

		$classPath .= $className . '.php';

		// Loop through registered namespaces until we find a match.
		foreach (self::$namespaces as $ns => $paths)
		{
			if (strpos($class, "{$ns}\\") === 0)
			{
				$nsPath = trim(str_replace('\\', DIRECTORY_SEPARATOR, $ns), DIRECTORY_SEPARATOR);

				// Loop through paths registered to this namespace until we find a match.
				foreach ($paths as $path)
				{
					$classFilePath = realpath($path . DIRECTORY_SEPARATOR . substr_replace($classPath, '', 0, strlen($nsPath) + 1));

					// We do not allow files outside the namespace root to be loaded
					if (strpos($classFilePath, realpath($path)) !== 0)
					{
						continue;
					}

					// We check for class_exists to handle case-sensitive file systems
					if (is_file($classFilePath) && !class_exists($class, false))
					{
						$found = (bool) include_once $classFilePath;

						if ($found)
						{
							self::loadAliasFor($class);
						}

						return $found;
					}
				}
			}
		}

		return false;
	}

	/**
	 * Method to autoload classes that have been aliased using the registerAlias method.
	 *
	 * @param   string  $class  The fully qualified class name to autoload.
	 *
	 * @return  boolean  True on success, false otherwise.
	 *
	 * @since   3.2
	 */
	public static function loadByAlias($class)
	{
		$class = strtolower(self::stripFirstBackslash($class));

		if (isset(self::$classAliases[$class]))
		{
			// Force auto-load of the regular class
			class_exists(self::$classAliases[$class], true);

			// Normally this shouldn't execute as the autoloader will execute applyAliasFor when the regular class is
			// auto-loaded above.
			if (!class_exists($class, false) && !interface_exists($class, false))
			{
				class_alias(self::$classAliases[$class], $class);
			}
		}
	}

	/**
	 * Applies a class alias for an already loaded class, if a class alias was created for it.
	 *
	 * @param   string  $class  We'll look for and register aliases for this (real) class name
	 *
	 * @return  void
	 *
	 * @since   3.4
	 */
	public static function applyAliasFor($class)
	{
		$class = self::stripFirstBackslash($class);

		if (isset(self::$classAliasesInverse[$class]))
		{
			foreach (self::$classAliasesInverse[$class] as $alias)
			{
				class_alias($class, $alias);
			}
		}
	}

	/**
	 * Autoload a class based on name.
	 *
	 * @param   string  $class  The class to be loaded.
	 *
	 * @return  boolean  True if the class was loaded, false otherwise.
	 *
	 * @since   1.7.3
	 */
	public static function _autoload($class)
	{
		foreach (self::$prefixes as $prefix => $lookup)
		{
			$chr = strlen($prefix) < strlen($class) ? $class[strlen($prefix)] : 0;

			if (strpos($class, $prefix) === 0 && ($chr === strtoupper($chr)))
			{
				return self::_load(substr($class, strlen($prefix)), $lookup);
			}
		}

		return false;
	}

	/**
	 * Load a class based on name and lookup array.
	 *
	 * @param   string  $class   The class to be loaded (without prefix).
	 * @param   array   $lookup  The array of base paths to use for finding the class file.
	 *
	 * @return  boolean  True if the class was loaded, false otherwise.
	 *
	 * @since   3.0.0
	 */
	private static function _load($class, $lookup)
	{
		// Split the class name into parts separated by camelCase.
		$parts = preg_split('/(?<=[a-z0-9])(?=[A-Z])/x', $class);
		$partsCount = count($parts);

		foreach ($lookup as $base)
		{
			// Generate the path based on the class name parts.
			$path = realpath($base . '/' . implode('/', array_map('strtolower', $parts)) . '.php');

			// Load the file if it exists and is in the lookup path.
			if (strpos($path, realpath($base)) === 0 && is_file($path))
			{
				$found = (bool) include_once $path;

				if ($found)
				{
					self::loadAliasFor($class);
				}

				return $found;
			}

			// Backwards compatibility patch

			// If there is only one part we want to duplicate that part for generating the path.
			if ($partsCount === 1)
			{
				// Generate the path based on the class name parts.
				$path = realpath($base . '/' . implode('/', array_map('strtolower', array($parts[0], $parts[0]))) . '.php');

				// Load the file if it exists and is in the lookup path.
				if (strpos($path, realpath($base)) === 0 && is_file($path))
				{
					$found = (bool) include_once $path;

					if ($found)
					{
						self::loadAliasFor($class);
					}

					return $found;
				}
			}
		}

		return false;
	}

	/**
	 * Loads the aliases for the given class.
	 *
	 * @param   string  $class  The class.
	 *
	 * @return  void
	 *
	 * @since   3.8.0
	 */
	private static function loadAliasFor($class)
	{
		if (!array_key_exists($class, self::$classAliasesInverse))
		{
			return;
		}

		foreach (self::$classAliasesInverse[$class] as $alias)
		{
			// Force auto-load of the alias class
			class_exists($alias, true);
		}
	}

	/**
	 * Strips the first backslash from the given class if present.
	 *
	 * @param   string  $class  The class to strip the first prefix from.
	 *
	 * @return  string  The striped class name.
	 *
	 * @since   3.8.0
	 */
	private static function stripFirstBackslash($class)
	{
		return $class && $class[0] === '\\' ? substr($class, 1) : $class;
	}
}