#!/usr/bin/perl -w

use strict;
use Data::Dumper;


sub main {
    my @filenames = @ARGV;
    my @times;
    my ($file, $tr, $dir, $day, $k);
    my (%seen, %times);

    for $file (@filenames) {
	push @times, handle_file($file);
    }

    for $tr (@times) {
	for $dir (keys %$tr) {
	    for $day (keys %{$tr->{$dir}}) {
		$seen{$dir . $day}++;
	    }
	}
    }
    for $k (keys %seen) {
	if ($seen{$k} > 1) {
	    die "More than one hashref had the same day/dir combination: $k";
	}
    }
    for $tr (@times) {
	for $dir (keys %$tr) {
	    for $day (keys %{$tr->{$dir}}) {
		$times{$dir}{$day} = $tr->{$dir}{$day};
	    }
	}
    }

    output(%times);
}

sub splitline ($) {
    my $l = shift;
    chomp $l;
    return split /\t/, $l;
}

sub zipper (\@\@) {
    my ($a, $b) = @_;
    my (@a, @b);
    my @result;

    @a = @$a;
    @b = @$b;

    while (@a and @b) {
	push @result, shift(@a), shift(@b);
    }
    if (@a) {
	push @result, @a;
    } elsif (@b) {
	push @result, @b;
    }
    return @result;
}

sub handle_file {
    my $filename = shift;
    my %times;
    my (@timepoints, @days, @linenos, @tmpdays, @times);
    my ($curline, $day, $dir, $tp);

    open(CSV, $filename);

    @timepoints = splitline(<CSV>);
    @days       = splitline(<CSV>);
    @linenos    = splitline(<CSV>);
    
    $curline = 4;
    push @linenos, -1;
    @tmpdays = @days;
    $dir = 1;

    while (<CSV>) {
	if ($curline++ == $linenos[0]) {
	    if (@tmpdays == 0) {
		@timepoints = reverse @timepoints;
		@tmpdays = @days;
		$dir++;
	    }
	    shift @linenos;
	    $day = shift @tmpdays;
	    for $tp (@timepoints) {
		@{$times{$dir}{$day}{$tp}} = ();
	    }
	}

	chomp;
	@times = split /\t/;
	for $tp (@timepoints) {
	    push @{$times{$dir}{$day}{$tp}}, shift @times;
	}
    }

    close(CSV);

    return \%times;
}

sub output (%) {
    my (%times) = @_;

    my (%seentp, %seendays);
    my (@timepoints, @days);
    my ($dir, $day, $tp);

    # Pull the timepoints out of the structure.
    for $dir (keys %times) {
	for $day (keys %{$times{$dir}}) {
	    $seendays{$day}++;
	    for $tp (keys %{$times{$dir}{$day}}) {
		$seentp{$tp}++;
	    }
	}
    }

    # Sort the timepoints.  The order is dictated by the first direction;
    # order of the second direction is swapped so both arrays point the same
    # way.
    @timepoints = sort {
	my $result = cmptimes($a, $b, 1, \%times);
	if ($result == 0) {
	    $result = cmptimes($b, $a, 2, \%times);
	}
	$result;
    } keys %seentp;

    @days = keys %seendays;

    # Time points are easy now.
    print join("\t", @timepoints), "\n";

    # As are days.
    print join("\t", @days), "\n";

    my $trips = "";
    my @startlines;
    my $line = 4;
    $dir = 1;
    for my $day (@days) {
	# Remember where this block of data started.
	push @startlines, $line;

	while (more_data($dir, $day, %times)) {
	    for my $tp (@timepoints) {
		if (exists $times{$dir}{$day}{$tp}) {
		    $trips .= shift(@{$times{$dir}{$day}{$tp}}) . "\t";
		} else {
		    $trips .= "-----\t";
		}
	    }
	    chop($trips);
	    $trips .= "\n";
	    $line++;
	}
    }

    # Kinda bad, but it'd be more work to actually write a subroutine for it.
    $dir = 2;
    @timepoints = reverse @timepoints;
    for $day (@days) {
	# Remember where this block of data started.
	push @startlines, $line;
	
	while (more_data($dir, $day, %times)) {
	    for $tp (@timepoints) {
		if (exists $times{$dir}{$day}{$tp}) {
		    $trips .= shift(@{$times{$dir}{$day}{$tp}}) . "\t";
		} else {
		    $trips .= "-----\t";
		}
	    }
	    chop($trips);
	    $trips .= "\n";
	    $line++;
	}
    }

    print join("\t", @startlines), "\n";
    print $trips;
}

sub cmptimes ($$$\%) {
    my ($a, $b, $dir, $tr) = @_;
    my $i;
    my @days = keys %{$tr->{$dir}};
    my $day = $days[0];
    
    if (exists $tr->{$dir}{$day}{$a} and exists $tr->{$dir}{$day}{$b}) {
	for ($i = 0; $i < $#{$tr->{$dir}{$day}{$a}}; $i++) {
	    if (${$tr->{$dir}{$day}{$a}}[$i] ne "-----" and
		${$tr->{$dir}{$day}{$b}}[$i] ne "-----") {
		last;
	    }
	}
	if ($i < $#{$tr->{$dir}{$day}{$a}}) {
	    # Because of the format of the data, string compare will work.
	    return ${$tr->{$dir}{$day}{$a}}[$i] cmp
		   ${$tr->{$dir}{$day}{$b}}[$i];
	}
    }
    return 0;
}

sub more_data {
    my ($dir, $day, %times) = @_;

    my @keys = keys %{$times{$dir}{$day}};
    my $count = @{$times{$dir}{$day}{$keys[0]}};
    return $count > 0;
}

main;