<?php

namespace Civi\Core;

use Symfony\Component\EventDispatcher\EventDispatcher;
use Symfony\Component\EventDispatcher\Event;

/**
 * Class CiviEventDispatcher
 * @package Civi\Core
 *
 * The CiviEventDispatcher is a Symfony dispatcher. Additionally, if an event
 * follows the naming convention of "hook_*", then it will also be dispatched
 * through CRM_Utils_Hook::invoke().
 *
 * @see \CRM_Utils_Hook
 */
class CiviEventDispatcher extends EventDispatcher {

  const DEFAULT_HOOK_PRIORITY = -100;

  /**
   * Track the list of hook-events for which we have autoregistered
   * the hook adapter.
   *
   * @var array
   *   Array(string $eventName => trueish).
   */
  private $autoListeners = [];

  /**
   * A list of dispatch-policies (based on an exact-match to the event name).
   *
   * Note: $dispatchPolicyExact and $dispatchPolicyRegex should coexist; e.g.
   * if one is NULL, then both are NULL. If one is an array, then both are arrays.
   *
   * @var array|null
   *   Array(string $eventName => string $action)
   */
  private $dispatchPolicyExact = NULL;

  /**
   * A list of dispatch-policies (based on an regex-match to the event name).
   *
   * Note: $dispatchPolicyExact and $dispatchPolicyRegex should coexist; e.g.
   * if one is NULL, then both are NULL. If one is an array, then both are arrays.
   *
   * @var array|null
   *   Array(string $eventRegex => string $action)
   */
  private $dispatchPolicyRegex = NULL;

  /**
   * Determine whether $eventName should delegate to the CMS hook system.
   *
   * @param string $eventName
   *   Ex: 'civi.token.eval', 'hook_civicrm_post`.
   * @return bool
   */
  protected function isHookEvent($eventName) {
    return (substr($eventName, 0, 5) === 'hook_') && (strpos($eventName, '::') === FALSE);
  }

  /**
   * Adds a service as event listener.
   *
   * This provides partial backwards compatibility with ContainerAwareEventDispatcher.
   *
   * @param string $eventName Event for which the listener is added
   * @param array $callback The service ID of the listener service & the method
   *                        name that has to be called
   * @param int $priority The higher this value, the earlier an event listener
   *                      will be triggered in the chain.
   *                      Defaults to 0.
   *
   * @throws \InvalidArgumentException
   */
  public function addListenerService($eventName, $callback, $priority = 0) {
    if (!\is_array($callback) || 2 !== \count($callback)) {
      throw new \InvalidArgumentException('Expected an array("service", "method") argument');
    }

    $this->addListener($eventName, function($event) use ($callback) {
      static $svc;
      if ($svc === NULL) {
        $svc = \Civi::container()->get($callback[0]);
      }
      return call_user_func([$svc, $callback[1]], $event);
    }, $priority);
  }

  /**
   * @inheritDoc
   */
  public function dispatch($eventName, Event $event = NULL) {
    // Dispatch policies add systemic overhead and (normally) should not be evaluated. JNZ.
    if ($this->dispatchPolicyRegex !== NULL) {
      switch ($mode = $this->checkDispatchPolicy($eventName)) {
        case 'run':
          // Continue on the normal execution.
          break;

        case 'drop':
          // Quietly ignore the event.
          return $event;

        case 'warn':
          // Run the event, but complain about it.
          error_log("Unexpectedly dispatching event \"$eventName\".");
          break;

        case 'warn-drop':
          // Ignore the event, but complaint about it.
          error_log("Unexpectedly dispatching event \"$eventName\".");
          return $event;

        case 'fail':
          throw new \RuntimeException("The dispatch policy prohibits event \"$eventName\".");

        case 'not-ready':
          throw new \RuntimeException("CiviCRM has not bootstrapped sufficiently to fire event \"$eventName\".");

        default:
          throw new \RuntimeException("The dispatch policy for \"$eventName\" is unrecognized ($mode).");

      }
    }
    $this->bindPatterns($eventName);
    return parent::dispatch($eventName, $event);
  }

  /**
   * @inheritDoc
   */
  public function getListeners($eventName = NULL) {
    $this->bindPatterns($eventName);
    return parent::getListeners($eventName);
  }

  /**
   * @inheritDoc
   */
  public function hasListeners($eventName = NULL) {
    // All hook_* events have default listeners, so hasListeners(NULL) is a truism.
    return ($eventName === NULL || $this->isHookEvent($eventName))
      ? TRUE : parent::hasListeners($eventName);
  }

  /**
   * Invoke hooks using an event object.
   *
   * @param \Civi\Core\Event\GenericHookEvent $event
   * @param string $eventName
   *   Ex: 'hook_civicrm_dashboard'.
   */
  public static function delegateToUF($event, $eventName) {
    $hookName = substr($eventName, 5);
    $hooks = \CRM_Utils_Hook::singleton();
    $params = $event->getHookValues();
    $count = count($params);

    switch ($count) {
      case 0:
        $fResult = $hooks->invokeViaUF($count, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, $hookName);
        break;

      case 1:
        $fResult = $hooks->invokeViaUF($count, $params[0], \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, $hookName);
        break;

      case 2:
        $fResult = $hooks->invokeViaUF($count, $params[0], $params[1], \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, $hookName);
        break;

      case 3:
        $fResult = $hooks->invokeViaUF($count, $params[0], $params[1], $params[2], \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, $hookName);
        break;

      case 4:
        $fResult = $hooks->invokeViaUF($count, $params[0], $params[1], $params[2], $params[3], \CRM_Utils_Hook::$_nullObject, \CRM_Utils_Hook::$_nullObject, $hookName);
        break;

      case 5:
        $fResult = $hooks->invokeViaUF($count, $params[0], $params[1], $params[2], $params[3], $params[4], \CRM_Utils_Hook::$_nullObject, $hookName);
        break;

      case 6:
        $fResult = $hooks->invokeViaUF($count, $params[0], $params[1], $params[2], $params[3], $params[4], $params[5], $hookName);
        break;

      default:
        throw new \RuntimeException("hook_{$hookName} cannot support more than 6 parameters");
    }

    $event->addReturnValues($fResult);
  }

  /**
   * Attach any pattern-based listeners which may be interested in $eventName.
   *
   * @param string $eventName
   *   Ex: 'civi.api.resolve' or 'hook_civicrm_dashboard'.
   */
  protected function bindPatterns($eventName) {
    if ($eventName !== NULL && !isset($this->autoListeners[$eventName])) {
      $this->autoListeners[$eventName] = 1;
      if ($this->isHookEvent($eventName)) {
        // WISHLIST: For native extensions (and possibly D6/D7/D8/BD), enumerate
        // the listeners and list them one-by-one. This would make it easier to
        // inspect via "cv debug:event-dispatcher".
        $this->addListener($eventName, [
          '\Civi\Core\CiviEventDispatcher',
          'delegateToUF',
        ], self::DEFAULT_HOOK_PRIORITY);
      }
    }
  }

  /**
   * Set the dispatch policy. This allows you to filter certain events.
   * This can be useful during upgrades or debugging.
   *
   * Enforcement will add systemic overhead, so this should normally be NULL.
   *
   * @param array|null $dispatchPolicy
   *   Each key is either the string-literal name of an event, or a regex delimited by '/'.
   *   Each value is one of: 'run', 'drop', 'warn', 'fail'.
   *   Exact name matches take precedence over regexes. Regexes are evaluated in order.
   *
   *   Ex: ['hook_civicrm_pre' => 'fail']
   *   Ex: ['/^hook_/' => 'warn']
   *
   * @return static
   */
  public function setDispatchPolicy($dispatchPolicy) {
    if (is_array($dispatchPolicy)) {
      // Split $dispatchPolicy in two (exact rules vs regex rules).
      $this->dispatchPolicyExact = [];
      $this->dispatchPolicyRegex = [];
      foreach ($dispatchPolicy as $pattern => $action) {
        if ($pattern[0] === '/') {
          $this->dispatchPolicyRegex[$pattern] = $action;
        }
        else {
          $this->dispatchPolicyExact[$pattern] = $action;
        }
      }
    }
    else {
      $this->dispatchPolicyExact = NULL;
      $this->dispatchPolicyRegex = NULL;
    }

    return $this;
  }

  //  /**
  //   * @return array|NULL
  //   */
  //  public function getDispatchPolicy() {
  //    return  $this->dispatchPolicyRegex === NULL ? NULL : array_merge($this->dispatchPolicyExact, $this->dispatchPolicyRegex);
  //  }

  /**
   * Determine whether the dispatch policy applies to a given event.
   *
   * @param string $eventName
   *   Ex: 'civi.api.resolve' or 'hook_civicrm_dashboard'.
   * @return string
   *   Ex: 'run', 'drop', 'fail'
   */
  protected function checkDispatchPolicy($eventName) {
    if (isset($this->dispatchPolicyExact[$eventName])) {
      return $this->dispatchPolicyExact[$eventName];
    }
    foreach ($this->dispatchPolicyRegex as $eventPat => $action) {
      if ($eventPat[0] === '/' && preg_match($eventPat, $eventName)) {
        return $action;
      }
    }
    return 'fail';
  }

}