<?php

/**
 * NOTE: Do not extend this!
 *
 * @concrete-extensible
 */
class DifferentialReplyHandler extends PhabricatorMailReplyHandler {

  private $receivedMail;

  public function validateMailReceiver($mail_receiver) {
    if (!($mail_receiver instanceof DifferentialRevision)) {
      throw new Exception('Receiver is not a DifferentialRevision!');
    }
  }

  public function getPrivateReplyHandlerEmailAddress(
    PhabricatorObjectHandle $handle) {
    return $this->getDefaultPrivateReplyHandlerEmailAddress($handle, 'D');
  }

  public function getPublicReplyHandlerEmailAddress() {
    return $this->getDefaultPublicReplyHandlerEmailAddress('D');
  }

  public function getReplyHandlerDomain() {
    return PhabricatorEnv::getEnvConfig(
      'metamta.differential.reply-handler-domain');
  }

  /*
   * Generate text like the following from the supported commands.
   * "
   *
   * ACTIONS
   * Reply to comment, or !accept, !reject, !abandon, !resign, !reclaim.
   *
   * "
   */
  public function getReplyHandlerInstructions() {
    if (!$this->supportsReplies()) {
      return null;
    }

    $supported_commands = $this->getSupportedCommands();
    $text = '';
    if (empty($supported_commands)) {
      return $text;
    }

    $comment_command_printed = false;
    if (in_array(DifferentialAction::ACTION_COMMENT, $supported_commands)) {
      $text .= pht('Reply to comment');
      $comment_command_printed = true;

      $supported_commands = array_diff(
        $supported_commands, array(DifferentialAction::ACTION_COMMENT));
    }

    if (!empty($supported_commands)) {
      if ($comment_command_printed) {
        $text .= ', or ';
      }

      $modified_commands = array();
      foreach ($supported_commands as $command) {
        $modified_commands[] = '!'.$command;
      }

      $text .= implode(', ', $modified_commands);
    }

    $text .= '.';

    return $text;
  }

  public function getSupportedCommands() {
    $actions = array(
      DifferentialAction::ACTION_COMMENT,
      DifferentialAction::ACTION_REJECT,
      DifferentialAction::ACTION_ABANDON,
      DifferentialAction::ACTION_RECLAIM,
      DifferentialAction::ACTION_RESIGN,
      DifferentialAction::ACTION_RETHINK,
      'unsubscribe',
    );

    if (PhabricatorEnv::getEnvConfig('differential.enable-email-accept')) {
      $actions[] = DifferentialAction::ACTION_ACCEPT;
    }

    return $actions;
  }

  protected function receiveEmail(PhabricatorMetaMTAReceivedMail $mail) {
    $this->receivedMail = $mail;
    $this->handleAction($mail->getCleanTextBody(), $mail->getAttachments());
  }

  public function handleAction($body, array $attachments) {
    // all commands start with a bang and separated from the body by a newline
    // to make sure that actual feedback text couldn't trigger an action.
    // unrecognized commands will be parsed as part of the comment.
    $command = DifferentialAction::ACTION_COMMENT;
    $supported_commands = $this->getSupportedCommands();
    $regex = "/\A\n*!(".implode('|', $supported_commands).")\n*/";
    $matches = array();
    if (preg_match($regex, $body, $matches)) {
      $command = $matches[1];
      $body = trim(str_replace('!'.$command, '', $body));
    }

    $actor = $this->getActor();
    if (!$actor) {
      throw new Exception('No actor is set for the reply action.');
    }

    switch ($command) {
      case 'unsubscribe':
        id(new PhabricatorSubscriptionsEditor())
          ->setActor($actor)
          ->setObject($this->getMailReceiver())
          ->unsubscribe(array($actor->getPHID()))
          ->save();
        // TODO: Send the user a confirmation email?
        return null;
    }

    $body = $this->enhanceBodyWithAttachments($body, $attachments);

    $xactions = array();

    if ($command && ($command != DifferentialAction::ACTION_COMMENT)) {
      $xactions[] = id(new DifferentialTransaction())
        ->setTransactionType(DifferentialTransaction::TYPE_ACTION)
        ->setNewValue($command);
    }

    if (strlen($body)) {
      $xactions[] = id(new DifferentialTransaction())
        ->setTransactionType(PhabricatorTransactions::TYPE_COMMENT)
        ->attachComment(
          id(new DifferentialTransactionComment())
            ->setContent($body));
    }

    $editor = id(new DifferentialTransactionEditor())
      ->setActor($actor)
      ->setExcludeMailRecipientPHIDs($this->getExcludeMailRecipientPHIDs())
      ->setContinueOnMissingFields(true)
      ->setContinueOnNoEffect(true);

    // NOTE: We have to be careful about this because Facebook's
    // implementation jumps straight into handleAction() and will not have
    // a PhabricatorMetaMTAReceivedMail object.
    if ($this->receivedMail) {
      $content_source = PhabricatorContentSource::newForSource(
        PhabricatorContentSource::SOURCE_EMAIL,
        array(
          'id' => $this->receivedMail->getID(),
        ));
      $editor->setContentSource($content_source);
      $editor->setParentMessageID($this->receivedMail->getMessageID());
    } else {
      $content_source = PhabricatorContentSource::newForSource(
        PhabricatorContentSource::SOURCE_LEGACY,
        array());
      $editor->setContentSource($content_source);
    }

    $editor->applyTransactions($this->getMailReceiver(), $xactions);
  }

}