<?php

// Copyright (c) 2004-2013 Fabien Potencier

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is furnished
// to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

class ClassLoader 
{
    private $namespaces = array();
    private $prefixes = array();
    private $namespaceFallbacks = array();
    private $prefixFallbacks = array();
    private $useIncludePath = false;

    /**
     * Turns on searching the include for class files. Allows easy loading
     * of installed PEAR packages
     *
     * @param Boolean $useIncludePath
     */
    public function useIncludePath($useIncludePath)
    {
        $this->useIncludePath = $useIncludePath;
    }

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

    /**
     * Gets the configured namespaces.
     *
     * @return array A hash with namespaces as keys and directories as values
     */
    public function getNamespaces()
    {
        return $this->namespaces;
    }

    /**
     * Gets the configured class prefixes.
     *
     * @return array A hash with class prefixes as keys and directories as values
     */
    public function getPrefixes()
    {
        return $this->prefixes;
    }

    /**
     * Gets the directory(ies) to use as a fallback for namespaces.
     *
     * @return array An array of directories
     */
    public function getNamespaceFallbacks()
    {
        return $this->namespaceFallbacks;
    }

    /**
     * Gets the directory(ies) to use as a fallback for class prefixes.
     *
     * @return array An array of directories
     */
    public function getPrefixFallbacks()
    {
        return $this->prefixFallbacks;
    }

    /**
     * Registers the directory to use as a fallback for namespaces.
     *
     * @param array $dirs An array of directories
     *
     * @api
     */
    public function registerNamespaceFallbacks(array $dirs)
    {
        $this->namespaceFallbacks = $dirs;
    }

    /**
     * Registers a directory to use as a fallback for namespaces.
     *
     * @param string $dir A directory
     */
    public function registerNamespaceFallback($dir)
    {
        $this->namespaceFallbacks[] = $dir;
    }

    /**
     * Registers directories to use as a fallback for class prefixes.
     *
     * @param array $dirs An array of directories
     *
     * @api
     */
    public function registerPrefixFallbacks(array $dirs)
    {
        $this->prefixFallbacks = $dirs;
    }

    /**
     * Registers a directory to use as a fallback for class prefixes.
     *
     * @param string $dir A directory
     */
    public function registerPrefixFallback($dir)
    {
        $this->prefixFallbacks[] = $dir;
    }

    /**
     * Registers an array of namespaces
     *
     * @param array $namespaces An array of namespaces (namespaces as keys and locations as values)
     *
     * @api
     */
    public function registerNamespaces(array $namespaces)
    {
        foreach ($namespaces as $namespace => $locations) {
            $this->namespaces[$namespace] = (array) $locations;
        }
    }

    /**
     * Registers a namespace.
     *
     * @param string       $namespace The namespace
     * @param array|string $paths     The location(s) of the namespace
     *
     * @api
     */
    public function registerNamespace($namespace, $paths)
    {
        $this->namespaces[$namespace] = (array) $paths;
    }

    /**
     * Registers an array of classes using the PEAR naming convention.
     *
     * @param array $classes An array of classes (prefixes as keys and locations as values)
     *
     * @api
     */
    public function registerPrefixes(array $classes)
    {
        foreach ($classes as $prefix => $locations) {
            $this->prefixes[$prefix] = (array) $locations;
        }
    }

    /**
     * Registers a set of classes using the PEAR naming convention.
     *
     * @param string       $prefix The classes prefix
     * @param array|string $paths  The location(s) of the classes
     *
     * @api
     */
    public function registerPrefix($prefix, $paths)
    {
        $this->prefixes[$prefix] = (array) $paths;
    }

    /**
     * Registers this instance as an autoloader.
     *
     * @param Boolean $prepend Whether to prepend the autoloader or not
     *
     * @api
     */
    public function register($prepend = false)
    {
        spl_autoload_register(array($this, 'loadClass'), true, $prepend);
    }

    /**
     * Fix for certain versions of PHP that have trouble with
     * namespaces with leading separators.
     * 
     * @access private
     * @param mixed $className
     * @return void
     */
    private function makeBackwardsCompatible($className)
    {
        return (phpversion() < '5.3.3') ? ltrim($className, '\\') : $className;
    }

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

            return true;
        }
    }

    /**
     * Finds the path to the file where the class is defined.
     *
     * @param string $class The name of the class
     *
     * @return string|null The path, if found
     */
    public function findFile($class)
    {
        if (false !== $pos = strrpos($class, '\\')) {
            // namespaced class name
            $namespace = substr($class, 0, $pos);
            $className = substr($class, $pos + 1);
            $normalizedClass = str_replace('\\', DIRECTORY_SEPARATOR, $namespace).DIRECTORY_SEPARATOR.str_replace('_', DIRECTORY_SEPARATOR, $className).'.php';
            foreach ($this->namespaces as $ns => $dirs) {
                if (0 !== strpos($namespace, $ns)) {
                    continue;
                }

                foreach ($dirs as $dir) {
                    $file = $dir.DIRECTORY_SEPARATOR.$normalizedClass;
                    if (is_file($file)) {
                        return $file;
                    }
                }
            }

            foreach ($this->namespaceFallbacks as $dir) {
                $file = $dir.DIRECTORY_SEPARATOR.$normalizedClass;
                if (is_file($file)) {
                    return $file;
                }
            }

        } else {
            // PEAR-like class name
            $normalizedClass = str_replace('_', DIRECTORY_SEPARATOR, $class).'.php';
            foreach ($this->prefixes as $prefix => $dirs) {
                if (0 !== strpos($class, $prefix)) {
                    continue;
                }

                foreach ($dirs as $dir) {
                    $file = $dir.DIRECTORY_SEPARATOR.$normalizedClass;
                    if (is_file($file)) {
                        return $file;
                    }
                }
            }

            foreach ($this->prefixFallbacks as $dir) {
                $file = $dir.DIRECTORY_SEPARATOR.$normalizedClass;
                if (is_file($file)) {
                    return $file;
                }
            }
        }

        if ($this->useIncludePath && $file = stream_resolve_include_path($normalizedClass)) {
            return $file;
        }
    }    
}