import { beforeEach, describe, expect, it, jest, test } from "@jest/globals";
import { ApiBasedRepositoryLoader, ApiResponseError } from "../../src/loaders/ApiBasedRepositoryLoader";
import { UnoptimizedInMemoryRepository } from "../../src/repositories/UnoptimizedInMemoryRepository";
import { fetchSystemDataSuccessfulResponse } from "../jsonSnapshots/fetchSystemData/fetchSystemDataSuccessfulResponse";
import { fetchSystemDataFailedResponse } from "../jsonSnapshots/fetchSystemData/fetchSystemDataFailedResponse";
import { fetchRouteDataSuccessfulResponse } from "../jsonSnapshots/fetchRouteData/fetchRouteDataSuccessfulResponse";
import { ISystem } from "../../src/entities/entities";
import {
  fetchStopAndPolylineDataSuccessfulResponse
} from "../jsonSnapshots/fetchStopAndPolylineData/fetchStopAndPolylineDataSuccessfulResponse";

/**
 * Function to update behavior of the global `fetch` function.
 * Note that the Passio GO API returns status code 200 for failed responses.
 * @param obj
 * @param status
 */
function updateGlobalFetchMockJson(
  obj: any,
  status: number = 200
) {
  // @ts-ignore
  global.fetch = jest.fn(() => {
    return Promise.resolve({
      json: () => Promise.resolve(obj),
      status,
      ok: status.toString().startsWith("2"), // 200-level codes are OK
    })
  }) as jest.Mock;
}

/**
 * Reset the global fetch function mock's JSON to return an empty object.
 * @param obj
 */
function resetGlobalFetchMockJson() {
  updateGlobalFetchMockJson({});
}

async function assertAsyncCallbackThrowsApiResponseError(callback: () => Promise<any>) {
  await expect(callback).rejects.toThrow(ApiResponseError);
}

function updateGlobalFetchMockJsonToThrowSyntaxError() {
  // @ts-ignore
  global.fetch = jest.fn(() => {
    return Promise.resolve({
      json: () => Promise.reject(new SyntaxError("Unable to parse JSON")),
      status: 200,
      ok: true,
    })
  }) as jest.Mock;
}

describe("ApiBasedRepositoryLoader", () => {
  let loader: ApiBasedRepositoryLoader;

  beforeEach(() => {
    loader = new ApiBasedRepositoryLoader(new UnoptimizedInMemoryRepository());
    resetGlobalFetchMockJson();
  });

  describe("fetchAndUpdateSystemData", () => {
    it("updates system data in repository if response received", async () => {
      const numberOfSystemsInResponse = fetchSystemDataSuccessfulResponse.all.length;
      updateGlobalFetchMockJson(fetchSystemDataSuccessfulResponse);

      await loader.fetchAndUpdateSystemData();

      const systems = await loader.repository.getSystems();
      if (loader.supportedSystemIds.length < numberOfSystemsInResponse) {
        expect(systems).toHaveLength(loader.supportedSystemIds.length);
      } else {
        expect(systems).toHaveLength(numberOfSystemsInResponse);
      }
    });

    it("throws the correct error if the API response contains no data", async () => {
      updateGlobalFetchMockJson(fetchSystemDataFailedResponse);

      await assertAsyncCallbackThrowsApiResponseError(async () => {
        await loader.fetchAndUpdateSystemData();
      });
    });

    it("throws the correct error if HTTP status code is not 200", async () => {
      updateGlobalFetchMockJson(fetchSystemDataFailedResponse, 400);

      await assertAsyncCallbackThrowsApiResponseError(async () => {
        await loader.fetchAndUpdateSystemData();
      });
    });
  });


  describe("fetchAndUpdateRouteDataForExistingSystemsInRepository", () => {
    test("calls fetchAndUpdateRouteDataForSystemId for all systems in repository", async () => {
      const spy = jest.spyOn(loader, "fetchAndUpdateRouteDataForSystemId");

      const systems: ISystem[] = [
        {
          name: "Chapman University",
          id: "1",
        },
        {
          name: "City of Monterey Park",
          id: "2",
        }
      ];

      await Promise.all(systems.map(async (system) => {
        await loader.repository.addOrUpdateSystem(system);
      }));

      await loader.fetchAndUpdateRouteDataForExistingSystemsInRepository();

      expect(spy.mock.calls.length).toBe(2);
    });
  });

  describe("fetchAndUpdateRouteDataForSystemId", () => {
    it("updates route data in repository if there are systems and response received", async () => {
      updateGlobalFetchMockJson(fetchRouteDataSuccessfulResponse);

      await loader.fetchAndUpdateRouteDataForSystemId("263");

      const routes = await loader.repository.getRoutesBySystemId("263");

      expect(routes.length).toEqual(fetchRouteDataSuccessfulResponse.all.length)
    });

    it("throws the correct error if the API response contains no data", async () => {
      // The Passio API returns some invalid JSON if there is no data,
      // so simulate a JSON parsing error

      updateGlobalFetchMockJsonToThrowSyntaxError();

      await assertAsyncCallbackThrowsApiResponseError(async () => {
        await loader.fetchAndUpdateRouteDataForSystemId("263");
      });
    });
  });

  describe("fetchAndUpdateStopAndPolylineDataForRoutesWithSystemId", () => {
    it("updates stop and polyline data if there are systems and response received", async () => {
      updateGlobalFetchMockJson(fetchStopAndPolylineDataSuccessfulResponse);

      const stopsArray = Object.values(fetchStopAndPolylineDataSuccessfulResponse.stops);

      await loader.fetchAndUpdateStopAndPolylineDataForRoutesWithSystemId("263");

      const stops = await loader.repository.getStopsBySystemId("263");
      expect(stops.length).toEqual(stopsArray.length);

      await Promise.all(stops.map(async (stop) => {
        const orderedStops = await loader.repository.getOrderedStopsByStopId(stop.id)
        expect(orderedStops.length).toBeGreaterThan(0);
      }));

      const routes = await loader.repository.getRoutesBySystemId("263");
      routes.forEach((route) => {
        expect(route.polylineCoordinates.length).toBeGreaterThan(0);
      });
    });

    it("throws the correct error if the API response contains no data", async () => {
      updateGlobalFetchMockJsonToThrowSyntaxError();

      await assertAsyncCallbackThrowsApiResponseError(async () => {
        await loader.fetchAndUpdateStopAndPolylineDataForRoutesWithSystemId("263");
      });
    })
  });

  describe("fetchAndUpdateShuttleDataForExistingSystems", () => {
    it("updates shuttle data in repository if there are systems and response received", async () => {

    });

    it("throws the correct error if the API response contains no data", async () => {

    });
  });

  describe("fetchAndUpdateEtaDataForExistingSystems", () => {
    it("updates shuttle data in repository if there are systems and response received", async () => {

    });

    it("throws the correct error if the API response contains no data", async () => {

    });
  });
});