/**
 * Transit backend switch e2e (#1699) — the whole path a self-hoster actually
 * walks, through the real Nest stack: an admin flips Admin → Settings → Transit
 * Provider, and the next /api/transit/plan leaves for a different upstream.
 *
 * Unlike transit.e2e.test.ts, TransitService is NOT stubbed here — only the
 * outbound `fetch` is, so what is asserted is the URL the install would really
 * have called and the setting/key state that decided it.
 */
import { db } from '../../src/db/database';
import { AppSettings } from '../../src/db/entities/AppSettings.entity';
import { Users } from '../../src/db/entities/Users.entity';
import { TrekExceptionFilter } from '../../src/nest/common/trek-exception.filter';
import { GoogleQuotaService } from '../../src/nest/google-quota/google-quota.service';
import { RealtimeModule } from '../../src/nest/realtime/realtime.module';
import { clearGoogleTransitCache } from '../../src/nest/transit/google-transit.provider';
import { TransitModule } from '../../src/nest/transit/transit.module';
import { deleteRows, updateRows } from '../helpers/factories/rows';
import { setAppSetting } from '../helpers/factories/settings';
import { makeAdmin } from '../helpers/factories/users';
import { createTestMikroOrmModule, createTestOrm, type TestOrm } from '../helpers/test-orm';
import { TestUnitOfWorkModule } from '../helpers/test-uow';
import { sessionCookie } from './harness';
import { Test } from '@nestjs/testing';

import cookieParser from 'cookie-parser';
import type { Server } from 'http';
import request from 'supertest';
import { describe, it, expect, beforeAll, afterAll, beforeEach, vi } from 'vitest';

vi.mock('../../src/db/database', async () => {
  const { createSnapshotTestDb, buildDbMock } = await import('../helpers/db-mock');
  return buildDbMock(createSnapshotTestDb());
});

let orm: TestOrm;

const ADMIN = 1;

// TransitService's Transitous cache is module-scoped with no reset hook, so
// each case plans between its own pair of Osaka coordinates rather than being
// answered by the previous one.
let planNo = 0;
const nextPlanUrl = () => `/api/transit/plan?from=34.69${planNo},135.4900&to=34.68${planNo++},135.5155`;

describe('Transit backend switch e2e (#1699)', () => {
  let server: Server;
  let app: Awaited<ReturnType<typeof build>>;
  const fetchMock = vi.fn();

  async function build() {
    const moduleRef = await Test.createTestingModule({
      imports: [
        await TestUnitOfWorkModule.forRoot(db),
        await createTestMikroOrmModule(db),
        RealtimeModule,
        TransitModule,
      ],
    }).compile();
    const nest = moduleRef.createNestApplication();
    nest.use(cookieParser());
    nest.useGlobalFilters(new TrekExceptionFilter());
    await nest.init();
    return nest;
  }

  beforeAll(async () => {
    orm = await createTestOrm(db);
    await makeAdmin(orm, { id: ADMIN });
    app = await build();
    server = app.getHttpServer();
  });
  afterAll(async () => {
    await app?.close();
    await orm?.close();
  });

  beforeEach(async () => {
    vi.restoreAllMocks();
    vi.stubGlobal('fetch', fetchMock);
    fetchMock.mockReset();
    // MOTIS and Routes shapes both parse as "no itineraries", which is all this
    // suite needs — it asserts where the request went, not how it mapped.
    fetchMock.mockResolvedValue({
      ok: true,
      status: 200,
      headers: { get: () => null },
      json: async () => ({}),
    });
    await deleteRows(orm, AppSettings);
    await updateRows(orm, Users, { id: ADMIN }, { maps_api_key: null });
    clearGoogleTransitCache();
  });

  let lastBody: Record<string, unknown> = {};

  async function planUpstream(): Promise<string> {
    const res = await request(server).get(nextPlanUrl()).set('Cookie', sessionCookie(ADMIN));
    expect(res.status).toBe(200);
    lastBody = res.body;
    return String(fetchMock.mock.calls[0][0]);
  }

  it('TRANSIT-PROV-E2E-001: an untouched install plans through Transitous', async () => {
    expect(await planUpstream()).toContain('transitous.org');
    expect(lastBody.provider).toBe('transitous');
  });

  it('TRANSIT-PROV-E2E-002: selecting Google without a key still plans through Transitous', async () => {
    await setAppSetting(orm, 'transit_provider', 'google');
    expect(await planUpstream()).toContain('transitous.org');
    // The response says who really answered, so the empty state cannot blame
    // Google for a Transitous result.
    expect(lastBody.provider).toBe('transitous');
  });

  it('TRANSIT-PROV-E2E-003: with the switch on and a key set, the plan leaves for the Routes API', async () => {
    await setAppSetting(orm, 'transit_provider', 'google');
    await setAppSetting(orm, 'maps_api_key', 'instance-key');
    expect(await planUpstream()).toBe('https://routes.googleapis.com/directions/v2:computeRoutes');
    expect(lastBody.provider).toBe('google');
  });

  it('TRANSIT-PROV-E2E-004: the picker follows the switch to Google Places', async () => {
    await setAppSetting(orm, 'transit_provider', 'google');
    await setAppSetting(orm, 'maps_api_key', 'instance-key');

    const res = await request(server)
      .get('/api/transit/geocode?q=Nakanoshima&lang=ja')
      .set('Cookie', sessionCookie(ADMIN));
    expect(res.status).toBe(200);
    expect(String(fetchMock.mock.calls[0][0])).toBe('https://places.googleapis.com/v1/places:searchText');
  });

  it("TRANSIT-PROV-E2E-005: a member's own key is used when the instance has none", async () => {
    await setAppSetting(orm, 'transit_provider', 'google');
    await updateRows(orm, Users, { id: ADMIN }, { maps_api_key: 'personal-key' });

    expect(await planUpstream()).toBe('https://routes.googleapis.com/directions/v2:computeRoutes');
    expect(fetchMock.mock.calls[0][1].headers['X-Goog-Api-Key']).toBe('personal-key');
  });

  const motisRoute = {
    itineraries: [
      {
        startTime: '2026-09-10T09:00:00Z',
        endTime: '2026-09-10T09:08:00Z',
        legs: [
          {
            mode: 'SUBWAY',
            duration: 480,
            from: { name: 'A', lat: 34.69, lon: 135.49 },
            to: { name: 'B', lat: 34.68, lon: 135.51 },
          },
        ],
      },
    ],
  };
  const googleRoute = {
    routes: [
      {
        legs: [
          {
            steps: [
              {
                travelMode: 'TRANSIT',
                staticDuration: '480s',
                transitDetails: {
                  stopDetails: {
                    departureStop: { name: 'A', location: { latLng: { latitude: 34.69, longitude: 135.49 } } },
                    arrivalStop: { name: 'B', location: { latLng: { latitude: 34.68, longitude: 135.51 } } },
                    departureTime: '2026-09-10T09:00:00Z',
                    arrivalTime: '2026-09-10T09:08:00Z',
                  },
                  transitLine: { vehicle: { type: 'SUBWAY' } },
                },
              },
            ],
          },
        ],
      },
    ],
  };
  const okJson = (data: unknown) => ({ ok: true, status: 200, headers: { get: () => null }, json: async () => data });

  describe.each(['google', 'transitous'] as const)('%s primary fallback', (primary) => {
    it.each(['success', 'primary-success', 'empty', 'secondary-error', 'primary-error'])('%s', async (outcome) => {
      await setAppSetting(orm, 'transit_provider', primary);
      await setAppSetting(orm, 'maps_api_key', 'instance-key');
      const secondary = primary === 'google' ? 'transitous' : 'google';
      fetchMock.mockImplementation(async (url: string) => {
        const provider = String(url).includes('googleapis') ? 'google' : 'transitous';
        if (
          (outcome === 'primary-error' && provider === primary) ||
          (outcome === 'secondary-error' && provider === secondary)
        ) {
          return { ok: false, status: 500, headers: { get: () => null }, json: async () => ({}) };
        }
        const hasRoutes =
          (outcome === 'success' && provider === secondary) || (outcome === 'primary-success' && provider === primary);
        return okJson(hasRoutes ? (provider === 'google' ? googleRoute : motisRoute) : {});
      });
      const res = await request(server).get(nextPlanUrl()).set('Cookie', sessionCookie(ADMIN));
      expect(res.status).toBe(outcome === 'primary-error' ? 502 : 200);
      if (outcome !== 'primary-error') {
        expect(res.body.provider).toBe(outcome === 'success' ? secondary : primary);
        expect(res.body.itineraries).toHaveLength(['success', 'primary-success'].includes(outcome) ? 1 : 0);
      }
      expect(fetchMock).toHaveBeenCalledTimes(outcome.startsWith('primary-') ? 1 : 2);
      expect(String(fetchMock.mock.calls[0][0]).includes('googleapis')).toBe(primary === 'google');
      if (secondary === 'google' && outcome === 'success') {
        expect(fetchMock.mock.calls[1][1].headers['X-Goog-Api-Key']).toBe('instance-key');
      }
    });
  });

  it.each(['absent', 'personal-only', 'quota-exhausted'])('does not fall back to Google when %s', async (state) => {
    if (state === 'personal-only') await updateRows(orm, Users, { id: ADMIN }, { maps_api_key: 'personal-key' });
    if (state === 'quota-exhausted') {
      await setAppSetting(orm, 'maps_api_key', 'instance-key');
      vi.spyOn(app.get(GoogleQuotaService), 'exhausted').mockResolvedValue(true);
    }
    await planUpstream();
    expect(lastBody.provider).toBe('transitous');
    expect(fetchMock).toHaveBeenCalledTimes(1);
  });

  it('uses the operator key for Google fallback', async () => {
    vi.stubEnv('PLACES_API_KEY', 'operator-key');
    try {
      fetchMock.mockResolvedValueOnce(okJson({})).mockResolvedValueOnce(okJson(googleRoute));
      await planUpstream();
      expect(lastBody.provider).toBe('google');
      expect(fetchMock.mock.calls[1][1].headers['X-Goog-Api-Key']).toBe('operator-key');
    } finally {
      vi.unstubAllEnvs();
    }
  });
});