Methods for finding audio previews with PHP

 public function findTracksInITunesFor($artistName, $albumTitle)
{
    $iTunesTracks = null;

    try
    {
        $iTunesArtistInfo = $this->getArtistResultsFromITunes($artistName);

        if (($iTunesArtistInfo != null) && ( count($iTunesArtistInfo->results) > 0))
        {
            $iTunesAlbumInfo = $this->getAlbumAndTracksFromITunes($iTunesArtistInfo->results[0]->artistId, $albumTitle);

            if($iTunesAlbumInfo != null)
            {
                for( $i = 1 ; $i < count($iTunesAlbumInfo->results); $i++)
                {
                    // The first result is the album/artist info with the tracks taking up the rest of the space in the results array
                    $correctIndex = $i - 1;
                    $iTunesTracks[$correctIndex]['title'] = $iTunesAlbumInfo->results[$i]->trackName;
                    $iTunesTracks[$correctIndex]['URL'] = $iTunesAlbumInfo->results[$i]->previewUrl;
                    $iTunesTracks[$correctIndex]['purchaseURL'] = $iTunesAlbumInfo->results[$i]->trackViewUrl;
                }
            }
        }
    }
    catch (Exception $e)
    {
        throw new Exception("Not going to get Tracks for: " . $albumTitle . " from iTunes.");
    }


    return $iTunesTracks;
}

protected function getArtistResultsFromITunes($artistName)
{
    $iTunesInfo = null;

    $strippedArtistName = $artistName;
    $strippedArtistName = preg_replace("/[^a-zA-Z0-9]/", "", $strippedArtistName);

    if(is_string($artistName) && strlen($strippedArtistName) > 0)
    {
        $myCache = new Caching("./MashupCache/iTunes/", $strippedArtistName);

        if ($myCache->needToRenewData())
        {
            try
            {
                $formattedArtistString = str_replace(' ', '+', $artistName);
                $iTunesSearchString = 'http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/wa/wsSearch?term=' . $formattedArtistString . '&entity=musicArtist';
                $searchResult = fetchThisURL($iTunesSearchString);
                $iTunesInfo = json_decode($searchResult);
            }
            catch(Exception $e)
            {
                echo $e->getMessage();
            }
                $serializedObject = serialize($iTunesInfo);

                $myCache->saveSerializedDataToFile($serializedObject);
            }
            else
            {
                // It doesn't need to be renewed so use local copy of array
                $iTunesInfo =  $myCache->getUnserializedData();
            }
        }
        else
        {
            throw new Exception('Incorrect data type passed to getArtistResultsFromITunes()');
        }

    return $iTunesInfo;
}

protected function getAlbumAndTracksFromITunes($iTunesID, $albumName)
{
    $iTunesInfo = null;

    $properFileName = $iTunesID . $albumName;
    $properFileName = preg_replace("/[^a-zA-Z0-9]/", "", $properFileName);

    if(strlen($properFileName) > 0)
    {
        $myCache = new Caching("./MashupCache/iTunes/", $properFileName);

        if ($myCache->needToRenewData())
        {
            try
            {
                // First get all the albums by an artist using a lookup request
                //http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/wa/wsLookup?id=909253&entity=album
                $iTunesLookUpString = 'http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/wa/wsLookup?id=' . $iTunesID . '&entity=album';
                $lookUpResult = fetchThisURL($iTunesLookUpString);
                // Now we have the look up results but we need to find the $iTunesID for the correct album then get the tracks that go with it
                // We need collectionName to equal $albumName
                $lookUp = json_decode($lookUpResult);
                if ( ! empty($lookUp))
                {
                    $resultCount = $lookUp->resultCount;  // This isn't always correct, maybe have to check more carefully what was returned...

                    $i = 1;  // First result is the artist not an album, I already had the artist info.
                    $collectionID = null;

                    while(($i < $resultCount) && ($collectionID == null))
                    {
                        // Look for album in iTunes...
                        $collectionName = (string) $lookUp->results[$i]->collectionName;
                        if( strcasecmp($collectionName, $albumName) == 0)
                        {
                            // We have our match
                            $collectionID = $lookUp->results[$i]->collectionId;
                        }

                        // remember to increment!
                        $i++;
                    }

                    if( $collectionID != null)
                    {
                        // If collectionID isn't null... lookup album again in iTunes with tracks and that is what we really really want!
                        // cache and return...
                                //http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/wa/wsLookup?upc=075678317729&entity=song
                        $newLookupString = 'http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/wa/wsLookup?id=' . $collectionID . '&entity=song';
                        $newLookUpResult = fetchThisURL($newLookupString);
                        $iTunesInfo = json_decode($newLookUpResult);

                        $serializedObject = serialize($iTunesInfo);
                        $myCache->saveSerializedDataToFile($serializedObject);
                    }
                }
            }
            catch(Exception $e)
            {
                echo $e->getMessage();
            }
        }
        else
        {
            // It doesn't need to be renewed so use local copy
            $iTunesInfo =  $myCache->getUnserializedData();
        }
    }

    return $iTunesInfo;
}