import java.io.FileNotFoundException;
import java.util.List;

/**
 * Instances of this interface can be used to load weather data either from the API, or an XML file.
 * 
 * @author Tommy F
 */
public interface IForecastLoader {

  /**
   * This method loads the weather forecast from the API.
   * 
   * @return A list of forecast objects
   * @throws IllegalStateException if an error occurred and the data could not be fetched/parsed
   */
  public List<IForecast> fetchWeather() throws IllegalStateException;

  /**
   * This method loads the weather forecast from an XML file. This is for backup only if the API
   * does not work. It requires an XML file with the same exact contents as the API response.
   * 
   * @param filepathToXML path to the XML file relative to the executable
   * @return A list of forecast objects
   * @throws FileNotFoundException If the file given does not exist
   * @throws IllegalStateException if an error occurred and the data could not be parsed
   */
  public List<IForecast> fetchWeatherXML(String filepathToXML)
      throws FileNotFoundException, IllegalStateException;
}