<?php

/*
 * This file is part of Composer.
 *
 * (c) Nils Adermann <naderman@naderman.de>
 *     Jordi Boggiano <j.boggiano@seld.be>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Composer\Autoload;

/**
 * ClassLoader implements a PSR-0, PSR-4 and classmap class loader.
 *
 *     $loader = new \Composer\Autoload\ClassLoader();
 *
 *     // register classes with namespaces
 *     $loader->add('Symfony\Component', __DIR__.'/component');
 *     $loader->add('Symfony',           __DIR__.'/framework');
 *
 *     // activate the autoloader
 *     $loader->register();
 *
 *     // to enable searching the include path (eg. for PEAR packages)
 *     $loader->setUseIncludePath(true);
 *
 * In this example, if you try to use a class in the Symfony\Component
 * namespace or one of its children (Symfony\Component\Console for instance),
 * the autoloader will first look for the class under the component/
 * directory, and it will then fallback to the framework/ directory if not
 * found before giving up.
 *
 * This class is loosely based on the Symfony UniversalClassLoader.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 * @author Jordi Boggiano <j.boggiano@seld.be>
 * @see    https://www.php-fig.org/psr/psr-0/
 * @see    https://www.php-fig.org/psr/psr-4/
 */
class ClassLoader {
	/** @var \Closure(string):void */
	private static $includeFile;

	/** @var ?string */
	private $vendorDir;

	// PSR-4
	/**
	 * @var array[]
	 * @psalm-var array<string, array<string, int>>
	 */
	private $prefixLengthsPsr4 = [];
	/**
	 * @var array[]
	 * @psalm-var array<string, array<int, string>>
	 */
	private $prefixDirsPsr4 = [];
	/**
	 * @var array[]
	 * @psalm-var array<string, string>
	 */
	private $fallbackDirsPsr4 = [];

	// PSR-0
	/**
	 * @var array[]
	 * @psalm-var array<string, array<string, string[]>>
	 */
	private $prefixesPsr0 = [];
	/**
	 * @var array[]
	 * @psalm-var array<string, string>
	 */
	private $fallbackDirsPsr0 = [];

	/** @var bool */
	private $useIncludePath = false;

	/**
	 * @var string[]
	 * @psalm-var array<string, string>
	 */
	private $classMap = [];

	/** @var bool */
	private $classMapAuthoritative = false;

	/**
	 * @var bool[]
	 * @psalm-var array<string, bool>
	 */
	private $missingClasses = [];

	/** @var ?string */
	private $apcuPrefix;

	/**
	 * @var self[]
	 */
	private static $registeredLoaders = [];

	/**
	 * @param ?string $vendorDir
	 */
	public function __construct($vendorDir = null) {
		$this->vendorDir = $vendorDir;
		self::initializeIncludeClosure();
	}

	/**
	 * @return string[]
	 */
	public function getPrefixes() {
		if (!empty($this->prefixesPsr0)) {
			return call_user_func_array('array_merge', array_values($this->prefixesPsr0));
		}

		return [];
	}

	/**
	 * @return array[]
	 * @psalm-return array<string, array<int, string>>
	 */
	public function getPrefixesPsr4() {
		return $this->prefixDirsPsr4;
	}

	/**
	 * @return array[]
	 * @psalm-return array<string, string>
	 */
	public function getFallbackDirs() {
		return $this->fallbackDirsPsr0;
	}

	/**
	 * @return array[]
	 * @psalm-return array<string, string>
	 */
	public function getFallbackDirsPsr4() {
		return $this->fallbackDirsPsr4;
	}

	/**
	 * @return string[] Array of classname => path
	 * @psalm-return array<string, string>
	 */
	public function getClassMap() {
		return $this->classMap;
	}

	/**
	 * @param string[] $classMap Class to filename map
	 * @psalm-param array<string, string> $classMap
	 *
	 * @return void
	 */
	public function addClassMap(array $classMap) {
		if ($this->classMap) {
			$this->classMap = array_merge($this->classMap, $classMap);
		} else {
			$this->classMap = $classMap;
		}
	}

	/**
	 * Registers a set of PSR-0 directories for a given prefix, either
	 * appending or prepending to the ones previously set for this prefix.
	 *
	 * @param string $prefix The prefix
	 * @param string[]|string $paths The PSR-0 root directories
	 * @param bool $prepend Whether to prepend the directories
	 *
	 * @return void
	 */
	public function add($prefix, $paths, $prepend = false) {
		if (!$prefix) {
			if ($prepend) {
				$this->fallbackDirsPsr0 = array_merge(
					(array)$paths,
					$this->fallbackDirsPsr0
				);
			} else {
				$this->fallbackDirsPsr0 = array_merge(
					$this->fallbackDirsPsr0,
					(array)$paths
				);
			}

			return;
		}

		$first = $prefix[0];
		if (!isset($this->prefixesPsr0[$first][$prefix])) {
			$this->prefixesPsr0[$first][$prefix] = (array)$paths;

			return;
		}
		if ($prepend) {
			$this->prefixesPsr0[$first][$prefix] = array_merge(
				(array)$paths,
				$this->prefixesPsr0[$first][$prefix]
			);
		} else {
			$this->prefixesPsr0[$first][$prefix] = array_merge(
				$this->prefixesPsr0[$first][$prefix],
				(array)$paths
			);
		}
	}

	/**
	 * Registers a set of PSR-4 directories for a given namespace, either
	 * appending or prepending to the ones previously set for this namespace.
	 *
	 * @param string $prefix The prefix/namespace, with trailing '\\'
	 * @param string[]|string $paths The PSR-4 base directories
	 * @param bool $prepend Whether to prepend the directories
	 *
	 * @throws \InvalidArgumentException
	 *
	 * @return void
	 */
	public function addPsr4($prefix, $paths, $prepend = false) {
		if (!$prefix) {
			// Register directories for the root namespace.
			if ($prepend) {
				$this->fallbackDirsPsr4 = array_merge(
					(array)$paths,
					$this->fallbackDirsPsr4
				);
			} else {
				$this->fallbackDirsPsr4 = array_merge(
					$this->fallbackDirsPsr4,
					(array)$paths
				);
			}
		} elseif (!isset($this->prefixDirsPsr4[$prefix])) {
			// Register directories for a new namespace.
			$length = strlen($prefix);
			if ($prefix[$length - 1] !== '\\') {
				throw new \InvalidArgumentException('A non-empty PSR-4 prefix must end with a namespace separator.');
			}
			$this->prefixLengthsPsr4[$prefix[0]][$prefix] = $length;
			$this->prefixDirsPsr4[$prefix] = (array)$paths;
		} elseif ($prepend) {
			// Prepend directories for an already registered namespace.
			$this->prefixDirsPsr4[$prefix] = array_merge(
				(array)$paths,
				$this->prefixDirsPsr4[$prefix]
			);
		} else {
			// Append directories for an already registered namespace.
			$this->prefixDirsPsr4[$prefix] = array_merge(
				$this->prefixDirsPsr4[$prefix],
				(array)$paths
			);
		}
	}

	/**
	 * Registers a set of PSR-0 directories for a given prefix,
	 * replacing any others previously set for this prefix.
	 *
	 * @param string $prefix The prefix
	 * @param string[]|string $paths The PSR-0 base directories
	 *
	 * @return void
	 */
	public function set($prefix, $paths) {
		if (!$prefix) {
			$this->fallbackDirsPsr0 = (array)$paths;
		} else {
			$this->prefixesPsr0[$prefix[0]][$prefix] = (array)$paths;
		}
	}

	/**
	 * Registers a set of PSR-4 directories for a given namespace,
	 * replacing any others previously set for this namespace.
	 *
	 * @param string $prefix The prefix/namespace, with trailing '\\'
	 * @param string[]|string $paths The PSR-4 base directories
	 *
	 * @throws \InvalidArgumentException
	 *
	 * @return void
	 */
	public function setPsr4($prefix, $paths) {
		if (!$prefix) {
			$this->fallbackDirsPsr4 = (array)$paths;
		} else {
			$length = strlen($prefix);
			if ($prefix[$length - 1] !== '\\') {
				throw new \InvalidArgumentException('A non-empty PSR-4 prefix must end with a namespace separator.');
			}
			$this->prefixLengthsPsr4[$prefix[0]][$prefix] = $length;
			$this->prefixDirsPsr4[$prefix] = (array)$paths;
		}
	}

	/**
	 * Turns on searching the include path for class files.
	 *
	 * @param bool $useIncludePath
	 *
	 * @return void
	 */
	public function setUseIncludePath($useIncludePath) {
		$this->useIncludePath = $useIncludePath;
	}

	/**
	 * Can be used to check if the autoloader uses the include path to check
	 * for classes.
	 *
	 * @return bool
	 */
	public function getUseIncludePath() {
		return $this->useIncludePath;
	}

	/**
	 * Turns off searching the prefix and fallback directories for classes
	 * that have not been registered with the class map.
	 *
	 * @param bool $classMapAuthoritative
	 *
	 * @return void
	 */
	public function setClassMapAuthoritative($classMapAuthoritative) {
		$this->classMapAuthoritative = $classMapAuthoritative;
	}

	/**
	 * Should class lookup fail if not found in the current class map?
	 *
	 * @return bool
	 */
	public function isClassMapAuthoritative() {
		return $this->classMapAuthoritative;
	}

	/**
	 * APCu prefix to use to cache found/not-found classes, if the extension is enabled.
	 *
	 * @param string|null $apcuPrefix
	 *
	 * @return void
	 */
	public function setApcuPrefix($apcuPrefix) {
		$this->apcuPrefix = function_exists('apcu_fetch') && filter_var(ini_get('apc.enabled'), FILTER_VALIDATE_BOOLEAN) ? $apcuPrefix : null;
	}

	/**
	 * The APCu prefix in use, or null if APCu caching is not enabled.
	 *
	 * @return string|null
	 */
	public function getApcuPrefix() {
		return $this->apcuPrefix;
	}

	/**
	 * Registers this instance as an autoloader.
	 *
	 * @param bool $prepend Whether to prepend the autoloader or not
	 *
	 * @return void
	 */
	public function register($prepend = false) {
		spl_autoload_register([$this, 'loadClass'], true, $prepend);

		if ($this->vendorDir === null) {
			return;
		}

		if ($prepend) {
			self::$registeredLoaders = [$this->vendorDir => $this] + self::$registeredLoaders;
		} else {
			unset(self::$registeredLoaders[$this->vendorDir]);
			self::$registeredLoaders[$this->vendorDir] = $this;
		}
	}

	/**
	 * Unregisters this instance as an autoloader.
	 *
	 * @return void
	 */
	public function unregister() {
		spl_autoload_unregister([$this, 'loadClass']);

		if ($this->vendorDir !== null) {
			unset(self::$registeredLoaders[$this->vendorDir]);
		}
	}

	/**
	 * Loads the given class or interface.
	 *
	 * @param string $class The name of the class
	 * @return true|null True if loaded, null otherwise
	 */
	public function loadClass($class) {
		if ($file = $this->findFile($class)) {
			(self::$includeFile)($file);

			return true;
		}

		return null;
	}

	/**
	 * Finds the path to the file where the class is defined.
	 *
	 * @param string $class The name of the class
	 *
	 * @return string|false The path if found, false otherwise
	 */
	public function findFile($class) {
		// class map lookup
		if (isset($this->classMap[$class])) {
			return $this->classMap[$class];
		}
		if ($this->classMapAuthoritative || isset($this->missingClasses[$class])) {
			return false;
		}
		if ($this->apcuPrefix !== null) {
			$file = apcu_fetch($this->apcuPrefix . $class, $hit);
			if ($hit) {
				return $file;
			}
		}

		$file = $this->findFileWithExtension($class, '.php');

		// Search for Hack files if we are running on HHVM
		if ($file === false && defined('HHVM_VERSION')) {
			$file = $this->findFileWithExtension($class, '.hh');
		}

		if ($this->apcuPrefix !== null) {
			apcu_add($this->apcuPrefix . $class, $file);
		}

		if ($file === false) {
			// Remember that this class does not exist.
			$this->missingClasses[$class] = true;
		}

		return $file;
	}

	/**
	 * Returns the currently registered loaders indexed by their corresponding vendor directories.
	 *
	 * @return self[]
	 */
	public static function getRegisteredLoaders() {
		return self::$registeredLoaders;
	}

	/**
	 * @param string $class
	 * @param string $ext
	 * @return string|false
	 */
	private function findFileWithExtension($class, $ext) {
		// PSR-4 lookup
		$logicalPathPsr4 = strtr($class, '\\', DIRECTORY_SEPARATOR) . $ext;

		$first = $class[0];
		if (isset($this->prefixLengthsPsr4[$first])) {
			$subPath = $class;
			while (false !== $lastPos = strrpos($subPath, '\\')) {
				$subPath = substr($subPath, 0, $lastPos);
				$search = $subPath . '\\';
				if (isset($this->prefixDirsPsr4[$search])) {
					$pathEnd = DIRECTORY_SEPARATOR . substr($logicalPathPsr4, $lastPos + 1);
					foreach ($this->prefixDirsPsr4[$search] as $dir) {
						if (file_exists($file = $dir . $pathEnd)) {
							return $file;
						}
					}
				}
			}
		}

		// PSR-4 fallback dirs
		foreach ($this->fallbackDirsPsr4 as $dir) {
			if (file_exists($file = $dir . DIRECTORY_SEPARATOR . $logicalPathPsr4)) {
				return $file;
			}
		}

		// PSR-0 lookup
		if (false !== $pos = strrpos($class, '\\')) {
			// namespaced class name
			$logicalPathPsr0 = substr($logicalPathPsr4, 0, $pos + 1)
				. strtr(substr($logicalPathPsr4, $pos + 1), '_', DIRECTORY_SEPARATOR);
		} else {
			// PEAR-like class name
			$logicalPathPsr0 = strtr($class, '_', DIRECTORY_SEPARATOR) . $ext;
		}

		if (isset($this->prefixesPsr0[$first])) {
			foreach ($this->prefixesPsr0[$first] as $prefix => $dirs) {
				if (strpos($class, $prefix) === 0) {
					foreach ($dirs as $dir) {
						if (file_exists($file = $dir . DIRECTORY_SEPARATOR . $logicalPathPsr0)) {
							return $file;
						}
					}
				}
			}
		}

		// PSR-0 fallback dirs
		foreach ($this->fallbackDirsPsr0 as $dir) {
			if (file_exists($file = $dir . DIRECTORY_SEPARATOR . $logicalPathPsr0)) {
				return $file;
			}
		}

		// PSR-0 include paths.
		if ($this->useIncludePath && $file = stream_resolve_include_path($logicalPathPsr0)) {
			return $file;
		}

		return false;
	}

	private static function initializeIncludeClosure(): void {
		if (self::$includeFile !== null) {
			return;
		}

		/**
		 * Scope isolated include.
		 *
		 * Prevents access to $this/self from included files.
		 *
		 * @param string $file
		 * @return void
		 */
		self::$includeFile = static function ($file) {
			include $file;
		};
	}
}
