import { encodeHex } from '@std/encoding/hex';
import { LRUCache } from 'lru-cache';
import type { AudioToken } from '../domain/types.ts';
import { TOKEN_CACHE_MAX_ITEMS, TOKEN_TTL_MS } from '../shared/constants.ts';

/**
 * Token store service for managing short-lived audio streaming tokens
 */
export class TokenStoreService {
  private readonly tokenCache: LRUCache<string, AudioToken>;

  constructor(ttlMs: number = TOKEN_TTL_MS) {
    this.tokenCache = new LRUCache<string, AudioToken>({
      max: TOKEN_CACHE_MAX_ITEMS,
      ttl: ttlMs,
      ttlAutopurge: true,
      allowStale: false,
      updateAgeOnGet: false,
      updateAgeOnHas: false,
    });
  }

  /**
   * Generate a random token
   */
  private generateToken(): string {
    const bytes = new Uint8Array(16);
    crypto.getRandomValues(bytes);
    return encodeHex(bytes);
  }

  /**
   * Create and store a new token
   */
  putToken(value: AudioToken, ttlMs?: number): string {
    const token = this.generateToken();
    
    const options = ttlMs ? { ttl: Math.max(1000, ttlMs) } : undefined;
    this.tokenCache.set(token, value, options);
    
    return token;
  }

  /**
   * Retrieve token data
   */
  getToken(token: string): AudioToken | undefined {
    if (!token) return undefined;
    return this.tokenCache.get(token);
  }

  /**
   * Remove a token
   */
  deleteToken(token: string): boolean {
    return this.tokenCache.delete(token);
  }

  /**
   * Clear all tokens
   */
  clearAll(): void {
    this.tokenCache.clear();
  }

  /**
   * Get cache size
   */
  getSize(): number {
    return this.tokenCache.size;
  }
}