Add a slice for tracking comments data

src/app/rootReducer.ts

@@ -3,11 +3,13 @@ import { combineReducers } from '@reduxjs/toolkit'
 import issuesDisplayReducer from 'features/issuesDisplay/issuesDisplaySlice'
 import repoDetailsReducer from 'features/repoSearch/repoDetailsSlice'
 import issuesReducer from 'features/issuesList/issuesSlice'
+import commentsReducer from 'features/issueDetails/commentsSlice'
 
 const rootReducer = combineReducers({
   issuesDisplay: issuesDisplayReducer,
   repoDetails: repoDetailsReducer,
-  issues: issuesReducer
+  issues: issuesReducer,
+  comments: commentsReducer
 })
 
 export type RootState = ReturnType<typeof rootReducer>

src/features/issueDetails/commentsSlice.ts

@@ -0,0 +1,59 @@
+import { createSlice, PayloadAction } from '@reduxjs/toolkit'
+
+import { Comment, getComments, Issue } from 'api/githubAPI'
+import { AppThunk } from 'app/store'
+
+interface CommentsState {
+  commentsByIssue: Record<number, Comment[] | undefined>
+  loading: boolean
+  error: string | null
+}
+
+interface CommentLoaded {
+  issueId: number
+  comments: Comment[]
+}
+
+const initialState: CommentsState = {
+  commentsByIssue: {},
+  loading: false,
+  error: null
+}
+
+const comments = createSlice({
+  name: 'comments',
+  initialState,
+  reducers: {
+    getCommentsStart(state) {
+      state.loading = true
+      state.error = null
+    },
+    getCommentsSuccess(state, action: PayloadAction<CommentLoaded>) {
+      const { comments, issueId } = action.payload
+      state.commentsByIssue[issueId] = comments
+      state.loading = false
+      state.error = null
+    },
+    getCommentsFailure(state, action: PayloadAction<string>) {
+      state.loading = false
+      state.error = action.payload
+    }
+  }
+})
+
+export const {
+  getCommentsStart,
+  getCommentsSuccess,
+  getCommentsFailure
+} = comments.actions
+export default comments.reducer
+
+export const fetchComments = (issue: Issue): AppThunk => async dispatch => {
+  try {
+    dispatch(getCommentsStart())
+    const comments = await getComments(issue.comments_url)
+    dispatch(getCommentsSuccess({ issueId: issue.number, comments }))
+  } catch (err) {
+    dispatch(getCommentsFailure(err))
+  }
+}