package grading;

import java.util.List;

/**
 * An implementation GradingStrategy that simply totals the scores for all grades.
 */
public class TotalStrategy implements GradingStrategy
{
  /**
   * Creates a new instance of TotalStrategy.
   */
  public TotalStrategy()
  {
  }

  /**
   * @param key
   *          The key of the final totaled grade
   * @param grades
   *          The list of grades to calculate the final total grade from
   * @return A new grade representing the total of grades
   */
  public Grade calculate(final String key, final List<Grade> grades) throws SizeException
  {
    if (grades == null || grades.isEmpty())
    {
      throw new SizeException();
    }

    Double total = 0.0;

    for (Grade grade : grades)
    {
      total += Missing.doubleValue(grade.getValue());
    }

    return new LeafGrade(key, total);
  }
}