Ajax handler for saving posts from the fullscreen editor.

function wp_ajax_wp_fullscreen_save_post() {
	$post_id = isset( $_POST['post_ID'] ) ? (int) $_POST['post_ID'] : 0;

	$post = null;

	if ( $post_id ) {
		$post = get_post( $post_id );
	}

	check_ajax_referer( 'update-post_' . $post_id, '_wpnonce' );

	$post_id = edit_post();

	if ( is_wp_error( $post_id ) ) {
		wp_send_json_error();
	}

	if ( $post ) {
		$last_date = mysql2date( __( 'F j, Y' ), $post->post_modified );
		$last_time = mysql2date( __( 'g:i a' ), $post->post_modified );
	} else {
		$last_date = date_i18n( __( 'F j, Y' ) );
		$last_time = date_i18n( __( 'g:i a' ) );
	}

	$last_id = get_post_meta( $post_id, '_edit_last', true );
	if ( $last_id ) {
		$last_user = get_userdata( $last_id );
		/* translators: 1: User's display name, 2: Date of last edit, 3: Time of last edit. */
		$last_edited = sprintf( __( 'Last edited by %1$s on %2$s at %3$s' ), esc_html( $last_user->display_name ), $last_date, $last_time );
	} else {
		/* translators: 1: Date of last edit, 2: Time of last edit. */
		$last_edited = sprintf( __( 'Last edited on %1$s at %2$s' ), $last_date, $last_time );
	}

	wp_send_json_success( array( 'last_edited' => $last_edited ) );
}