import { describe, it, expect, vi, beforeEach } from 'vitest';
import { AudioService } from '../src/services/audioService';
import { usePlayerStore } from '../src/stores/playerStore';

// ── WaveSurfer mock ───────────────────────────────────────────────────────────

type EventName = 'ready' | 'error' | 'play' | 'pause' | 'finish' | 'audioprocess';
type EventHandler = (...args: any[]) => void;

function createMockWaveSurfer(duration = 120) {
  const handlers: Partial<Record<EventName, EventHandler>> = {};

  const ws = {
    on: vi.fn((event: EventName, handler: EventHandler) => {
      handlers[event] = handler;
    }),
    load: vi.fn(),
    play: vi.fn().mockResolvedValue(undefined),
    pause: vi.fn(),
    setTime: vi.fn(),
    getCurrentTime: vi.fn(() => 0),
    getDuration: vi.fn(() => duration),
    isPlaying: vi.fn(() => false),
    unAll: vi.fn(),
    destroy: vi.fn(),
    setOptions: vi.fn(),
    // Helper to fire events from tests
    _emit: (event: EventName, ...args: any[]) => handlers[event]?.(...args),
  };
  return ws;
}

vi.mock('wavesurfer.js', () => ({
  default: { create: vi.fn() },
}));

// ── Helpers ───────────────────────────────────────────────────────────────────

function makeContainer(): HTMLElement {
  return document.createElement('div');
}

async function initService(
  service: AudioService,
  opts: { url?: string; duration?: number } = {}
): Promise<ReturnType<typeof createMockWaveSurfer>> {
  const { url = 'http://example.com/audio.mp3', duration = 120 } = opts;
  const WaveSurfer = (await import('wavesurfer.js')).default;
  const mockWs = createMockWaveSurfer(duration);
  vi.mocked(WaveSurfer.create).mockReturnValue(mockWs as any);

  const initPromise = service.initialize(makeContainer(), url);
  // Fire 'ready' to complete initialization
  mockWs._emit('ready');
  await initPromise;
  return mockWs;
}

// ── Tests ─────────────────────────────────────────────────────────────────────

describe('AudioService', () => {
  let service: AudioService;

  beforeEach(() => {
    AudioService.resetInstance();
    service = AudioService.getInstance();
    usePlayerStore.getState().reset();
  });

  // ── initialize() ────────────────────────────────────────────────────────────

  describe('initialize()', () => {
    it('throws if container is null', async () => {
      await expect(
        service.initialize(null as any, 'http://example.com/a.mp3')
      ).rejects.toThrow('Container element is required');
    });

    it('throws if url is empty', async () => {
      await expect(
        service.initialize(makeContainer(), '')
      ).rejects.toThrow('Valid audio URL is required');
    });

    it('resolves and marks ready when WaveSurfer fires ready with duration > 0', async () => {
      await initService(service);
      expect(service.isWaveformReady()).toBe(true);
    });

    it('sets duration in the player store on ready', async () => {
      await initService(service, { duration: 180 });
      expect(usePlayerStore.getState().duration).toBe(180);
    });

    it('rejects and stays not-ready when duration is 0', async () => {
      const WaveSurfer = (await import('wavesurfer.js')).default;
      const mockWs = createMockWaveSurfer(0);
      vi.mocked(WaveSurfer.create).mockReturnValue(mockWs as any);

      const initPromise = service.initialize(makeContainer(), 'http://example.com/a.mp3');
      mockWs._emit('ready');

      await expect(initPromise).rejects.toThrow('duration is 0');
      expect(service.isWaveformReady()).toBe(false);
    });

    it('rejects when WaveSurfer fires an error', async () => {
      const WaveSurfer = (await import('wavesurfer.js')).default;
      const mockWs = createMockWaveSurfer();
      vi.mocked(WaveSurfer.create).mockReturnValue(mockWs as any);

      const initPromise = service.initialize(makeContainer(), 'http://example.com/a.mp3');
      mockWs._emit('error', new Error('network error'));

      await expect(initPromise).rejects.toThrow('network error');
    });

    it('does nothing when called with same URL and same container', async () => {
      const WaveSurfer = (await import('wavesurfer.js')).default;
      const mockWs = createMockWaveSurfer();
      vi.mocked(WaveSurfer.create).mockReturnValue(mockWs as any);

      const url = 'http://example.com/same.mp3';
      const container = makeContainer();
      const p1 = service.initialize(container, url);
      mockWs._emit('ready');
      await p1;

      const createCount = vi.mocked(WaveSurfer.create).mock.calls.length;
      await service.initialize(container, url); // exact same reference
      expect(vi.mocked(WaveSurfer.create).mock.calls.length).toBe(createCount);
      expect(mockWs.setOptions).not.toHaveBeenCalled();
    });

    it('re-attaches waveform to new container when same URL but container changed (re-navigation)', async () => {
      const WaveSurfer = (await import('wavesurfer.js')).default;
      const mockWs = createMockWaveSurfer();
      vi.mocked(WaveSurfer.create).mockReturnValue(mockWs as any);

      const url = 'http://example.com/same.mp3';
      const p1 = service.initialize(makeContainer(), url);
      mockWs._emit('ready');
      await p1;

      const newContainer = makeContainer(); // different DOM element, same URL
      const createCount = vi.mocked(WaveSurfer.create).mock.calls.length;
      await service.initialize(newContainer, url);

      // No new WaveSurfer instance — just a canvas re-attach
      expect(vi.mocked(WaveSurfer.create).mock.calls.length).toBe(createCount);
      expect(mockWs.setOptions).toHaveBeenCalledWith({ container: newContainer });
    });

    it('resets store state when URL changes', async () => {
      await initService(service, { url: 'http://example.com/a.mp3', duration: 180 });
      usePlayerStore.getState().batchUpdate({ isPlaying: true, currentTime: 45 });

      const WaveSurfer = (await import('wavesurfer.js')).default;
      const mockWs2 = createMockWaveSurfer();
      vi.mocked(WaveSurfer.create).mockReturnValue(mockWs2 as any);
      const p2 = service.initialize(makeContainer(), 'http://example.com/b.mp3');
      mockWs2._emit('ready');
      await p2;

      // State should be reset, not carry over from the previous song
      expect(usePlayerStore.getState().currentTime).toBe(0);
      expect(usePlayerStore.getState().isPlaying).toBe(false);
    });

    it('destroys old instance when URL changes', async () => {
      const WaveSurfer = (await import('wavesurfer.js')).default;

      const mockWs1 = createMockWaveSurfer();
      vi.mocked(WaveSurfer.create).mockReturnValue(mockWs1 as any);
      const p1 = service.initialize(makeContainer(), 'http://example.com/a.mp3');
      mockWs1._emit('ready');
      await p1;

      const mockWs2 = createMockWaveSurfer();
      vi.mocked(WaveSurfer.create).mockReturnValue(mockWs2 as any);
      const p2 = service.initialize(makeContainer(), 'http://example.com/b.mp3');
      mockWs2._emit('ready');
      await p2;

      expect(mockWs1.destroy).toHaveBeenCalled();
    });
  });

  // ── play() ───────────────────────────────────────────────────────────────────

  describe('play()', () => {
    it('does nothing if not ready', async () => {
      // play() silently returns when not ready — no throw, no warn
      await expect(service.play('song-1', 'band-1')).resolves.toBeUndefined();
    });

    it('calls wavesurfer.play()', async () => {
      const mockWs = await initService(service);
      await service.play();
      expect(mockWs.play).toHaveBeenCalled();
    });

    it('updates currentSongId/BandId in the store', async () => {
      await initService(service);
      await service.play('song-1', 'band-1');
      const state = usePlayerStore.getState();
      expect(state.currentSongId).toBe('song-1');
      expect(state.currentBandId).toBe('band-1');
    });

    it('does not update store ids when called without ids', async () => {
      await initService(service);
      await service.play();
      const state = usePlayerStore.getState();
      expect(state.currentSongId).toBeNull();
    });
  });

  // ── pause() ──────────────────────────────────────────────────────────────────

  describe('pause()', () => {
    it('calls wavesurfer.pause() when ready', async () => {
      const mockWs = await initService(service);
      service.pause();
      expect(mockWs.pause).toHaveBeenCalled();
    });

    it('does nothing if not initialized', () => {
      expect(() => service.pause()).not.toThrow();
    });
  });

  // ── seekTo() ─────────────────────────────────────────────────────────────────

  describe('seekTo()', () => {
    it('calls wavesurfer.setTime() with the given time', async () => {
      const mockWs = await initService(service);
      service.seekTo(42);
      expect(mockWs.setTime).toHaveBeenCalledWith(42);
    });

    it('does nothing for non-finite values', async () => {
      const mockWs = await initService(service);
      service.seekTo(Infinity);
      service.seekTo(NaN);
      expect(mockWs.setTime).not.toHaveBeenCalled();
    });

    it('does nothing if not ready', () => {
      expect(() => service.seekTo(10)).not.toThrow();
    });
  });

  // ── cleanup() ────────────────────────────────────────────────────────────────

  describe('cleanup()', () => {
    it('destroys WaveSurfer and marks service not-ready', async () => {
      const mockWs = await initService(service);
      service.cleanup();
      expect(mockWs.destroy).toHaveBeenCalled();
      expect(service.isWaveformReady()).toBe(false);
    });

    it('resets isPlaying, currentTime, and duration in the store', async () => {
      await initService(service, { duration: 180 });
      usePlayerStore.getState().batchUpdate({ isPlaying: true, currentTime: 30 });
      service.cleanup();
      const state = usePlayerStore.getState();
      expect(state.isPlaying).toBe(false);
      expect(state.currentTime).toBe(0);
      expect(state.duration).toBe(0);
    });

    it('is safe to call when not initialized', () => {
      expect(() => service.cleanup()).not.toThrow();
    });
  });

  // ── WaveSurfer event → store sync ────────────────────────────────────────────

  describe('WaveSurfer event handlers', () => {
    it('play event sets store isPlaying=true', async () => {
      const mockWs = await initService(service);
      mockWs._emit('play');
      expect(usePlayerStore.getState().isPlaying).toBe(true);
    });

    it('pause event sets store isPlaying=false', async () => {
      const mockWs = await initService(service);
      usePlayerStore.getState().batchUpdate({ isPlaying: true });
      mockWs._emit('pause');
      expect(usePlayerStore.getState().isPlaying).toBe(false);
    });

    it('finish event sets store isPlaying=false', async () => {
      const mockWs = await initService(service);
      usePlayerStore.getState().batchUpdate({ isPlaying: true });
      mockWs._emit('finish');
      expect(usePlayerStore.getState().isPlaying).toBe(false);
    });

    it('audioprocess event updates store currentTime (throttled at 250ms)', async () => {
      const mockWs = await initService(service);
      // First emission at t=300 passes throttle (300 - lastUpdateTime:0 >= 250)
      vi.spyOn(Date, 'now').mockReturnValue(300);
      mockWs._emit('audioprocess', 15.5);
      expect(usePlayerStore.getState().currentTime).toBe(15.5);

      // Second emission at t=400 is throttled (400 - 300 = 100 < 250)
      vi.spyOn(Date, 'now').mockReturnValue(400);
      mockWs._emit('audioprocess', 16.0);
      expect(usePlayerStore.getState().currentTime).toBe(15.5); // unchanged
    });
  });
});