chore: reorganized GameRepository for better code presentation

frontend/src/services/GameRepository.tsx

@@ -31,37 +31,24 @@ interface GameEventHandler {
 }
 
 export class GameRepository {
- SOCKET_URL = (process.env.NODE_ENV == 'production') ?
- ( window.location.protocol == 'https:' ? 'wss://' : 'ws://' )
- + window.location.host + '/ws-message' : 'ws://localhost:8080/ws-message';
-
  client?: Client;
  currentGameState: Game | undefined
  lastReceivedSeqNo: number = -1
 
  public subscribeToGame(gameId: string, gameEventHandler: GameEventHandler) {
  if (this.client == null) {
- this.findGame(gameId, () => {
- this.client = new Client({
- brokerURL: this.SOCKET_URL,
- onConnect: () => {
- this.client!.subscribe('/game/' + gameId, message => {
- const wrapper: GameEventWrapper = JSON.parse(message.body);
- console.log(wrapper)
- this.handleEvent(wrapper, gameEventHandler)
- })
- },
- onWebSocketError: (e: Event) => {
- console.log(e)
- }
- });
- this.client.activate();
- })
+ // find
+ this.findGame(gameId, () => this.client = this.createStompClient(gameId, gameEventHandler))
  } else {
  console.log("Client already active - should not happen")
  }
  }
 
+ // STOMP connect URL
+ SOCKET_URL = (process.env.NODE_ENV == 'production') ?
+ (window.location.protocol == 'https:' ? 'wss://' : 'ws://')
+ + window.location.host + '/ws-message' : 'ws://localhost:8080/ws-message';
+
  public unsubscribeFromGame() {
  if (this.client != null) {
  this.client.deactivate()
@@ -73,16 +60,6 @@ export class GameRepository {
  }
  }
 
- private handleEvent(wrappedEvent: GameEventWrapper, gameEventHandler: GameEventHandler) {
- if (wrappedEvent.sequenceNumber <= this.lastReceivedSeqNo) {
- console.log("Ignoring event with SeqNo ", wrappedEvent.sequenceNumber)
- return
- }
- this.lastReceivedSeqNo = wrappedEvent.sequenceNumber
- this.currentGameState = this.currentGameState!.onGameEvent(wrappedEvent.payload, wrappedEvent.eventType)
- gameEventHandler.onGameEvent(wrappedEvent.payload, wrappedEvent.eventType, this.currentGameState)
- }
-
  public findGame(gameId: string, successHandler: (game: Game) => void, errorHandler: () => void = () => {
  }) {
  fetch('/api/game/' + gameId + '/events', {
@@ -97,10 +74,7 @@ export class GameRepository {
  console.log("game does no exist");
  errorHandler()
  } else {
- let game = new Game(events[0].payload as GameCreatedEvent)
- for (let i = 1; i < events.length; i++) {
- game = game.onGameEvent(events[i].payload, events[i].eventType)
- }
+ const game = this.initializeGameModel(events);
  this.currentGameState = game
 
  successHandler(game)
@@ -111,6 +85,58 @@ export class GameRepository {
  errorHandler()
  });
  }
+
+ /**
+ * Creates a STOMP-JS client and subscribes to messages on specified game channel
+
+ * @param gameId the game to subscribe
+ * @param gameEventHandler the event handler to forward the event and current state to
+ * @return the activated client
+ */
+ private createStompClient(gameId: string, gameEventHandler: GameEventHandler): Client {
+ const client = new Client({
+ brokerURL: this.SOCKET_URL,
+ onConnect: () => {
+ this.client!.subscribe('/game/' + gameId, message => {
+ const wrapper: GameEventWrapper = JSON.parse(message.body);
+ this.handleEvent(wrapper, gameEventHandler)
+ })
+ },
+ onWebSocketError: (e: Event) => {
+ console.log(e)
+ }
+ });
+ client.activate();
+
+ return client;
+ }
+
+ /**
+ * Uses the given wrapped event to evolve the current read model state to the next one.
+ * @param wrappedEvent the wrapped GameEvent
+ * @param gameEventHandler the eventHandler to forward the result to
+ */
+ private handleEvent(wrappedEvent: GameEventWrapper, gameEventHandler: GameEventHandler) {
+ if (wrappedEvent.sequenceNumber <= this.lastReceivedSeqNo) {
+ console.log("Ignoring duplicate event with SeqNo ", wrappedEvent.sequenceNumber)
+ } else {
+ this.lastReceivedSeqNo = wrappedEvent.sequenceNumber
+ // evolve read model to next state
+ this.currentGameState = this.currentGameState!.onGameEvent(wrappedEvent.payload, wrappedEvent.eventType)
+ // forward event and new read model state to the eventHandler
+ gameEventHandler.onGameEvent(wrappedEvent.payload, wrappedEvent.eventType, this.currentGameState)
+ }
+ }
+
+ private initializeGameModel(events: GameEventWrapper[]) {
+ // use first event to initialize read model
+ let game = new Game(events[0].payload as GameCreatedEvent)
+ // iterate over all following events to evolve the current read model state
+ for (let i = 1; i < events.length; i++) {
+ game = game.onGameEvent(events[i].payload, events[i].eventType)
+ }
+ return game;
+ }
 }
 
 export const gameRepository = new GameRepository()