import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
import nock from "nock";
import { BigNumber } from "bignumber.js";

vi.mock("../src/db.js", () => ({
  insertIntoDB: vi.fn().mockResolvedValue(undefined),
  initDB: vi.fn().mockResolvedValue(undefined),
  closePool: vi.fn().mockResolvedValue(undefined),
}));

vi.mock("../src/logger.js", () => ({
  default: {
    info: vi.fn(),
    warn: vi.fn(),
    error: vi.fn(),
    fatal: vi.fn(),
  },
}));

describe("Bot Core Functionality", () => {
  const CONFIG = {
    pair: "BTC-USD",
    interval: 100,
    threshold: 0.01,
  };

  let BotClass;
  let bot;
  let fetchRateMock;
  let onAlertSpy;

  beforeEach(async () => {
    vi.resetModules();

    fetchRateMock = vi.fn();
    vi.doMock("../src/api.js", () => ({
      fetchRate: fetchRateMock,
      prefetchRates: vi.fn(),
    }));

    const botModule = await import("../src/bot.js");
    BotClass = botModule.Bot;

    onAlertSpy = vi.fn();
    bot = new BotClass(CONFIG, onAlertSpy);
    bot.running = false;
  });

  afterEach(() => {
    vi.clearAllMocks();
  });

  describe("Initialization", () => {
    it("should initialize with correct parameters", () => {
      expect(bot.pair).toBe(CONFIG.pair);
      expect(bot.interval).toBe(CONFIG.interval);
      expect(bot.threshold).toBe(CONFIG.threshold);
      expect(bot.running).toBe(false);
      expect(bot.lastPrice).toBeNull();
    });

    it("should set baseline price on first check without alerting", async () => {
      fetchRateMock.mockResolvedValue(new BigNumber("60000.50"));

      await bot.loop();

      expect(bot.lastPrice).toBeDefined();
      expect(bot.lastPrice.toFixed(2)).toBe("60000.50");
      expect(onAlertSpy).not.toHaveBeenCalled();
    });
  });

  describe("Threshold Detection", () => {
    beforeEach(async () => {
      fetchRateMock.mockResolvedValue(new BigNumber("50000.00"));
      await bot.loop();
      fetchRateMock.mockReset();
    });

    it("should NOT alert when change is below threshold", async () => {
      fetchRateMock.mockResolvedValue(new BigNumber("50004.99"));

      await bot.loop();

      expect(onAlertSpy).not.toHaveBeenCalled();
      expect(bot.lastPrice.toFixed(2)).toBe("50000.00");
    });

    it("should alert when price moves exactly at threshold", async () => {
      fetchRateMock.mockResolvedValue(new BigNumber("50005.00"));

      await bot.loop();

      expect(onAlertSpy).toHaveBeenCalledTimes(1);
      const alertData = onAlertSpy.mock.calls[0][0];

      expect(alertData).toMatchObject({
        pair: "BTC-USD",
        direction: "UP",
        previousPrice: "50000.000000",
        newPrice: "50005.000000",
      });
      expect(bot.lastPrice.toFixed(2)).toBe("50005.00");
    });

    it("should alert on downward price movement", async () => {
      fetchRateMock.mockResolvedValue(new BigNumber("49995.00"));

      await bot.loop();

      expect(onAlertSpy).toHaveBeenCalledTimes(1);
      expect(onAlertSpy.mock.calls[0][0].direction).toBe("DOWN");
    });

    it("should alert on large price swing", async () => {
      fetchRateMock.mockResolvedValue(new BigNumber("51000.00"));

      await bot.loop();

      expect(onAlertSpy).toHaveBeenCalledTimes(1);
      expect(onAlertSpy.mock.calls[0][0].percentChange).toBe("2.0000");
    });
  });

  describe("Consecutive Alerts Logic", () => {
    it("should base next alert on last ALERT price, not last CHECKED price", async () => {
      fetchRateMock.mockResolvedValue(new BigNumber("50000.00"));
      await bot.loop();

      fetchRateMock.mockResolvedValue(new BigNumber("50003.00"));
      await bot.loop();
      expect(onAlertSpy).not.toHaveBeenCalled();

      fetchRateMock.mockResolvedValue(new BigNumber("50005.00"));
      await bot.loop();

      expect(onAlertSpy).toHaveBeenCalledTimes(1);
      expect(onAlertSpy.mock.calls[0][0].previousPrice).toBe("50000.000000");
      expect(onAlertSpy.mock.calls[0][0].newPrice).toBe("50005.000000");
    });
  });

  describe("Error Handling", () => {
    it("should handle network errors gracefully without crashing", async () => {
      fetchRateMock.mockRejectedValue(new Error("Network error"));
      await expect(bot.loop()).resolves.not.toThrow();
    });

    it("should handle alert callback errors", async () => {
      fetchRateMock.mockResolvedValue(new BigNumber("50000.00"));
      await bot.loop();

      fetchRateMock.mockResolvedValue(new BigNumber("51000.00"));
      onAlertSpy.mockRejectedValue(new Error("DB Connection Lost"));

      await expect(bot.loop()).resolves.not.toThrow();
    });
  });
});

describe("API", () => {
  let api;

  beforeEach(async () => {
    vi.resetModules();
    nock.cleanAll();

    vi.doMock("../src/api.js", async () => {
      return await vi.importActual("../src/api.js");
    });

    api = await import("../src/api.js");
  });

  afterEach(() => {
    nock.cleanAll();
  });

  describe("fetchRate Caching", () => {
    it("should cache successful responses", async () => {
      const scope = nock("https://api.uphold.com")
        .get("/v0/ticker/BTC-USD")
        .reply(200, { ask: "60000" });

      const price1 = await api.fetchRate("BTC-USD");
      expect(price1.toFixed(0)).toBe("60000");

      const price2 = await api.fetchRate("BTC-USD");
      expect(price2.toFixed(0)).toBe("60000");

      expect(scope.isDone()).toBe(true);
    });

    it("should bypass cache if forceRefresh is true", async () => {
      const scope = nock("https://api.uphold.com")
        .get("/v0/ticker/BTC-USD")
        .times(2)
        .reply(200, { ask: "60000" });

      await api.fetchRate("BTC-USD");
      await api.fetchRate("BTC-USD", true);

      expect(scope.isDone()).toBe(true);
    });
  });

  describe("Request Deduplication", () => {
    it("should deduplicate concurrent requests", async () => {
      const scope = nock("https://api.uphold.com")
        .get("/v0/ticker/BTC-USD")
        .delay(100)
        .reply(200, { ask: "60000" });

      const p1 = api.fetchRate("BTC-USD", true);
      const p2 = api.fetchRate("BTC-USD", true);

      const [r1, r2] = await Promise.all([p1, p2]);

      expect(r1).toEqual(r2);
      expect(scope.isDone()).toBe(true);
    });
  });

  describe("Retry Logic", () => {
    it("should retry on failure", async () => {
      const scope = nock("https://api.uphold.com")
        .get("/v0/ticker/BTC-USD")
        .replyWithError("Socket Hangup")
        .get("/v0/ticker/BTC-USD")
        .reply(200, { ask: "60000" });

      const price = await api.fetchRate("BTC-USD", true);
      expect(price.toFixed(0)).toBe("60000");
      expect(scope.isDone()).toBe(true);
    });

    it("should throw after max retries", async () => {
      const scope = nock("https://api.uphold.com")
        .get("/v0/ticker/BTC-USD")
        .times(3)
        .replyWithError("Persistent Fail");

      try {
        await api.fetchRate("BTC-USD", true);
        expect.fail("Should have thrown error");
      } catch (err) {
        expect(err.message).toContain("Persistent Fail");
      }

      expect(scope.isDone()).toBe(true);
    }, 10000);
  });
});