Add endorsed accounts to profiles in web UI (#34568)

app/javascript/mastodon/reducers/accounts_map.ts

@@ -0,0 +1,38 @@
+import { createReducer } from '@reduxjs/toolkit';
+import type { UnknownAction } from '@reduxjs/toolkit';
+
+import type { AxiosError } from 'axios';
+
+import { ACCOUNT_LOOKUP_FAIL } from 'mastodon/actions/accounts';
+import { importAccounts } from 'mastodon/actions/importer/accounts';
+import { domain } from 'mastodon/initial_state';
+
+interface AccountLookupFailAction extends UnknownAction {
+  acct: string;
+  error?: AxiosError;
+}
+
+const pattern = new RegExp(`@${domain}$`, 'gi');
+
+export const normalizeForLookup = (str: string) =>
+  str.toLowerCase().replace(pattern, '');
+
+const initialState: Record<string, string | null> = {};
+
+export const accountsMapReducer = createReducer(initialState, (builder) => {
+  builder
+    .addCase(importAccounts, (state, action) => {
+      action.payload.accounts.forEach((account) => {
+        state[normalizeForLookup(account.acct)] = account.id;
+      });
+    })
+    .addMatcher(
+      (action: UnknownAction): action is AccountLookupFailAction =>
+        action.type === ACCOUNT_LOOKUP_FAIL,
+      (state, action) => {
+        if (action.error?.response?.status === 404) {
+          state[normalizeForLookup(action.acct)] = null;
+        }
+      },
+    );
+});