1 files changed, 150 insertions, 0 deletions
diff --git a/web/source/settings/lib/query/query-modifiers.ts b/web/source/settings/lib/query/query-modifiers.ts
new file mode 100644
index 000000000..d6bf0b6ae
--- /dev/null
+++ b/web/source/settings/lib/query/query-modifiers.ts
@@ -0,0 +1,150 @@
+/*
+	GoToSocial
+	Copyright (C) GoToSocial Authors admin@gotosocial.org
+	SPDX-License-Identifier: AGPL-3.0-or-later
+
+	This program is free software: you can redistribute it and/or modify
+	it under the terms of the GNU Affero General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU Affero General Public License for more details.
+
+	You should have received a copy of the GNU Affero General Public License
+	along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+import { gtsApi } from "./gts-api";
+
+import type { 
+	Action,
+	CacheMutation,
+} from "../types/query";
+
+import { NoArg } from "../types/query";
+
+/**
+ * Cache mutation creator for pessimistic updates.
+ * 
+ * Feed it a function that you want to perform on the
+ * given draft and updated data, using the given parameters.
+ * 
+ * https://redux-toolkit.js.org/rtk-query/api/createApi#onquerystarted
+ * https://redux-toolkit.js.org/rtk-query/usage/manual-cache-updates#pessimistic-updates
+ */
+function makeCacheMutation(action: Action): CacheMutation {
+	return function cacheMutation(
+		queryName: string | ((_arg: any) => string),
+		{ key } = {},
+	) {
+		return {
+			onQueryStarted: async(mutationData, { dispatch, queryFulfilled }) => {
+				// queryName might be a function that returns
+				// a query name; trigger it if so. The returned
+				// queryName has to match one of the API endpoints
+				// we've defined. So if we have endpoints called
+				// (for example) `instanceV1` and `getPosts` then
+				// the queryName provided here has to line up with
+				// one of those in order to actually do anything.
+				if (typeof queryName !== "string") {
+					queryName = queryName(mutationData);
+				}
+				
+				if (queryName == "") {
+					throw (
+						"provided queryName resolved to an empty string;" +
+						"double check your mutation definition!"
+					);
+				}
+
+				try {
+					// Wait for the mutation to finish (this
+					// is why it's a pessimistic update).
+					const { data: newData } = await queryFulfilled;	
+					
+					// In order for `gtsApi.util.updateQueryData` to
+					// actually do something within a dispatch, the
+					// first two arguments passed into it have to line
+					// up with arguments that were used earlier to
+					// fetch the data whose cached version we're now
+					// trying to modify.
+					// 
+					// So, if we earlier fetched all reports with
+					// queryName `getReports`, and arg `undefined`,
+					// then we now need match those parameters in
+					// `updateQueryData` in order to modify the cache.
+					//
+					// If you pass something like `null` or `""` here
+					// instead, then the cache will not get modified!
+					// Redux will just quietly discard the thunk action.
+					dispatch(
+						gtsApi.util.updateQueryData(queryName as any, NoArg, (draft) => {
+							if (key != undefined && typeof key !== "string") {
+								key = key(draft, newData);
+							}
+							action(draft, newData, { key });
+						})
+					);
+				} catch (e) {
+					// eslint-disable-next-line no-console
+					console.error(`rolling back pessimistic update of ${queryName}: ${e}`);
+				}
+			}
+		};
+	};
+}
+
+/**
+ * 
+ */
+const replaceCacheOnMutation: CacheMutation = makeCacheMutation((draft, newData, _params) => {	
+	Object.assign(draft, newData);
+});
+
+const appendCacheOnMutation: CacheMutation = makeCacheMutation((draft, newData, _params) => {
+	draft.push(newData);
+});
+
+const spliceCacheOnMutation: CacheMutation = makeCacheMutation((draft, _newData, { key }) => {
+	if (key === undefined) {
+		throw ("key undefined");
+	}
+	
+	draft.splice(key, 1);
+});
+
+const updateCacheOnMutation: CacheMutation = makeCacheMutation((draft, newData, { key }) => {
+	if (key === undefined) {
+		throw ("key undefined");
+	}
+
+	if (typeof key !== "string") {
+		key = key(draft, newData);
+	}
+	
+	draft[key] = newData;
+});
+
+const removeFromCacheOnMutation: CacheMutation = makeCacheMutation((draft, newData, { key }) => {
+	if (key === undefined) {
+		throw ("key undefined");
+	}
+
+	if (typeof key !== "string") {
+		key = key(draft, newData);
+	}
+	
+	delete draft[key];
+});
+
+
+export {
+	replaceCacheOnMutation,
+	appendCacheOnMutation,
+	spliceCacheOnMutation,
+	updateCacheOnMutation,
+	removeFromCacheOnMutation,
+};