#! @perl@ -w -I@libexecdir@/nix

use strict;


my $addDrvLink = 0;
my $addOutLink = 1;

my $outLink;
my $drvLink;

my @instArgs = ();
my @buildArgs = ();
my @exprs = ();


END {
    foreach my $fn (glob ".nix-build-tmp-*") {
        unlink $fn;
    }
}

sub intHandler {
    exit 1;
}

$SIG{'INT'} = 'intHandler';


for (my $n = 0; $n < scalar @ARGV; $n++) {
    my $arg = $ARGV[$n];

    if ($arg eq "--help") {
        print STDERR <<EOF;
Usage: nix-build [OPTION]... [FILE]...

`nix-build' builds the given Nix expressions (which
default to ./default.nix if none are given).  A symlink called
`result' is placed in the current directory.

Flags:
  --add-drv-link: create a symlink `derivation' to the store derivation
  --drv-link NAME: create symlink NAME instead of `derivation'
  --no-out-link: do not create the `result' symlink
  --out-link / -o NAME: create symlink NAME instead of `result'
  --attr ATTR: select a specific attribution from the Nix expression

Any additional flags are passed to `nix-store'.
EOF
        exit 0;
        # '` hack
    }

    elsif ($arg eq "--add-drv-link") {
        $addDrvLink = 1;
    }

    elsif ($arg eq "--no-out-link" or $arg eq "--no-link") {
        $addOutLink = 1;
    }

    elsif ($arg eq "--drv-link") {
        $n++;
        die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
        $drvLink = $ARGV[$n];
    }

    elsif ($arg eq "--out-link" or $arg eq "-o") {
        $n++;
        die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
        $outLink = $ARGV[$n];
    }

    elsif ($arg eq "--attr" or $arg eq "-A") {
        $n++;
        die "$0: `--attr' requires an argument\n" unless $n < scalar @ARGV;
        push @instArgs, ("--attr", $ARGV[$n]);
    }

    elsif ($arg eq "--arg") {
        die "$0: `--arg' requires two arguments\n" unless $n + 2 < scalar @ARGV;
        push @instArgs, ("--arg", $ARGV[$n + 1], $ARGV[$n + 2]);
        $n += 2;
    }

    elsif (substr($arg, 0, 1) eq "-") {
        push @buildArgs, $arg;
    }

    else {
        push @exprs, $arg;
    }
}

@exprs = ("./default.nix") if scalar @exprs == 0;


if (!defined $drvLink) {
    $drvLink = "derivation";
    $drvLink = ".nix-build-tmp-" . $drvLink if !$addDrvLink;
}

if (!defined $outLink) {
    $outLink = "result";
    $outLink = ".nix-build-tmp-" . $outLink if !$addOutLink;
}


foreach my $expr (@exprs) {

    # Instantiate.
    my @drvPaths;
    # !!! would prefer the perl 5.8.0 pipe open feature here.
    my $pid = open(DRVPATHS, "-|") || exec "@bindir@/nix-instantiate", "--add-root", $drvLink, "--indirect", @instArgs, $expr;
    while (<DRVPATHS>) {chomp; push @drvPaths, $_;}
    close DRVPATHS or exit 1;

    foreach my $drvPath (@drvPaths) {
        my $target = readlink $drvPath;
        print STDERR "store derivation is $target\n";
    }

    # Build.
    my $outPaths = `@bindir@/nix-store --add-root "$outLink" --indirect -rv @buildArgs @drvPaths`;
    my @outPaths = split ' ', $outPaths;
    
    foreach my $outPath (@outPaths) {
        my $target = readlink $outPath;
        print "$target\n";
    }

}