package jalview.datamodel;

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

/**
 * A singleton object that holds all mappings between sequences
 * 
 * @author gmcarstairs
 *
 */
public class SequenceMappings
{
  private static SequenceMappings instance;

  private Map<SequenceI, List<SequenceMapping>> mappingsFrom;

  private Map<SequenceI, List<SequenceMapping>> mappingsTo;

  /**
   * Non-instantiable class
   */
  private SequenceMappings()
  {
    mappingsFrom = new HashMap<>();
    mappingsTo = new HashMap<>();
  }

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

  /**
   * Answers a (possibly empty) unmodifiable list of mappings from the given
   * sequence
   * 
   * @param seq
   * @return
   */
  public List<SequenceMapping> getMappingsFromSequence(SequenceI seq)
  {
    List<SequenceMapping> from = mappingsFrom.get(seq);
    return from == null ? Collections.emptyList()
            : Collections.unmodifiableList(from);
  }

  /**
   * Answers a (possibly empty) unmodifiable list of mappings to the given
   * sequence
   * 
   * @param seq
   * @return
   */
  public List<SequenceMapping> getMappingsToSequence(SequenceI seq)
  {
    List<SequenceMapping> from = mappingsTo.get(seq);
    return from == null ? Collections.emptyList()
            : Collections.unmodifiableList(from);
  }

  /**
   * Answers a (possibly empty) list of mappings from the given sequence to its
   * complement(s), defined as mappings that are either CdsToPeptide or
   * PeptideToCds
   * 
   * @param seq
   * @return
   */
  public List<SequenceMapping> getMappingsToComplement(SequenceI seq)
  {
    List<SequenceMapping> from = mappingsTo.get(seq);
    List<SequenceMapping> result = new ArrayList<>();
    for (SequenceMapping mapping : from)
    {
      MappingType type = mapping.getType();
    }
    return result;
  }
}