package jalview.datamodel;

import jalview.io.HMMFile;
import jalview.schemes.ResidueProperties;
import jalview.util.Comparison;
import jalview.util.MapList;

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

/**
 * Data structure which stores a hidden Markov model
 * 
 * @author TZVanaalten
 * 
 */
public class HiddenMarkovModel
{
  private static final char GAP_DASH = '-';

  public final static String YES = "yes";

  public final static String NO = "no";

  public static final int MATCHTOMATCH = 0;

  public static final int MATCHTOINSERT = 1;

  public static final int MATCHTODELETE = 2;

  public static final int INSERTTOMATCH = 3;

  public static final int INSERTTOINSERT = 4;

  public static final int DELETETOMATCH = 5;

  public static final int DELETETODELETE = 6;

  private static final double LOG2 = Math.log(2);

  /*
   * properties read from HMM file header lines
   */
  private Map<String, String> fileProperties = new HashMap<>();

  private String fileHeader;
  
  /*
   * the symbols used in this model e.g. "ACGT"
   */
  private String alphabet;

  /*
   * symbol lookup index into the alphabet for 'A' to 'Z'
   */
  private int[] symbolIndexLookup = new int['Z' - 'A' + 1];

  /*
   * Nodes in the model. The begin node is at index 0, and contains 
   * average emission probabilities for each symbol.
   */
  private List<HMMNode> nodes = new ArrayList<>();

  /*
   * the aligned HMM consensus sequence extracted from the HMM profile
   */
  private SequenceI hmmSeq;

  /*
   * mapping from HMM nodes to residues of the hmm consensus sequence
   */
  private Mapping mapToHmmConsensus;

  // stores background frequencies of alignment from which this model came
  private Map<Character, Float> backgroundFrequencies;

  /**
   * Constructor
   */
  public HiddenMarkovModel()
  {
  }

  /**
   * Copy constructor given a new aligned sequence with which to associate the
   * HMM profile
   * 
   * @param hmm
   * @param sq
   */
  public HiddenMarkovModel(HiddenMarkovModel hmm, SequenceI sq)
  {
    super();
    this.fileProperties = new HashMap<>(hmm.fileProperties);
    this.alphabet = hmm.alphabet;
    this.nodes = new ArrayList<>(hmm.nodes);
    this.symbolIndexLookup = hmm.symbolIndexLookup;
    this.fileHeader = new String(hmm.fileHeader);
    this.hmmSeq = sq;
    this.backgroundFrequencies = hmm.getBackgroundFrequencies();
    if (sq.getDatasetSequence() == hmm.mapToHmmConsensus.getTo())
    {
      // same dataset sequence e.g. after realigning search results
      this.mapToHmmConsensus = hmm.mapToHmmConsensus;
    }
    else
    {
      // different dataset sequence e.g. after loading HMM from project
      this.mapToHmmConsensus = new Mapping(sq.getDatasetSequence(),
              hmm.mapToHmmConsensus.getMap());
    }
  }

  /**
   * Returns the information content at a specified column, calculated as the
   * sum (over possible symbols) of the log ratio
   * 
   * <pre>
   *  log(emission probability / background probability) / log(2)
   * </pre>
   * 
   * @param column
   *          column position (base 0)
   * @return
   */
  public float getInformationContent(int column)
  {
    float informationContent = 0f;

    for (char symbol : getSymbols().toCharArray())
    {
      float freq = ResidueProperties.backgroundFrequencies
              .get(getAlphabetType()).get(symbol);
      float prob = (float) getMatchEmissionProbability(column, symbol);
      informationContent += prob * Math.log(prob / freq);
    }

    informationContent = informationContent / (float) LOG2;

    return informationContent;
  }

  /**
   * Gets the file header of the .hmm file this model came from
   * 
   * @return
   */
  public String getFileHeader()
  {
    return fileHeader;
  }

  /**
   * Sets the file header of this model.
   * 
   * @param header
   */
  public void setFileHeader(String header)
  {
    fileHeader = header;
  }

  /**
   * Returns the symbols used in this hidden Markov model
   * 
   * @return
   */
  public String getSymbols()
  {
    return alphabet;
  }
  
  /**
   * Gets the node in the hidden Markov model at the specified position.
   * 
   * @param nodeIndex
   *          The index of the node requested. Node 0 optionally contains the
   *          average match emission probabilities across the entire model, and
   *          always contains the insert emission probabilities and state
   *          transition probabilities for the begin node. Node 1 contains the
   *          first node in the HMM that can correspond to a column in the
   *          alignment.
   * @return
   */
  public HMMNode getNode(int nodeIndex)
  {
    return nodes.get(nodeIndex);
  }

  /**
   * Returns the name of the sequence alignment on which the HMM is based.
   * 
   * @return
   */
  public String getName()
  {
    return fileProperties.get(HMMFile.NAME);
  }
  
  /**
   * Answers the string value of the property (parsed from an HMM file) for the
   * given key, or null if the property is not present
   * 
   * @param key
   * @return
   */
  public String getProperty(String key)
  {
    return fileProperties.get(key);
  }

  /**
   * Answers true if the property with the given key is present with a value of
   * "yes" (not case-sensitive), else false
   * 
   * @param key
   * @return
   */
  public boolean getBooleanProperty(String key)
  {
    return YES.equalsIgnoreCase(fileProperties.get(key));
  }

  /**
   * Returns the length of the hidden Markov model. The value returned is the
   * LENG property if specified, else the number of nodes, excluding the begin
   * node (which should be the same thing).
   * 
   * @return
   */
  public int getLength()
  {
    if (fileProperties.get(HMMFile.LENGTH) == null)
    {
      return nodes.size() - 1; // not counting BEGIN node
    }
    return Integer.parseInt(fileProperties.get(HMMFile.LENGTH));
  }

  /**
   * Returns the value of mandatory property "ALPH" - "amino", "DNA", "RNA" are
   * the options. Other alphabets may be added.
   * 
   * @return
   */
  public String getAlphabetType()
  {
    return fileProperties.get(HMMFile.ALPHABET);
  }

  /**
   * Sets the model alphabet to the symbols in the given string (ignoring any
   * whitespace), and returns the number of symbols
   * 
   * @param symbols
   */
  public int setAlphabet(String symbols)
  {
    String trimmed = symbols.toUpperCase().replaceAll("\\s", "");
    int count = trimmed.length();
    alphabet = trimmed;
    symbolIndexLookup = new int['Z' - 'A' + 1];
    Arrays.fill(symbolIndexLookup, -1);
    int ignored = 0;

    /*
     * save the symbols in order, and a quick lookup of symbol position
     */
    for (short i = 0; i < count; i++)
    {
      char symbol = trimmed.charAt(i);
      if (symbol >= 'A' && symbol <= 'Z'
              && symbolIndexLookup[symbol - 'A'] == -1)
      {
        symbolIndexLookup[symbol - 'A'] = i;
      }
      else
      {
        System.err
                .println(
                        "Unexpected or duplicated character in HMM ALPHabet: "
                                + symbol);
        ignored++;
      }
    }
    return count - ignored;
  }

  /**
   * Answers the node of the model corresponding to an aligned column position
   * (0...), or null if there is no such node
   * 
   * @param column
   * @return
   */
  HMMNode getNodeForColumn(int column)
  {
    /*
     * if the hmm consensus is gapped at the column,
     * there is no corresponding node
     */
    if (Comparison.isGap(hmmSeq.getCharAt(column)))
    {
      return null;
    }

    /*
     * find the node (if any) that is mapped to the
     * consensus sequence residue position at the column
     */
    int seqPos = hmmSeq.findPosition(column);
    int[] nodeNo = mapToHmmConsensus.getMap().locateInFrom(seqPos, seqPos);
    if (nodeNo != null)
    {
      return getNode(nodeNo[0]);
    }
    return null;
  }

  /**
   * Gets the match emission probability for a given symbol at a column in the
   * alignment.
   * 
   * @param alignColumn
   *          The index of the alignment column, starting at index 0. Index 0
   *          usually corresponds to index 1 in the HMM.
   * @param symbol
   *          The symbol for which the desired probability is being requested.
   * @return
   * 
   */
  public double getMatchEmissionProbability(int alignColumn, char symbol)
  {
    HMMNode node = getNodeForColumn(alignColumn);
    int symbolIndex = getSymbolIndex(symbol);
    if (node != null && symbolIndex != -1)
    {
      return node.getMatchEmission(symbolIndex);
    }
    return 0D;
  }

  /**
   * Gets the insert emission probability for a given symbol at a column in the
   * alignment.
   * 
   * @param alignColumn
   *          The index of the alignment column, starting at index 0. Index 0
   *          usually corresponds to index 1 in the HMM.
   * @param symbol
   *          The symbol for which the desired probability is being requested.
   * @return
   * 
   */
  public double getInsertEmissionProbability(int alignColumn, char symbol)
  {
    HMMNode node = getNodeForColumn(alignColumn);
    int symbolIndex = getSymbolIndex(symbol);
    if (node != null && symbolIndex != -1)
    {
      return node.getInsertEmission(symbolIndex);
    }
    return 0D;
  }
  
  /**
   * Gets the state transition probability for a given symbol at a column in the
   * alignment.
   * 
   * @param alignColumn
   *          The index of the alignment column, starting at index 0. Index 0
   *          usually corresponds to index 1 in the HMM.
   * @param symbol
   *          The symbol for which the desired probability is being requested.
   * @return
   * 
   */
  public double getStateTransitionProbability(int alignColumn,
          int transition)
  {
    HMMNode node = getNodeForColumn(alignColumn);
    if (node != null)
    {
      return node.getStateTransition(transition);
    }
    return 0D;
  }
  
  /**
   * Returns the sequence position linked to the node at the given index. This
   * corresponds to an aligned column position (counting from 1).
   * 
   * @param nodeIndex
   *          The index of the node, starting from index 1. Index 0 is the begin
   *          node, which does not correspond to a column in the alignment.
   * @return
   */
  public int getNodeMapPosition(int nodeIndex)
  {
    return nodes.get(nodeIndex).getResidueNumber();
  }
  
  /**
   * Returns the consensus residue at the specified node.
   * 
   * @param nodeIndex
   *          The index of the specified node.
   * @return
   */
  public char getConsensusResidue(int nodeIndex)
  {
   char value = nodes.get(nodeIndex).getConsensusResidue();
   return value;
  }
  
  /**
   * Returns the reference annotation at the specified node.
   * 
   * @param nodeIndex
   *          The index of the specified node.
   * @return
   */
  public char getReferenceAnnotation(int nodeIndex)
  {
   char value = nodes.get(nodeIndex).getReferenceAnnotation();
   return value;
  }
  
  /**
   * Returns the mask value at the specified node.
   * 
   * @param nodeIndex
   *          The index of the specified node.
   * @return
   */
  public char getMaskedValue(int nodeIndex)
  {
   char value = nodes.get(nodeIndex).getMaskValue();
   return value;
  }
  
  /**
   * Returns the consensus structure at the specified node.
   * 
   * @param nodeIndex
   *          The index of the specified node.
   * @return
   */
  public char getConsensusStructure(int nodeIndex)
  {
   char value = nodes.get(nodeIndex).getConsensusStructure();
   return value;
  }
  
  /**
   * Sets a property read from an HMM file
   * 
   * @param key
   * @param value
   */
  public void setProperty(String key, String value)
  {
    fileProperties.put(key, value);
  }

  /**
   * Temporary implementation, should not be used.
   * 
   * @return
   */
  public String getViterbi()
  {
    String value;
    value = fileProperties.get(HMMFile.VITERBI);
    return value;
  }

  /**
   * Temporary implementation, should not be used.
   * 
   * @return
   */
  public String getMSV()
  {
    String value;
    value = fileProperties.get(HMMFile.MSV);
    return value;
  }

  /**
   * Temporary implementation, should not be used.
   * 
   * @return
   */
  public String getForward()
  {
    String value;
    value = fileProperties.get(HMMFile.FORWARD);
    return value;
  }

  /**
   * Constructs the consensus sequence based on the most probable symbol at each
   * position. Gap characters are inserted for discontinuities in the node map
   * numbering (if provided), else an ungapped sequence is generated.
   * <p>
   * A mapping between the HMM nodes and residue positions of the sequence is
   * also built and saved.
   * 
   * @return
   */
  void buildConsensusSequence()
  {
    List<int[]> toResidues = new ArrayList<>();

    /*
     * if the HMM provided a map to sequence, use those start/end values,
     * else just treat it as for a contiguous sequence numbered from 1
     */
    boolean hasMap = getBooleanProperty(HMMFile.MAP);
    int start = hasMap ? getNode(1).getResidueNumber() : 1;
    int endResNo = hasMap ? getNode(nodes.size() - 1).getResidueNumber()
            : (start + getLength() - 1);
    char[] sequence = new char[endResNo];

    int lastResNo = start - 1;
    int seqOffset = -1;
    int gapCount = 0;


    for (int seqN = 0; seqN < start; seqN++)
    {
      sequence[seqN] = GAP_DASH;
      seqOffset++;
    }
    
    for (int nodeNo = 1; nodeNo < nodes.size(); nodeNo++)
    {
      HMMNode node = nodes.get(nodeNo);
      final int resNo = hasMap ? node.getResidueNumber() : lastResNo + 1;

      /*
       * insert gaps if map numbering is not continuous
       */
      while (resNo > lastResNo + 1)
      {
        sequence[seqOffset++] = GAP_DASH;
        lastResNo++;
        gapCount++;
      }
      char consensusResidue = node.getConsensusResidue();
      if (GAP_DASH == consensusResidue)
      {
        /*
         * no residue annotation in HMM - scan for the symbol
         * with the highest match emission probability
         */
        int symbolIndex = node.getMaxMatchEmissionIndex();
        consensusResidue = alphabet.charAt(symbolIndex);
        if (node.getMatchEmission(symbolIndex) < 0.5D)
        {
          // follow convention of lower case if match emission prob < 0.5
          consensusResidue = Character.toLowerCase(consensusResidue);
        }
      }
      sequence[seqOffset++] = consensusResidue;
      lastResNo = resNo;
    }

    Sequence seq = new Sequence(getName(), sequence, start,
            lastResNo - gapCount);
    seq.createDatasetSequence();
    seq.setHMM(this);
    this.hmmSeq = seq;

    /*
     * construct and store Mapping of nodes to residues
     * note as constructed this is just an identity mapping, 
     * but it allows for greater flexibility in future
     */
    List<int[]> fromNodes = new ArrayList<>();
    fromNodes.add(new int[] { 1, getLength() });
    toResidues.add(new int[] { seq.getStart(), seq.getEnd() });
    MapList mapList = new MapList(fromNodes, toResidues, 1, 1);
    mapToHmmConsensus = new Mapping(seq.getDatasetSequence(), mapList);
  }


  /**
   * Answers the aligned consensus sequence for the profile. Note this will
   * return null if called before <code>setNodes</code> has been called.
   * 
   * @return
   */
  public SequenceI getConsensusSequence()
  {
    return hmmSeq;
  }

  /**
   * Answers the index position (0...) of the given symbol, or -1 if not a valid
   * symbol for this HMM
   * 
   * @param symbol
   * @return
   */
  private int getSymbolIndex(char symbol)
  {
    /*
     * symbolIndexLookup holds the index for 'A' to 'Z'
     */
    char c = Character.toUpperCase(symbol);
    if ('A' <= c && c <= 'Z')
    {
      return symbolIndexLookup[c - 'A'];
    }
    return -1;
  }

  /**
   * Sets the nodes of this HMM, and also extracts the HMM consensus sequence
   * and a mapping between node numbers and sequence positions
   * 
   * @param nodeList
   */
  public void setNodes(List<HMMNode> nodeList)
  {
    nodes = nodeList;
    if (nodes.size() > 1)
    {
      buildConsensusSequence();
    }
  }

  /**
   * Sets the aligned consensus sequence this HMM is the model for
   * 
   * @param hmmSeq
   */
  public void setHmmSeq(SequenceI hmmSeq)
  {
    this.hmmSeq = hmmSeq;
  }

  public void setBackgroundFrequencies(Map<Character, Float> bkgdFreqs)
  {
    backgroundFrequencies = bkgdFreqs;
  }

  public void setBackgroundFrequencies(ResidueCount bkgdFreqs)
  {
    backgroundFrequencies = new HashMap<>();

    int total = bkgdFreqs.getTotalResidueCount();

    for (char c : bkgdFreqs.getSymbolCounts().symbols)
    {
      backgroundFrequencies.put(c, bkgdFreqs.getCount(c) * 1f / total);
    }

  }

  public Map<Character, Float> getBackgroundFrequencies()
  {
    return backgroundFrequencies;
  }

}