Amazon resolver for Playdar (30 sec clips only)

playdar-amazon.php

#!/usr/bin/php
<?php

define('AWSACCESSID', '1SVFNCKVJ7JWK2NPG002');

$in = fopen('php://STDIN','r');

// report our settings before entering the main query loop:
send_reply(get_settings());

// main loop: wait for a query, try and find match and reply.
while (!feof($in)){      
    // read $len bytes for the actual payload and assume it's a JSON object.
    $len = unpack('N', fread($in, 4));
    $q = json_decode(fread($in, $len[1]));
    if (!is_object($q))
      continue;
    
    $results = get_matches($q);
    
    // don't reply with anything if there were no matches:
    if (empty($results)) 
      continue;
    
    send_reply((object) array(
      '_msgtype' => 'results',
      'qid' => $q->qid,
      'results' => $results,
    ));
}

// put a 4-byte big-endian int first, denoting length of message
function send_reply($obj){
    $str = str_replace('\/','/',json_encode($obj)); // i think json_spirit rejects \/ even tho it's valid json. doh.
    print pack('N', strlen($str)) . $str;
}

function get_matches($q){
    $params = array(
     'Service' => 'AWSECommerceService',
     'AWSAccessKeyId' => AWSACCESSID,
     'Operation' => 'ItemSearch',
     'SearchIndex' => 'MP3Downloads',
     'Author' => $q->artist,
     'Title' => $q->track,
     'ResponseGroup' => 'ItemAttributes',
     'TagsPerPage' => 3 , // 3 results
    );    
    
    $xml = simplexml_load_string(file_get_contents('http://ecs.amazonaws.com/onca/xml?' . http_build_query($params)));
    
    if (!is_object($xml) || empty($xml->Items->Item))
      return array();
    
    $items = array();
    foreach ($xml->Items->Item as $item){
      if ((string) $item->ItemAttributes->ProductGroup != 'Digital Music Track')
        continue;
        
      $meta = $item->ItemAttributes;
      
      $output = (object) array(
        'artist' =>  (string) $meta->Creator,
        'track' => (string) $meta->Title,
        'album' => $meta->Label ? (string) $meta->Label : 'Unknown',
        
        'source' => 'Amazon',
        'url' => 'http://www.amazon.com/gp/dmusic/get_sample_url.html?DownloadLocation=WEBSITE&ie=UTF8&ASIN=' . (string) $item->ASIN,
                          
        'mimetype' => 'audio/mpeg',
        'bitrate' => 128,
        
        'duration' => 30,
        'size' => 524288, // (30 / 60) * 1024 * 1024,
      );

      if (strtolower($output->artist) == strtolower($q->artist) && strtolower($output->track) == strtolower($q->track))
        $output->score = (float) 1.0;
      else
        $output->score = (float) 0.5;
      
      $items[] = $output;
    }
      
    return $items;
}

// settings for this resolver, reported when we start:
function get_settings(){
  return (object) array(
    '_msgtype' => 'settings',
    'name' => 'Amazon MP3 clips resolver script',
    'targettime' => 2000, // ms
    'weight' => 50, // 1-100. higher means preferable.
  );
}