// Copyright (c) 2026 Gordon Bolton. MIT License.
import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
import { createRequire } from 'module';

const require = createRequire(import.meta.url);

// Set environment variables before requiring any modules
process.env.POLL_INTERVAL = '5000';
process.env.WEBHOOK_FALLBACK_TIMEOUT = '10';

const cache = require('../../../server/utils/cache.js');
const downloadClients = require('../../../server/utils/downloadClients.js');
const arrRetrieverRegistry = require('../../../server/utils/arrRetrievers.js');
const config = require('../../../server/utils/config.js');

// Set up mock/spies before requiring poller so destructuring in poller captures the spied versions!
const initializeClientsSpy = vi.spyOn(downloadClients, 'initializeClients').mockResolvedValue(true);
const getDownloadsByClientTypeSpy = vi.spyOn(downloadClients, 'getDownloadsByClientType').mockResolvedValue({
  sabnzbd: [],
  qbittorrent: []
});

const arrRegistryInitializeSpy = vi.spyOn(arrRetrieverRegistry, 'initialize').mockResolvedValue(true);
const getTagsByTypeSpy = vi.spyOn(arrRetrieverRegistry, 'getTagsByType').mockResolvedValue({
  sonarr: [],
  radarr: []
});
const getQueuesByTypeSpy = vi.spyOn(arrRetrieverRegistry, 'getQueuesByType').mockResolvedValue({
  sonarr: [],
  radarr: []
});
const getHistoryByTypeSpy = vi.spyOn(arrRetrieverRegistry, 'getHistoryByType').mockResolvedValue({
  sonarr: [],
  radarr: []
});
const getOmbiRequestsSpy = vi.spyOn(arrRetrieverRegistry, 'getOmbiRequests').mockResolvedValue({
  movie: [],
  tv: []
});

const getSonarrInstancesSpy = vi.spyOn(config, 'getSonarrInstances').mockReturnValue([]);
const getRadarrInstancesSpy = vi.spyOn(config, 'getRadarrInstances').mockReturnValue([]);
const getOmbiInstancesSpy = vi.spyOn(config, 'getOmbiInstances').mockReturnValue([]);

const cacheSetSpy = vi.spyOn(cache, 'set').mockImplementation(() => {});
const cacheGetSpy = vi.spyOn(cache, 'get').mockReturnValue(null);
const getWebhookMetricsSpy = vi.spyOn(cache, 'getWebhookMetrics').mockReturnValue(null);
const getGlobalWebhookMetricsSpy = vi.spyOn(cache, 'getGlobalWebhookMetrics').mockReturnValue({
  lastGlobalWebhookTimestamp: null
});
const incrementPollsSkippedSpy = vi.spyOn(cache, 'incrementPollsSkipped').mockImplementation(() => {});

// Now require the poller
const poller = require('../../../server/utils/poller.js');

describe('Background Poller Utility', () => {
  beforeEach(() => {
    vi.clearAllMocks();

    // Re-apply standard resolved values
    initializeClientsSpy.mockResolvedValue(true);
    getDownloadsByClientTypeSpy.mockResolvedValue({ sabnzbd: [], qbittorrent: [] });
    arrRegistryInitializeSpy.mockResolvedValue(true);
    getTagsByTypeSpy.mockResolvedValue({ sonarr: [], radarr: [] });
    getQueuesByTypeSpy.mockResolvedValue({ sonarr: [], radarr: [] });
    getHistoryByTypeSpy.mockResolvedValue({ sonarr: [], radarr: [] });
    getOmbiRequestsSpy.mockResolvedValue({ movie: [], tv: [] });

    getSonarrInstancesSpy.mockReturnValue([]);
    getRadarrInstancesSpy.mockReturnValue([]);
    getOmbiInstancesSpy.mockReturnValue([]);

    cacheSetSpy.mockImplementation(() => {});
    cacheGetSpy.mockReturnValue(null);
    getWebhookMetricsSpy.mockReturnValue(null);
    getGlobalWebhookMetricsSpy.mockReturnValue({ lastGlobalWebhookTimestamp: null });
    incrementPollsSkippedSpy.mockImplementation(() => {});
  });

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

  describe('Poller Core Logic', () => {
    it('POLL_INTERVAL matches parsed environment variable', () => {
      expect(poller.POLL_INTERVAL).toBe(5000);
      expect(poller.POLLING_ENABLED).toBe(true);
    });

    it('successfully registers and notifies SSE subscribers on poll completion', async () => {
      let callbackFired = false;
      const callback = () => {
        callbackFired = true;
      };

      poller.onPollComplete(callback);

      await poller.pollAllServices();

      expect(callbackFired).toBe(true);

      // Clean up/Deregister callback
      poller.offPollComplete(callback);
      callbackFired = false;

      await poller.pollAllServices();
      expect(callbackFired).toBe(false);
    });

    it('prevents concurrent executions of pollAllServices via the polling guard', async () => {
      // Stub initializeClients to delay using a promise
      let resolveInit;
      const delayPromise = new Promise((resolve) => {
        resolveInit = resolve;
      });
      initializeClientsSpy.mockImplementation(() => delayPromise);

      // Start the first poll (which remains pending on initializeClients)
      const firstPollPromise = poller.pollAllServices();

      const logSpy = vi.spyOn(console, 'log').mockImplementation(() => {});

      // Trigger second poll immediately while first is in progress
      await poller.pollAllServices();

      expect(logSpy).toHaveBeenCalledWith('[Poller] Previous poll still running, skipping');

      // Resolve the delay to let the first poll finish
      resolveInit();
      await firstPollPromise;
    });

    it('resets the polling guard flag on error so future polls can run', async () => {
      initializeClientsSpy.mockRejectedValue(new Error('Initialization failed'));
      
      // Setup error spy
      const errorSpy = vi.spyOn(console, 'error').mockImplementation(() => {});

      await poller.pollAllServices();

      expect(errorSpy).toHaveBeenCalledWith('[Poller] Poll error:', 'Initialization failed');

      // Verify polling flag has been reset in the finally block by running a successful poll
      initializeClientsSpy.mockResolvedValue(true);
      await poller.pollAllServices();
      expect(initializeClientsSpy).toHaveBeenCalledTimes(2);
    });
  });

  describe('Webhook-Based Instance Bypassing', () => {
    it('skips polling for an instance with recent active webhook events', async () => {
      const mockSonarrInstance = { id: 'sonarr-1', name: 'Main Sonarr', url: 'https://sonarr.test' };
      const mockRadarrInstance = { id: 'radarr-1', name: 'Main Radarr', url: 'https://radarr.test' };
      getSonarrInstancesSpy.mockReturnValue([mockSonarrInstance]);
      getRadarrInstancesSpy.mockReturnValue([mockRadarrInstance]);

      // Mock recent webhook activity within the 10 min window (Date.now() - 1 min)
      const recentTimestamp = Date.now() - 60000;
      getWebhookMetricsSpy.mockImplementation((url) => {
        if (url === 'https://sonarr.test' || url === 'https://radarr.test') {
          return { eventsReceived: 5, lastWebhookTimestamp: recentTimestamp };
        }
        return null;
      });

      await poller.pollAllServices();

      // Verify that skips are incremented for both
      expect(incrementPollsSkippedSpy).toHaveBeenCalledWith('https://sonarr.test');
      expect(incrementPollsSkippedSpy).toHaveBeenCalledWith('https://radarr.test');

      // Verify that Sonarr/Radarr-specific API retrievers were not called
      expect(getTagsByTypeSpy).not.toHaveBeenCalled();
      expect(getQueuesByTypeSpy).not.toHaveBeenCalled();
      expect(getHistoryByTypeSpy).not.toHaveBeenCalled();
    });

    it('forces polling if the last webhook timestamp exceeds fallback timeout', async () => {
      const mockSonarrInstance = { id: 'sonarr-1', name: 'Main Sonarr', url: 'https://sonarr.test' };
      getSonarrInstancesSpy.mockReturnValue([mockSonarrInstance]);

      // Mock stale webhook activity (Date.now() - 11 mins, fallback is 10 mins)
      const staleTimestamp = Date.now() - 11 * 60000;
      getWebhookMetricsSpy.mockImplementation((url) => {
        if (url === 'https://sonarr.test') {
          return { eventsReceived: 5, lastWebhookTimestamp: staleTimestamp };
        }
        return null;
      });

      await poller.pollAllServices();

      // Should bypass the skip and perform a full poll
      expect(getTagsByTypeSpy).toHaveBeenCalled();
    });

    it('forces polling via global webhook fallback if no global webhooks received for timeout duration', async () => {
      const mockSonarrInstance = { id: 'sonarr-1', name: 'Main Sonarr', url: 'https://sonarr.test' };
      getSonarrInstancesSpy.mockReturnValue([mockSonarrInstance]);

      // Mock recent metrics on individual level but stale globally
      const recentTimestamp = Date.now() - 60000;
      getWebhookMetricsSpy.mockImplementation((url) => {
        if (url === 'https://sonarr.test') {
          return { eventsReceived: 5, lastWebhookTimestamp: recentTimestamp };
        }
        return null;
      });

      // Global webhook is stale
      getGlobalWebhookMetricsSpy.mockReturnValue({
        lastGlobalWebhookTimestamp: Date.now() - 12 * 60000
      });

      await poller.pollAllServices();

      // Stale global webhooks should trigger fallback, bypassing the individual skip
      expect(getTagsByTypeSpy).toHaveBeenCalled();
    });
  });

  describe('Hybrid Timer Behavior (Fake Timers)', () => {
    beforeEach(() => {
      vi.useFakeTimers();
    });

    it('schedules periodic polls in startPoller on standard interval', async () => {
      poller.startPoller();

      // Triggered immediately on start (flush microtasks)
      await vi.advanceTimersByTimeAsync(0);
      expect(getDownloadsByClientTypeSpy).toHaveBeenCalledTimes(1);

      // Advance time by 5000ms
      await vi.advanceTimersByTimeAsync(5000);
      expect(getDownloadsByClientTypeSpy).toHaveBeenCalledTimes(2);

      // Advance by another 5000ms
      await vi.advanceTimersByTimeAsync(5000);
      expect(getDownloadsByClientTypeSpy).toHaveBeenCalledTimes(3);

      poller.stopPoller();
    });

    it('clears intervals cleanly when stopPoller is called', async () => {
      poller.startPoller();
      await vi.advanceTimersByTimeAsync(0);
      expect(getDownloadsByClientTypeSpy).toHaveBeenCalledTimes(1);

      poller.stopPoller();

      await vi.advanceTimersByTimeAsync(10000);
      expect(getDownloadsByClientTypeSpy).toHaveBeenCalledTimes(1); // No new execution since poller was stopped
    });
  });
});