<?php 
namespace Aws\CloudFront; 
 
use GuzzleHttp\Psr7; 
use GuzzleHttp\Psr7\Uri; 
use Psr\Http\Message\UriInterface; 
 
/** 
 * Creates signed URLs for Amazon CloudFront resources. 
 */ 
class UrlSigner 
{ 
    private $signer; 
 
    /** 
     * @param $keyPairId  string ID of the key pair 
     * @param $privateKey string Path to the private key used for signing 
     * 
     * @throws \RuntimeException if the openssl extension is missing 
     * @throws \InvalidArgumentException if the private key cannot be found. 
     */ 
    public function __construct($keyPairId, $privateKey) 
    { 
        $this->signer = new Signer($keyPairId, $privateKey); 
    } 
 
    /** 
     * Create a signed Amazon CloudFront URL. 
     * 
     * Keep in mind that URLs meant for use in media/flash players may have 
     * different requirements for URL formats (e.g. some require that the 
     * extension be removed, some require the file name to be prefixed 
     * - mp4:<path>, some require you to add "/cfx/st" into your URL). 
     * 
     * @param string              $url     URL to sign (can include query 
     *                                     string string and wildcards) 
     * @param string|integer|null $expires UTC Unix timestamp used when signing 
     *                                     with a canned policy. Not required 
     *                                     when passing a custom $policy. 
     * @param string              $policy  JSON policy. Use this option when 
     *                                     creating a signed URL for a custom 
     *                                     policy. 
     * 
     * @return string The file URL with authentication parameters 
     * @throws \InvalidArgumentException if the URL provided is invalid 
     * @link http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/WorkingWithStreamingDistributions.html 
     */ 
    public function getSignedUrl($url, $expires = null, $policy = null) 
    { 
        // Determine the scheme of the url 
        $urlSections = explode('://', $url); 
 
        if (count($urlSections) < 2) { 
            throw new \InvalidArgumentException("Invalid URL: {$url}"); 
        } 
 
        // Get the real scheme by removing wildcards from the scheme 
        $scheme = str_replace('*', '', $urlSections[0]); 
        $uri = new Uri($scheme . '://' . $urlSections[1]); 
        $query = Psr7\parse_query($uri->getQuery(), PHP_QUERY_RFC3986); 
        $signature = $this->signer->getSignature( 
            $this->createResource($scheme, (string) $uri), 
            $expires, 
            $policy 
        ); 
        $uri = $uri->withQuery( 
            http_build_query($query + $signature, null, '&', PHP_QUERY_RFC3986) 
        ); 
 
        return $scheme === 'rtmp' 
            ? $this->createRtmpUrl($uri) 
            : (string) $uri; 
    } 
 
    private function createRtmpUrl(UriInterface $uri) 
    { 
        // Use a relative URL when creating Flash player URLs 
        $result = ltrim($uri->getPath(), '/'); 
 
        if ($query = $uri->getQuery()) { 
            $result .= '?' . $query; 
        } 
 
        return $result; 
    } 
 
    /** 
     * @param $scheme 
     * @param $url 
     * 
     * @return string 
     */ 
    private function createResource($scheme, $url) 
    { 
        switch ($scheme) { 
            case 'http': 
            case 'http*': 
            case 'https': 
                return $url; 
            case 'rtmp': 
                $parts = parse_url($url); 
                $pathParts = pathinfo($parts['path']); 
                $resource = ltrim( 
                    $pathParts['dirname'] . '/' . $pathParts['basename'], 
                    '/' 
                ); 
 
                // Add a query string if present. 
                if (isset($parts['query'])) { 
                    $resource .= "?{$parts['query']}"; 
                } 
 
                return $resource; 
        } 
 
        throw new \InvalidArgumentException("Invalid URI scheme: {$scheme}. " 
            . "Scheme must be one of: http, https, or rtmp"); 
    } 
} 
 
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