#!/usr/bin/env python

"""mut2sscs.py

Author -- Gundula Povysil
Contact -- povysil@bioinf.jku.at

Takes a tabular file with mutations from DCS and a BAM file of SSCS as input
and extracts all tags of reads that carry the mutation.
Calculates statistics about number of ab/ba/duplex per mutation.

=======  ==========  =================  ================================
Version  Date        Author             Description
0.2.1    2019-10-27  Gundula Povysil    -
=======  ==========  =================  ================================

USAGE: python mut2sscs.py DCS_Mutations.tabular SSCS.bam SSCS_counts.json

"""

from __future__ import division

import argparse
import json
import os
import sys

import numpy as np
import pysam


def make_argparser():
    parser = argparse.ArgumentParser(description='Takes a tabular file with mutations and a BAM file as input and prints all tags of reads that carry the mutation to a user specified output file.')
    parser.add_argument('--mutFile',
                        help='TABULAR file with DCS mutations.')
    parser.add_argument('--bamFile',
                        help='BAM file with aligned SSCS reads.')
    parser.add_argument('--outputJson',
                        help='Output JSON file to store SSCS counts.')
    return parser


def mut2sscs(argv):
    parser = make_argparser()
    args = parser.parse_args(argv[1:])

    file1 = args.mutFile
    file2 = args.bamFile
    sscs_counts_json = args.outputJson

    if os.path.isfile(file1) is False:
        sys.exit("Error: Could not find '{}'".format(file1))

    if os.path.isfile(file2) is False:
        sys.exit("Error: Could not find '{}'".format(file2))

    # 1. read mut file
    with open(file1, 'r') as mut:
        mut_array = np.genfromtxt(mut, skip_header=1, delimiter='\t', comments='#', dtype=str)

    # 2 read SSCS bam file
    # pysam.index(file2)
    bam = pysam.AlignmentFile(file2, "rb")

    # get tags
    mut_pos_dict = {}
    ref_pos_dict = {}
    if mut_array.shape == (1,13):
        mut_array = mut_array.reshape((1, len(mut_array)))

    for m in range(0, len(mut_array[:, 0])):
        print(str(m + 1) + " of " + str(len(mut_array[:, 0])))
        chrom = mut_array[m, 1]
        stop_pos = mut_array[m, 2].astype(int)
        chrom_stop_pos = str(chrom) + "#" + str(stop_pos)
        ref = mut_array[m, 9]
        alt = mut_array[m, 10]

        for pileupcolumn in bam.pileup(chrom.tostring(), stop_pos - 2, stop_pos, max_depth=1000000000):
            if pileupcolumn.reference_pos == stop_pos - 1:
                count_alt = 0
                count_ref = 0
                count_indel = 0
                print("unfiltered reads=", pileupcolumn.n, "filtered reads=", len(pileupcolumn.pileups),
                      "difference= ", len(pileupcolumn.pileups) - pileupcolumn.n)
                for pileupread in pileupcolumn.pileups:
                    if not pileupread.is_del and not pileupread.is_refskip:
                        tag = pileupread.alignment.query_name
                        abba = tag[-2:]
                        # query position is None if is_del or is_refskip is set.
                        if pileupread.alignment.query_sequence[pileupread.query_position] == alt:
                            count_alt += 1
                            if chrom_stop_pos in mut_pos_dict:
                                if abba in mut_pos_dict[chrom_stop_pos]:
                                    mut_pos_dict[chrom_stop_pos][abba] += 1
                                else:
                                    mut_pos_dict[chrom_stop_pos][abba] = 1
                            else:
                                mut_pos_dict[chrom_stop_pos] = {}
                                mut_pos_dict[chrom_stop_pos][abba] = 1
                        elif pileupread.alignment.query_sequence[pileupread.query_position] == ref:
                            count_ref += 1
                            if chrom_stop_pos in ref_pos_dict:
                                if abba in ref_pos_dict[chrom_stop_pos]:
                                    ref_pos_dict[chrom_stop_pos][abba] += 1
                                else:
                                    ref_pos_dict[chrom_stop_pos][abba] = 1
                            else:
                                ref_pos_dict[chrom_stop_pos] = {}
                                ref_pos_dict[chrom_stop_pos][abba] = 1
                        else:
                            count_indel += 1

                print("coverage at pos %s = %s, ref = %s, alt = %s, indel = %s,\n" %
                      (pileupcolumn.pos, count_ref + count_alt, count_ref, count_alt, count_indel))

        # if mutation is in DCS file but not in SSCS, then set counts to NA
        if chrom_stop_pos not in mut_pos_dict.keys():
            mut_pos_dict[chrom_stop_pos] = {}
            mut_pos_dict[chrom_stop_pos]["ab"] = 0
            mut_pos_dict[chrom_stop_pos]["ba"] = 0
            ref_pos_dict[chrom_stop_pos] = {}
            ref_pos_dict[chrom_stop_pos]["ab"] = 0
            ref_pos_dict[chrom_stop_pos]["ba"] = 0
    bam.close()

    # save counts
    with open(sscs_counts_json, "w") as f:
        json.dump((mut_pos_dict, ref_pos_dict), f)


if __name__ == '__main__':
    sys.exit(mut2sscs(sys.argv))