import {
  afterEach,
  beforeEach,
  describe,
  expect,
  it,
  type MockedFunction,
  vi,
} from "vitest";
import { CircuitBreaker } from "./utils/circuitBreaker";
import {
  describeUnresponsiveEngines,
  fetchSearXNG,
  getWebSearchStatus,
} from "./webSearchService";

function createMockResponse(
  text: string,
  ok = true,
  status?: number,
): Response {
  const resolvedStatus = status ?? (ok ? 200 : 503);
  return {
    ok,
    status: resolvedStatus,
    statusText: ok ? "OK" : "Error",
    headers: new Headers(),
    redirected: false,
    type: "basic" as ResponseType,
    url: "http://test.com",
    clone: function () {
      return this;
    },
    body: null,
    bodyUsed: false,
    arrayBuffer: () => Promise.resolve(new ArrayBuffer(0)),
    blob: () => Promise.resolve(new Blob()),
    formData: () => Promise.resolve(new FormData()),
    json: () => Promise.resolve(JSON.parse(text)),
    text: () => Promise.resolve(text),
  } as unknown as Response;
}

const successResponse = () =>
  createMockResponse(
    JSON.stringify({
      results: [
        {
          title: "example",
          url: "https://example.com",
          content: "example content",
          category: "general",
        },
      ],
    }),
  );

let originalFetch: typeof fetch;
let fetchMock: MockedFunction<typeof fetch>;

beforeEach(() => {
  originalFetch = global.fetch;
  fetchMock = vi.fn() as unknown as MockedFunction<typeof fetch>;
  global.fetch = fetchMock;
});

afterEach(() => {
  global.fetch = originalFetch;
});

describe("WebSearchService", () => {
  it("should report service not available when fetch throws", async () => {
    (global.fetch as MockedFunction<typeof fetch>).mockImplementation(() => {
      throw new Error("Network error");
    });
    const status = await getWebSearchStatus();
    expect(status).toBe(false);
  });

  it("should return false when health endpoint does not return OK", async () => {
    (global.fetch as MockedFunction<typeof fetch>).mockResolvedValue(
      createMockResponse("NOT_OK", false),
    );
    const status = await getWebSearchStatus();
    expect(status).toBe(false);
  });

  it("should return true when health endpoint returns OK", async () => {
    (global.fetch as MockedFunction<typeof fetch>).mockResolvedValueOnce(
      createMockResponse("OK"),
    );

    const status = await getWebSearchStatus();
    expect(status).toBe(true);
    expect(fetchMock).toHaveBeenCalledTimes(1);
  });

  it("should return empty array on fetchSearXNG error", async () => {
    (global.fetch as MockedFunction<typeof fetch>).mockRejectedValue(
      new Error("Network failure"),
    );
    const results = await fetchSearXNG("test query", "text");
    expect(Array.isArray(results)).toBe(true);
    expect(results).toHaveLength(0);
  });
});

describe("describeUnresponsiveEngines", () => {
  it("returns null when there are no unresponsive engines", () => {
    expect(describeUnresponsiveEngines(undefined)).toBeNull();
    expect(describeUnresponsiveEngines([])).toBeNull();
    expect(describeUnresponsiveEngines("not-an-array")).toBeNull();
  });

  it("formats engine/reason pairs from SearXNG", () => {
    expect(
      describeUnresponsiveEngines([
        ["google", "Timeout"],
        ["bing", "Suspended: Access denied"],
      ]),
    ).toBe("google (Timeout), bing (Suspended: Access denied)");
  });

  it("handles entries without a reason", () => {
    expect(describeUnresponsiveEngines([["duckduckgo"]])).toBe("duckduckgo");
  });

  it("falls back to string conversion for unexpected shapes", () => {
    expect(describeUnresponsiveEngines(["qwant"])).toBe("qwant");
  });
});

describe("retry logic", () => {
  beforeEach(() => {
    vi.useFakeTimers();
  });

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

  it("retries on 500 and returns results on eventual success", async () => {
    fetchMock
      .mockResolvedValueOnce(createMockResponse("", false, 500))
      .mockResolvedValueOnce(createMockResponse("", false, 500))
      .mockResolvedValueOnce(successResponse());

    const promise = fetchSearXNG("test", "text");
    await vi.runAllTimersAsync();
    const results = await promise;

    expect(fetchMock).toHaveBeenCalledTimes(3);
    expect(results).toHaveLength(1);
  });

  it("returns empty array when all retries return 500", async () => {
    fetchMock.mockResolvedValue(createMockResponse("", false, 500));

    const promise = fetchSearXNG("test", "text");
    await vi.runAllTimersAsync();
    const results = await promise;

    expect(fetchMock).toHaveBeenCalledTimes(4);
    expect(results).toHaveLength(0);
  });
});

describe("circuit breaker", () => {
  it("opens after exactly 5 non-retriable failures", async () => {
    const breaker = new CircuitBreaker({ failureThreshold: 5 });
    fetchMock.mockResolvedValue(createMockResponse("", false, 503));

    for (let i = 0; i < 5; i++) {
      await fetchSearXNG("test", "text", 30, breaker);
    }

    const callsBeforeBreak = fetchMock.mock.calls.length;
    await fetchSearXNG("test", "text", 30, breaker);

    expect(fetchMock.mock.calls.length).toBe(callsBeforeBreak);
  });

  it("does not open before 5 failures", async () => {
    const breaker = new CircuitBreaker({ failureThreshold: 5 });
    fetchMock.mockResolvedValue(createMockResponse("", false, 503));

    for (let i = 0; i < 4; i++) {
      await fetchSearXNG("test", "text", 30, breaker);
    }

    const callsBefore = fetchMock.mock.calls.length;
    await fetchSearXNG("test", "text", 30, breaker);

    expect(fetchMock.mock.calls.length).toBe(callsBefore + 1);
  });
});