SAAS-505: Extract Amazon_S3 class and have it inherit from a general 'cloud backend' class

airtime_mvc/application/cloud_storage/Amazon_S3.php

@@ -0,0 +1,74 @@
+<?php
+
+require_once 'StorageBackend.php';
+
+class Amazon_S3 extends StorageBackend
+{
+    private $zendServiceAmazonS3;
+    
+    public function Amazon_S3()
+    {
+        $CC_CONFIG = Config::getConfig();
+        
+        $this->setBucket($CC_CONFIG['storage_backend']['bucket']);
+        $this->setAccessKey($CC_CONFIG['storage_backend']['api_key']);
+        $this->setSecretKey($CC_CONFIG['storage_backend']['api_key_secret']);
+        
+        $this->zendServiceAmazonS3 = new Zend_Service_Amazon_S3(
+            $this->getAccessKey(),
+            $this->getSecretKey());
+    }
+    
+    public function getAbsoluteFilePath($resourceId)
+    {
+        $endpoint = $this->zendServiceAmazonS3->getEndpoint();
+        $scheme = $endpoint->getScheme();
+        $host = $endpoint->getHost();
+        $bucket = $this->getBucket();
+        return "$scheme://$bucket.$host/".utf8_encode($resourceId);
+    }
+
+    public function getSignedURL($resourceId)
+    {
+        //URL will be active for 30 minutes
+        $expires = time()+1800;
+        
+        $bucket = $this->getBucket();
+        $secretKey = $this->getSecretKey();
+        $accessKey = $this->getAccessKey();
+        
+        $string_to_sign = utf8_encode("GET\n\n\n$expires\n/$bucket/$resourceId");
+        // We need to urlencode the entire signature in case the hashed signature
+        // has spaces. (NOTE: utf8_encode() does not work here because it turns
+        // spaces into non-breaking spaces)
+        $signature = urlencode(base64_encode((hash_hmac("sha1", $string_to_sign, $secretKey, true))));
+        
+        $resourceURL = $this->getAbsoluteFilePath($resourceId);
+        return $resourceURL."?AWSAccessKeyId=$accessKey&Expires=$expires&Signature=$signature";
+    }
+    
+    public function getFileSize($resourceId)
+    {
+        $bucket = $this->getBucket();
+        
+        $amz_resource = utf8_encode("$bucket/$resourceId");
+        $amz_resource_info = $this->zendServiceAmazonS3->getInfo($amz_resource);
+        return $amz_resource_info["size"];
+    }
+    
+    public function deletePhysicalFile($resourceId)
+    {
+        $bucket = $this->getBucket();
+        $amz_resource = utf8_encode("$bucket/$resourceId");
+        
+        if ($this->zendServiceAmazonS3->isObjectAvailable($amz_resource)) {
+           // removeObject() returns true even if the object was not deleted (bug?)
+           // so that is not a good way to do error handling. isObjectAvailable()
+           // does however return the correct value; We have to assume that if the
+           // object is available the removeObject() function will work.
+           $this->zendServiceAmazonS3->removeObject($amz_resource);
+           } else {
+               throw new Exception("ERROR: Could not locate object on Amazon S3");
+           }
+    }
+}

airtime_mvc/application/cloud_storage/ProxyStorageBackend.php

@@ -0,0 +1,44 @@
+<?php
+
+require_once 'StorageBackend.php';
+require_once 'Amazon_S3.php';
+
+/**
+ * 
+ * Controls access to the storage backend class where a file is stored.
+ *
+ */
+class ProxyStorageBackend extends StorageBackend
+{
+    private $storageBackend;
+    
+    /**
+     * Receives the file's storage backend and instantiates the approriate
+     * object.
+     */
+    public function ProxyStorageBackend($storageBackend)
+    {
+        $this->storageBackend = new $storageBackend();
+    }
+    
+    public function getAbsoluteFilePath($resourceId)
+    {
+        return $this->storageBackend->getAbsoluteFilePath($resourceId);
+    }
+    
+    public function getSignedURL($resourceId)
+    {
+        return $this->storageBackend->getSignedURL($resourceId);
+    }
+    
+    public function getFileSize($resourceId)
+    {
+        return $this->storageBackend->getFileSize($resourceId);
+    }
+    
+    public function deletePhysicalFile($resourceId)
+    {
+        $this->storageBackend->deletePhysicalFile($resourceId);
+    }
+
+}

airtime_mvc/application/cloud_storage/StorageBackend.php

@@ -0,0 +1,55 @@
+<?php
+
+/**
+ * 
+ * Provides access to file objects stored on a specific storage backend.
+ */
+abstract class StorageBackend
+{
+    private $bucket;
+    private $accessKey;
+    private $secretKey;
+    
+    /** Returns the file object's URL to the storage backend it is located on. */
+    abstract public function getAbsoluteFilePath($resourceId);
+    
+    /** Returns the file object's signed URL. The URL must be signed since they
+     *  privately stored on the storage backend. */
+    abstract public function getSignedURL($resourceId);
+    
+    /** Returns the file's size in bytes. */
+    abstract public function getFileSize($resourceId);
+    
+    /** Deletes the file from the storage backend. */
+    abstract public function deletePhysicalFile($resourceId);
+    
+    protected function getBucket()
+    {
+        return $this->bucket;
+    }
+    
+    protected function setBucket($bucket)
+    {
+        $this->bucket = $bucket;
+    }
+    
+    protected function getAccessKey()
+    {
+        return $this->accessKey;
+    }
+    
+    protected function setAccessKey($accessKey)
+    {
+        $this->accessKey = $accessKey;
+    }
+    
+    protected function getSecretKey()
+    {
+        return $this->secretKey;
+    }
+    
+    protected function setSecretKey($secretKey)
+    {
+        $this->secretKey = $secretKey;
+    }
+}