/*
 * Copyright (c) 2010, The Broad Institute
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

package org.broadinstitute.sting.utils;

import net.sf.samtools.CigarElement;
import net.sf.samtools.CigarOperator;
import net.sf.samtools.Cigar;

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

/**
 * Created by IntelliJ IDEA.
 * User: asivache
 * Date: Mar 23, 2009
 * Time: 1:54:54 PM
 * To change this template use File | Settings | File Templates.
 */
public class SWPairwiseAlignment {
    private int alignment_offset; // offset of s2 w/respect to s1
    private Cigar alignmentCigar;

    private final double w_match;
    private final double w_mismatch;
    private final double w_open;
    private final double w_extend;

    private static final int MSTATE = 0;
    private static final int ISTATE = 1;
    private static final int DSTATE = 2;

    // ************************************************************************
    // ****                    IMPORTANT NOTE:                             ****
    // ****  This class assumes that all bytes come from UPPERCASED chars! ****
    // ************************************************************************
    public SWPairwiseAlignment(byte[] seq1, byte[] seq2, double match, double mismatch, double open, double extend ) {
        w_match = match;
        w_mismatch = mismatch;
        w_open = open;
        w_extend = extend;
        align(seq1,seq2);
    }

    public SWPairwiseAlignment(byte[] seq1, byte[] seq2) {
        this(seq1,seq2,1.0,-1.0/3.0,-1.0-1.0/3.0,-1.0/3.0); // match=1, mismatch = -1/3, gap=-(1+k/3)
    }

    public Cigar getCigar() { return alignmentCigar ; }

    public int getAlignmentStart2wrt1() { return alignment_offset; }

    public void align(final byte[] a, final byte[] b) {
        final int n = a.length;
        final int m = b.length;
        double [][] sw = new double[n+1][m+1];
        int [][] btrack = new int[n+1][m+1];
        calculateMatrix(a, b, sw, btrack);
        calculateCigar(n, m, sw, btrack); // length of the segment (continuous matches, insertions or deletions)
    }

    private void calculateMatrix(final byte[] a, final byte[] b, double [][] sw, int [][] btrack ) {
        final int n = a.length;
        final int m = b.length;

        // build smith-waterman matrix and keep backtrack info:
        for ( int i = 1 ; i < n+1 ; i++ ) {
            byte a_base = a[i-1]; // letter in a at the current pos
            for ( int j = 1 ; j < m+1 ; j++ ) {
                final byte b_base = b[j-1]; // letter in b at the current pos
                double step_diag = sw[i-1][j-1] + wd(a_base,b_base);
                double step_down = 0.0 ;
                int kd = 0;
                for ( int k = 1 ; k < i ; k++ ) {
                    final double gap_penalty = wk(k);
                    if ( step_down < sw[i-k][j]+gap_penalty ) {
                        step_down=sw[i-k][j]+gap_penalty;
                        kd = k;
                    }
                }

                double step_right = 0;
                int ki = 0;
                for ( int k = 1 ; k < j ; k++ ) {
                    final double gap_penalty = wk(k);
                    if ( step_right < sw[i][j-k]+gap_penalty ) {
                        step_right=sw[i][j-k]+gap_penalty;
                        ki = k;
                    }
                }

                if ( step_down > step_right ) {
                    if ( step_down > step_diag ) {
                        sw[i][j] = Math.max(0,step_down);
                        btrack[i][j] = kd; // positive=vertical
                    }
                    else {
                        sw[i][j] = Math.max(0,step_diag);
                        btrack[i][j] = 0; // 0 = diagonal
                    }
                } else {
                    // step_down < step_right
                    if ( step_right > step_diag ) {
                        sw[i][j] = Math.max(0,step_right);
                        btrack[i][j] = -ki; // negative = horizontal
                    } else {
                        sw[i][j] = Math.max(0,step_diag);
                        btrack[i][j] = 0; // 0 = diagonal
                    }
                }

                sw[i][j] = Math.max(0, Math.max(step_diag,Math.max(step_down,step_right)));
            }
        }
//            print(sw,a,b);
    }

    private void calculateCigar(int n, int m, double [][] sw, int [][] btrack) {
        // p holds the position we start backtracking from; we will be assembling a cigar in the backwards order
        //PrimitivePair.Int p = new PrimitivePair.Int();
        int p1 = 0, p2 = 0;

        double maxscore = 0.0;
        int segment_length = 0; // length of the segment (continuous matches, insertions or deletions)

        // look for largest score. we use >= combined with the traversal direction
        // to ensure that if two scores are equal, the one closer to diagonal gets picked
        for ( int i = 1 ; i < n+1 ; i++ ) {
            if ( sw[i][m] >= maxscore ) {
                p1 = i; p2 = m ; maxscore = sw[i][m];
            }
        }

        for ( int j = 1 ; j < m+1 ; j++ ) {
            if ( sw[n][j] > maxscore || sw[n][j] == maxscore && Math.abs(n-j) < Math.abs(p1 - p2)) {
                p1 = n;
                p2 = j ;
                maxscore = sw[n][j];
                segment_length = m - j ; // end of sequence 2 is overhanging; we will just record it as 'M' segment
            }
        }


        // we will be placing all insertions and deletions into sequence b, so the state are named w/regard
        // to that sequence

        int state = MSTATE;
        List<CigarElement> lce = new ArrayList<CigarElement>(5);

        do {
            int btr = btrack[p1][p2];
            int step_left = ( btr < 0 ? -btr : 1);
            int step_up = ( btr > 0 ? btr : 1 );

            int new_state;
            if ( btr > 0 ) new_state = DSTATE;
            else if ( btr < 0 ) new_state = ISTATE;
            else new_state = MSTATE;

            int step_length = 1;

            // move to next best location in the sw matrix:
            switch( new_state ) {
                case MSTATE: p1--; p2--; break;
                case ISTATE: p2-=step_left; step_length = step_left; break;
                case DSTATE: p1-=step_up; step_length = step_up; break;
            }

            // now let's see if the state actually changed:
            if ( new_state == state ) segment_length+=step_length;
            else {
                // state changed, lets emit previous segment, whatever it was (Insertion Deletion, or (Mis)Match).
                lce.add(makeElement(state, segment_length));
                segment_length = step_length;
                state = new_state;
            }
        } while ( sw[p1][p2] != 0 );

        // post-process the last segment we are still keeping
        lce.add(makeElement(state, segment_length + p2));
        alignment_offset = p1 - p2;

        Collections.reverse(lce);
        alignmentCigar = new Cigar(lce);
    }

    private CigarElement makeElement(int state, int segment_length) {
        CigarOperator o = null;
        switch(state) {
            case MSTATE: o = CigarOperator.M; break;
            case ISTATE: o = CigarOperator.I; break;
            case DSTATE: o = CigarOperator.D; break;
        }
        return new CigarElement(segment_length,o);
    }

    private double wd(byte x, byte y) {
        return (x == y ? w_match : w_mismatch);
    }

    private double wk(int k) {
        return w_open+(k-1)*w_extend; // gap
    }

    private void print(int[][] s) {
        for ( int i = 0 ; i < s.length ; i++) {
            for ( int j = 0; j < s[i].length ; j++ ) {
                System.out.printf(" %4d",s[i][j]);
            }
            System.out.println();
        }
    }

    private void print(double[][] s) {
        for ( int i = 0 ; i < s.length ; i++) {
            for ( int j = 0; j < s[i].length ; j++ ) {
                System.out.printf(" %4g",s[i][j]);
            }
            System.out.println();
        }
    }

    private void print(int[][] s, String a, String b) {

        System.out.print("        ");
        for ( int j = 1 ; j < s[0].length ; j++) System.out.printf(" %4c",b.charAt(j-1)) ;
        System.out.println();

        for ( int i = 0 ; i < s.length ; i++) {
            if ( i > 0 ) System.out.print(a.charAt(i-1));
            else System.out.print(' ');
            System.out.print("  ");
            for ( int j = 0; j < s[i].length ; j++ ) {
                System.out.printf(" %4d",s[i][j]);
            }
            System.out.println();
        }
    }


    private void print(double[][] s, String a, String b) {

        System.out.print("");
        for ( int j = 1 ; j < s[0].length ; j++) System.out.printf(" %4c",b.charAt(j-1)) ;
        System.out.println();

        for ( int i = 0 ; i < s.length ; i++) {
            if ( i > 0 ) System.out.print(a.charAt(i-1));
            else System.out.print(' ');
            System.out.print("  ");
            for ( int j = 0; j < s[i].length ; j++ ) {
                System.out.printf(" %2.1f",s[i][j]);
            }
            System.out.println();
        }
    }

}