package jalview.datamodel.features;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;

/**
 * A singleton class to hold the set of attributes known for each feature type
 */
public class FeatureAttributes
{
  private static FeatureAttributes instance = new FeatureAttributes();

  private Map<String, Set<String>> attributes;

  /**
   * Answers the singleton instance of this class
   * 
   * @return
   */
  public static FeatureAttributes getInstance()
  {
    return instance;
  }

  private FeatureAttributes()
  {
    attributes = new HashMap<>();
  }

  /**
   * Answers the attributes known for the given feature type, in alphabetical
   * order (not case sensitive), or an empty set if no attributes are known
   * 
   * @param featureType
   * @return
   */
  public List<String> getAttributes(String featureType)
  {
    if (!attributes.containsKey(featureType))
    {
      return Collections.<String> emptyList();
    }

    return new ArrayList<>(attributes.get(featureType));
  }

  /**
   * Answers true if at least one attribute is known for the given feature type,
   * else false
   * 
   * @param featureType
   * @return
   */
  public boolean hasAttributes(String featureType)
  {

    if (attributes.containsKey(featureType))
    {
      if (!attributes.get(featureType).isEmpty())
      {
        return true;
      }
    }
    return false;
  }

  /**
   * Records the given attribute name for the given feature type
   * 
   * @param featureType
   * @param attName
   */
  public void addAttribute(String featureType, String attName)
  {
    if (featureType == null || attName == null)
    {
      return;
    }

    if (!attributes.containsKey(featureType))
    {
      attributes.put(featureType, new TreeSet<String>(
              String.CASE_INSENSITIVE_ORDER));
    }

    attributes.get(featureType).add(attName);
  }
}