#!/usr/bin/env perl

use strict;
use warnings;
use Carp;
use Vcf;
use FindBin;
use lib "$FindBin::Bin";
use FaSlice;

my $opts = parse_params();
convert_file($opts);

exit;

#--------------------------------

sub error
{
    my (@msg) = @_;
    if ( scalar @msg )
    {
        croak @msg;
    }
    die
        "About: Convert between VCF versions.\n",
        "Usage: cat in.vcf | vcf-convert [OPTIONS] > out.vcf\n",
        "Options:\n",
        "   -r, --refseq <file>              The reference sequence in samtools faindexed fasta file. (Not required with SNPs only.)\n",
        "   -v, --version <string>           4.0, 4.1\n",
        "   -h, -?, --help                   This help message.\n",
        "\n";
}


sub parse_params
{
    my $opts = { version=>'4.1' };
    while (my $arg=shift(@ARGV))
    {
        if ( $arg eq '-r' || $arg eq '--refseq' ) { $$opts{refseq}=shift(@ARGV); next; }
        if ( $arg eq '-v' || $arg eq '--version' ) { $$opts{version}=shift(@ARGV); next; }
        if ( $arg eq '-?' || $arg eq '-h' || $arg eq '--help' ) { error(); }
        error("Unknown parameter \"$arg\". Run -h for help.\n");
    }
    return $opts;
}


sub convert_file
{
    my ($opts) = @_;

    # How to recognise a number
    my $FLOAT_RE = qr/^\-?\d+\.?\d*(?:[eE][+-]\d+)?$/;

    my $vcf_in  = Vcf->new(fh=>\*STDIN);
    my $vcf_out = Vcf->new(version=>$$opts{version});

    if ( $$opts{version} < $$vcf_in{version} ) { warn("Downgrading of VCF versions is experimental: expect troubles!\n"); }

    # Convert the header
    $vcf_in->parse_header();
    for (my $i=1; $i<@{$$vcf_in{header_lines}}; $i++)
    {
        $vcf_out->add_header_line($$vcf_in{header_lines}[$i]);
    }
    $vcf_out->add_columns(@{$$vcf_in{columns}});
    print $vcf_out->format_header();

    # Convert each data line
    my $fa;
    while (my $x=$vcf_in->next_data_hash())
    {
        # Convert missing (default) FORMAT values
        for my $gt (values %{$$x{gtypes}})
        {
            for my $field (@{$$x{FORMAT}})
            {
                # Skip the GT tag, so that ploidy information is not lost ("./." would become ".")
                if ( $field eq 'GT' ) { next; }
                if ( $field eq 'FT' && $$gt{$field} eq $$vcf_in{filter_passed} ) { $$gt{$field}=$$vcf_out{filter_passed}; }
                if ( exists($$vcf_in{defaults}{$field}) && $$vcf_in{defaults}{$field} eq $$gt{$field} )
                {
                    $$gt{$field} = $$vcf_out{defaults}{$field};
                    next;
                }
                if ( exists($$vcf_in{header}{FORMAT}{$field}{default}) && $$vcf_in{header}{FORMAT}{$field}{default} eq $$gt{$field} )
                {
                    delete($$gt{$field});
                    next;
                }
            }
        }


        # Change missing QUAL: In case they are numbers, do numeric comparison, as -1.0 is sometimes used instead of -1
        if ( $$x{QUAL} eq $$vcf_in{defaults}{QUAL} 
            or ($$x{QUAL}=~$FLOAT_RE && $$vcf_in{defaults}{QUAL}=~$FLOAT_RE && $$x{QUAL}==$$vcf_in{defaults}{QUAL}) ) 
        { 
            $$x{QUAL} = $$vcf_out{defaults}{QUAL}; 
        }
        for (my $i=0; $i<@{$$x{FILTER}}; $i++)
        {
            if ( $$x{FILTER}[$i] eq $$vcf_in{filter_passed} ) { $$x{FILTER}[$i] = $$vcf_out{filter_passed}; }
        }

        # Parse the ALT column and see if there are indels
        my $has_indel = 0;
        for my $alt (@{$$x{ALT}})
        {
            my ($type,$len,$ht) = $vcf_in->event_type($x,$alt);
            if ( $type eq 's' or $type eq 'r' ) { next; }
            if ( $type ne 'i' ) { error("FIXME: expected indel at $$x{CHROM}:$$x{POS}\n"); }

            $has_indel = 1;
        }

        # If there is an indel, new REF and ALT must be changed
        if ( $has_indel )
        {
            my $map = {};
            my $alt_to_mapref = {};

            for my $alt (@{$$x{ALT}})
            {
                my ($type,$len,$ht) = $vcf_in->event_type($x,$alt);
                if ( $type eq 's' or $type eq 'r' )
                {
                    $$alt_to_mapref{$alt} = { ref=>$$x{REF}, alt=>$alt };
                    $$map{$$x{REF}}{$alt} = 1;
                    next;
                }

                if ( $type eq 'i' && $len>0 )
                {
                    my $tmp = $$x{REF}.$ht;
                    $$alt_to_mapref{$alt} = { ref=>$$x{REF}, alt=>$tmp };
                    $$map{$$x{REF}}{$tmp} = 1;
                    next;
                }
                elsif ( $type eq 'i' && $len<0 )
                {
                    if ( !$fa )
                    {
                        if ( !$$opts{refseq} ) { error("Indels present, missing the -r option.\n"); }
                        $fa = FaSlice->new(file=>$$opts{refseq},size=>1_000_000);
                    }
                    my $ref   = $fa->get_slice($$x{CHROM},$$x{POS},$$x{POS}+abs($len));
                    my $first = substr($ref,0,1);

                    # Sanity check
                    if ( $$x{REF} ne $first ) 
                    { 
                        error("Sanity check failed: the ref does not agree at $$x{CHROM}:$$x{POS} .. [$$x{REF}] in .fa,  [$first] in .vcf\n"); 
                    }

                    $$alt_to_mapref{$alt} = { ref=>$ref, alt=>$$x{REF} };
                    $$map{$ref}{$$x{REF}} = 1;
                    next;
                }
                else 
                { 
                    error("Uh, FIXME: $$x{CHROM}:$$x{POS} [$type] [$len] [$ht]\n"); 
                }
            }

            $$x{REF} = $vcf_out->fill_ref_alt_mapping($map);
            for (my $i=0; $i<@{$$x{ALT}}; $i++)
            {
                my $ori_ref = $$alt_to_mapref{$$x{ALT}[$i]}{ref};
                my $ori_alt = $$alt_to_mapref{$$x{ALT}[$i]}{alt};
                $$x{ALT}[$i] = $$map{$ori_ref}{$ori_alt};
            }
        }

        print $vcf_out->format_line($x);
    }
}