#!/usr/bin/env perl

use warnings;

#
# xchatlogsplit - split IRC logs, created by xchat, by date
#
# $Id$

use strict;

my $me = $0;
$me =~ s#.*/##;

sub usage
{
  @_ and warn join( ' ', "Error:", @_ ), "\n";
  die "Usage: $me xchatlog1 [xchatlog2 [...]] targetdirectory\n";
}

my $targetdir = pop(@ARGV);
defined $targetdir or &usage;
-d $targetdir && -w $targetdir
 or &usage("no directory or not writeable: $targetdir");
my @files = grep { !/^-/ } @ARGV
 or &usage("no file arguments given");
map {
  -f $_ && -r $_
   or &usage("nonexistent, nonreadable or non-plain file: '$_'")
} @files;

sub start2file

 # given a $starttime (a starting moment)
 # supplies the basename of a file in which the chunk will be stored
 # note that multiple chunks may be stored within that file
{
  # no check on the input format
  defined $_[0] or die "bug: start2file called with undefined argument";
  my ( $weekday, $month, $monthday, $time, $year ) =
   grep { defined $_ } split( / +/, $_[0] );
  defined $year ? lc( $monthday . $month . $year ) : $_[0];
}

sub startofchunk

 # given the BEGIN LOGGING AT line of a chunk, returns the starting moment
{
  if ( $_[0] =~ /BEGIN LOGGING AT / )
  {
    my $start = $';
    chomp $start;
    $start;
  }
  else
  {
    undef;
  }
}

my %starttime2lines;    # a hash mapping chunk names to refs of arrays of lines

while ( my $inputfile = shift @files )
{
  my $starttime = undef;

  open( INPUT, '<' . $inputfile )
   or &usage("cannot open input file '$inputfile'");

  while (<INPUT>)
  {
    if (/^\*\*\*\* BEGIN LOGGING AT /)
    {
      # a new chunk begins
      if ( defined $starttime )
      {
        warn "unfinished chunk '$starttime' at $inputfile:$.\n";
      }
      $starttime = &startofchunk($_);
      warn "chunk saved to file ", &start2file($starttime), "\n";
      push( @{ $starttime2lines{$starttime} }, $_ );
    }
    elsif (/^\*\*\*\* ENDING LOGGING AT /)
    {
      if ( !defined $starttime )
      {
        warn "unstarted chunk at $inputfile:$.\n" if !defined $starttime;
      }
      else
      {
        push( @{ $starttime2lines{$starttime} }, $_ );
        warn scalar( @{ $starttime2lines{$starttime} } )
         . " lines in chunk started at $starttime\n";
        undef $starttime;
      }
    }

    #elsif (!defined($starttime) && defined($_) && /\S/)
    elsif ( !defined $starttime )
    {
      /\S/ and warn "text outside chunk at $inputfile:$.\n";
    }
    else
    {
      push( @{ $starttime2lines{$starttime} }, $_ );
    }
  }

  close(INPUT);
}

warn "hey\n";

foreach my $starttime ( sort keys %starttime2lines )
{
  warn "saving for $starttime\n";

  map { print "$starttime: $_" } @{ $starttime2lines{$starttime} };
}