<?php

namespace NoccyLabs\Hotfix\Hotfix;

use NoccyLabs\Hotfix\Exception\HotfixException;
use NoccyLabs\Hotfix\Service\ServiceManager;
use NoccyLabs\Hotfix\Hotfix\AliasManager;

class HotfixLoader
{

    const PGP_HEADER_TOKEN = '-----BEGIN PGP SIGNATURE-----';

    public static function load($uri)
    {
        // First, check if this is a valid URL or filename
        if ((strpos($uri,"://")!==false) || (file_exists($uri))) {
            return self::loadFromUri($uri);
        }

        if (strpos($uri,":")!==false) {
            list($prefix,$id) = explode(":",$uri,2);
        } else {
            throw new HotfixException("Invalid hotfix specified {$uri}");
        }

        // Check services first, as aliases should for security reasons not
        // be allowed to overload services.
        if (($service = ServiceManager::getService($prefix))) {
            return self::loadFromService($service,$id);
        }

        // Check aliases
        if (($alias = AliasManager::getAlias($prefix))) {
            $url = str_replace('{fix}', $id, $alias);
            return self::loadFromUri($url);
        }

        throw new HotfixException("Could not read hotfix {$uri}");
    }

    private static function loadFromUri($url)
    {
        $source = file_get_contents($url);
        return self::loadHotfix($source,$url);
    }

    private static function loadFromService(ReaderInterface $service, $id)
    {
        $source = $service->read($id);
        return self::loadHotfix($source,$service->getName());
    }

    private static function loadHotfix($source,$origin)
    {

        // Check for a signature header 
        if (false === strpos($source, self::PGP_HEADER_TOKEN)) {
            $body = $source;
            $signature = new Signature($body,null);
        } else {
            list ($body, $sig) = explode(self::PGP_HEADER_TOKEN, $source);
            $sig = self::PGP_HEADER_TOKEN.$sig;
            $signature = new Signature($body,$sig);
        }
        
        // Extract header next
        list ($header,$body) = explode("\n---\n", $body, 2);
        $header = new Header($header);

        $hotfix = new Hotfix($body, $header, $signature, $origin);
        return $hotfix;
    }

}