[Feature] Stop random trainers from spawning near fixed battles (#2610)

* Stop trainer spawns on evil team and E4 floors

* Thanks Xavion

* change "floors" to "wave" in coment

* at test for not spawning 3 waves within fixed trainer battle

* remove out-commented code

* apply code formatting

* Updated test and make sure isWaveTrainer returns a boolean

* Update comment

---------

Co-authored-by: Felix Staud <felix.staud@headwire.com>

src/field/arena.ts

@@ -384,6 +384,10 @@ export class Arena {
     return weatherMultiplier * terrainMultiplier;
   }
 
+  /**
+   * Gets the denominator for the chance for a trainer spawn
+   * @returns n where 1/n is the chance of a trainer battle
+   */
   getTrainerChance(): integer {
     switch (this.biomeType) {
     case Biome.METROPOLIS:

src/game-mode.ts

@@ -107,22 +107,37 @@ export class GameMode implements GameModeConfig {
     }
   }
 
+  /**
+   * Determines whether or not to generate a trainer
+   * @param waveIndex the current floor the player is on (trainer sprites fail to generate on X1 floors)
+   * @param arena the arena that contains the scene and functions
+   * @returns true if a trainer should be generated, false otherwise
+   */
   isWaveTrainer(waveIndex: integer, arena: Arena): boolean {
+    /**
+     * Daily spawns trainers on floors 5, 15, 20, 25, 30, 35, 40, and 45
+     */
     if (this.isDaily) {
       return waveIndex % 10 === 5 || (!(waveIndex % 10) && waveIndex > 10 && !this.isWaveFinal(waveIndex));
     }
     if ((waveIndex % 30) === (arena.scene.offsetGym ? 0 : 20) && !this.isWaveFinal(waveIndex)) {
       return true;
     } else if (waveIndex % 10 !== 1 && waveIndex % 10) {
+      /**
+       * Do not check X1 floors since there's a bug that stops trainer sprites from appearing
+       * after a X0 full party heal
+       */
+
       const trainerChance = arena.getTrainerChance();
       let allowTrainerBattle = true;
       if (trainerChance) {
         const waveBase = Math.floor(waveIndex / 10) * 10;
+        // Stop generic trainers from spawning in within 3 waves of a trainer battle
         for (let w = Math.max(waveIndex - 3, waveBase + 2); w <= Math.min(waveIndex + 3, waveBase + 9); w++) {
           if (w === waveIndex) {
             continue;
           }
-          if ((w % 30) === (arena.scene.offsetGym ? 0 : 20) || this.isFixedBattle(waveIndex)) {
+          if ((w % 30) === (arena.scene.offsetGym ? 0 : 20) || this.isFixedBattle(w)) {
             allowTrainerBattle = false;
             break;
           } else if (w < waveIndex) {
@@ -138,7 +153,7 @@ export class GameMode implements GameModeConfig {
           }
         }
       }
-      return allowTrainerBattle && trainerChance && !Utils.randSeedInt(trainerChance);
+      return Boolean(allowTrainerBattle && trainerChance && !Utils.randSeedInt(trainerChance));
     }
     return false;
   }

src/test/game-mode.test.ts

@@ -0,0 +1,52 @@
+import { GameMode, GameModes, getGameMode } from "#app/game-mode.js";
+import {
+  afterEach,
+  beforeAll,
+  beforeEach,
+  describe,
+  expect,
+  it,
+  vi,
+} from "vitest";
+import GameManager from "./utils/gameManager";
+import * as Utils from "../utils";
+describe("game-mode", () => {
+  let phaserGame: Phaser.Game;
+  let game: GameManager;
+  beforeAll(() => {
+    phaserGame = new Phaser.Game({
+      type: Phaser.HEADLESS,
+    });
+  });
+  afterEach(() => {
+    game.phaseInterceptor.restoreOg();
+    vi.resetAllMocks();
+  });
+  beforeEach(() => {
+    game = new GameManager(phaserGame);
+  });
+  describe("classic", () => {
+    let classicGameMode: GameMode;
+    beforeEach(() => {
+      classicGameMode = getGameMode(GameModes.CLASSIC);
+    });
+    it("does NOT spawn trainers within 3 waves of fixed battle", () => {
+      const { arena } = game.scene;
+      /** set wave 16 to be a fixed trainer fight meaning wave 13-19 don't allow trainer spawns */
+      vi.spyOn(classicGameMode, "isFixedBattle").mockImplementation(
+        (n: number) => (n === 16 ? true : false)
+      );
+      vi.spyOn(arena, "getTrainerChance").mockReturnValue(1);
+      vi.spyOn(Utils, "randSeedInt").mockReturnValue(0);
+      expect(classicGameMode.isWaveTrainer(11, arena)).toBeFalsy();
+      expect(classicGameMode.isWaveTrainer(12, arena)).toBeTruthy();
+      expect(classicGameMode.isWaveTrainer(13, arena)).toBeFalsy();
+      expect(classicGameMode.isWaveTrainer(14, arena)).toBeFalsy();
+      expect(classicGameMode.isWaveTrainer(15, arena)).toBeFalsy();
+      // Wave 16 is a fixed trainer battle
+      expect(classicGameMode.isWaveTrainer(17, arena)).toBeFalsy();
+      expect(classicGameMode.isWaveTrainer(18, arena)).toBeFalsy();
+      expect(classicGameMode.isWaveTrainer(19, arena)).toBeFalsy();
+    });
+  });
+});