boardgame-core/tests/core/game-host.test.ts

import { describe, it, expect } from "vitest";
import {
  registry,
  createInitialState,
  start,
  TicTacToeState,
} from "@/samples/tic-tac-toe";
import { createGameHost, GameHost } from "@/core/game-host";
import type { PromptEvent } from "@/utils/command";

function createTestHost() {
  const host = createGameHost({ registry, createInitialState, start });
  return { host };
}

function waitForPromptEvent(host: GameHost<any>): Promise<PromptEvent> {
  return new Promise((resolve) => {
    // @ts-ignore - accessing private _context for testing
    host._context._commands.on("prompt", resolve);
  });
}

describe("GameHost", () => {
  describe("creation", () => {
    it("should create host with initial state", () => {
      const { host } = createTestHost();

      expect(host.state.value.currentPlayer).toBe("X");
      expect(host.state.value.winner).toBeNull();
      expect(host.state.value.turn).toBe(0);
      expect(Object.keys(host.state.value.parts).length).toBe(0);
    });

    it('should have status "created" by default', () => {
      const { host } = createTestHost();

      expect(host.status.value).toBe("created");
    });

    it("should have null activePromptSchema initially", () => {
      const { host } = createTestHost();

      expect(host.activePromptSchema.value).toBeNull();
    });
  });

  describe("tryInput", () => {
    it('should return "No active prompt" when no prompt is active', () => {
      const { host } = createTestHost();

      const result = host.tryInput("play X 1 1");
      expect(result).toBe("No active prompt");
    });

    it("should accept valid input when prompt is active", async () => {
      const { host } = createTestHost();

      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      const promptEvent = await promptPromise;
      expect(promptEvent.schema.name).toBe("play");
      expect(host.activePromptSchema.value?.name).toBe("play");

      const error = host.tryInput("play X 1 1");
      expect(error).toBeNull();

      // Cancel to end the game since start runs until game over
      const nextPromptPromise = waitForPromptEvent(host);
      const nextPrompt = await nextPromptPromise;
      nextPrompt.cancel("test cleanup");

      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toBe("test cleanup");
      }
    });

    it("should reject invalid input", async () => {
      const { host } = createTestHost();

      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      const promptEvent = await promptPromise;

      const error = host.tryInput("invalid command");
      expect(error).not.toBeNull();

      promptEvent.cancel("test cleanup");
      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toBe("test cleanup");
      }
    });

    it("should return error when disposed", () => {
      const { host } = createTestHost();
      host.dispose();

      const result = host.tryInput("play X 1 1");
      expect(result).toBe("GameHost is disposed");
    });
  });

  describe("getActivePromptSchema", () => {
    it("should return schema when prompt is active", async () => {
      const { host } = createTestHost();

      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      const promptEvent = await promptPromise;
      const schema = host.activePromptSchema.value;

      expect(schema).not.toBeNull();
      expect(schema?.name).toBe("play");

      promptEvent.cancel("test cleanup");
      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toBe("test cleanup");
      }
    });

    it("should return null when no prompt is active", () => {
      const { host } = createTestHost();

      expect(host.activePromptSchema.value).toBeNull();
    });
  });

  describe("start", () => {
    it("should reset state and run start command", async () => {
      const { host } = createTestHost();

      // First setup - make one move
      let promptPromise = waitForPromptEvent(host);
      let runPromise = host.start();
      let promptEvent = await promptPromise;

      // Make a move
      promptEvent.tryCommit({
        name: "play",
        params: ["X", 1, 1],
        options: {},
        flags: {},
      });

      // Wait for next prompt (next turn) and cancel
      promptPromise = waitForPromptEvent(host);
      promptEvent = await promptPromise;
      promptEvent.cancel("test end");

      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toBe("test end");
      }
      expect(Object.keys(host.state.value.parts).length).toBe(1);

      // Setup listener before calling start
      const newPromptPromise = waitForPromptEvent(host);

      // Reset - should reset state and start new game
      const newRunPromise = host.start();

      // State should be back to initial
      expect(host.state.value.currentPlayer).toBe("X");
      expect(host.state.value.winner).toBeNull();
      expect(host.state.value.turn).toBe(0);
      expect(Object.keys(host.state.value.parts).length).toBe(0);

      // New game should be running and prompting
      const newPrompt = await newPromptPromise;
      expect(newPrompt.schema.name).toBe("play");
      newPrompt.cancel("test end");

      try {
        await newRunPromise;
      } catch {
        // Expected - cancelled
      }
    });

    it("should cancel active prompt during start", async () => {
      const { host } = createTestHost();

      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      await promptPromise;

      // Setup should cancel the active prompt and reset state
      host.start();

      // The original runPromise should be rejected due to cancellation
      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toContain("Cancelled");
      }

      // State should be reset
      expect(host.state.value.currentPlayer).toBe("X");
      expect(host.state.value.turn).toBe(0);
    });

    it("should throw error when disposed", () => {
      const { host } = createTestHost();
      host.dispose();

      expect(() => host.start()).toThrow("GameHost is disposed");
    });
  });

  describe("dispose", () => {
    it("should change status to disposed", () => {
      const { host } = createTestHost();
      host.dispose();

      expect(host.status.value).toBe("disposed");
    });

    it("should cancel active prompt on dispose", async () => {
      const { host } = createTestHost();

      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      await promptPromise;

      host.dispose();

      // The runPromise should be rejected due to cancellation
      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toContain("Cancelled");
      }
    });

    it("should be idempotent", () => {
      const { host } = createTestHost();
      host.dispose();
      host.dispose(); // Should not throw

      expect(host.status.value).toBe("disposed");
    });
  });

  describe("events", () => {
    it("should emit start event", async () => {
      const { host } = createTestHost();

      let setupCount = 0;
      host.on("start", () => {
        setupCount++;
      });

      // Setup listener before calling setup
      const promptPromise = waitForPromptEvent(host);

      // Initial setup via reset
      const runPromise = host.start();
      expect(setupCount).toBe(1);

      // State should be running
      expect(host.status.value).toBe("running");

      // Cancel the background setup command
      const prompt = await promptPromise;
      prompt.cancel("test end");

      try {
        await runPromise;
      } catch {
        // Expected - cancelled
      }
    });

    it("should emit dispose event", () => {
      const { host } = createTestHost();

      let disposeCount = 0;
      host.on("dispose", () => {
        disposeCount++;
      });

      host.dispose();
      expect(disposeCount).toBe(1);
    });

    it("should allow unsubscribing from events", () => {
      const { host } = createTestHost();

      let setupCount = 0;
      const unsubscribe = host.on("start", () => {
        setupCount++;
      });

      unsubscribe();

      // No event should be emitted
      // (we can't easily test this without triggering setup, but we verify unsubscribe works)
      expect(typeof unsubscribe).toBe("function");
    });
  });

  describe("reactive state", () => {
    it("should have state that reflects game progress", async () => {
      const { host } = createTestHost();

      // Initial state
      expect(host.state.value.currentPlayer).toBe("X");
      expect(host.state.value.turn).toBe(0);

      // Make a move
      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      const promptEvent = await promptPromise;
      promptEvent.tryCommit({
        name: "play",
        params: ["X", 1, 1],
        options: {},
        flags: {},
      });

      // Wait for next prompt and cancel
      const nextPromptPromise = waitForPromptEvent(host);
      const nextPrompt = await nextPromptPromise;
      nextPrompt.cancel("test end");

      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toBe("test end");
      }

      expect(host.state.value.currentPlayer).toBe("O");
      expect(host.state.value.turn).toBe(1);
      expect(Object.keys(host.state.value.parts).length).toBe(1);
    });

    it("should update activePromptSchema reactively", async () => {
      const { host } = createTestHost();

      // Initially null
      expect(host.activePromptSchema.value).toBeNull();

      // Start a command that triggers prompt
      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      await promptPromise;

      // Now schema should be set
      expect(host.activePromptSchema.value).not.toBeNull();
      expect(host.activePromptSchema.value?.name).toBe("play");

      // Cancel and wait
      // @ts-ignore - accessing private _context for testing
      host._context._commands._cancel();
      try {
        await runPromise;
      } catch {
        // Expected
      }

      // Schema should be null again
      expect(host.activePromptSchema.value).toBeNull();
    });
  });

  describe("full game", () => {
    it("should run a complete game of tic-tac-toe with X winning diagonally", async () => {
      const { host } = createTestHost();

      // Initial state
      expect(host.state.value.currentPlayer).toBe("X");
      expect(host.state.value.winner).toBeNull();
      expect(host.state.value.turn).toBe(0);
      expect(Object.keys(host.state.value.parts).length).toBe(0);

      // X wins diagonally: (0,0), (1,1), (2,2)
      // O plays: (0,1), (2,1)
      const moves = [
        "play X 0 0", // turn 1: X
        "play O 0 1", // turn 2: O
        "play X 1 1", // turn 3: X
        "play O 2 1", // turn 4: O
        "play X 2 2", // turn 5: X wins!
      ];

      // Track prompt events in a queue
      const promptEvents: PromptEvent[] = [];
      // @ts-ignore - accessing private _context for testing
      host._context._commands.on("prompt", (e) => {
        promptEvents.push(e);
      });

      // Start setup command (runs game loop until completion)
      const setupPromise = host.start();

      for (let i = 0; i < moves.length; i++) {
        // Wait until the next prompt event arrives
        while (i >= promptEvents.length) {
          await new Promise((r) => setTimeout(r, 10));
        }

        const promptEvent = promptEvents[i];
        expect(promptEvent.schema.name).toBe("play");

        // Submit the move
        const error = host.tryInput(moves[i]);
        expect(error).toBeNull();

        // Wait for the command to complete before submitting next move
        await new Promise((resolve) => setImmediate(resolve));
      }

      // Wait for setup to complete (game ended with winner)
      try {
        const finalState = await setupPromise;
        expect(finalState.winner).toBe("X");

        // Final state checks
        expect(host.state.value.winner).toBe("X");
        expect(host.state.value.currentPlayer).toBe("X");
        expect(Object.keys(host.state.value.parts).length).toBe(5);

        // Verify winning diagonal
        const parts = Object.values(host.state.value.parts);
        const xPieces = parts.filter((p: any) => p.player === "X");
        expect(xPieces).toHaveLength(3);
        expect(
          xPieces.some(
            (p: any) => JSON.stringify(p.position) === JSON.stringify([0, 0]),
          ),
        ).toBe(true);
        expect(
          xPieces.some(
            (p: any) => JSON.stringify(p.position) === JSON.stringify([1, 1]),
          ),
        ).toBe(true);
        expect(
          xPieces.some(
            (p: any) => JSON.stringify(p.position) === JSON.stringify([2, 2]),
          ),
        ).toBe(true);
      } catch (e) {
        // If setup fails due to cancellation, check state directly
        const error = e as Error;
        if (!error.message.includes("Cancelled")) {
          throw e;
        }
      }

      host.dispose();
      expect(host.status.value).toBe("disposed");
    });
  });

  describe("currentPlayer in prompt", () => {
    it("should have currentPlayer in PromptEvent", async () => {
      const { host } = createTestHost();

      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      const promptEvent = await promptPromise;
      expect(promptEvent.currentPlayer).toBe("X");
      expect(host.activePromptPlayer.value).toBe("X");

      promptEvent.cancel("test cleanup");
      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toBe("test cleanup");
      }
    });

    it("should update activePromptPlayer reactively", async () => {
      const { host } = createTestHost();

      // Initially null
      expect(host.activePromptPlayer.value).toBeNull();

      // First prompt - X's turn
      let promptPromise = waitForPromptEvent(host);
      let runPromise = host.start();
      let promptEvent = await promptPromise;
      expect(promptEvent.currentPlayer).toBe("X");
      expect(host.activePromptPlayer.value).toBe("X");

      // Make a move
      promptEvent.tryCommit({
        name: "play",
        params: ["X", 1, 1],
        options: {},
        flags: {},
      });

      // Second prompt - O's turn
      promptPromise = waitForPromptEvent(host);
      promptEvent = await promptPromise;
      expect(promptEvent.currentPlayer).toBe("O");
      expect(host.activePromptPlayer.value).toBe("O");

      // Cancel
      promptEvent.cancel("test cleanup");
      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toBe("test cleanup");
      }

      // After prompt ends, player should be null
      expect(host.activePromptPlayer.value).toBeNull();
    });
  });

  describe("tryAnswerPrompt", () => {
    it("should answer prompt with valid arguments", async () => {
      const { host } = createTestHost();

      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      const promptEvent = await promptPromise;
      expect(promptEvent.schema.name).toBe("play");

      // Use tryAnswerPrompt with the prompt def
      const { prompts } = await import("@/samples/tic-tac-toe");
      const error = host.tryAnswerPrompt(prompts.play, "X", 1, 1);
      expect(error).toBeNull();

      // Wait for next prompt and cancel
      const nextPromptPromise = waitForPromptEvent(host);
      const nextPrompt = await nextPromptPromise;
      nextPrompt.cancel("test cleanup");

      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toBe("test cleanup");
      }
    });

    it("should reject invalid arguments", async () => {
      const { host } = createTestHost();

      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      const promptEvent = await promptPromise;

      // Use tryAnswerPrompt with invalid position
      const { prompts } = await import("@/samples/tic-tac-toe");
      const error = host.tryAnswerPrompt(prompts.play, "X", 5, 5);
      expect(error).not.toBeNull();

      promptEvent.cancel("test cleanup");
      try {
        await runPromise;
      } catch (e) {
        const error = e as Error;
        expect(error.message).toBe("test cleanup");
      }
    });
  });

  describe("addInterruption and clearInterruptions", () => {
    it("should add interruption promise to state", async () => {
      const { host } = createTestHost();

      let resolveInterruption: () => void;
      const interruptionPromise = new Promise<void>((resolve) => {
        resolveInterruption = resolve;
      });

      // Add interruption
      host.addInterruption(interruptionPromise);

      // Start the game - produceAsync should wait for interruption
      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      const promptEvent = await promptPromise;

      // Resolve interruption
      resolveInterruption!();

      // Cancel and cleanup
      promptEvent.cancel("test cleanup");
      try {
        await runPromise;
      } catch {
        // Expected
      }
    });

    it("should clear all pending interruptions", async () => {
      const { host } = createTestHost();

      let resolveInterruption1: () => void;
      let resolveInterruption2: () => void;
      const interruptionPromise1 = new Promise<void>((resolve) => {
        resolveInterruption1 = resolve;
      });
      const interruptionPromise2 = new Promise<void>((resolve) => {
        resolveInterruption2 = resolve;
      });

      // Add multiple interruptions
      host.addInterruption(interruptionPromise1);
      host.addInterruption(interruptionPromise2);

      // Clear all interruptions
      host.clearInterruptions();

      // Start the game - should not wait for cleared interruptions
      const promptPromise = waitForPromptEvent(host);
      const runPromise = host.start();

      const promptEvent = await promptPromise;
      promptEvent.cancel("test cleanup");

      try {
        await runPromise;
      } catch {
        // Expected
      }

      // Original interruption promises should still be pending
      // (they were cleared, not resolved)
    });
  });
});