Add hook and basic handler for automation triggers

For now trigger keys are stored in the workflow as a JSON array.
This is not optimal in case someone has many workflows but as
workflows are user-created it's unlinkely someone will have thousands
of them. We can consider adding a workflow_triggers table as well.

[MAILPOET-4136]

mailpoet/lib/Automation/Engine/Control/TriggerHandler.php

@@ -0,0 +1,46 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\Automation\Engine\Control;
+
+use MailPoet\Automation\Engine\Exceptions;
+use MailPoet\Automation\Engine\Hooks;
+use MailPoet\Automation\Engine\Storage\WorkflowStorage;
+use MailPoet\Automation\Engine\WordPress;
+use MailPoet\Automation\Engine\Workflows\Trigger;
+
+class TriggerHandler {
+  /** @var ActionScheduler */
+  private $actionScheduler;
+
+  /** @var WordPress */
+  private $wordPress;
+
+  /** @var WorkflowStorage */
+  private $workflowStorage;
+
+  public function __construct(
+    ActionScheduler $actionScheduler,
+    WordPress $wordPress,
+    WorkflowStorage $workflowStorage
+  ) {
+    $this->actionScheduler = $actionScheduler;
+    $this->wordPress = $wordPress;
+    $this->workflowStorage = $workflowStorage;
+  }
+
+  public function initialize(): void {
+    $this->wordPress->addAction(Hooks::TRIGGER, [$this, 'processTrigger']);
+  }
+
+  public function processTrigger(Trigger $trigger): void {
+    $workflows = $this->workflowStorage->getActiveWorkflowsByTrigger($trigger);
+    foreach ($workflows as $workflow) {
+      $step = $workflow->getTrigger($trigger->getKey());
+      if (!$step) {
+        throw Exceptions::workflowTriggerNotFound($workflow->getId(), $trigger->getKey());
+      }
+
+      // TODO: create new workflow run
+    }
+  }
+}

mailpoet/lib/Automation/Engine/Engine.php

@@ -3,6 +3,7 @@
 namespace MailPoet\Automation\Engine;
 
 use MailPoet\Automation\Engine\API\API;
+use MailPoet\Automation\Engine\Control\TriggerHandler;
 use MailPoet\Automation\Engine\Storage\WorkflowStorage;
 
 class Engine {
@@ -12,6 +13,9 @@ class Engine {
   /** @var Registry */
   private $registry;
 
+  /** @var TriggerHandler */
+  private $triggerHandler;
+
   /** @var WordPress */
   private $wordPress;
 
@@ -21,11 +25,13 @@ class Engine {
   public function __construct(
     API $api,
     Registry $registry,
+    TriggerHandler $triggerHandler,
     WordPress $wordPress,
     WorkflowStorage $workflowStorage
   ) {
     $this->api = $api;
     $this->registry = $registry;
+    $this->triggerHandler = $triggerHandler;
     $this->wordPress = $wordPress;
     $this->workflowStorage = $workflowStorage;
   }
@@ -35,6 +41,7 @@ class Engine {
     require_once __DIR__ . '/../../../vendor/woocommerce/action-scheduler/action-scheduler.php';
 
     $this->api->initialize();
+    $this->triggerHandler->initialize();
 
     $this->wordPress->doAction(Hooks::INITIALIZE, [$this->registry]);
     $this->registerActiveTriggerHooks();

mailpoet/lib/Automation/Engine/Exceptions.php

@@ -3,6 +3,7 @@
 namespace MailPoet\Automation\Engine;
 
 use MailPoet\Automation\Engine\Exceptions\InvalidStateException;
+use MailPoet\Automation\Engine\Exceptions\NotFoundException;
 use MailPoet\Automation\Engine\Exceptions\UnexpectedValueException;
 
 class Exceptions {
@@ -10,6 +11,7 @@ class Exceptions {
   private const DATABASE_ERROR = 'mailpoet_automation_database_error';
   private const API_METHOD_NOT_ALLOWED = 'mailpoet_automation_api_method_not_allowed';
   private const API_NO_JSON_BODY = 'mailpoet_automation_api_no_json_body';
+  private const WORKFLOW_TRIGGER_NOT_FOUND = 'mailpoet_automation_workflow_trigger_not_found';
 
   public function __construct() {
     throw new InvalidStateException(
@@ -41,4 +43,10 @@ class Exceptions {
       ->withErrorCode(self::API_NO_JSON_BODY)
       ->withMessage(__('No JSON body passed.', 'mailpoet'));
   }
+
+  public static function workflowTriggerNotFound(int $workflowId, string $key): NotFoundException {
+    return NotFoundException::create()
+      ->withErrorCode(self::WORKFLOW_TRIGGER_NOT_FOUND)
+      ->withMessage(__(sprintf("Workflow trigger with key '%s' not found in workflow ID '%s'.", $key, $workflowId), 'mailpoet'));
+  }
 }

mailpoet/lib/Automation/Engine/Hooks.php

@@ -4,4 +4,5 @@ namespace MailPoet\Automation\Engine;
 
 class Hooks {
   public const INITIALIZE = 'mailpoet/automation/initialize';
+  public const TRIGGER = 'mailpoet/automation/trigger';
 }

mailpoet/lib/Automation/Engine/Storage/WorkflowStorage.php

@@ -3,6 +3,7 @@
 namespace MailPoet\Automation\Engine\Storage;
 
 use MailPoet\Automation\Engine\Exceptions;
+use MailPoet\Automation\Engine\Workflows\Trigger;
 use MailPoet\Automation\Engine\Workflows\Workflow;
 use wpdb;
 
@@ -45,4 +46,20 @@ class WorkflowStorage {
     }
     return array_unique($triggerKeys);
   }
+
+  /** @return Workflow[] */
+  public function getActiveWorkflowsByTrigger(Trigger $trigger): array {
+    $query = strval(
+      $this->wpdb->prepare(
+        "SELECT * FROM $this->table WHERE status = %s AND trigger_keys LIKE %s",
+        Workflow::STATUS_ACTIVE,
+        '%' . $this->wpdb->esc_like($trigger->getKey()) . '%'
+      )
+    );
+
+    $data = $this->wpdb->get_results($query, ARRAY_A);
+    return array_map(function (array $workflowData) {
+      return Workflow::fromArray($workflowData);
+    }, (array)$data);
+  }
 }

mailpoet/lib/DI/ContainerConfigurator.php

@@ -108,6 +108,7 @@ class ContainerConfigurator implements IContainerConfigurator {
     $container->autowire(\MailPoet\Automation\Engine\API\Endpoints\SystemDatabaseEndpoint::class)->setPublic(true);
     $container->autowire(\MailPoet\Automation\Engine\API\Endpoints\WorkflowsEndpoint::class)->setPublic(true);
     $container->autowire(\MailPoet\Automation\Engine\Builder\CreateWorkflowController::class)->setPublic(true);
+    $container->autowire(\MailPoet\Automation\Engine\Control\TriggerHandler::class)->setPublic(true);
     $container->autowire(\MailPoet\Automation\Engine\Engine::class)->setPublic(true);
     $container->autowire(\MailPoet\Automation\Engine\Migrations\Migrator::class)->setPublic(true);
     $container->autowire(\MailPoet\Automation\Engine\Registry::class)->setPublic(true);