import type { PersistedSession, PersistenceService } from "../app/types";
import { PERSISTENCE_VERSION } from "../app/types";

const STORAGE_KEY = "private-voice-agent/session";

interface StorageLike {
  getItem(key: string): string | null;
  setItem(key: string, value: string): void;
  removeItem(key: string): void;
}

export class LocalPersistenceService implements PersistenceService {
  #storage: StorageLike | null;

  constructor(storage: StorageLike | null = typeof localStorage !== "undefined" ? localStorage : null) {
    this.#storage = storage;
  }

  load(): PersistedSession | null {
    if (!this.#storage) {
      return null;
    }

    const raw = this.#storage.getItem(STORAGE_KEY);
    if (!raw) {
      return null;
    }

    try {
      const parsed = JSON.parse(raw) as PersistedSession;
      if (parsed.version !== PERSISTENCE_VERSION) {
        this.clear();
        return null;
      }
      return parsed;
    } catch {
      this.clear();
      return null;
    }
  }

  save(value: PersistedSession): void {
    if (!this.#storage) {
      return;
    }
    this.#storage.setItem(STORAGE_KEY, JSON.stringify(value));
  }

  clear(): void {
    this.#storage?.removeItem(STORAGE_KEY);
  }
}