Refactor sending methods to use error mappers

We want to add some logic to error handling.
This commit extracts error handling code from sending methods classes,
which already do a lot of other stuff, to error mappers which are responsible
for creating proper error object (MailerError). This error object is a replacement
for assoc. array which already had some special keys for certain usecases and
can not be properly type hinted.

[MAILPOET-1154]

lib/Mailer/Methods/ErrorMappers/AmazonSESMapper.php

@@ -0,0 +1,23 @@
+<?php
+namespace MailPoet\Mailer\Methods\ErrorMappers;
+
+use MailPoet\Mailer\MailerError;
+use MailPoet\Mailer\Mailer;
+
+class AmazonSESMapper {
+  use ConnectionErrorMapperTrait;
+
+  function getErrorFromException(\Exception $e) {
+    return new MailerError(MailerError::OPERATION_SEND, MailerError::LEVEL_HARD, $e->getMessage());
+  }
+
+  function getErrorFromResponse($response, $subscriber, $extra_params) {
+    $response = ($response) ?
+      $response->Error->Message->__toString() :
+      sprintf(__('%s has returned an unknown error.', 'mailpoet'), Mailer::METHOD_AMAZONSES);
+    if(empty($extra_params['test_email'])) {
+      $response .= sprintf(' %s: %s', __('Unprocessed subscriber', 'mailpoet'), $subscriber);
+    }
+    return new MailerError(MailerError::OPERATION_SEND, MailerError::LEVEL_HARD, $response);
+  }
+}

lib/Mailer/Methods/ErrorMappers/ConnectionErrorMapperTrait.php

@@ -0,0 +1,14 @@
+<?php
+namespace MailPoet\Mailer\Methods\ErrorMappers;
+
+use MailPoet\Mailer\MailerError;
+
+trait ConnectionErrorMapperTrait {
+  function getConnectionError($message) {
+    return new MailerError(
+      MailerError::OPERATION_CONNECT,
+      MailerError::LEVEL_HARD,
+      $message
+    );
+  }
+}

lib/Mailer/Methods/ErrorMappers/MailPoetMapper.php

@@ -0,0 +1,80 @@
+<?php
+namespace MailPoet\Mailer\Methods\ErrorMappers;
+
+use MailPoet\Mailer\MailerError;
+use MailPoet\Services\Bridge\API;
+
+if(!defined('ABSPATH')) exit;
+
+class MailPoetMapper {
+  use ConnectionErrorMapperTrait;
+
+  const TEMPORARY_UNAVAILABLE_RETRY_INTERVAL = 300; // seconds
+
+  function getInvalidApiKeyError() {
+    return new MailerError(
+      MailerError::OPERATION_SEND,
+      MailerError::LEVEL_HARD,
+      __('MailPoet API key is invalid!', 'mailpoet')
+    );
+  }
+
+  function getErrorForResult(array $result, $subscribers) {
+    $message = $result['message'];
+    $level = MailerError::LEVEL_HARD;
+    $retry_interval = null;
+
+    if(!empty($result['code'])) {
+      switch($result['code']) {
+        case API::RESPONSE_CODE_NOT_ARRAY:
+          $message = __('JSON input is not an array', 'mailpoet');
+          break;
+        case API::RESPONSE_CODE_PAYLOAD_ERROR:
+          $message = $this->parseErrorResponse($result['message'], $subscribers);
+          break;
+        case API::RESPONSE_CODE_TEMPORARY_UNAVAILABLE:
+          $message = __('Email service is temporarily not available, please try again in a few minutes.', 'mailpoet');
+          $retry_interval = self::TEMPORARY_UNAVAILABLE_RETRY_INTERVAL;
+          break;
+        case API::RESPONSE_CODE_KEY_INVALID:
+        case API::RESPONSE_CODE_PAYLOAD_TOO_BIG:
+        default:
+          $message = $result['message'];
+      }
+    }
+    return new MailerError(MailerError::OPERATION_SEND, $level, $message, $retry_interval);
+  }
+
+  private function parseErrorResponse($result, $subscriber) {
+    $result_parsed = json_decode($result, true);
+    $errors = [];
+    if(is_array($result_parsed)) {
+      foreach($result_parsed as $result_error) {
+        $errors[] = $this->processSingleSubscriberError($result_error, $subscriber);
+      }
+    }
+    if(!empty($errors)) {
+      return __('Error while sending: ', 'mailpoet') . join(', ', $errors);
+    } else {
+      return __('Error while sending newsletters. ', 'mailpoet') . $result;
+    }
+  }
+
+  private function processSingleSubscriberError($result_error, $subscriber) {
+    $error = '';
+    if(is_array($result_error)) {
+      $subscriber_errors = [];
+      if(isset($result_error['errors']) && is_array($result_error['errors'])) {
+        array_walk_recursive($result_error['errors'], function($item) use (&$subscriber_errors) {
+          $subscriber_errors[] = $item;
+        });
+      }
+      $error .= join(', ', $subscriber_errors);
+
+      if(isset($result_error['index']) && isset($subscriber[$result_error['index']])) {
+        $error = '(' . $subscriber[$result_error['index']] . ': ' . $error . ')';
+      }
+    }
+    return $error;
+  }
+}

lib/Mailer/Methods/ErrorMappers/PHPMailMapper.php

@@ -0,0 +1,21 @@
+<?php
+namespace MailPoet\Mailer\Methods\ErrorMappers;
+
+use MailPoet\Mailer\MailerError;
+use MailPoet\Mailer\Mailer;
+
+class PHPMailMapper {
+  use ConnectionErrorMapperTrait;
+
+  function getErrorFromException(\Exception $e) {
+    return new MailerError(MailerError::OPERATION_SEND, MailerError::LEVEL_HARD, $e->getMessage());
+  }
+
+  function getErrorForSubscriber($subscriber, $extra_params) {
+    $message = sprintf(__('%s has returned an unknown error.', 'mailpoet'), Mailer::METHOD_PHPMAIL);
+    if(empty($extra_params['test_email'])) {
+      $message .= sprintf(' %s: %s', __('Unprocessed subscriber', 'mailpoet'), $subscriber);
+    }
+    return new MailerError(MailerError::OPERATION_SEND, MailerError::LEVEL_HARD, $message);
+  }
+}

lib/Mailer/Methods/ErrorMappers/SMTPMapper.php

@@ -0,0 +1,31 @@
+<?php
+namespace MailPoet\Mailer\Methods\ErrorMappers;
+
+use MailPoet\Mailer\MailerError;
+use MailPoet\Mailer\Mailer;
+
+class SMTPMapper {
+  use ConnectionErrorMapperTrait;
+
+  function getErrorFromException(\Exception $e) {
+    // remove redundant information appended by Swift logger to exception messages
+    $message = explode(PHP_EOL, $e->getMessage());
+    return new MailerError(MailerError::OPERATION_SEND, MailerError::LEVEL_HARD, $message[0]);
+  }
+
+  function getErrorFromLog($log, $subscriber, $extra_params = []) {
+    // extract error message from log
+    preg_match('/!! (.*?)>>/ism', $log, $message);
+    if(!empty($message[1])) {
+      $message = $message[1];
+      // remove line breaks from the message due to how logger's dump() method works
+      $message = preg_replace('/\r|\n/', '', $message);
+    } else {
+      $message = sprintf(__('%s has returned an unknown error.', 'mailpoet'), Mailer::METHOD_SMTP);
+    }
+    if(empty($extra_params['test_email'])) {
+      $message .= sprintf(' %s: %s', __('Unprocessed subscriber', 'mailpoet'), $subscriber);
+    }
+    return new MailerError(MailerError::OPERATION_SEND, MailerError::LEVEL_HARD, $message);
+  }
+}

lib/Mailer/Methods/ErrorMappers/SendGridMapper.php

@@ -0,0 +1,19 @@
+<?php
+namespace MailPoet\Mailer\Methods\ErrorMappers;
+
+use MailPoet\Mailer\MailerError;
+use MailPoet\Mailer\Mailer;
+
+class SendGridMapper {
+  use ConnectionErrorMapperTrait;
+
+  function getErrorFromResponse($response, $subscriber, $extra_params) {
+    $response = (!empty($response['errors'][0])) ?
+      $response['errors'][0] :
+      sprintf(__('%s has returned an unknown error.', 'mailpoet'), Mailer::METHOD_SENDGRID);
+    if(empty($extra_params['test_email'])) {
+      $response .= sprintf(' %s: %s', __('Unprocessed subscriber', 'mailpoet'), $subscriber);
+    }
+    return new MailerError(MailerError::OPERATION_SEND, MailerError::LEVEL_HARD, $response);
+  }
+}