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.TreeMap;

/**
 * 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, Map<String, AttributeData>> attributes;

  private class AttributeData
  {
    /*
     * description(s) for this attribute, if known
     * (different feature source might have differing descriptions)
     */
    List<String> description;

    /*
     * minimum value (of any numeric values recorded)
     */
    float min = 0f;

    /*
     * maximum value (of any numeric values recorded)
     */
    float max = 0f;

    /**
     * Note one instance of this attribute, recording unique, non-null names,
     * and the min/max of any numerical values
     * 
     * @param desc
     * @param value
     */
    void addInstance(String desc, String value)
    {
      if (desc != null)
      {
        if (description == null)
        {
          description = new ArrayList<>();
        }
        if (!description.contains(desc))
        {
          description.add(desc);
        }
        if (value != null)
        {
          try
          {
            float f = Float.valueOf(value);
            min = Float.min(min, f);
            max = Float.max(max, f);
          } catch (NumberFormatException e)
          {
            // ok, wasn't a number
          }
        }
      }
    }

    /**
     * Answers the description of the attribute, if recorded and unique, or null if either no, or more than description is recorded
     * @return
     */
    public String getDescription()
    {
      if (description != null && description.size() == 1)
      {
        return description.get(0);
      }
      return null;
    }
  }

  /**
   * 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).keySet());
  }

  /**
   * 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 and description for the given feature
   * type, and updates the min-max for any numeric value
   * 
   * @param featureType
   * @param attName
   * @param description
   * @param value
   */
  public void addAttribute(String featureType, String attName,
          String description, String value)
  {
    if (featureType == null || attName == null)
    {
      return;
    }

    Map<String, AttributeData> atts = attributes.get(featureType);
    if (atts == null)
    {
      atts = new TreeMap<String, AttributeData>(
              String.CASE_INSENSITIVE_ORDER);
      attributes.put(featureType, atts);
    }
    AttributeData attData = atts.get(attName);
    if (attData == null)
    {
      attData = new AttributeData();
      atts.put(attName, attData);
    }
    attData.addInstance(description, value);
  }

  /**
   * Answers the description of the given attribute for the given feature type,
   * if known and unique, else null
   * 
   * @param featureType
   * @param attName
   * @return
   */
  public String getDescription(String featureType, String attName)
  {
    String desc = null;
    Map<String, AttributeData> atts = attributes.get(featureType);
    if (atts != null)
    {
      AttributeData attData = atts.get(attName);
      if (attData != null)
      {
        desc = attData.getDescription();
      }
    }
    return desc;
  }
}