export class Store {
  public storage: Storage;
  public prefix: string;
  public ttl: number;

  constructor(storage: Storage, prefix: string, ttl: number = 0) {
    this.storage = storage;
    this.prefix = prefix;
    this.ttl = ttl * 1000;
    //TODO: Improve this to run once per prefix
    this.cleanup();
  }

  public get(key: string): null | string {
    if (!key || key.length < 1) {
      return null;
    }

    return this.stripTtl(this.storage.getItem(this.prefix + key));
  }

  public stripTtl(value: string | null): null | string {
    if (value === null) {
      return null;
    }
    const parts = value.split(",");
    if (parts.length === 1) {
      return parts[0];
    }
    const i = parts.shift()
    const ttl = i ? parseInt(i) : 0;
    if (ttl > 0 && ttl < Date.now()) {
      return null;
    }
    return parts.join(",") || '';
  }

  public setWithTTL(key: string, value: string, ttl: number): void {
    if (!key || key.length < 1) {
      return;
    }
    ttl = ttl > 0 ? Date.now() + (ttl * 1000) : 0;
    this.storage.setItem(this.prefix + key, ttl + "," + value);
  }

  public set(key: string, value: string): void {
    this.setWithTTL(key, value, this.ttl);
  }

  public remove(key: string): void {
    this.storage.removeItem(this.prefix + key);
  }

  public cleanup() {
    for (let i = 0; i < this.storage.length; i++) {
      const key = this.storage.key(i);
      if (key === null) {
        continue;
      }

      if (key.startsWith(this.prefix)) {
        const value = this.stripTtl(this.storage.getItem(key));
        if (value === null) // Check for TTLed values
        {
          this.storage.removeItem(key);
        }
      }
    }
  }
}