// Volumes of a game: shared by all games unless the game has been given its own.

import type { Volumes } from "./audio";

type Store = Pick<Storage, "getItem" | "setItem" | "removeItem">;

function usable(v: any): v is number {
  return typeof v === "number" && Number.isFinite(v);
}

const clamp = (v: number) => Math.max(0, Math.min(1, v));

export class VolumeStore {
  constructor(private key: string | null, private storage: Store = localStorage) {}

  get available() {
    return this.key !== null;
  }

  /** This game's own volumes, or null when it has none (it then plays with the shared ones). */
  read(): Volumes | null {
    if (!this.key) return null;
    try {
      const data = JSON.parse(this.storage.getItem(this.key) ?? "null");
      if (data && usable(data.music) && usable(data.sound) && usable(data.voice)) {
        return { music: clamp(data.music), sound: clamp(data.sound), voice: clamp(data.voice) };
      }
    } catch {
      /* storage unavailable or damaged: fall back to the shared volumes */
    }
    return null;
  }

  write({ music, sound, voice }: Volumes) {
    if (!this.key) return;
    try {
      this.storage.setItem(this.key, JSON.stringify({ music, sound, voice }));
    } catch {
      /* the change still applies for this session */
    }
  }

  clear() {
    if (!this.key) return;
    try {
      this.storage.removeItem(this.key);
    } catch {
      /* nothing to remove */
    }
  }
}