Add basic version of Comments component

app/javascript/reducers/commentsReducer.ts

@@ -0,0 +1,70 @@
+import {
+  CommentsRequestActionTypes,
+  COMMENTS_REQUEST_START,
+  COMMENTS_REQUEST_SUCCESS,
+  COMMENTS_REQUEST_FAILURE,
+} from '../actions/requestComments';
+import { commentRequestSuccess } from '../actions/requestComment';
+
+import commentReducer from './commentReducer';
+
+import IComment from '../interfaces/IComment';
+
+export interface CommentsState {
+  items: Array<IComment>;
+  areLoading: boolean;
+  error: string;
+  page: number;
+  haveMore: boolean;
+}
+
+const initialState: CommentsState = {
+  items: [],
+  areLoading: false,
+  error: '',
+  page: 0,
+  haveMore: true,
+};
+
+const commentsReducer = (
+  state = initialState,
+  action,
+): CommentsState => {
+  switch (action.type) {
+    case COMMENTS_REQUEST_START:
+      return {
+        ...state,
+        areLoading: true,
+      };
+
+    case COMMENTS_REQUEST_SUCCESS:
+      return {
+        ...state,
+        items: action.page === 1 ?
+          action.comments.map(comment => commentReducer(undefined, commentRequestSuccess(comment)))
+          :
+          [
+            ...state.items,
+            ...action.comments.map(
+              comment => commentReducer(undefined, commentRequestSuccess(comment))
+            ),
+          ],
+        page: action.page,
+        haveMore: action.comments.length === 15,
+        areLoading: false,
+        error: '',
+      };
+
+    case COMMENTS_REQUEST_FAILURE:
+      return {
+        ...state,
+        areLoading: false,
+        error: action.error,
+      };
+
+    default:
+      return state;
+  }
+}
+
+export default commentsReducer;