<?php
/**
 * @Author neun
 * @since 20.04.2015 23:55
 */

Autoload::load();

class Autoload
{
    /**
     * The class map.
     *
     * @var array
     */
    private static $aClasses = array();

    /**
     * Root directory of the application.
     *
     * @var string
     */
    private static $sRootDir;

    /**
     * Load class map and register.
     */
    public static function load()
    {
        self::$sRootDir = str_replace(
            array('libs\mine', 'libs/mine', '\\'),
            array('', '', '/'),
            __DIR__
        );

        self::loadClassMap();
        self::register();
    }

    /**
     * Register mapped classes.
     */
    private static function register()
    {
        spl_autoload_register(
        /**
         * @param $sClass
         */
            function($sClass)
            {
                $sClassFile = self::preRegister($sClass);

                if (is_readable($sClassFile))
                {
                    require_once($sClassFile);
                }

                if (!class_exists($sClass))
                {
                    die("Class {$sClass} not found!");
                }
            });
    }

    /**
     * Check whether the requested class exists, re-generate map if neccessary.
     *
     * @param	string	$sClass
     * @param	bool	$isRetry
     * @return	string
     * @throws	Exception
     */
    private static function preRegister($sClass, $isRetry = false)
    {
        if (!array_key_exists($sClass, self::$aClasses))
        {
            if (false === $isRetry)
            {
                // Try to regenerate once.
                self::generateClassMap();
            }
            elseif(!array_key_exists($sClass, self::$aClasses))
            {
                // Die if the class is still not there
                die("Class {$sClass} appears to be invalid - dying!");
            }

            self::preRegister($sClass, true);
        }
        else
        {
            return rtrim(self::$sRootDir) .'/'. self::$aClasses[$sClass];
        }

        return rtrim(self::$sRootDir) .'/'. self::$aClasses[$sClass];
    }

    /**
     * Try loading the classmap from an existing file else regenerate.
     */
    private static function loadClassMap()
    {
        if (is_readable('classmap.json'))
        {
            // Load from existing file.
            self::$aClasses = (array) json_decode(file_get_contents(__DIR__ .'/classmap.json'));
        }
        else
        {
            // Regenerate and write file.
            self::generateClassMap();
        }
    }

    /**
     *	Generate Classmap and dump to json file.
     */
    private static function generateClassMap()
    {
        // Generate class map.
        self::readFolders(self::$sRootDir);

        // Dump class map to json file.
        file_put_contents(__DIR__ .'/classmap.json', json_encode(self::$aClasses, JSON_UNESCAPED_SLASHES));
    }

    /**
     * Add classes and paths recursive.
     *
     * @param $sDir
     */
    private static function readFolders($sDir)
    {
        foreach (glob($sDir . '/*') as $sPath)
        {
            // If its a directory, scan again else add class to map.
            if (is_dir($sPath))
            {
                self::readFolders($sPath);
            }
            else
            {
                if (preg_match('#.*\/([A-Z][A-Za-z\d]+)\.php$#', $sPath, $m) && $m[1] != 'Autoload')
                {
                    self::$aClasses[$m[1]] = str_replace(self::$sRootDir . '/', '', $m[0]);
                }
            }
        }
    }
}