Rocket.Chat/apps/meteor/client/lib/utils/modifyMessageOnFilesDelete.ts

import { isFileAttachment } from '@rocket.chat/core-typings';
import type { IMessage, MessageAttachment } from '@rocket.chat/core-typings';

/**
 * Clone a message and clear or replace its file attachments.
 *
 * - Performs a deep clone via `structuredClone` to avoid mutating the source.
 * - Removes the single-file `file` field and empties the `files` array.
 * - If `replaceFileAttachmentsWith` is given, swaps out any file-type
 *   attachments; otherwise filters them out entirely.
 *
 * @param message  The original `IMessage` to copy.
 * @param replaceFileAttachmentsWith
 *   Optional attachment to substitute for each file attachment.
 * @returns A new message object with `file`, `files`, and `attachments` updated.
 */

export const modifyMessageOnFilesDelete = <T extends IMessage = IMessage>(message: T, replaceFileAttachmentsWith?: MessageAttachment) => {
	const { attachments, file: _, ...rest } = message;

	if (!attachments?.length) {
		return message;
	}

	if (replaceFileAttachmentsWith) {
		return { ...rest, files: [], attachments: attachments?.map((att) => (isFileAttachment(att) ? replaceFileAttachmentsWith : att)) };
	}

	return { ...rest, files: [], attachments: attachments?.filter((att) => !isFileAttachment(att)) };
};