wp_ajax_save_attachment() WordPress Function

function wp_ajax_save_attachment() {
	if ( ! isset( $_REQUEST['id'] ) || ! isset( $_REQUEST['changes'] ) ) {
		wp_send_json_error();
	}

	$id = absint( $_REQUEST['id'] );
	if ( ! $id ) {
		wp_send_json_error();
	}

	check_ajax_referer( 'update-post_' . $id, 'nonce' );

	if ( ! current_user_can( 'edit_post', $id ) ) {
		wp_send_json_error();
	}

	$changes = $_REQUEST['changes'];
	$post    = get_post( $id, ARRAY_A );

	if ( 'attachment' !== $post['post_type'] ) {
		wp_send_json_error();
	}

	if ( isset( $changes['parent'] ) ) {
		$post['post_parent'] = $changes['parent'];
	}

	if ( isset( $changes['title'] ) ) {
		$post['post_title'] = $changes['title'];
	}

	if ( isset( $changes['caption'] ) ) {
		$post['post_excerpt'] = $changes['caption'];
	}

	if ( isset( $changes['description'] ) ) {
		$post['post_content'] = $changes['description'];
	}

	if ( MEDIA_TRASH && isset( $changes['status'] ) ) {
		$post['post_status'] = $changes['status'];
	}

	if ( isset( $changes['alt'] ) ) {
		$alt = wp_unslash( $changes['alt'] );
		if ( get_post_meta( $id, '_wp_attachment_image_alt', true ) !== $alt ) {
			$alt = wp_strip_all_tags( $alt, true );
			update_post_meta( $id, '_wp_attachment_image_alt', wp_slash( $alt ) );
		}
	}

	if ( wp_attachment_is( 'audio', $post['ID'] ) ) {
		$changed = false;
		$id3data = wp_get_attachment_metadata( $post['ID'] );

		if ( ! is_array( $id3data ) ) {
			$changed = true;
			$id3data = array();
		}

		foreach ( wp_get_attachment_id3_keys( (object) $post, 'edit' ) as $key => $label ) {
			if ( isset( $changes[ $key ] ) ) {
				$changed         = true;
				$id3data[ $key ] = sanitize_text_field( wp_unslash( $changes[ $key ] ) );
			}
		}

		if ( $changed ) {
			wp_update_attachment_metadata( $id, $id3data );
		}
	}

	if ( MEDIA_TRASH && isset( $changes['status'] ) && 'trash' === $changes['status'] ) {
		wp_delete_post( $id );
	} else {
		wp_update_post( $post );
	}

	wp_send_json_success();
}