Add support for multiple features in single call

[vladciulley]

Hello,

I would suggest adding support for launching calls with multiple detection types, since some of them are free if used in conjunction with another. For example, Safe Search Detection is free with Label Detection or Crop Hints, which is free if used with Image Properties.

Check this link: https://cloud.google.com/vision/pricing#prices to better understand my point.

In order to achieve this I've changed the GoogleVisionApiHelper::_request() like this:

private function _request($base64Image, $types){
        
        if (empty($types)) {
            throw new \InvalidArgumentException('Type missing from request.');
        }
        
        $url    = $this->_url . $this->_api_key;
        $json   ='{
			  	"requests": [
					{
					  "image": {
					    "content":"' .$base64Image. '"
					  },
					  "features": [';
        
        $lastType = end($types);
        
        foreach ($types as $type) {
            
            $json .= '
                            {
                                "type": "' .$type. '",
                                "maxResults": 200
                            }';
            if ($type !== $lastType) {
                $json .= ',';
            }
        }
					 
        $json .= '    ]
					}
				]
			}';

        $data                       = $this->_makeCall($url,$json);
        $jsonResponse               = json_decode($data['raw_response']);
        
        if($data['http_code'] !== 200){
            $data['status']          = $jsonResponse->error->status;
            $data['message']         = $jsonResponse->error->message;
            $data['error']           = $jsonResponse->error;
            $data['parsed_response'] = [];
        }else{
            
            foreach ($types as $type) {
                $_type                  = strtolower($type);
                $_type                  = str_replace('_', ' ', $_type);
                $_type                  = ucwords($_type);
                $_type                  = str_replace(' ', '', $_type);
                $parseFunction          = '_parse' . $_type;
                $data['parsed_response'][$type] = $this->$parseFunction($jsonResponse->responses[0]);
            }

            $data['raw_response'] = $jsonResponse->responses;
        }

        return $data;
    }

Hope it helps!