Complex classes like Amplitude often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Amplitude, and based on these observations, apply Extract Interface, too.
| 1 | <?php | ||
| 6 | class Amplitude | ||
| 7 | { | ||
| 8 | use Log\LoggerAwareTrait; | ||
| 9 | |||
| 10 | const AMPLITUDE_API_URL = 'https://api.amplitude.com/httpapi'; | ||
| 11 | |||
| 12 | const EXCEPTION_MSG_NO_API_KEY = 'API Key is required to log an event'; | ||
| 13 | const EXCEPTION_MSG_NO_EVENT_TYPE = 'Event Type is required to log or queue an event'; | ||
| 14 | const EXCEPTION_MSG_NO_USER_OR_DEVICE = 'Either user_id or device_id required to log an event'; | ||
| 15 | |||
| 16 | /** | ||
| 17 | * The API key to use for all events generated by this instance | ||
| 18 | * | ||
| 19 | * @var string | ||
| 20 | */ | ||
| 21 | protected $apiKey; | ||
| 22 | |||
| 23 | /** | ||
| 24 | * The event that will be used for the next event being tracked | ||
| 25 | * | ||
| 26 | * @var \Zumba\Amplitude\Event | ||
| 27 | */ | ||
| 28 | protected $event; | ||
| 29 | |||
| 30 | /** | ||
| 31 | * The user ID to use for events generated by this instance | ||
| 32 | * | ||
| 33 | * @var string | ||
| 34 | */ | ||
| 35 | protected $userId; | ||
| 36 | |||
| 37 | /** | ||
| 38 | * The user data to set on the next event logged to Amplitude | ||
| 39 | * | ||
| 40 | * @var array | ||
| 41 | */ | ||
| 42 | protected $userProperties = []; | ||
| 43 | |||
| 44 | /** | ||
| 45 | * The device ID to use for events generated by this instance | ||
| 46 | * | ||
| 47 | * @var string | ||
| 48 | */ | ||
| 49 | protected $deviceId; | ||
| 50 | |||
| 51 | /** | ||
| 52 | * Queue of events, used to allow generating events that might happen prior to amplitude being fully initialized | ||
| 53 | * | ||
| 54 | * @var \Zumba\Amplitude\Event[] | ||
| 55 | */ | ||
| 56 | protected $queue = []; | ||
| 57 | |||
| 58 | /** | ||
| 59 | * Flag for if user is opted out of tracking | ||
| 60 | * | ||
| 61 | * @var boolean | ||
| 62 | */ | ||
| 63 | protected $optOut = false; | ||
| 64 | |||
| 65 | /** | ||
| 66 | * Flag for if should save the last HTTP response for debugging purposes | ||
| 67 | * | ||
| 68 | * @var boolean True to enable saving the last response | ||
| 69 | */ | ||
| 70 | protected $debugResponse = false; | ||
| 71 | |||
| 72 | /** | ||
| 73 | * Last response from logging event | ||
| 74 | * | ||
| 75 | * @var array|null | ||
| 76 | */ | ||
| 77 | protected $lastHttpResponse; | ||
| 78 | |||
| 79 | /** | ||
| 80 | * Array of Amplitude instances | ||
| 81 | * | ||
| 82 | * @var \Zumba\Amplitude\Amplitude[] | ||
| 83 | */ | ||
| 84 | private static $instances = []; | ||
| 85 | |||
| 86 | /** | ||
| 87 | * Singleton to get named instance | ||
| 88 | * | ||
| 89 | * Using this is optional, it depends on the use-case if it is better to use a singleton instance or just create | ||
| 90 | * a new object directly. | ||
| 91 | * | ||
| 92 | * Useful if want to possibly send multiple events for the same user in a single page load, or even keep track | ||
| 93 | * of multiple named instances, each could track to it's own api key and/or user/device ID. | ||
| 94 | * | ||
| 95 | * Each instance maintains it's own: | ||
| 96 | * - API Key | ||
| 97 | * - User ID | ||
| 98 | * - Device ID | ||
| 99 | * - User Properties | ||
| 100 | * - Event Queue (if events are queued before the amplitude instance is initialized) | ||
| 101 | * - Event object - for the next event that will be sent or queued | ||
| 102 | * - Logger | ||
| 103 | * - Opt out status | ||
| 104 | * | ||
| 105 | * @param string $instanceName Optional, can use to maintain multiple singleton instances of amplitude, each with | ||
| 106 | * it's own API key set | ||
| 107 | * @return \Zumba\Amplitude\Amplitude | ||
| 108 | */ | ||
| 109 | public static function getInstance($instanceName = 'default') | ||
| 110 |     { | ||
| 111 |         if (empty(self::$instances[$instanceName])) { | ||
| 112 | self::$instances[$instanceName] = new static(); | ||
| 113 | } | ||
| 114 | return self::$instances[$instanceName]; | ||
| 115 | } | ||
| 116 | |||
| 117 | /** | ||
| 118 | * Constructor, optionally sets the api key | ||
| 119 | * | ||
| 120 | * @param string $apiKey | ||
| 121 | * @param \Psr\Log $logger | ||
|  | |||
| 122 | */ | ||
| 123 | public function __construct($apiKey = null) | ||
| 124 |     { | ||
| 125 |         if (!empty($apiKey)) { | ||
| 126 | $this->apiKey = (string)$apiKey; | ||
| 127 | } | ||
| 128 | // Initialize logger to be null logger | ||
| 129 | $this->setLogger(new Log\NullLogger()); | ||
| 130 | } | ||
| 131 | |||
| 132 | /** | ||
| 133 | * Initialize amplitude | ||
| 134 | * | ||
| 135 | * This lets you set the api key, and optionally the user ID. | ||
| 136 | * | ||
| 137 | * @param string $apiKey Amplitude API key | ||
| 138 | * @param string $userId | ||
| 139 | * @return \Zumba\Amplitude\Amplitude | ||
| 140 | */ | ||
| 141 | public function init($apiKey, $userId = null) | ||
| 142 |     { | ||
| 143 | $this->apiKey = (string)$apiKey; | ||
| 144 |         if ($userId !== null) { | ||
| 145 | $this->setUserId($userId); | ||
| 146 | } | ||
| 147 | return $this; | ||
| 148 | } | ||
| 149 | |||
| 150 | /** | ||
| 151 | * Log any events that were queued before amplitude was initialized | ||
| 152 | * | ||
| 153 | * Note that api key, and either the user ID or device ID need to be set prior to calling this. | ||
| 154 | * | ||
| 155 | * @return \Zumba\Amplitude\Amplitude | ||
| 156 | * @throws \LogicException | ||
| 157 | */ | ||
| 158 | public function logQueuedEvents() | ||
| 159 |     { | ||
| 160 |         if (empty($this->queue)) { | ||
| 161 | return $this; | ||
| 162 | } | ||
| 163 |         foreach ($this->queue as $event) { | ||
| 164 | $this->event = $event; | ||
| 165 | $this->logEvent(); | ||
| 166 | } | ||
| 167 | return $this->resetEvent() | ||
| 168 | ->resetQueue(); | ||
| 169 | } | ||
| 170 | |||
| 171 | /** | ||
| 172 | * Clear out all events in the queue, without sending them to amplitude | ||
| 173 | * | ||
| 174 | * @return \Zumba\Amplitude\Amplitude | ||
| 175 | */ | ||
| 176 | public function resetQueue() | ||
| 177 |     { | ||
| 178 | $this->queue = []; | ||
| 179 | return $this; | ||
| 180 | } | ||
| 181 | |||
| 182 | /** | ||
| 183 | * Gets the event that will be used for the next event logged by call to logEvent() or queueEvent() | ||
| 184 | * | ||
| 185 | * You can also pass in an event or array of event properties. If you pass in an event, it will be set as the | ||
| 186 | * event to be used for the next call to queueEvent() or logEvent() | ||
| 187 | * | ||
| 188 | * @param null|array|\Zumba\Amplitude\Event Can pass in an event to set as the next event to run, or array to set | ||
| 189 | * properties on that event | ||
| 190 | * @return \Zumba\Amplitude\Event | ||
| 191 | */ | ||
| 192 | public function event($event = null) | ||
| 193 |     { | ||
| 194 |         if (!empty($event) && $event instanceof \Zumba\Amplitude\Event) { | ||
| 195 | $this->event = $event; | ||
| 196 |         } elseif (empty($this->event)) { | ||
| 197 | // Set the values that persist between tracking events | ||
| 198 | $this->event = new Event(); | ||
| 199 | } | ||
| 200 |         if (!empty($event) && is_array($event)) { | ||
| 201 | // Set properties on the event | ||
| 202 | $this->event->set($event); | ||
| 203 | } | ||
| 204 | return $this->event; | ||
| 205 | } | ||
| 206 | |||
| 207 | /** | ||
| 208 | * Resets the event currently in the process of being set up (what is returned by event()) | ||
| 209 | * | ||
| 210 | * @return \Zumba\Amplitude\Amplitude | ||
| 211 | */ | ||
| 212 | public function resetEvent() | ||
| 217 | |||
| 218 | /** | ||
| 219 | * Log an event immediately | ||
| 220 | * | ||
| 221 | * Requires amplitude is already initialized and user ID or device ID is set. If need to wait until amplitude | ||
| 222 | * is initialized, use queueEvent() method instead. | ||
| 223 | * | ||
| 224 | * Can either pass in information to be logged, or can set up the Event object before hand, see the event() | ||
| 225 | * method for more information | ||
| 226 | * | ||
| 227 | * @param string $eventType Required if not set on event object prior to calling this | ||
| 228 | * @param array $eventProperties Optional, properties to set on event | ||
| 229 | * @return \Zumba\Amplitude\Amplitude | ||
| 230 | * @throws \LogicException Thorws exception if any of the requirments are not met, such as api key set | ||
| 231 | */ | ||
| 232 | public function logEvent($eventType = '', array $eventProperties = []) | ||
| 261 | |||
| 262 | /** | ||
| 263 | * Set the persistent data on the event object | ||
| 264 | * | ||
| 265 | * @return void | ||
| 266 | */ | ||
| 267 | protected function setPersistentEventData() | ||
| 281 | |||
| 282 | /** | ||
| 283 | * Log or queue the event, depending on if amplitude instance is already set up or not | ||
| 284 | * | ||
| 285 | * Note that this is an internal queue, the queue is lost between page loads. | ||
| 286 | * | ||
| 287 | * This functions identically to logEvent, with the exception that if Amplitude is not yet set up, it queues the | ||
| 288 | * event to be logged later (during same page load). | ||
| 289 | * | ||
| 290 | * If the API key, and either user ID or device ID are already set in the amplitude instance, and there is not | ||
| 291 | * already events in the queue that have not been run, this will log the event immediately. Note that having | ||
| 292 | * the userId or deviceId set on the event itself does not affect if it queues the event or not, only if set on | ||
| 293 | * the Amplitude instance. | ||
| 294 | * | ||
| 295 | * Otherwise it will queue the event, and will be run after the amplitude instance is initialized and | ||
| 296 | * logQueuedEvents() method is run | ||
| 297 | * | ||
| 298 | * @param string $eventType | ||
| 299 | * @param array $eventProperties | ||
| 300 | * @return \Zumba\Amplitude\Amplitude | ||
| 301 | * @throws \LogicException | ||
| 302 | */ | ||
| 303 | public function queueEvent($eventType = '', array $eventProperties = []) | ||
| 325 | |||
| 326 | /** | ||
| 327 | * Set the user ID for future events logged | ||
| 328 | * | ||
| 329 | * Any set with this will take precedence over any set on the Event object | ||
| 330 | * | ||
| 331 | * @param string $userId | ||
| 332 | * @return \Zumba\Amplitude\Amplitude | ||
| 333 | */ | ||
| 334 | public function setUserId($userId) | ||
| 339 | |||
| 340 | /** | ||
| 341 | * Set the device ID for future events logged | ||
| 342 | * | ||
| 343 | * Any set with this will take precedence over any set on the Event object | ||
| 344 | * | ||
| 345 | * @param string $deviceId | ||
| 346 | * @return \Zumba\Amplitude\Amplitude | ||
| 347 | */ | ||
| 348 | public function setDeviceId($deviceId) | ||
| 353 | |||
| 354 | /** | ||
| 355 | * Set the user properties, will be sent with the next event sent to Amplitude | ||
| 356 | * | ||
| 357 | * Any set with this will take precedence over any set on the Event object | ||
| 358 | * | ||
| 359 | * If no events are logged, it will not get sent to Amplitude | ||
| 360 | * | ||
| 361 | * @param array $userProperties | ||
| 362 | */ | ||
| 363 | public function setUserProperties(array $userProperties) | ||
| 368 | |||
| 369 | /** | ||
| 370 | * Resets user properties added with setUserProperties() if they have not already been sent in an event to Amplitude | ||
| 371 | * | ||
| 372 | * @return \Zumba\Amplitude\Amplitude | ||
| 373 | */ | ||
| 374 | public function resetUserProperties() | ||
| 379 | |||
| 380 | /** | ||
| 381 | * Check if there are events in the queue that have not been sent | ||
| 382 | * | ||
| 383 | * @return boolean | ||
| 384 | */ | ||
| 385 | public function hasQueuedEvents() | ||
| 389 | |||
| 390 | /** | ||
| 391 | * Resets all user information | ||
| 392 | * | ||
| 393 | * This resets the user ID, device ID previously set using setUserId or setDeviceId. | ||
| 394 | * | ||
| 395 | * If additional information was previously set using setUserProperties() method, and the event has not already | ||
| 396 | * been sent to Amplitude, it will reset that information as well. | ||
| 397 | * | ||
| 398 | * Does not reset user information if set manually on an individual event in the queue. | ||
| 399 | * | ||
| 400 | * @return \Zumba\Amplitude\Amplitude | ||
| 401 | */ | ||
| 402 | public function resetUser() | ||
| 409 | |||
| 410 | /** | ||
| 411 | * Set opt out for the current user. | ||
| 412 | * | ||
| 413 | * If set to true, will not send any future events to amplitude for this amplitude instance. | ||
| 414 | * | ||
| 415 | * @param boolean $optOut | ||
| 416 | * @return \Zumba\Amplitude\Amplitude | ||
| 417 | */ | ||
| 418 | public function setOptOut($optOut) | ||
| 423 | |||
| 424 | /** | ||
| 425 | * Getter for currently set api key | ||
| 426 | * | ||
| 427 | * @return string|null | ||
| 428 | */ | ||
| 429 | public function getApiKey() | ||
| 433 | |||
| 434 | /** | ||
| 435 | * Getter for currently set user ID | ||
| 436 | * | ||
| 437 | * @return string|null | ||
| 438 | */ | ||
| 439 | public function getUserId() | ||
| 443 | |||
| 444 | /** | ||
| 445 | * Getter for currently set device ID | ||
| 446 | * | ||
| 447 | * @return string|null | ||
| 448 | */ | ||
| 449 | public function getDeviceId() | ||
| 453 | |||
| 454 | /** | ||
| 455 | * Getter for all currently set user properties, that will be automatically sent on next Amplitude event | ||
| 456 | * | ||
| 457 | * Once the properties have been sent in an Amplitude event, they will be cleared. | ||
| 458 | * | ||
| 459 | * @return array | ||
| 460 | */ | ||
| 461 | public function getUserProperties() | ||
| 465 | |||
| 466 | /** | ||
| 467 | * Get the current value for opt out. | ||
| 468 | * | ||
| 469 | * @return boolean | ||
| 470 | */ | ||
| 471 | public function getOptOut() | ||
| 475 | |||
| 476 | /** | ||
| 477 | * Send the event currently set in $this->event to amplitude | ||
| 478 | * | ||
| 479 | * Requres $this->event and $this->apiKey to be set, otherwise it throws an exception. | ||
| 480 | * | ||
| 481 | * @return void | ||
| 482 | * @throws \InternalErrorException If event or api key not set | ||
| 483 | */ | ||
| 484 | protected function sendEvent() | ||
| 521 | } | ||
| 522 | 
This check looks for PHPDoc comments describing methods or function parameters that do not exist on the corresponding method or function.
Consider the following example. The parameter
$italyis not defined by the methodfinale(...).The most likely cause is that the parameter was removed, but the annotation was not.