| 1 |  |  | <?php | 
            
                                                                                                            
                            
            
                                    
            
            
                | 2 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 3 |  |  | namespace Scriptotek\GoogleBooks; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 4 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 5 |  |  | use GuzzleHttp\Client; | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 6 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 7 |  |  | class GoogleBooks | 
            
                                                                        
                            
            
                                    
            
            
                | 8 |  |  | { | 
            
                                                                        
                            
            
                                    
            
            
                | 9 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 10 |  |  |      * @var string | 
            
                                                                        
                            
            
                                    
            
            
                | 11 |  |  |      */ | 
            
                                                                        
                            
            
                                    
            
            
                | 12 |  |  |     protected $baseUri = 'https://www.googleapis.com/books/v1/'; | 
            
                                                                        
                            
            
                                    
            
            
                | 13 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 14 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 15 |  |  |      * @var integer (Number of results to retrieve per batch, between 1 and 40) | 
            
                                                                        
                            
            
                                    
            
            
                | 16 |  |  |      */ | 
            
                                                                        
                            
            
                                    
            
            
                | 17 |  |  |     protected $batchSize = 40; | 
            
                                                                        
                            
            
                                    
            
            
                | 18 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 19 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 20 |  |  |      * @var Client | 
            
                                                                        
                            
            
                                    
            
            
                | 21 |  |  |      */ | 
            
                                                                        
                            
            
                                    
            
            
                | 22 |  |  |     protected $http; | 
            
                                                                        
                            
            
                                    
            
            
                | 23 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 24 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 25 |  |  |      * @var key string API key | 
            
                                                                        
                            
            
                                    
            
            
                | 26 |  |  |      */ | 
            
                                                                        
                            
            
                                    
            
            
                | 27 |  |  |     protected $key; | 
            
                                                                        
                            
            
                                    
            
            
                | 28 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 29 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 30 |  |  |      * @var country string 2 letter ISO 639 country code. | 
            
                                                                        
                            
            
                                    
            
            
                | 31 |  |  |      * | 
            
                                                                        
                            
            
                                    
            
            
                | 32 |  |  |      * The Books API must honor copyright laws from various countries, and have | 
            
                                                                        
                            
            
                                    
            
            
                | 33 |  |  |      * country-specific rights from publishers. It uses the IP address of the | 
            
                                                                        
                            
            
                                    
            
            
                | 34 |  |  |      * client to geo-locate the user, but if this fails for some reason, it will | 
            
                                                                        
                            
            
                                    
            
            
                | 35 |  |  |      * return 403 Forbidden with reason "unknownLocation". To avoid this, we can | 
            
                                                                        
                            
            
                                    
            
            
                | 36 |  |  |      * manually set the country code. | 
            
                                                                        
                            
            
                                    
            
            
                | 37 |  |  |      */ | 
            
                                                                        
                            
            
                                    
            
            
                | 38 |  |  |     protected $country; | 
            
                                                                        
                            
            
                                    
            
            
                | 39 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 40 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 41 |  |  |      * @var Volumes | 
            
                                                                        
                            
            
                                    
            
            
                | 42 |  |  |      */ | 
            
                                                                        
                            
            
                                    
            
            
                | 43 |  |  |     public $volumes; | 
            
                                                                        
                            
            
                                    
            
            
                | 44 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 45 |  |  |     /** | 
            
                                                                        
                            
            
                                    
            
            
                | 46 |  |  |      * @var Bookshelves | 
            
                                                                        
                            
            
                                    
            
            
                | 47 |  |  |      */ | 
            
                                                                        
                            
            
                                    
            
            
                | 48 |  |  |     public $bookshelves; | 
            
                                                                        
                            
            
                                    
            
            
                | 49 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 50 |  |  |     public function __construct($options = []) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 51 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 52 |  |  |         $this->http = new Client([ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 53 |  |  |             'base_uri' => $this->baseUri, | 
            
                                                                                                            
                            
            
                                    
            
            
                | 54 |  |  |             'handler' => isset($options['handler']) ? $options['handler'] : null, | 
            
                                                                                                            
                            
            
                                    
            
            
                | 55 |  |  |         ]); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 56 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 57 |  |  |         $this->key = isset($options['key']) ? $options['key'] : null; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 58 |  |  |         $this->country = isset($options['country']) ? $options['country'] : null; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 59 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 60 |  |  |         $this->volumes = new Volumes($this); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 61 |  |  |         $this->bookshelves = new Bookshelves($this); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 62 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 63 |  |  |         $this->batchSize = isset($options['batchSize']) ? $options['batchSize'] : 40; | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 64 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 65 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 66 |  |  |     protected function raw($endpoint, $params = [], $method='GET') | 
            
                                                                                                            
                            
            
                                    
            
            
                | 67 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 68 |  |  |         if (!is_null($this->key)) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 69 |  |  |             $params['key'] = $this->key; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 70 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 71 |  |  |         if (!is_null($this->country)) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 72 |  |  |             $params['country'] = $this->country; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 73 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 74 |  |  |         try { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 75 |  |  |             $response = $this->http->request($method, $endpoint, [ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 76 |  |  |                 'query' => $params, | 
            
                                                                                                            
                            
            
                                    
            
            
                | 77 |  |  |             ]); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 78 |  |  |         } catch (\GuzzleHttp\Exception\ClientException $e) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 79 |  |  |             // 400 level errors | 
            
                                                                                                            
                            
            
                                    
            
            
                | 80 |  |  |             if ($e->getResponse()->getStatusCode() == 403) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 81 |  |  |                 $json = json_decode($e->getResponse()->getBody()); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 82 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 83 |  |  |                 $domain = $json->error->errors[0]->domain; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 84 |  |  |                 $reason = $json->error->errors[0]->reason; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 85 |  |  |                 $message = $json->error->errors[0]->message; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 86 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 87 |  |  |                 if ($domain == 'usageLimits') { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 88 |  |  |                     throw new Exceptions\UsageLimitExceeded($message, $reason); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 89 |  |  |                 } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 90 |  |  |             } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 91 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 92 |  |  |             throw $e; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 93 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 94 |  |  |         } catch (\GuzzleHttp\Exception\RequestException $e) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 95 |  |  |             // networking error (connection timeout, DNS errors, etc.) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 96 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 97 |  |  |             // TODO: sleep and retry | 
            
                                                                                                            
                            
            
                                    
            
            
                | 98 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 99 |  |  |             throw $e; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 100 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 101 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 102 |  |  |         return json_decode($response->getBody()); | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 103 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 104 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 105 |  |  |     public function getItem($path) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 106 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 107 |  |  |         return $this->raw($path); | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 108 |  |  |     } | 
            
                                                                        
                            
            
                                    
            
            
                | 109 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 110 |  |  |     public function listItems($endpoint, $params = []) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 111 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 112 |  |  |         $params['maxResults'] = $this->batchSize; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 113 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 114 |  |  |         $i = 0; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 115 |  |  |         while (true) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 116 |  |  |             $n = $i % $this->batchSize; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 117 |  |  |             if ($n == 0) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 118 |  |  |                 $params['startIndex'] = $i; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 119 |  |  |                 $response = $this->raw($endpoint, $params); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 120 |  |  |             } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 121 |  |  |             if (isset($response->totalItems) && $i >= $response->totalItems) { | 
                            
                    |  |  |  | 
                                                                                        
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                | 122 |  |  |                 return; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 123 |  |  |             } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 124 |  |  |             if (!isset($response->items[$n])) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 125 |  |  |                 return; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 126 |  |  |             } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 127 |  |  |             yield $response->items[$n]; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 128 |  |  |             $i++; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 129 |  |  |         } | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 130 |  |  |     } | 
            
                                                        
            
                                    
            
            
                | 131 |  |  |  | 
            
                                                        
            
                                    
            
            
                | 132 |  |  | } | 
            
                                                        
            
                                    
            
            
                | 133 |  |  |  | 
            
                        
If you define a variable conditionally, it can happen that it is not defined for all execution paths.
Let’s take a look at an example:
In the above example, the variable $x is defined if you pass “foo” or “bar” as argument for $a. However, since the switch statement has no default case statement, if you pass any other value, the variable $x would be undefined.
Available Fixes
Check for existence of the variable explicitly:
Define a default value for the variable:
Add a value for the missing path: