function bbp_new_reply_handler( $action = '' ) {

	// Bail if action is not bbp-new-reply
	if ( 'bbp-new-reply' !== $action ) {
		return;
	}

	// Nonce check
	if ( ! bbp_verify_nonce_request( 'bbp-new-reply' ) ) {
		bbp_add_error( 'bbp_new_reply_nonce', __( '<strong>ERROR</strong>: Are you sure you wanted to do that?', 'bbpress' ) );
		return;
	}

	// Define local variable(s)
	$topic_id = $forum_id = $reply_author = $reply_to = 0;
	$reply_title = $reply_content = $terms = '';
	$anonymous_data = array();

	/** Reply Author **********************************************************/

	// User is anonymous
	if ( bbp_is_anonymous() ) {

		// Filter anonymous data (variable is used later)
		$anonymous_data = bbp_filter_anonymous_post_data();

		// Anonymous data checks out, so set cookies, etc...
		bbp_set_current_anonymous_user_data( $anonymous_data );

	// User is logged in
	} else {

		// User cannot create replies
		if ( ! current_user_can( 'publish_replies' ) ) {
			bbp_add_error( 'bbp_reply_permission', __( '<strong>ERROR</strong>: You do not have permission to reply.', 'bbpress' ) );
		}

		// Reply author is current user
		$reply_author = bbp_get_current_user_id();
	}

	/** Topic ID **************************************************************/

	// Topic id was not passed
	if ( empty( $_POST['bbp_topic_id'] ) ) {
		bbp_add_error( 'bbp_reply_topic_id', __( '<strong>ERROR</strong>: Topic ID is missing.', 'bbpress' ) );

	// Topic id is not a number
	} elseif ( ! is_numeric( $_POST['bbp_topic_id'] ) ) {
		bbp_add_error( 'bbp_reply_topic_id', __( '<strong>ERROR</strong>: Topic ID must be a number.', 'bbpress' ) );

	// Topic id might be valid
	} else {

		// Get the topic id
		$posted_topic_id = intval( $_POST['bbp_topic_id'] );

		// Topic id is a negative number
		if ( 0 > $posted_topic_id ) {
			bbp_add_error( 'bbp_reply_topic_id', __( '<strong>ERROR</strong>: Topic ID cannot be a negative number.', 'bbpress' ) );

		// Topic does not exist
		} elseif ( ! bbp_get_topic( $posted_topic_id ) ) {
			bbp_add_error( 'bbp_reply_topic_id', __( '<strong>ERROR</strong>: Topic does not exist.', 'bbpress' ) );

		// Use the POST'ed topic id
		} else {
			$topic_id = $posted_topic_id;
		}
	}

	/** Forum ID **************************************************************/

	// Try to use the forum id of the topic
	if ( ! isset( $_POST['bbp_forum_id'] ) && ! empty( $topic_id ) ) {
		$forum_id = bbp_get_topic_forum_id( $topic_id );

	// Error check the POST'ed forum id
	} elseif ( isset( $_POST['bbp_forum_id'] ) ) {

		// Empty Forum id was passed
		if ( empty( $_POST['bbp_forum_id'] ) ) {
			bbp_add_error( 'bbp_reply_forum_id', __( '<strong>ERROR</strong>: Forum ID is missing.', 'bbpress' ) );

		// Forum id is not a number
		} elseif ( ! is_numeric( $_POST['bbp_forum_id'] ) ) {
			bbp_add_error( 'bbp_reply_forum_id', __( '<strong>ERROR</strong>: Forum ID must be a number.', 'bbpress' ) );

		// Forum id might be valid
		} else {

			// Get the forum id
			$posted_forum_id = intval( $_POST['bbp_forum_id'] );

			// Forum id is empty
			if ( 0 === $posted_forum_id ) {
				bbp_add_error( 'bbp_topic_forum_id', __( '<strong>ERROR</strong>: Forum ID is missing.', 'bbpress' ) );

			// Forum id is a negative number
			} elseif ( 0 > $posted_forum_id ) {
				bbp_add_error( 'bbp_topic_forum_id', __( '<strong>ERROR</strong>: Forum ID cannot be a negative number.', 'bbpress' ) );

			// Forum does not exist
			} elseif ( ! bbp_get_forum( $posted_forum_id ) ) {
				bbp_add_error( 'bbp_topic_forum_id', __( '<strong>ERROR</strong>: Forum does not exist.', 'bbpress' ) );

			// Use the POST'ed forum id
			} else {
				$forum_id = $posted_forum_id;
			}
		}
	}

	// Forum exists
	if ( ! empty( $forum_id ) ) {

		// Forum is a category
		if ( bbp_is_forum_category( $forum_id ) ) {
			bbp_add_error( 'bbp_new_reply_forum_category', __( '<strong>ERROR</strong>: This forum is a category. No replies can be created in this forum.', 'bbpress' ) );

		// Forum is not a category
		} else {

			// Forum is closed and user cannot access
			if ( bbp_is_forum_closed( $forum_id ) && ! current_user_can( 'edit_forum', $forum_id ) ) {
				bbp_add_error( 'bbp_new_reply_forum_closed', __( '<strong>ERROR</strong>: This forum has been closed to new replies.', 'bbpress' ) );
			}

			// Forum is private and user cannot access
			if ( bbp_is_forum_private( $forum_id ) && ! current_user_can( 'read_forum', $forum_id ) ) {
				bbp_add_error( 'bbp_new_reply_forum_private', __( '<strong>ERROR</strong>: This forum is private and you do not have the capability to read or create new replies in it.', 'bbpress' ) );

			// Forum is hidden and user cannot access
			} elseif ( bbp_is_forum_hidden( $forum_id ) && ! current_user_can( 'read_forum', $forum_id ) ) {
				bbp_add_error( 'bbp_new_reply_forum_hidden', __( '<strong>ERROR</strong>: This forum is hidden and you do not have the capability to read or create new replies in it.', 'bbpress' ) );
			}
		}
	}

	/** Unfiltered HTML *******************************************************/

	// Remove kses filters from title and content for capable users and if the nonce is verified
	if ( current_user_can( 'unfiltered_html' ) && ! empty( $_POST['_bbp_unfiltered_html_reply'] ) && wp_create_nonce( 'bbp-unfiltered-html-reply_' . $topic_id ) === $_POST['_bbp_unfiltered_html_reply'] ) {
		remove_filter( 'bbp_new_reply_pre_title',   'wp_filter_kses'      );
		remove_filter( 'bbp_new_reply_pre_content', 'bbp_encode_bad',  10 );
		remove_filter( 'bbp_new_reply_pre_content', 'bbp_filter_kses', 30 );
	}

	/** Reply Title ***********************************************************/

	if ( ! empty( $_POST['bbp_reply_title'] ) ) {
		$reply_title = sanitize_text_field( $_POST['bbp_reply_title'] );
	}

	// Filter and sanitize
	$reply_title = apply_filters( 'bbp_new_reply_pre_title', $reply_title );

	// Title too long
	if ( bbp_is_title_too_long( $reply_title ) ) {
		bbp_add_error( 'bbp_reply_title', __( '<strong>ERROR</strong>: Your title is too long.', 'bbpress' ) );
	}

	/** Reply Content *********************************************************/

	if ( ! empty( $_POST['bbp_reply_content'] ) ) {
		$reply_content = $_POST['bbp_reply_content'];
	}

	// Filter and sanitize
	$reply_content = apply_filters( 'bbp_new_reply_pre_content', $reply_content );

	// No reply content
	if ( empty( $reply_content ) ) {
		bbp_add_error( 'bbp_reply_content', __( '<strong>ERROR</strong>: Your reply cannot be empty.', 'bbpress' ) );
	}

	/** Reply Flooding ********************************************************/

	if ( ! bbp_check_for_flood( $anonymous_data, $reply_author ) ) {
		bbp_add_error( 'bbp_reply_flood', __( '<strong>ERROR</strong>: Slow down; you move too fast.', 'bbpress' ) );
	}

	/** Reply Duplicate *******************************************************/

	if ( ! bbp_check_for_duplicate( array( 'post_type' => bbp_get_reply_post_type(), 'post_author' => $reply_author, 'post_content' => $reply_content, 'post_parent' => $topic_id, 'anonymous_data' => $anonymous_data ) ) ) {
		bbp_add_error( 'bbp_reply_duplicate', __( '<strong>ERROR</strong>: Duplicate reply detected; it looks as though you&#8217;ve already said that.', 'bbpress' ) );
	}

	/** Reply Bad Words *******************************************************/

	if ( ! bbp_check_for_moderation( $anonymous_data, $reply_author, $reply_title, $reply_content, true ) ) {
		bbp_add_error( 'bbp_reply_moderation', __( '<strong>ERROR</strong>: Your reply cannot be created at this time.', 'bbpress' ) );
	}

	/** Reply Status **********************************************************/

	// Maybe put into moderation
	if ( bbp_is_topic_pending( $topic_id ) || ! bbp_check_for_moderation( $anonymous_data, $reply_author, $reply_title, $reply_content ) ) {
		$reply_status = bbp_get_pending_status_id();

	// Default
	} else {
		$reply_status = bbp_get_public_status_id();
	}

	/** Reply To **************************************************************/

	// Handle Reply To of the reply; $_REQUEST for non-JS submissions
	if ( isset( $_REQUEST['bbp_reply_to'] ) ) {
		$reply_to = bbp_validate_reply_to( $_REQUEST['bbp_reply_to'] );
	}

	/** Topic Closed **********************************************************/

	// If topic is closed, moderators can still reply
	if ( bbp_is_topic_closed( $topic_id ) && ! current_user_can( 'moderate', $topic_id ) ) {
		bbp_add_error( 'bbp_reply_topic_closed', __( '<strong>ERROR</strong>: Topic is closed.', 'bbpress' ) );
	}

	/** Topic Tags ************************************************************/

	// Either replace terms
	if ( bbp_allow_topic_tags() && current_user_can( 'assign_topic_tags', $topic_id ) && ! empty( $_POST['bbp_topic_tags'] ) ) {
		$terms = sanitize_text_field( $_POST['bbp_topic_tags'] );

	// ...or remove them.
	} elseif ( isset( $_POST['bbp_topic_tags'] ) ) {
		$terms = '';

	// Existing terms
	} else {
		$terms = bbp_get_topic_tag_names( $topic_id );
	}

	/** Additional Actions (Before Save) **************************************/

	do_action( 'bbp_new_reply_pre_extras', $topic_id, $forum_id );

	// Bail if errors
	if ( bbp_has_errors() ) {
		return;
	}

	/** No Errors *************************************************************/

	// Add the content of the form to $reply_data as an array
	// Just in time manipulation of reply data before being created
	$reply_data = apply_filters( 'bbp_new_reply_pre_insert', array(
		'post_author'    => $reply_author,
		'post_title'     => $reply_title,
		'post_content'   => $reply_content,
		'post_status'    => $reply_status,
		'post_parent'    => $topic_id,
		'post_type'      => bbp_get_reply_post_type(),
		'comment_status' => 'closed',
		'menu_order'     => bbp_get_topic_reply_count( $topic_id, true ) + 1
	) );

	// Insert reply
	$reply_id = wp_insert_post( $reply_data, true );

	/** No Errors *************************************************************/

	// Check for missing reply_id or error
	if ( ! empty( $reply_id ) && ! is_wp_error( $reply_id ) ) {

		/** Topic Tags ********************************************************/

		// Just in time manipulation of reply terms before being edited
		$terms = apply_filters( 'bbp_new_reply_pre_set_terms', $terms, $topic_id, $reply_id );

		// Insert terms
		$terms = wp_set_post_terms( $topic_id, $terms, bbp_get_topic_tag_tax_id(), false );

		// Term error
		if ( is_wp_error( $terms ) ) {
			bbp_add_error( 'bbp_reply_tags', __( '<strong>ERROR</strong>: There was a problem adding the tags to the topic.', 'bbpress' ) );
		}

		/** Trash Check *******************************************************/

		// If this reply starts as trash, add it to pre_trashed_replies
		// for the topic, so it is properly restored.
		if ( bbp_is_topic_trash( $topic_id ) || ( $reply_data['post_status'] === bbp_get_trash_status_id() ) ) {

			// Trash the reply
			wp_trash_post( $reply_id );

			// Only add to pre-trashed array if topic is trashed
			if ( bbp_is_topic_trash( $topic_id ) ) {

				// Get pre_trashed_replies for topic
				$pre_trashed_replies = (array) get_post_meta( $topic_id, '_bbp_pre_trashed_replies', true );

				// Add this reply to the end of the existing replies
				$pre_trashed_replies[] = $reply_id;

				// Update the pre_trashed_reply post meta
				update_post_meta( $topic_id, '_bbp_pre_trashed_replies', $pre_trashed_replies );
			}

		/** Spam Check ********************************************************/

		// If reply or topic are spam, officially spam this reply
		} elseif ( bbp_is_topic_spam( $topic_id ) || ( $reply_data['post_status'] === bbp_get_spam_status_id() ) ) {
			add_post_meta( $reply_id, '_bbp_spam_meta_status', bbp_get_public_status_id() );

			// Only add to pre-spammed array if topic is spam
			if ( bbp_is_topic_spam( $topic_id ) ) {

				// Get pre_spammed_replies for topic
				$pre_spammed_replies = (array) get_post_meta( $topic_id, '_bbp_pre_spammed_replies', true );

				// Add this reply to the end of the existing replies
				$pre_spammed_replies[] = $reply_id;

				// Update the pre_spammed_replies post meta
				update_post_meta( $topic_id, '_bbp_pre_spammed_replies', $pre_spammed_replies );
			}
		}

		/** Update counts, etc... *********************************************/

		do_action( 'bbp_new_reply', $reply_id, $topic_id, $forum_id, $anonymous_data, $reply_author, false, $reply_to );

		/** Additional Actions (After Save) ***********************************/

		do_action( 'bbp_new_reply_post_extras', $reply_id );

		/** Redirect **********************************************************/

		// Redirect to
		$redirect_to = bbp_get_redirect_to();

		// Get the reply URL
		$reply_url = bbp_get_reply_url( $reply_id, $redirect_to );

		// Allow to be filtered
		$reply_url = apply_filters( 'bbp_new_reply_redirect_to', $reply_url, $redirect_to, $reply_id );

		/** Successful Save ***************************************************/

		// Redirect back to new reply
		bbp_redirect( $reply_url );

	/** Errors ****************************************************************/

	// WP_Error
	} elseif ( is_wp_error( $reply_id ) ) {
		bbp_add_error( 'bbp_reply_error', sprintf( __( '<strong>ERROR</strong>: The following problem(s) occurred: %s', 'bbpress' ), $reply_id->get_error_message() ) );

	// Generic error
	} else {
		bbp_add_error( 'bbp_reply_error', __( '<strong>ERROR</strong>: The reply was not created.', 'bbpress' ) );
	}
}