#! @perl@ -w

use strict;
use Cwd;
use IO::Handle;
use Fcntl;

STDOUT->autoflush(1);

my $out = $ENV{"out"};
mkdir "$out", 0755 || die "error creating $out";

sub readlink_or_StateWrapper;

my $symlinks = 0;
my %path_state_identifier;
my %path_runtimeArgs;


my $nixBinDir = $ENV{"nixBinDir"};
my $nixStore = $ENV{"nixStore"};

# For each activated package, create symlinks.

sub createLinks {
    my $srcDir = shift;
    
    #Lookup each $stateIdentifiers in $path_state_identifier
    #we strip $srcDir to its rootdir e.g. /nix/store/......./
    my @srcDirParts = split /\// , substr($srcDir, length ($nixStore), length ($srcDir));
    my $srcDirRoot = $nixStore . "/" . $srcDirParts[1];
	# print "srcDirRoot $srcDirRoot \n";
    my $pkgStateIdentifier = $path_state_identifier{$srcDirRoot};
    my $pkgRuntimeStateArgs = $path_runtimeArgs{$srcDirRoot};
    
    my $dstDir = shift;
    my $ignoreCollisions = shift;

	# print "createLinks $srcDir to $dstDir with iden $pkgStateIdentifier \n";

    my @srcFiles = glob("$srcDir/*");

    foreach my $srcFile (@srcFiles) {
        my $baseName = $srcFile;
        $baseName =~ s/^.*\///g; # strip directory
        my $dstFile = "$dstDir/$baseName";

    	# Urgh, hacky...
		if ($srcFile =~ /\/propagated-build-inputs$/ ||
            $srcFile =~ /\/nix-support$/ ||
            $srcFile =~ /\/perllocal.pod$/ ||
            $srcFile =~ /\/info\/dir$/ ||
            $srcFile =~ /\/log$/)
        {
            # Do nothing.
		}

        elsif (-d $srcFile) {

            lstat $dstFile;
            
            #go recursive on directorys
            if (-d _) {
                createLinks($srcFile, $dstFile, $ignoreCollisions);
            }

            elsif (-l _) {
                my $target = readlink $dstFile or die;
                if (!-d $target) {
                    die "collission between directory `$srcFile' and non-directory `$target'";
                }
                unlink $dstFile or die "error unlinking `$dstFile': $!";
                mkdir $dstFile, 0755 || die "error creating directory `$dstFile': $!";
                createLinks($target, $dstFile, $ignoreCollisions);
                createLinks($srcFile, $dstFile, $ignoreCollisions);
            }

            else {
                
                # print "1STLINK $srcFile to $dstFile with iden $pkgStateIdentifier \n";
                
                symlink($srcFile, $dstFile) ||
                    die "error creating link `$dstFile': $!";
                $symlinks++;
            }
        }

        else {

			# print "ELSE LINK $srcFile to $dstFile with iden $pkgStateIdentifier \n";

			# if we have .....
			if($pkgStateIdentifier ne "__NOSTATE__" && $pkgStateIdentifier ne ""){
	            
	            my @pathparts = split /\// , $srcFile;
	            my $parentDir = $pathparts[scalar(@pathparts) - 2];
	            
	            if( $parentDir eq "bin" || $parentDir eq "sbin"){		#hacky....
		            
		            print "STATELINK $srcFile to $dstFile - $pkgStateIdentifier \n";
		            
		            my $new_dstFile;
		            my $new_stateIdentifier;		            
		            if($pkgStateIdentifier eq "__EMTPY__"){
		            	$new_dstFile = $dstFile;
		            	$new_stateIdentifier = "";
		            }
		            else{
		            	$new_dstFile = "$dstFile-$pkgStateIdentifier";
		            	$new_stateIdentifier = $pkgStateIdentifier;
		            }
		            
		            # We also check with -e if the wrapperscript-file exists, and if is it a symlink (with -l)
		            if (-l $new_dstFile || -e $new_dstFile) {
			            if (!$ignoreCollisions) {
			                my $target = readlink_or_StateWrapper $new_dstFile;
			                die "(state) collission between `$srcFile' and `$target' (over $new_dstFile)";
			            }
			        }
		            
		            sysopen (DSTFILEHANDLE, $new_dstFile, O_RDWR|O_EXCL|O_CREAT, 0755);
					printf DSTFILEHANDLE "#! @shell@ \n";
					
					if($pkgRuntimeStateArgs eq "__NOARGS__"){ 
						printf DSTFILEHANDLE "$nixBinDir/nix-state --run --identifier=$new_stateIdentifier $srcFile \"\$@\" \n"; 
					}
					else{ 
						printf DSTFILEHANDLE "$nixBinDir/nix-state --run --identifier=$new_stateIdentifier $srcFile \"\$@\" $pkgRuntimeStateArgs \n"; 
					}	# TODO, maybe first R.T.A. then other args ?
					
					close (DSTFILEHANDLE);
	            }
            }
            else{
	            if (-l $dstFile || -e $dstFile) {
		            if (!$ignoreCollisions) {
		                my $target = readlink_or_StateWrapper $dstFile;
		                die "collission between `$srcFile' and `$target'";
		            }
		        }
	            
	            symlink($srcFile, $dstFile) ||
	                die "error creating link `$dstFile': $!";
	            $symlinks++;
            }
        }
    }
}


my %done;
my %postponed;

sub addPkg;
sub addPkg {
    my $pkgDir = shift;
    my $ignoreCollisions = shift;

    return if (defined $done{$pkgDir});
    $done{$pkgDir} = 1;

#    print "symlinking $pkgDir\n";
    createLinks("$pkgDir", "$out", $ignoreCollisions);

    my $propagatedFN = "$pkgDir/nix-support/propagated-user-env-packages";
    if (-e $propagatedFN) {
        open PROP, "<$propagatedFN" or die;
        my $propagated = <PROP>;
        close PROP;
        my @propagated = split ' ', $propagated;
        foreach my $p (@propagated) {
            $postponed{$p} = 1 unless defined $done{$p};
        }
    }
}

sub readlink_or_StateWrapper {

	my $src = shift;
	my $target;

    if (-l $src)
    {   $target = readlink $src;    }
    else{
    	open(DAT, $src) || die("Could not open file!");
        my @raw_data=<DAT>;
        close(DAT);
        $target = $raw_data[1];
    }
    return $target
}

# Symlink to the packages that have been installed explicitly by the user.
my @storePaths = split ' ', $ENV{"derivations"};
my @stateIdentifiers = split ' ', $ENV{"stateIdentifiers"};
my @runtimeStateArgs = split ' ', $ENV{"runtimeStateArgs_arg"};
my $si_counter = 0;

foreach my $pkgDir (@storePaths) {					#Commented the sort out

	#Link each $pkgDir to a $stateIdentifiers in $path_state_identifier
	$path_state_identifier{$pkgDir} = $stateIdentifiers[$si_counter];
	$path_runtimeArgs{$pkgDir} = $runtimeStateArgs[$si_counter];

	# print "SP: $pkgDir \n";
	# print "SI: $path_state_identifier{$pkgDir} \n";
	# print "RT: $path_runtimeArgs{$pkgDir} \n";	
	
    addPkg($pkgDir, 0);
    $si_counter++;
}


# Symlink to the packages that have been "propagated" by packages
# installed by the user (i.e., package X declares that it want Y
# installed as well).  We do these later because they have a lower
# priority in case of collisions.
while (scalar(keys %postponed) > 0) {
    
    my @pkgDirs = keys %postponed;
    %postponed = ();
    foreach my $pkgDir (sort @pkgDirs) {			   
        addPkg($pkgDir, 1);
    }
}

print STDERR "created $symlinks symlinks in user environment\n";

symlink($ENV{"manifest"}, "$out/manifest") or die "cannot create manifest";