velopert · February 16, 2019 14:50 · Feb 16, 2019
diff --git a/header.ts b/header.ts
@@ -0,0 +1,34 @@
+import {
+  createAction,
+  createStandardAction,
+  ActionType,
+} from 'typesafe-actions';
+import { createReducer } from '../utils';
+
+const SET_KEYWORD = 'header/SET_KEYWORD';
+
+export const setKeyword = createStandardAction(SET_KEYWORD)<string>();
+
+type SetKeyword = ReturnType<typeof setKeyword>;
+
+export interface HeaderState {
+  keyword: string;
+}
+
+const initialState: HeaderState = {
+  keyword: '',
+};
+
+const reducer = createReducer<HeaderState>(
+  {
+    [SET_KEYWORD]: (state, { payload }: SetKeyword) => {
+      return {
+        ...state,
+        keyword: payload,
+      };
+    },
+  },
+  initialState,
+);
+
+export default reducer;
diff --git a/utils.ts b/utils.ts
@@ -0,0 +1,11 @@
+export type Handlers<T> = {
+  [type: string]: (state: T, action: any) => T;
+};
+
+export function createReducer<S>(handlers: Handlers<S>, initialState: S) {
+  return (state: S = initialState, action: AnyAction) => {
+    const handler = handlers[action.type];
+    if (handler) return handler(state, action);
+    return state;
+  };
+}