#! @perl@ -w @perlFlags@

use strict;
use Nix::Config;
use Nix::Store;
use Nix::Utils;
use File::Temp qw(tempdir);


my $dryRun = 0;
my $verbose = 0;
my $runEnv = $0 =~ /nix-shell$/;
my $pure = 0;

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

my $shell = $ENV{SHELL} || "/bin/sh";
my $envCommand = ""; # interactive shell
my @envExclude = ();

my $myName = $runEnv ? "nix-shell" : "nix-build";


my $tmpDir = tempdir("$myName.XXXXXX", CLEANUP => 1, TMPDIR => 1)
    or die "cannot create a temporary directory";

my $outLink = "./result";
my $drvLink = "$tmpDir/derivation";

# Ensure that the $tmpDir is deleted.
$SIG{'INT'} = sub { exit 1 };


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

    if ($arg eq "--help") {
        exec "man $myName" or die;
    }

    elsif ($arg eq "--version") {
        print "$myName (Nix) $Nix::Config::version\n";
        exit 0;
    }

    elsif ($arg eq "--add-drv-link") {
        $drvLink = "./derivation";
    }

    elsif ($arg eq "--no-out-link" or $arg eq "--no-link") {
        $outLink = "$tmpDir/result";
    }

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

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

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

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

    elsif ($arg eq "--max-jobs" or $arg eq "-j" or $arg eq "--max-silent-time" or $arg eq "--log-type" or $arg eq "--cores" or $arg eq "--timeout") {
        $n++;
        die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
        push @buildArgs, ($arg, $ARGV[$n]);
    }

    elsif ($arg eq "--dry-run") {
        push @buildArgs, "--dry-run";
        $dryRun = 1;
    }

    elsif ($arg eq "--show-trace") {
        push @instArgs, $arg;
    }

    elsif ($arg eq "-") {
        @exprs = ("-");
    }

    elsif ($arg eq "--verbose" or substr($arg, 0, 2) eq "-v") {
        push @buildArgs, $arg;
        push @instArgs, $arg;
        $verbose = 1;
    }

    elsif ($arg eq "--quiet" || $arg eq "--repair") {
        push @buildArgs, $arg;
        push @instArgs, $arg;
    }

    elsif ($arg eq "--run-env") { # obsolete
        $runEnv = 1;
    }

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

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

    elsif ($arg eq "--pure") {
        $pure = 1;
    }

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

    else {
        push @exprs, $arg;
    }
}

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


foreach my $expr (@exprs) {

    # Instantiate.
    my @drvPaths;
    # !!! would prefer the perl 5.8.0 pipe open feature here.
    my $pid = open(DRVPATHS, "-|") || exec "$Nix::Config::binDir/nix-instantiate", "--add-root", $drvLink, "--indirect", @instArgs, $expr;
    while (<DRVPATHS>) {chomp; push @drvPaths, $_;}
    if (!close DRVPATHS) {
        die "nix-instantiate killed by signal " . ($? & 127) . "\n" if ($? & 127);
        exit 1;
    }

    if ($runEnv) {
        die "$0: a single derivation is required\n" if scalar @drvPaths != 1;
        my $drvPath = readlink $drvPaths[0] or die "cannot read symlink `$drvPaths[0]'";
        my $drv = derivationFromPath($drvPath);

        # Build or fetch all dependencies of the derivation.
        my @inputDrvs = grep { my $x = $_; (grep { $x =~ $_ } @envExclude) == 0 } @{$drv->{inputDrvs}};
        system("$Nix::Config::binDir/nix-store -r @buildArgs @inputDrvs @{$drv->{inputSrcs}} > /dev/null") == 0
            or die "$0: failed to build all dependencies\n";

        # Set the environment.
        if ($pure) {
            foreach my $name (keys %ENV) {
                next if $name eq "HOME" || $name eq "USER" || $name eq "LOGNAME" || $name eq "DISPLAY" || $name eq "PATH";
                delete $ENV{$name};
            }
            # NixOS hack: prevent /etc/bashrc from sourcing /etc/profile.
            $ENV{'__ETC_PROFILE_SOURCED'} = 1;
        }
        $ENV{'NIX_BUILD_TOP'} = $ENV{'TMPDIR'} || "/tmp";
        $ENV{$_} = $drv->{env}->{$_} foreach keys %{$drv->{env}};

        # Run a shell using the derivation's environment.  For
        # convenience, source $stdenv/setup to setup additional
        # environment variables and shell functions.  Also don't lose
        # the current $PATH directories.
        my $rcfile = "$tmpDir/rc";
        writeFile(
            $rcfile,
            '[ -e ~/.bashrc ] && source ~/.bashrc; ' .
            ($pure ? '' : 'p=$PATH; ' ).
            '[ -e $stdenv/setup ] && source $stdenv/setup; ' .
            ($pure ? '' : 'PATH=$PATH:$p; ') .
            'set +e; ' .
            'PS1="\n\[\033[1;32m\][nix-shell:\w]$\[\033[0m\] "; ' .
            $envCommand);
        exec($ENV{NIX_BUILD_SHELL} // "bash", "--rcfile", $rcfile);
        die;
    }

    # Ugly hackery to make "nix-build -A foo.all" produce symlinks
    # ./result, ./result-dev, and so on, rather than ./result,
    # ./result-2-dev, and so on.  This combines multiple derivation
    # paths into one "/nix/store/drv-path!out1,out2,..." argument.
    my $prevDrvPath = "";
    my @drvPaths2;
    foreach my $drvPath (@drvPaths) {
        my $p = $drvPath; my $output = "out";
        if ($drvPath =~ /(.*)!(.*)/) {
            $p = $1; $output = $2;
        } else {
            $p = $drvPath;
        }
        my $target = readlink $p or die "cannot read symlink `$p'";
        print STDERR "derivation is $target\n" if $verbose;
        if ($target eq $prevDrvPath) {
            push @drvPaths2, (pop @drvPaths2) . "," . $output;
        } else {
            push @drvPaths2, $target . "!" . $output;
            $prevDrvPath = $target;
        }
    }

    # Build.
    my @outPaths;
    $pid = open(OUTPATHS, "-|") || exec "$Nix::Config::binDir/nix-store", "--add-root", $outLink, "--indirect", "-r",
        @buildArgs, @drvPaths2;
    while (<OUTPATHS>) {chomp; push @outPaths, $_;}
    if (!close OUTPATHS) {
        die "nix-store killed by signal " . ($? & 127) . "\n" if ($? & 127);
        exit 1;
    }

    next if $dryRun;

    foreach my $outPath (@outPaths) {
        my $target = readlink $outPath or die "cannot read symlink `$outPath'";
        print "$target\n";
    }
}