leaderboard api polling

webapp/src/App.js

@@ -8,10 +8,15 @@ import Game from "./components/Game"
 import About from "./components/About"
 
 import Polling from './reducer/polling';
+import { LeaderboardApi } from './api/leaderboard';
+// import { UserApi } from './api/user';
 
 function App() {
   const [polling, dispatchPolling] = useReducer(Polling.reducer, Polling.initialState)
  
+  const leaderboard = LeaderboardApi(polling, dispatchPolling).get();
+  // const user = UserApi(polling, dispatchPolling).get();
+
   return <div className="App">
     <BrowserRouter>
       <Header polling={polling} dispatchPolling={dispatchPolling} />
@@ -22,7 +27,7 @@ function App() {
         <Route path="/game/proposal" element={<Game />} />
         <Route path="/game/active" element={<Game />} />
         <Route path="/game/archive" element={<Game />} />
-        <Route path="/leaderboard" element={<Leaderboard />} />
+        <Route path="/leaderboard" element={<Leaderboard leaderboard={leaderboard} />} />
         <Route path="/about" element={<About />} />
       </Routes>
     </BrowserRouter>

webapp/src/api/leaderboard.js

@@ -0,0 +1,24 @@
+import usePolling from "../util/Polling"
+
+const uri = '/api/leaderboard';
+
+export function LeaderboardApi(polling, dispatchPolling) {
+
+    const useGet = () => {
+        const mode = (polling.enabled === true)
+            ? { interval_sec: 300 }     // update leaderbord stats every 5 min
+            : { interval_stop: true }   // user has fliped OfflineToggel
+
+        const [leaderboard, isFetching] = usePolling(uri, mode);
+
+        if (polling.leaderboard !== isFetching) {
+            dispatchPolling({ type: 'setLeaderboard', value: isFetching });
+        }
+
+        return leaderboard;
+    }
+
+    return {
+        get: useGet
+    }
+}

webapp/src/components/Leaderboard/index.jsx

@@ -1,11 +1,9 @@
 import React from "react"
 import './index.css';
-import { AppData } from "../../context/data"
 
-export default function Leaderboard() {
-  const [data] = React.useContext(AppData)
+export default function Leaderboard({ leaderboard }) {
 
-  if (data.leaderboard == null) 
+  if (leaderboard == null)
     return <p>Loading...</p>
 
   //  var listItems = Object.keys(data).map(playerName => {
@@ -17,10 +15,11 @@ export default function Leaderboard() {
   //  });
   //  return <ul>{listItems}</ul>;
 
-  const tableRows = Object.keys(data.leaderboard).map(playerName => {
-    var rank = data.leaderboard[playerName];
+  const tableRows = Object.keys(leaderboard).map(playerName => {
+    var rank = leaderboard[playerName];
 
-    return <tr key={playerName} className={data.isCurrentUser(playerName) && 'username'}>
+    // TODO tr:  className={data.isCurrentUser(playerName) && 'username'}
+    return <tr key={playerName} >
       <td>{playerName}</td>
       <td>{rank.gamesPlayed}</td>
       <td>{rank.gamesWon}</td>

webapp/src/reducer/polling.js

@@ -1,4 +1,4 @@
-import { useLocalStorage } from './util/PersistentStorage'
+import { useLocalStorage } from '../util/PersistentStorage'
 
 const Persistent = (() => {
   const [getEnabled, setEnabled] = useLocalStorage('polling.enabled', true);
@@ -26,18 +26,18 @@ export function pollingReducer(state, action) {
       enabled: Persistent.setEnabled(!state.enabled)
     };
 
-    case 'games': return {
+    case 'setGames': return {
       ...state,
       games: action.value
     };
 
-    case 'leaderboard': return {
+    case 'setLeaderboard': return {
       ...state,
       leaderboard: action.value
     };
 
     default:
-      throw Error('Unknown action:' + action.type);
+      throw Error('Unknown action.type:' + action.type);
   }
 }
 

webapp/src/util/Polling.js

@@ -0,0 +1,53 @@
+import { useState, useCallback, useEffect, } from "react"
+
+/*
+  - uri: string
+  - mode:
+    - null  - default, return cashed value while polling fresh one from server)
+    - interval_sec
+    - interval_stop
+*/
+
+export default function usePolling(url, mode) {
+    const [cache, setCache] = useState(null);
+    const [isFetching, setFetching] = useState(false);
+    const [delayID, setDelayID] = useState(null);
+
+    const fetchData = useCallback(() => {
+        setDelayID(null);
+        setFetching(true);
+
+        fetch(url)
+            .then((response) => response.json())
+            .then((freshData) => {
+                setCache(freshData);
+                setFetching(false);
+            })
+            .catch((err) => {
+                console.warn(err.message);
+                setFetching(false);
+            })
+    }, [url])
+
+    useEffect(() => {
+        if (cache === null && isFetching === false) {
+            fetchData();
+        }
+
+        if (mode?.interval_sec && delayID === null) {
+            const timeoutID = setTimeout(fetchData, mode.interval_sec * 1000)
+            setDelayID(timeoutID)
+            console.log("Fetch '" + url + "' scheduled in " + mode.interval_sec + " sec")
+        }
+        else if (mode?.interval_stop) {
+            clearTimeout(delayID);  // cancel already scheduled fetch
+            setDelayID(null);       
+        }
+
+    }, [url, mode, isFetching, cache, fetchData, delayID]);
+
+    return [
+        cache, // API response
+        isFetching  // true / false
+    ]
+}