Rocket.Chat/packages/rocketchat-message-snippet/client/actionButton.js

Meteor.startup(function() {
	RocketChat.MessageAction.addButton({
		id: "snippeted-message",
		icon: "icon-code",
		i18nnLabel: 'Snippet',
		context: [
			'snippeted',
			'message',
			'message-mobile'
		],
		action: function(event, instance) {
			let message = this._arguments[1];

			swal({
				title: "Create a Snippet",
				text: "The name of your snippet (with file extension):",
				type: "input",
				showCancelButton: true,
				closeOnConfirm: false,
				animation: "slide-from-top",
				inputPlaceholder: "Snippet name"
			}, function (filename) {
				if (filename === false) return false;
				if (filename === "") {
					swal.showInputError("You need to write something!");
					return false
				}
				message.snippeted = true;
				Meteor.call('snippetMessage', message, filename, function(error, result) {
					if (error) {
						return handleError(error);
					}
					swal("Nice!", `Snippet '${filename}' created.`, "success");
				});
			});

		},
		validation: function(message) {
			let room = RocketChat.models.Rooms.findOne({_id: message.rid});

			if (Array.isArray(room.usernames) && (room.usernames.indexOf(Meteor.user().username) == -1)) {
				console.log("Nope Array");
				return false;
			} else {
				if (message.snippeted || ((typeof RocketChat.settings.get('Message_AllowSnippeting') == "undefined") ||
										(RocketChat.settings.get("Message_AllowSnippeting") == null))) {
					return false;
				} else {
					return RocketChat.authz.hasAtLeastOnePermission('snippet-message', message.rid);
				}
			}
		}
    });
});