<?php declare(strict_types = 1);

namespace MailPoet\Automation\Engine\Control;

if (!defined('ABSPATH')) exit;


use Exception;
use MailPoet\Automation\Engine\Control\Steps\ActionStepRunner;
use MailPoet\Automation\Engine\Data\Automation;
use MailPoet\Automation\Engine\Data\AutomationRun;
use MailPoet\Automation\Engine\Data\AutomationRunLog;
use MailPoet\Automation\Engine\Data\Step;
use MailPoet\Automation\Engine\Data\StepRunArgs;
use MailPoet\Automation\Engine\Data\StepValidationArgs;
use MailPoet\Automation\Engine\Data\SubjectEntry;
use MailPoet\Automation\Engine\Exceptions;
use MailPoet\Automation\Engine\Exceptions\InvalidStateException;
use MailPoet\Automation\Engine\Hooks;
use MailPoet\Automation\Engine\Integration\Action;
use MailPoet\Automation\Engine\Integration\Payload;
use MailPoet\Automation\Engine\Integration\Subject;
use MailPoet\Automation\Engine\Registry;
use MailPoet\Automation\Engine\Storage\AutomationRunLogStorage;
use MailPoet\Automation\Engine\Storage\AutomationRunStorage;
use MailPoet\Automation\Engine\Storage\AutomationStorage;
use MailPoet\Automation\Engine\WordPress;
use Throwable;

class StepHandler {
  /** @var ActionScheduler */
  private $actionScheduler;

  /** @var ActionStepRunner */
  private $actionStepRunner;

  /** @var SubjectLoader */
  private $subjectLoader;

  /** @var WordPress */
  private $wordPress;

  /** @var AutomationRunStorage */
  private $automationRunStorage;

  /** @var AutomationStorage */
  private $automationStorage;

  /** @var array<string, StepRunner> */
  private $stepRunners = [];

  /** @var AutomationRunLogStorage */
  private $automationRunLogStorage;

  /** @var Hooks */
  private $hooks;

  /** @var Registry */
  private $registry;

  public function __construct(
    ActionScheduler $actionScheduler,
    ActionStepRunner $actionStepRunner,
    Hooks $hooks,
    SubjectLoader $subjectLoader,
    WordPress $wordPress,
    AutomationRunStorage $automationRunStorage,
    AutomationRunLogStorage $automationRunLogStorage,
    AutomationStorage $automationStorage,
    Registry $registry
  ) {
    $this->actionScheduler = $actionScheduler;
    $this->actionStepRunner = $actionStepRunner;
    $this->hooks = $hooks;
    $this->subjectLoader = $subjectLoader;
    $this->wordPress = $wordPress;
    $this->automationRunStorage = $automationRunStorage;
    $this->automationRunLogStorage = $automationRunLogStorage;
    $this->automationStorage = $automationStorage;
    $this->registry = $registry;
  }

  public function initialize(): void {
    $this->wordPress->addAction(Hooks::AUTOMATION_STEP, [$this, 'handle']);
    $this->addStepRunner(Step::TYPE_ACTION, $this->actionStepRunner);
    $this->wordPress->doAction(Hooks::STEP_RUNNER_INITIALIZE, [$this]);
  }

  public function addStepRunner(string $stepType, StepRunner $stepRunner): void {
    $this->stepRunners[$stepType] = $stepRunner;
  }

  public function getStepRunners(): array {
    return $this->stepRunners;
  }

  /**
   * @param array<string, StepRunner> $stepRunners
   */
  public function setStepRunners(array $stepRunners): void {
    $this->stepRunners = $stepRunners;
  }

  /** @param mixed $args */
  public function handle($args): void {
    // TODO: args validation
    if (!is_array($args)) {
      throw new InvalidStateException();
    }

    // Action Scheduler catches only Exception instances, not other errors.
    // We need to convert them to exceptions to be processed and logged.
    try {
      $this->handleStep($args);
    } catch (Throwable $e) {
      $status = $e instanceof InvalidStateException && $e->getErrorCode() === 'mailpoet_automation_not_active' ? AutomationRun::STATUS_CANCELLED : AutomationRun::STATUS_FAILED;
      $this->automationRunStorage->updateStatus((int)$args['automation_run_id'], $status);
      $this->postProcessAutomationRun((int)$args['automation_run_id']);
      if (!$e instanceof Exception) {
        throw new Exception($e->getMessage(), intval($e->getCode()), $e);
      }
      throw $e;
    }
    $this->postProcessAutomationRun((int)$args['automation_run_id']);
  }

  private function handleStep(array $args): void {
    $automationRunId = $args['automation_run_id'];
    $stepId = $args['step_id'];

    $automationRun = $this->automationRunStorage->getAutomationRun($automationRunId);
    if (!$automationRun) {
      throw Exceptions::automationRunNotFound($automationRunId);
    }

    if ($automationRun->getStatus() !== AutomationRun::STATUS_RUNNING) {
      throw Exceptions::automationRunNotRunning($automationRunId, $automationRun->getStatus());
    }

    $automation = $this->automationStorage->getAutomation($automationRun->getAutomationId(), $automationRun->getVersionId());
    if (!$automation) {
      throw Exceptions::automationVersionNotFound($automationRun->getAutomationId(), $automationRun->getVersionId());
    }
    if (!in_array($automation->getStatus(), [Automation::STATUS_ACTIVE, Automation::STATUS_DEACTIVATING], true)) {
      throw Exceptions::automationNotActive($automationRun->getAutomationId());
    }

    // complete automation run
    if (!$stepId) {
      $this->automationRunStorage->updateStatus($automationRunId, AutomationRun::STATUS_COMPLETE);
      return;
    }

    $stepData = $automation->getStep($stepId);
    if (!$stepData) {
      throw Exceptions::automationStepNotFound($stepId);
    }
    $step = $this->registry->getStep($stepData->getKey());
    $stepType = $stepData->getType();
    if (isset($this->stepRunners[$stepType])) {
      $log = new AutomationRunLog($automationRun->getId(), $stepData->getId());
      try {
        $requiredSubjects = $step instanceof Action ? $step->getSubjectKeys() : [];
        $subjectEntries = $this->getSubjectEntries($automationRun, $requiredSubjects);
        $args = new StepRunArgs($automation, $automationRun, $stepData, $subjectEntries);
        $validationArgs = new StepValidationArgs($automation, $stepData, array_map(function (SubjectEntry $entry) {
          return $entry->getSubject();
        }, $subjectEntries));
        $this->stepRunners[$stepType]->run($args, $validationArgs);
        $log->markCompletedSuccessfully();
      } catch (Throwable $e) {
        $log->markFailed();
        $log->setError($e);
        throw $e;
      } finally {
        try {
          $this->hooks->doAutomationStepAfterRun($log);
        } catch (Throwable $e) {
          // Ignore integration errors
        }
        $this->automationRunLogStorage->createAutomationRunLog($log);
      }
    } else {
      throw new InvalidStateException();
    }

    $nextStep = $stepData->getNextSteps()[0] ?? null;
    $nextStepArgs = [
      [
        'automation_run_id' => $automationRunId,
        'step_id' => $nextStep ? $nextStep->getId() : null,
      ],
    ];

    $this->automationRunStorage->updateNextStep($automationRunId, $nextStep ? $nextStep->getId() : null);

    // next step scheduled by action
    if ($this->actionScheduler->hasScheduledAction(Hooks::AUTOMATION_STEP, $nextStepArgs)) {
      return;
    }

    // no need to schedule a new step if the next step is null, complete the run
    if (!$nextStep) {
      $this->automationRunStorage->updateStatus($automationRunId, AutomationRun::STATUS_COMPLETE);
      return;
    }

    // enqueue next step
    $this->actionScheduler->enqueue(Hooks::AUTOMATION_STEP, $nextStepArgs);
    // TODO: allow long-running steps (that are not done here yet)
  }

  /** @return SubjectEntry<Subject<Payload>>[] */
  private function getSubjectEntries(AutomationRun $automationRun, array $requiredSubjectKeys): array {
    $subjectDataMap = [];
    foreach ($automationRun->getSubjects() as $data) {
      $subjectDataMap[$data->getKey()] = array_merge($subjectDataMap[$data->getKey()] ?? [], [$data]);
    }

    $subjectEntries = [];
    foreach ($requiredSubjectKeys as $key) {
      $subjectData = $subjectDataMap[$key] ?? null;
      if (!$subjectData) {
        throw Exceptions::subjectDataNotFound($key, $automationRun->getId());
      }
    }
    foreach ($subjectDataMap as $subjectData) {
      foreach ($subjectData as $data) {
        $subjectEntries[] = $this->subjectLoader->getSubjectEntry($data);
      }
    }
    return $subjectEntries;
  }

  private function postProcessAutomationRun(int $automationRunId): void {
    $automationRun = $this->automationRunStorage->getAutomationRun($automationRunId);
    if (!$automationRun) {
      return;
    }
    $automation = $this->automationStorage->getAutomation($automationRun->getAutomationId());
    if (!$automation) {
      return;
    }
    $this->postProcessAutomation($automation);
  }

  private function postProcessAutomation(Automation $automation): void {
    if ($automation->getStatus() === Automation::STATUS_DEACTIVATING) {
      $activeRuns = $this->automationRunStorage->getCountForAutomation($automation, AutomationRun::STATUS_RUNNING);

      // Set a deactivating Automation to draft once all automation runs are finished.
      if ($activeRuns === 0) {
        $automation->setStatus(Automation::STATUS_DRAFT);
        $this->automationStorage->updateAutomation($automation);
      }
    }
  }
}