import { describe, expect, it, vi } from 'vitest';
import { createAudioController } from '@/audio/create-audio-controller';
import { createSynthEngine } from '@/audio/synth-engine';
import type { AudioGraph, AudioGraphFactory } from '@/audio/types';

describe('audio controller lifecycle', () => {
  it('constructs no graph before activation and only one graph for rapid repeated activation', async () => {
    const harness = createHarness();
    const controller = createAudioController({ createGraph: harness.createGraph });

    expect(harness.constructed).toBe(0);
    const first = controller.startFromGesture();
    const second = controller.startFromGesture();

    expect(harness.constructed).toBe(1);
    await Promise.all([first, second]);
    expect(harness.constructed).toBe(1);
    expect(controller.snapshot()).toEqual({ kind: 'running', muted: false, volume: 0.4 });
    expect(harness.graph.connectOutput).toHaveBeenCalledOnce();
  });

  it('applies clamped volume and mute changes made while starting without changing lifecycle intent', async () => {
    const resume = deferred<void>();
    const harness = createHarness({ resume });
    const controller = createAudioController({ createGraph: harness.createGraph, initialVolume: 3 });

    const starting = controller.startFromGesture();
    controller.setVolume(-1);
    controller.setMuted(true);
    expect(controller.snapshot()).toEqual({ kind: 'starting' });

    resume.resolve();
    await starting;
    expect(controller.snapshot()).toEqual({ kind: 'running', muted: true, volume: 0 });
    expect(harness.graph.setOutputGain).toHaveBeenLastCalledWith(0);
  });

  it('retains one initialization when hidden then visible before starting completes', async () => {
    const resume = deferred<void>();
    const harness = createHarness({ resume });
    const controller = createAudioController({ createGraph: harness.createGraph });

    const starting = controller.startFromGesture();
    controller.setVisible(false);
    controller.setVisible(true);
    resume.resolve();
    await starting;

    expect(controller.snapshot().kind).toBe('running');
    expect(harness.constructed).toBe(1);
    expect(harness.graph.suspend).not.toHaveBeenCalled();
    expect(harness.graph.connectOutput).toHaveBeenCalledOnce();
  });

  it('finishes an interrupted initialization only into safely suspended user-required state', async () => {
    const resume = deferred<void>();
    const harness = createHarness({ resume });
    const controller = createAudioController({ createGraph: harness.createGraph });

    const starting = controller.startFromGesture();
    controller.noteInterruption();
    resume.resolve();
    await starting;

    expect(controller.snapshot()).toEqual({ kind: 'suspended', resumeRequiresGesture: true });
    expect(harness.graph.connectOutput).not.toHaveBeenCalled();
    expect(harness.graph.suspend).toHaveBeenCalledOnce();
  });

  it('automatically suspends and resumes an intact graph across visibility and persisted BFCache', async () => {
    const harness = createHarness();
    const controller = createAudioController({ createGraph: harness.createGraph });
    await controller.startFromGesture();

    await controller.pageHide(true);
    expect(controller.snapshot()).toEqual({ kind: 'suspended', resumeRequiresGesture: false });
    expect(harness.graph.disconnectOutput).toHaveBeenCalledOnce();

    await controller.pageShow(true);
    expect(controller.snapshot()).toEqual({ kind: 'running', muted: false, volume: 0.4 });
    expect(harness.constructed).toBe(1);
    expect(harness.graph.resume).toHaveBeenCalledTimes(2);
    expect(harness.graph.connectOutput).toHaveBeenCalledTimes(2);
  });

  it('honors a visible event that arrives before a running suspension completes', async () => {
    const suspension = deferred<void>();
    const harness = createHarness({ suspend: suspension });
    const controller = createAudioController({ createGraph: harness.createGraph });
    await controller.startFromGesture();

    const hiding = controller.setVisible(false);
    const showing = controller.setVisible(true);
    suspension.resolve();
    await Promise.all([hiding, showing]);
    await controller.whenSettled();

    expect(controller.snapshot()).toEqual({ kind: 'running', muted: false, volume: 0.4 });
    expect(harness.graph.suspend).toHaveBeenCalledOnce();
    expect(harness.graph.resume).toHaveBeenCalledTimes(2);
    expect(harness.constructed).toBe(1);
  });

  it('does not convert an interruption into automatic resume on later visibility events', async () => {
    const harness = createHarness();
    const controller = createAudioController({ createGraph: harness.createGraph });
    await controller.startFromGesture();

    await controller.noteInterruption();
    await controller.setVisible(false);
    await controller.setVisible(true);

    expect(controller.snapshot()).toEqual({ kind: 'suspended', resumeRequiresGesture: true });
    expect(harness.graph.resume).toHaveBeenCalledOnce();

    await controller.resumeFromGesture();
    expect(controller.snapshot().kind).toBe('running');
    expect(harness.constructed).toBe(1);
    expect(harness.graph.resume).toHaveBeenCalledTimes(2);
  });

  it('enters a recoverable visible failure when the first explicit start rejects', async () => {
    const harness = createHarness({ resumeRejects: true });
    const controller = createAudioController({ createGraph: harness.createGraph });

    await controller.startFromGesture();

    expect(controller.snapshot()).toEqual({ kind: 'failed', message: 'Audio unavailable' });
    expect(harness.graph.setOutputGain).toHaveBeenLastCalledWith(0);
    expect(harness.graph.disconnectOutput).toHaveBeenCalledOnce();
    expect(harness.graph.close).toHaveBeenCalledOnce();
  });

  it('keeps an existing graph suspended and user-recoverable when automatic resume rejects', async () => {
    const harness = createHarness();
    const controller = createAudioController({ createGraph: harness.createGraph });
    await controller.startFromGesture();
    await controller.setVisible(false);
    harness.rejectNextResume();

    await controller.setVisible(true);

    expect(controller.snapshot()).toEqual({ kind: 'suspended', resumeRequiresGesture: true });
    expect(harness.graph.close).not.toHaveBeenCalled();
    expect(harness.constructed).toBe(1);
  });

  it('forces silence, closes once, and fails when suspension cannot be guaranteed', async () => {
    const harness = createHarness({ suspendRejects: true });
    const controller = createAudioController({ createGraph: harness.createGraph });
    await controller.startFromGesture();

    await controller.setVisible(false);
    await controller.setVisible(true);

    expect(controller.snapshot()).toEqual({ kind: 'failed', message: 'Audio unavailable' });
    expect(harness.graph.setOutputGain).toHaveBeenLastCalledWith(0);
    expect(harness.graph.disconnectOutput).toHaveBeenCalled();
    expect(harness.graph.close).toHaveBeenCalledOnce();
  });

  it('invalidates a pending start and closes exactly once on final pagehide or repeated disposal', async () => {
    const resume = deferred<void>();
    const harness = createHarness({ resume });
    const controller = createAudioController({ createGraph: harness.createGraph });
    const starting = controller.startFromGesture();

    const closing = controller.pageHide(false);
    controller.dispose();
    resume.resolve();
    await Promise.all([starting, closing]);
    await controller.whenSettled();

    expect(controller.snapshot()).toEqual({ kind: 'disposed' });
    expect(harness.graph.connectOutput).not.toHaveBeenCalled();
    expect(harness.graph.close).toHaveBeenCalledOnce();
  });

  it('ignores lifecycle events before activation and after failure without creating another graph', async () => {
    const harness = createHarness({ resumeRejects: true });
    const controller = createAudioController({ createGraph: harness.createGraph });

    await controller.setVisible(false);
    await controller.pageShow(true);
    expect(harness.constructed).toBe(0);
    await controller.startFromGesture();
    await controller.setVisible(true);
    await controller.pageShow(true);

    expect(harness.constructed).toBe(1);
    expect(controller.snapshot().kind).toBe('failed');
  });

  it('clamps and slowly smooths drive intensity before forwarding it to the graph', async () => {
    const harness = createHarness();
    const controller = createAudioController({ createGraph: harness.createGraph });
    await controller.startFromGesture();

    controller.setIntensity(2);
    controller.setIntensity(Number.NaN);

    expect(harness.graph.setIntensity).toHaveBeenNthCalledWith(3, 0.12);
    expect(harness.graph.setIntensity).toHaveBeenNthCalledWith(4, 0.1056);
  });
});

describe('procedural audio graph', () => {
  it('builds an original oscillator, filtered-noise, gain, and dynamics bed while output stays disconnected', async () => {
    const context = new FakeAudioContext();

    const graph = createSynthEngine(() => context as unknown as AudioContext);

    expect(context.oscillators).toHaveLength(3);
    expect(context.bufferSources).toHaveLength(1);
    expect(context.filters).toHaveLength(2);
    expect(context.gains.length).toBeGreaterThanOrEqual(4);
    expect(context.compressors).toHaveLength(1);
    expect(context.startedNodes).toBe(4);
    expect(context.destinationConnections).toBe(0);

    graph.connectOutput();
    graph.setOutputGain(0.6);
    graph.setIntensity(1);
    expect(context.destinationConnections).toBe(1);
    expect(context.parameters.some((parameter) => parameter.targetValues.includes(930))).toBe(true);

    graph.disconnectOutput();
    await graph.close();
    await graph.close();
    expect(context.destinationConnections).toBe(0);
    expect(context.closeCalls).toBe(1);
    expect(context.stoppedNodes).toBe(4);
  });
});

interface HarnessOptions {
  resume?: Deferred<void>;
  suspend?: Deferred<void>;
  resumeRejects?: boolean;
  suspendRejects?: boolean;
}

function createHarness(options: HarnessOptions = {}) {
  let rejectNextResume = options.resumeRejects === true;
  const stateListeners = new Set<(state: string) => void>();
  const graph: AudioGraph = {
    resume: vi.fn(async () => {
      if (options.resume) return options.resume.promise;
      if (rejectNextResume) {
        rejectNextResume = false;
        throw new DOMException('blocked', 'NotAllowedError');
      }
    }),
    suspend: vi.fn(async () => {
      if (options.suspend) return options.suspend.promise;
      if (options.suspendRejects) throw new Error('suspend failed');
    }),
    close: vi.fn(async () => undefined),
    connectOutput: vi.fn(),
    disconnectOutput: vi.fn(),
    setOutputGain: vi.fn(),
    setIntensity: vi.fn(),
    onContextStateChange: vi.fn((listener) => {
      stateListeners.add(listener);
      return () => stateListeners.delete(listener);
    }),
  };
  let constructed = 0;
  const createGraph: AudioGraphFactory = () => {
    constructed += 1;
    return graph;
  };
  return {
    graph,
    createGraph,
    get constructed() { return constructed; },
    rejectNextResume() { rejectNextResume = true; },
    emitState(state: string) { for (const listener of stateListeners) listener(state); },
  };
}

interface Deferred<T> {
  promise: Promise<T>;
  resolve(value: T | PromiseLike<T>): void;
  reject(reason?: unknown): void;
}

function deferred<T>(): Deferred<T> {
  let resolve!: (value: T | PromiseLike<T>) => void;
  let reject!: (reason?: unknown) => void;
  const promise = new Promise<T>((onResolve, onReject) => {
    resolve = onResolve;
    reject = onReject;
  });
  return { promise, resolve, reject };
}

class FakeAudioParam {
  value = 0;
  readonly targetValues: number[] = [];

  setValueAtTime(value: number): void { this.value = value; }
  setTargetAtTime(value: number): void { this.targetValues.push(value); this.value = value; }
  linearRampToValueAtTime(value: number): void { this.value = value; }
  exponentialRampToValueAtTime(value: number): void { this.value = value; }
  cancelScheduledValues(): void {}
}

class FakeNode extends EventTarget {
  readonly connections = new Set<unknown>();
  constructor(protected readonly owner: FakeAudioContext) { super(); }
  connect(target: unknown): unknown {
    this.connections.add(target);
    if (target === this.owner.destination) this.owner.destinationConnections += 1;
    return target;
  }
  disconnect(target?: unknown): void {
    if (target === undefined) {
      if (this.connections.delete(this.owner.destination)) this.owner.destinationConnections -= 1;
      this.connections.clear();
      return;
    }
    if (this.connections.delete(target) && target === this.owner.destination) this.owner.destinationConnections -= 1;
  }
}

class FakeScheduledNode extends FakeNode {
  start(): void { this.owner.startedNodes += 1; }
  stop(): void { this.owner.stoppedNodes += 1; }
}

class FakeAudioContext extends EventTarget {
  readonly destination = {};
  readonly sampleRate = 8_000;
  readonly currentTime = 0;
  readonly parameters: FakeAudioParam[] = [];
  readonly oscillators: Array<FakeScheduledNode & { type: string; frequency: FakeAudioParam }> = [];
  readonly bufferSources: Array<FakeScheduledNode & { buffer: unknown; loop: boolean }> = [];
  readonly filters: Array<FakeNode & { type: string; frequency: FakeAudioParam; Q: FakeAudioParam }> = [];
  readonly gains: Array<FakeNode & { gain: FakeAudioParam }> = [];
  readonly compressors: FakeNode[] = [];
  destinationConnections = 0;
  startedNodes = 0;
  stoppedNodes = 0;
  closeCalls = 0;
  state: AudioContextState = 'suspended';

  private parameter(value = 0): FakeAudioParam {
    const parameter = new FakeAudioParam();
    parameter.value = value;
    this.parameters.push(parameter);
    return parameter;
  }

  createOscillator() {
    const node = Object.assign(new FakeScheduledNode(this), { type: 'sine', frequency: this.parameter(440) });
    this.oscillators.push(node);
    return node;
  }
  createBufferSource() {
    const node = Object.assign(new FakeScheduledNode(this), { buffer: null as unknown, loop: false });
    this.bufferSources.push(node);
    return node;
  }
  createBiquadFilter() {
    const node = Object.assign(new FakeNode(this), {
      type: 'lowpass', frequency: this.parameter(350), Q: this.parameter(1),
    });
    this.filters.push(node);
    return node;
  }
  createGain() {
    const node = Object.assign(new FakeNode(this), { gain: this.parameter(1) });
    this.gains.push(node);
    return node;
  }
  createDynamicsCompressor() {
    const node = new FakeNode(this);
    this.compressors.push(node);
    return node;
  }
  createBuffer(channels: number, length: number) {
    const data = Array.from({ length: channels }, () => new Float32Array(length));
    return { getChannelData: (channel: number) => data[channel] };
  }
  async resume(): Promise<void> { this.state = 'running'; }
  async suspend(): Promise<void> { this.state = 'suspended'; }
  async close(): Promise<void> { this.closeCalls += 1; this.state = 'closed'; }
}