#!/usr/bin/perl

use POSIX;

$action=0;
defined($umask=umask) or die $!;
$home= $ENV{'HOME'}.'/';

while ($ARGV[0] =~ m/^-/) {
    $_= shift(@ARGV);
    last if m/^--$/;
    while (m/^-./) {
	if (s/^-y/-/) {
	    $action=1;
	} elsif (s/^-u([0-7]{3})/-/) {
	    $umask= oct $1;
	} elsif (s/^-h/-/) {
	    $home= $';
	} else {
	    die;
	}
    }
}
die if @ARGV;

stat $home or die $!;
-d _ or die;

sub read_prep ($) {
    my ($inputfile) = @_;
    defined($c= open P, "-|") or die $!;
    if (!$c) { exec './gpt','config',$inputfile; die $!; }
}
sub fin_prep () {
    close P; die "$?" if $?;
}

read_prep('perms');
for (;;) {
    $!=0; defined($_=<P>) or die $!;
    chomp; s/^\s+//; s/\s+$//;
    next if m/^\#/; next unless m/\S/;
    last if m/^\.$/;
    if (m/(.*\S)\s+\-\>\s+(\S.*)/) {
	$linktargs{$1}= $2;
    } elsif (m/^(.*\S)\s+(\S+)$/) {
	($of,$pe)=($1,$2);
	$isdir= $of =~ s,/$,,;
	if ($pe =~ m/^[0-7]+$/) {
	    $pe= oct $&;
	} elsif ($pe eq '+x') {
	    $pe= 0777&~$umask;
	} elsif ($pe eq '/') {
	    $pe= 02777&~$umask;
	} else {
	    die "$pe ?";
	}
	($isdir ? $dirperms{$of} : $fileperms{$of}) = $pe;
    }
}
fin_prep();

sub mkparents ($) {
    my ($parent) = @_;
    $parent =~ s,/[^/]+$,, or return;
    ensuredir($parent);
}

sub maybe_chmod ($$$) {
    my ($nowperms,$perms,$obj) = @_;
    return if $nowperms==$perms;
    if ($action) {
	chmod $perms, $home.$obj or die $!;
    } else {
	would($obj, sprintf 'chmod %04o -> %04o', $nowperms, $perms);
    }
}

sub ensuredir ($) {
    my ($dir) = @_;
    mkparents($dir);
    $perms= exists $dirperms{$dir} ? $dirperms{$dir} : 02777&~$umask;
    if (stat $home.$dir) {
	-d _ or die "$dir is not a directory!";
	$nowperms= (stat _)[2] & 07777;
	maybe_chmod($nowperms,$perms,$dir);
    } else {
	die $! unless $!==&ENOENT;
	if ($action) {
	    mkdir $home.$dir, $perms or die $!;
	} else {
	    would($dir, sprintf 'mkdir %04o', $perms);
	}
    }
}

-d 'new' or mkdir 'new', 02700 or die $!;

sub prep_proc ($$) {
    my ($if,$newf) = @_;
    my ($c);
    defined($c= fork) or die $!;
    if (!$c) {
	unlink $newf;
	open STDOUT, "> $newf" or die "$newf $!";
	exec './gpt','config',$if; die $!;
    }
    $!=0; waitpid($c,0)==$c or die $!;
    $? and die $?;
}

opendir D, "files" or die $!;
while ($if=readdir D) {
    next unless $if =~ m/^[_a-z0-9\\]/;
    $of= $if; 
    $of =~ s,_,/,g; 
    $of =~ s,^/,,;
    $of =~ s,//,_,g;
    $of =~ s/\\([0-9a-f][0-9a-f]|_|\\)/
	length $1 eq 1 ? $1 : sprintf '%c', hex $1 
	    /ge;

    mkparents($of);
    $newf= 'new/'.$if;
    prep_proc('files/'.$if,$newf);

    $perms= exists $fileperms{$of} ? $fileperms{$of} : 00666&~$umask;
    chmod $perms, $newf or die $!;
    
    if (stat $home.$of) {
	-f _ or die "$of is not a file!";
	$nowperms= (stat _)[2] & 07777;
	if ($nowperms != $perms) {
	    would($of, sprintf 'chmod %04o -> %04o', $nowperms, $perms);
	}
	system 'diff','-u',$home.$of,$newf;
	$?==0 or $?==256 or die $?;
	$changes++ if $?;
    } else {
	die unless $!==&ENOENT;
	would($of, sprintf 'create %04o', $perms);
    }
    if ($action) {
	rename $newf,$home.$of or die $!;
    }

    delete $fileperms{$of};
}
closedir D or die $!;

die join(', ', keys %fileperms) if %fileperms;

foreach $link (keys %linktargs) {
    mkparents($link);
    $targ= $linktargs{$link};
    if (lstat $home.$link) {
	-l _ or die "$link is not a link!";
	defined($rl= readlink $home.$link) or die $!;
    } else {
	die unless $!==&ENOENT;
	$rl= undef;
    }
    if ($rl ne $targ) {
	would($link, "symlink $targ <-");
	if ($action) {
	    unlink $home.$link if defined $rl;
	    symlink $targ,$home.$link or die $!;
	}
    }
}

foreach $dir (keys %dirperms) {
    ensuredir($dir);
}

sub would ($$) {
    my ($obj,$what) = @_;
    return if $would_done{$obj}++;
    print STDOUT "*** $what $obj\n" or die $!;
    $changes++;
}

if ($changes) {
    print STDOUT "=== $changes changes\n" or die $!;
} else {
    print STDOUT "=== no changes\n" or die $!;
}

prep_proc('execute','new/,execute');
if ($action) {
    chmod 0700,'new/,execute' or die $!;
    system 'new/,execute'; $? and die $?;
}

close STDOUT or die $!;