#!/usr/bin/perl -w

# Shell commands
$find="find";
$rm="rm";
$mkdir="mkdir";
$touch="touch";

sub help
{
	print "$0 <old dir> <new dir>\n\n",
		"Makes old dir match new dir by removing or making or touching\n",
		"directories and files\n",
		"Outputs to stdout so pipe it through bash to execute\n\n";
	exit;
}

sub read_entities
{
	my $dir=$_[0];
	my $type=$_[1];
	my $table=$_[2];

	open(F,"$find $dir -type $type |") or die("Can't find $dir: $!\n");
	my @names=<F>;
	close F;

	for(@names){
		chomp;
		s/^$dir\/{0,1}//;
		$table->{$_}=1 if length($_);
	}
}

# Do command on things in a that aren't in b. a and b are references to hashes.
sub process
{
	my $command=$_[0];
	my $a=$_[1];
	my $b=$_[2];

	for(keys %$a){
		unless(defined($b->{$_})){
			print "$command$_\n";
		}
	}
}

help unless @ARGV;

$olddir=$ARGV[0];
$newdir=$ARGV[1];

# It doesn't matter, but looks neater
$olddir=~s/\/*$//;
$newdir=~s/\/*$//;

# Subdirectories first
read_entities($olddir,"d",\%old);
read_entities($newdir,"d",\%new);

print "# Directories\n";
process("$rm -rf $olddir/",\%old,\%new);
process("$mkdir -p $olddir/",\%new,\%old);

undef %old;
undef %new;

# Now files
print "# Files\n";
read_entities($olddir,"f",\%old);
read_entities($newdir,"f",\%new);

process("$rm -f $olddir/",\%old,\%new);
process("$touch $olddir/",\%new,\%old);