import {
  AudioListener,
  Group,
  PositionalAudio,
  Scene,
  Vector3,
  type PerspectiveCamera
} from "three";

import type { LoadedAudioAsset } from "../assets/audio-assets";
import type { ProjectAssetRecord } from "../assets/project-assets";
import type { InteractionLink } from "../interactions/interaction-links";
import type { RuntimePlayerAudioHookState } from "./navigation-controller";
import type {
  RuntimeSceneDefinition,
  RuntimeSoundEmitter
} from "./runtime-scene-build";

interface RuntimeSoundEmitterState {
  entity: RuntimeSoundEmitter;
  group: Group;
  audio: PositionalAudio | null;
  buffer: AudioBuffer | null;
}

const _listenerPosition = /*@__PURE__*/ new Vector3();
const _emitterPosition = /*@__PURE__*/ new Vector3();

function getErrorDetail(error: unknown): string {
  if (error instanceof Error && error.message.trim().length > 0) {
    return error.message.trim();
  }

  return "Unknown error.";
}

function formatSoundEmitterLabel(
  entityId: string,
  link: InteractionLink | null
): string {
  return link === null ? entityId : `${entityId} (${link.id})`;
}

export function computeSoundEmitterDistanceGain(
  distance: number,
  refDistance: number,
  maxDistance: number
): number {
  if (
    !Number.isFinite(distance) ||
    !Number.isFinite(refDistance) ||
    !Number.isFinite(maxDistance)
  ) {
    return 0;
  }

  if (distance <= refDistance) {
    return 1;
  }

  if (maxDistance <= refDistance) {
    return 0;
  }

  if (distance >= maxDistance) {
    return 0;
  }

  const normalizedDistance =
    (distance - refDistance) / (maxDistance - refDistance);
  const clampedDistance = Math.min(1, Math.max(0, normalizedDistance));
  const proximity = 1 - clampedDistance;
  const easedProximity = proximity * proximity * proximity * proximity;

  return easedProximity;
}

export class RuntimeAudioSystem {
  private readonly camera: PerspectiveCamera;
  private readonly scene: Scene;
  private readonly soundGroup = new Group();
  private readonly soundEmitters = new Map<string, RuntimeSoundEmitterState>();
  private readonly pendingPlayEmitterIds = new Set<string>();
  private readonly listener: AudioListener | null;
  private runtimeScene: RuntimeSceneDefinition | null = null;
  private projectAssets: Record<string, ProjectAssetRecord> = {};
  private loadedAudioAssets: Record<string, LoadedAudioAsset> = {};
  private runtimeMessageHandler: ((message: string | null) => void) | null;
  private currentRuntimeMessage: string | null = null;
  private unlockRequested = false;
  private playerAudioHooks: RuntimePlayerAudioHookState | null = null;

  constructor(
    scene: Scene,
    camera: PerspectiveCamera,
    runtimeMessageHandler: ((message: string | null) => void) | null
  ) {
    this.scene = scene;
    this.camera = camera;
    this.runtimeMessageHandler = runtimeMessageHandler;
    this.scene.add(this.soundGroup);

    let listener: AudioListener | null = null;

    try {
      listener = new AudioListener();
      this.camera.add(listener);
    } catch (error) {
      console.warn(
        `Audio is unavailable in this browser environment: ${getErrorDetail(error)}`
      );
    }

    this.listener = listener;
  }

  setRuntimeMessageHandler(handler: ((message: string | null) => void) | null) {
    this.runtimeMessageHandler = handler;
  }

  loadScene(runtimeScene: RuntimeSceneDefinition) {
    this.runtimeScene = runtimeScene;
    this.rebuildSoundEmitters();
    this.queueAutoplayEmitters();
  }

  updateAssets(
    projectAssets: Record<string, ProjectAssetRecord>,
    loadedAudioAssets: Record<string, LoadedAudioAsset>
  ) {
    this.projectAssets = projectAssets;
    this.loadedAudioAssets = loadedAudioAssets;
    this.rebuildSoundEmitters();
    this.queueAutoplayEmitters();
  }

  updateListenerTransform() {
    this.listener?.updateMatrixWorld(true);
    this.updateSoundEmitterVolumes();
  }

  setPlayerControllerAudioHooks(hooks: RuntimePlayerAudioHookState | null) {
    this.playerAudioHooks = hooks;
    this.updateSoundEmitterVolumes();
  }

  handleUserGesture() {
    if (this.listener === null) {
      return;
    }

    const context = this.listener.context;

    if (context.state === "running") {
      if (this.unlockRequested) {
        this.unlockRequested = false;
        this.setRuntimeMessage(null);
      }

      return;
    }

    this.unlockRequested = true;

    void context
      .resume()
      .then(() => {
        this.unlockRequested = false;
        this.flushPendingPlays();
        this.setRuntimeMessage(null);
      })
      .catch((error) => {
        this.setRuntimeMessage(`Audio unlock failed: ${getErrorDetail(error)}`);
      });
  }

  playSound(soundEmitterId: string, link: InteractionLink | null = null) {
    const soundEmitter = this.soundEmitters.get(soundEmitterId);

    if (soundEmitter === undefined) {
      this.setRuntimeMessage(
        `Sound emitter ${formatSoundEmitterLabel(soundEmitterId, link)} could not be found.`
      );
      return;
    }

    if (this.listener === null) {
      this.setRuntimeMessage(
        "Audio is unavailable in this browser environment."
      );
      return;
    }

    if (soundEmitter.buffer === null) {
      const assetLabel = this.describeAudioAssetAvailability(
        soundEmitter.entity.audioAssetId
      );
      this.setRuntimeMessage(
        `Sound emitter ${formatSoundEmitterLabel(soundEmitterId, link)} cannot play because ${assetLabel}.`
      );
      console.warn(
        `playSound: ${soundEmitterId} has no playable audio buffer.`
      );
      return;
    }

    if (this.listener.context.state !== "running") {
      this.pendingPlayEmitterIds.add(soundEmitterId);
      this.setRuntimeMessage(
        "Audio is locked. Click the runner to enable sound."
      );
      return;
    }

    this.playBufferedSound(soundEmitterId);
  }

  hasSoundEmitter(soundEmitterId: string): boolean {
    return this.soundEmitters.has(soundEmitterId);
  }

  stopSound(soundEmitterId: string) {
    this.pendingPlayEmitterIds.delete(soundEmitterId);

    const soundEmitter = this.soundEmitters.get(soundEmitterId);

    if (soundEmitter === undefined || soundEmitter.audio === null) {
      return;
    }

    try {
      soundEmitter.audio.stop();
    } catch (error) {
      console.warn(
        `stopSound: ${soundEmitterId} could not be stopped: ${getErrorDetail(error)}`
      );
    }
  }

  setSoundEmitterVolume(soundEmitterId: string, volume: number) {
    const soundEmitter = this.soundEmitters.get(soundEmitterId);

    if (soundEmitter === undefined) {
      return;
    }

    soundEmitter.entity.volume = volume;
    this.updateSoundEmitterVolume(soundEmitter);
  }

  dispose() {
    for (const soundEmitterId of this.soundEmitters.keys()) {
      this.stopSound(soundEmitterId);
    }

    this.pendingPlayEmitterIds.clear();

    for (const soundEmitter of this.soundEmitters.values()) {
      this.soundGroup.remove(soundEmitter.group);
      if (soundEmitter.audio !== null) {
        soundEmitter.group.remove(soundEmitter.audio);
      }
    }

    this.soundEmitters.clear();
    this.scene.remove(this.soundGroup);

    if (this.listener !== null) {
      this.camera.remove(this.listener);
    }
  }

  private setRuntimeMessage(message: string | null) {
    if (this.currentRuntimeMessage === message) {
      return;
    }

    this.currentRuntimeMessage = message;
    this.runtimeMessageHandler?.(message);
  }

  private rebuildSoundEmitters() {
    if (this.runtimeScene === null) {
      return;
    }

    for (const soundEmitter of this.soundEmitters.values()) {
      this.stopSound(soundEmitter.entity.entityId);
      this.soundGroup.remove(soundEmitter.group);
      if (soundEmitter.audio !== null) {
        soundEmitter.group.remove(soundEmitter.audio);
      }
    }

    this.soundEmitters.clear();

    for (const entity of this.runtimeScene.entities.soundEmitters) {
      const group = new Group();
      group.position.set(
        entity.position.x,
        entity.position.y,
        entity.position.z
      );

      let audio: PositionalAudio | null = null;

      if (this.listener !== null) {
        audio = new PositionalAudio(this.listener);
        this.configurePositionalAudio(audio, entity);
        audio.position.set(0, 0, 0);
        group.add(audio);
      }

      const buffer = this.resolveAudioBuffer(entity.audioAssetId);

      if (audio !== null && buffer !== null) {
        audio.setBuffer(buffer);
      }

      this.soundGroup.add(group);
      this.soundEmitters.set(entity.entityId, {
        entity,
        group,
        audio,
        buffer
      });
    }
  }

  private resolveAudioBuffer(audioAssetId: string | null): AudioBuffer | null {
    if (audioAssetId === null) {
      return null;
    }

    const loadedAsset = this.loadedAudioAssets[audioAssetId];

    if (loadedAsset !== undefined) {
      return loadedAsset.buffer;
    }

    const asset = this.projectAssets[audioAssetId];

    if (asset === undefined) {
      return null;
    }

    if (asset.kind !== "audio") {
      return null;
    }

    return null;
  }

  private describeAudioAssetAvailability(audioAssetId: string | null): string {
    if (audioAssetId === null) {
      return "no assigned audio asset";
    }

    const asset = this.projectAssets[audioAssetId];

    if (asset === undefined) {
      return `missing audio asset ${audioAssetId}`;
    }

    if (asset.kind !== "audio") {
      return `asset ${audioAssetId} is not an audio asset`;
    }

    return `audio asset ${audioAssetId} is unavailable`;
  }

  private queueAutoplayEmitters() {
    if (this.runtimeScene === null) {
      return;
    }

    for (const entity of this.runtimeScene.entities.soundEmitters) {
      if (entity.autoplay) {
        this.pendingPlayEmitterIds.add(entity.entityId);
      }
    }

    this.flushPendingPlays();
  }

  private flushPendingPlays() {
    if (this.listener === null || this.listener.context.state !== "running") {
      return;
    }

    const pendingEmitterIds = [...this.pendingPlayEmitterIds];
    this.pendingPlayEmitterIds.clear();

    for (const soundEmitterId of pendingEmitterIds) {
      this.playBufferedSound(soundEmitterId);
    }
  }

  private playBufferedSound(soundEmitterId: string) {
    const soundEmitter = this.soundEmitters.get(soundEmitterId);

    if (
      soundEmitter === undefined ||
      soundEmitter.audio === null ||
      soundEmitter.buffer === null
    ) {
      return;
    }

    try {
      soundEmitter.audio.stop();
    } catch {
      // three.js audio.stop() can throw when the underlying source is not active yet.
    }

    this.configurePositionalAudio(soundEmitter.audio, soundEmitter.entity);
    this.updateSoundEmitterVolume(soundEmitter);
    soundEmitter.audio.setBuffer(soundEmitter.buffer);
    soundEmitter.audio.play();
  }

  private configurePositionalAudio(
    audio: PositionalAudio,
    entity: RuntimeSoundEmitter
  ) {
    audio.setLoop(entity.loop);
    audio.setRefDistance(entity.refDistance);
    audio.setMaxDistance(entity.maxDistance);
    audio.setDistanceModel("inverse");
    audio.setRolloffFactor(0);
  }

  private updateSoundEmitterVolumes() {
    if (this.listener === null) {
      return;
    }

    for (const soundEmitter of this.soundEmitters.values()) {
      this.updateSoundEmitterVolume(soundEmitter);
    }
  }

  private updateSoundEmitterVolume(soundEmitter: RuntimeSoundEmitterState) {
    if (soundEmitter.audio === null) {
      return;
    }

    this.camera.getWorldPosition(_listenerPosition);
    soundEmitter.group.getWorldPosition(_emitterPosition);
    const distance = _listenerPosition.distanceTo(_emitterPosition);
    const attenuation = computeSoundEmitterDistanceGain(
      distance,
      soundEmitter.entity.refDistance,
      soundEmitter.entity.maxDistance
    );
    const underwaterDuck =
      1 - (this.playerAudioHooks?.underwaterAmount ?? 0) * 0.4;

    soundEmitter.audio.setVolume(
      soundEmitter.entity.volume * attenuation * underwaterDuck
    );
  }
}