import {Injectable} from '@angular/core';
import {ICache} from './cache.interface';
import {ISerializable} from './serializeable.interface';

@Injectable()
export class LocalStorageCache implements ICache {
  private localStorage: any;

  constructor() {
    if (!localStorage) {
      throw new Error('Current browser does not support Local Storage');
    }

    this.localStorage = localStorage;
  }

  get<T extends ISerializable>(key: string, type: {new(): ISerializable}): T {
    return this.restore<T>(key, new type());
  }

  restore<T extends ISerializable>(key: string, restoreInto: ISerializable): T {
    const result = this.localStorage.getItem(key);

    return result ? <T>restoreInto.deserialize(result) : null;
  }

  set(key: string, data: ISerializable): string {
    this.localStorage.setItem(key, data.serialize());
    return key;
  }

  keyExists(key: string) {
    return !!this.localStorage.getItem(key);
  }

  delete(key: string): boolean {
    const exists = this.keyExists(key);
    if (exists) {
      this.localStorage.removeItem(key);
    }

    return exists;
  }

  clear(): void {
    this.localStorage.clear();
  }
}