#! @perl@ -w @perlFlags@

use strict;
use File::Basename;
use File::Temp qw(tempdir);
use File::Path qw(mkpath);
use File::stat;
use File::Copy;
use Nix::Config;
use Nix::Store;

my $hashAlgo = "sha256";

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

my $nixExpr = "$tmpDir/create-nars.nix";

my $curl = "$Nix::Config::curl --fail --silent";
my $extraCurlFlags = ${ENV{'CURL_FLAGS'}};
$curl = "$curl $extraCurlFlags" if defined $extraCurlFlags;


# Parse the command line.
my $localCopy;
my $localArchivesDir;

my $archivesPutURL;
my $archivesGetURL;

sub showSyntax {
    print STDERR <<EOF
Usage: nix-push --copy ARCHIVES_DIR PATHS...
   or: nix-push ARCHIVES_PUT_URL ARCHIVES_GET_URL PATHS...

`nix-push' copies or uploads the closure of PATHS to the given
destination.
EOF
    ; # `
    exit 1;
}

showSyntax if scalar @ARGV < 1;

if ($ARGV[0] eq "--copy") {
    showSyntax if scalar @ARGV < 2;
    $localCopy = 1;
    shift @ARGV;
    $localArchivesDir = shift @ARGV;
    mkpath($localArchivesDir, 0, 0755);
} else {
    showSyntax if scalar @ARGV < 2;
    $localCopy = 0;
    $archivesPutURL = shift @ARGV;
    $archivesGetURL = shift @ARGV;
}


# From the given store paths, determine the set of requisite store
# paths, i.e, the paths required to realise them.
my %storePaths;

foreach my $path (@ARGV) {
    die unless $path =~ /^\//;

    # Get all paths referenced by the normalisation of the given 
    # Nix expression.
    my $pid = open(READ,
        "$Nix::Config::binDir/nix-store --query --requisites --force-realise " .
        "--include-outputs '$path'|") or die;
    
    while (<READ>) {
        chomp;
        die "bad: $_" unless /^\//;
        $storePaths{$_} = "";
    }

    close READ or die "nix-store failed: $?";
}

my @storePaths = keys %storePaths;


# Create a list of Nix derivations that turn each path into a Nix
# archive.
open NIX, ">$nixExpr";
print NIX "[";

foreach my $storePath (@storePaths) {
    die unless ($storePath =~ /\/[0-9a-z]{32}[^\"\\\$]*$/);

    # Construct a Nix expression that creates a Nix archive.
    my $nixexpr = 
        "(import <nix/nar.nix> " .
        "{ storePath = builtins.storePath \"$storePath\"; hashAlgo = \"$hashAlgo\"; }) ";
    
    print NIX $nixexpr;
}

print NIX "]";
close NIX;


# Build the Nix expression.
print STDERR "building compressed archives...\n";
my @narPaths;
my $pid = open(READ, "$Nix::Config::binDir/nix-build $nixExpr|")
    or die "cannot run nix-build";
while (<READ>) {
    chomp;
    die unless /^\//;
    push @narPaths, $_;
}
close READ or die "nix-build failed: $?";


# Upload the archives and the corresponding info files.
print STDERR "uploading/copying archives...\n";

my $totalNarSize = 0;
my $totalCompressedSize = 0;

for (my $n = 0; $n < scalar @storePaths; $n++) {
    my $storePath = $storePaths[$n];
    my $narDir = $narPaths[$n];
    my $baseName = basename $storePath;

    # Get info about the store path.
    my ($deriver, $narHash, $time, $narSize, $refs) = queryPathInfo($storePath);

    # In some exceptional cases (such as VM tests that use the Nix
    # store of the host), the database doesn't contain the hash.  So
    # compute it.
    if ($narHash =~ /^sha256:0*$/) {
        my $nar = "$tmpDir/nar";
        system("$Nix::Config::binDir/nix-store --dump $storePath > $nar") == 0
            or die "cannot dump $storePath\n";
        $narHash = `$Nix::Config::binDir/nix-hash --type sha256 --flat $nar`;
        die "cannot hash `$nar'" if $? != 0;
        chomp $narHash;
        $narHash = "sha256:$narHash";
        $narSize = stat("$nar")->size;
        unlink $nar or die;
    }

    $totalNarSize += $narSize;
    
    # Get info about the compressed NAR.
    open HASH, "$narDir/nar-compressed-hash" or die "cannot open nar-compressed-hash";
    my $compressedHash = <HASH>;
    chomp $compressedHash;
    $compressedHash =~ /^[0-9a-z]+$/ or die "invalid hash";
    close HASH;

    my $narName = "$compressedHash.nar.bz2";

    my $narFile = "$narDir/$narName";
    (-f $narFile) or die "NAR file for $storePath not found";

    my $compressedSize = stat($narFile)->size;    
    $totalCompressedSize += $compressedSize;

    printf STDERR "%s [%.2f MiB, %.1f%%]\n", $storePath,
        $compressedSize / (1024 * 1024), $compressedSize / $narSize * 100;

    # Upload the compressed NAR.
    if ($localCopy) {
        my $dst = "$localArchivesDir/$narName";
        if (! -f $dst) {
            my $tmp = "$localArchivesDir/.tmp.$$.$narName";
            copy($narFile, $tmp) or die "cannot copy $narFile to $tmp: $!\n";
            rename($tmp, $dst) or die "cannot rename $tmp to $dst: $!\n";
        }
    } else {
        die "unimplemented";
        #if (!archiveExists("$basename")) {
        #    system("$curl --show-error --upload-file " .
        #           "'$narArchive' '$archivesPutURL/$basename' > /dev/null") == 0 or
        #           die "curl failed on $narArchive: $?";
        #}
    }

    # Upload the info file.
    my $info;
    $info .= "StorePath: $storePath\n";
    $info .= "URL: $narName\n";
    $info .= "CompressedHash: sha256:$compressedHash\n";
    $info .= "CompressedSize: $compressedSize\n";
    $info .= "NarHash: $narHash\n";
    $info .= "NarSize: $narSize\n";
    $info .= "References: " . join(" ", map { basename $_ } @{$refs}) . "\n";
    if (defined $deriver) {
        $info .= "Deriver: " . basename $deriver . "\n";
        if (isValidPath($deriver)) {
            my $drv = derivationFromPath($deriver);
            $info .= "System: $drv->{platform}\n";
        }
    }

    my $infoName = hashString("sha256", 1, $storePath);
    
    if ($localCopy) {
        my $dst = "$localArchivesDir/$infoName.narinfo";
        if (! -f $dst) {
            my $tmp = "$localArchivesDir/.tmp.$$.$infoName";
            open INFO, ">$tmp" or die;
            print INFO "$info" or die;
            close INFO or die;
            rename($tmp, $dst) or die "cannot rename $tmp to $dst: $!\n";
        }
    } else {
        die "unimplemented";
    }
}

printf STDERR "total compressed size %.2f MiB, %.1f%%\n",
    $totalCompressedSize / (1024 * 1024), $totalCompressedSize / $totalNarSize * 100;