#!/usr/bin/perl

use strict;
use File::Temp qw/ tempdir /;
use File::Path qw/ rmtree /;
use File::Compare qw/ compare /;

sub print_file($$)
{
    my $prefix = shift;
    my $file = shift;

    open FILE, "<", $file;
    while (<FILE>) {
        print $prefix . $_;
    }
    close FILE;
}

my $olddir = tempdir();
my $newdir = tempdir();

my @input;
while (<>) {
   push @input, $_;
}

my ($nr_old, $nr_new);

#
# Break out the blocks into separate files
#
my $block;
my ($old, $new);
foreach (@input) {
    my $line = $_;

    if ($line =~ /^(---|\+\+\+)/ ||
       !($line =~ /^[+-]/) ||
       ($old && $line =~ /^[+]/) ||
       ($new && $line =~ /^[-]/)) {
        $block = "";
        $old = 0;
        $new = 0;
        next;
    }

    if ($line =~ /^[-]{$/) {
        $block = "{";
        $old = 1;
        next;
    }
    if ($line =~ /^[+]{$/) {
        $block = "{";
        $new = 1;
        next;
    }

    $line =~ s/^[+-]//;

    $block = $block . $line;

    if ($line =~ /^}$/) {
        if ($old) {
            $nr_old++;
            open OUT, ">", "$olddir/$nr_old";
            print OUT "$block";
            close OUT;
        } else {
            $nr_new++;
            open OUT, ">", "$newdir/$nr_new";
            print OUT "$block";
            close OUT;
        }
        $block = "";
        $old = 0;
        $new = 0;
        next;
    }
}

#
# Find any blocks which are exactly the same
#
for (my $i = 1; $i <= $nr_old; $i++) {
    for (my $j = 1; $j <= $nr_new; $j++) {
        if (compare("$olddir/$i", "$newdir/$j") == 0) {
            open OUT, ">", "$olddir/$i";
            print OUT "- MOVED {$i}\n";
            close OUT;

            open OUT, ">", "$newdir/$j";
            print OUT "+ MOVED {$j}\n";
            close OUT;
        }
    }
}

#
# Find any blocks which are partly the same
#
for (my $i = 1; $i <= $nr_old; $i++) {
    for (my $j = 1; $j <= $nr_new; $j++) {
        my $lines = `cat $olddir/$i | wc -l`;
        my $after = `diff $olddir/$i $newdir/$j | grep '^<' | wc -l`;
        my $percent;

        $lines =~ s/\n//;
        $after =~ s/\n//;
        $percent = $after/$lines;

        if ($percent >= .7) {
            next;
        }

        my $diff = `diff -u $olddir/$i $newdir/$j | tail -n +3`;

        open OUT, ">", "$olddir/$i";
        print OUT "- MOVED {$i}\n";
        close OUT;

        open OUT, ">", "$newdir/$j";
        print OUT "+ MOVED {$j} <- begin\n";
        print OUT $diff;
        print OUT "+ MOVED {$j} -> end\n";
        close OUT;
    }
}

#
# Print out the diff...
#
$nr_old = $nr_new = 0;
$old = $new = 0;
foreach (@input) {
    my $line = $_;

    if ($line =~ /^(---|\+\+\+)/ ||
       !($line =~ /^[+-]/) ||
       ($old && $line =~ /^[+]/) ||
       ($new && $line =~ /^[-]/)) {
        print $block;
        print $line;
        $block = "";
        $old = 0;
        $new = 0;
        next;
    }

    if ($line =~ /^[-]{$/) {
        print $block;
        $block = $line;
        $old = 1;
        next;
    }
    if ($line =~ /^[+]{$/) {
        print $block;
        $block = $line;
        $new = 1;
        next;
    }

    $block = $block . $line;

    if ($line =~ /^[+-]}$/) {
        if ($old) {
            $nr_old++;
            print_file("-", "$olddir/$nr_old");
        } else {
            $nr_new++;
            print_file("+", "$newdir/$nr_new");
        }
        $block = "";
        $old = 0;
        $new = 0;
        next;
    }
}

rmtree($olddir);
rmtree($newdir);