fix(events): Prevent infinite loops when using events on hooks

src/core/flow.test.ts

@@ -1022,6 +1022,21 @@ describe('infinite loops', () => {
     client.moves.endTurn();
     expect(client.getState().ctx.currentPlayer).toBe('1');
   });
+
+  test('loop 5', () => {
+    const onBegin = (G, ctx) => ctx.events.endPhase();
+    const game = {
+      phases: {
+        A: { onBegin, next: 'B', start: true },
+        B: { onBegin, next: 'C' },
+        C: { onBegin, next: 'A' },
+      },
+    };
+
+    const client = Client({ game, numPlayers: 3 });
+
+    expect(client.getState().ctx.phase).toBe(null);
+  });
 });
 
 describe('activePlayers', () => {

src/plugins/events/events.ts

@@ -40,13 +40,15 @@ export class Events {
     phase: string;
     turn: number;
   }>;
+  initialTurn: number;
   currentPhase: string;
   currentTurn: number;
 
   constructor(flow: Game['flow'], ctx: Ctx, playerID?: PlayerID) {
     this.flow = flow;
     this.playerID = playerID;
     this.dispatch = [];
+    this.initialTurn = ctx.turn;
     this.storeMetadata(ctx);
   }
 
@@ -83,6 +85,17 @@ export class Events {
    */
   update(state: State) {
     for (let i = 0; i < this.dispatch.length; i++) {
+      const endedTurns = this.currentTurn - this.initialTurn;
+      // This is an arbitrarily large number.
+      const threshold = state.ctx.numPlayers * 10;
+
+      // This protects against potential infinite loops if specific events are called on hooks.
+      // The moment we exceed the defined threshold, we just bail out of all phases.
+      if (endedTurns > threshold) {
+        state = { ...state, ctx: { ...state.ctx, phase: null } };
+        break;
+      }
+
       const item = this.dispatch[i];
 
       // If the turn already ended,