#! @perl@ -w @perlFlags@

use strict;
use File::Temp qw(tempdir);
use File::stat;
use Nix::Config;
use Nix::Manifest;

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 $manifest = "$tmpDir/MANIFEST";

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

my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";

my $dataDir = $ENV{"NIX_DATA_DIR"};
$dataDir = "@datadir@" unless defined $dataDir;


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

my $targetArchivesUrl;

my $archivesPutURL;
my $archivesGetURL;
my $manifestPutURL;

sub showSyntax {
    print STDERR <<EOF
Usage: nix-push --copy ARCHIVES_DIR MANIFEST_FILE PATHS...
   or: nix-push ARCHIVES_PUT_URL ARCHIVES_GET_URL MANIFEST_PUT_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 < 3;
    $localCopy = 1;
    shift @ARGV;
    $localArchivesDir = shift @ARGV;
    $localManifestFile = shift @ARGV;
    if ($ARGV[0] eq "--target") {
       shift @ARGV;
       $targetArchivesUrl = shift @ARGV;
    }
    else {
       $targetArchivesUrl = "file://$localArchivesDir";
    }
}
else {
    showSyntax if scalar @ARGV < 3;
    $localCopy = 0;
    $archivesPutURL = shift @ARGV;
    $archivesGetURL = shift @ARGV;
    $manifestPutURL = 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 $pid = open(READ,
        "$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;


# For each path, create a Nix expression that turns the 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 $dataDir/nix/corepkgs/nar/nar.nix) " .
        "{ storePath = builtins.storePath \"$storePath\"; system = \"@system@\"; hashAlgo = \"$hashAlgo\"; }) ";
    
    print NIX $nixexpr;
}

print NIX "]";
close NIX;


# Instantiate store derivations from the Nix expression.
my @storeExprs;
print STDERR "instantiating store derivations...\n";
my $pid = open(READ, "$binDir/nix-instantiate $nixExpr|")
    or die "cannot run nix-instantiate";
while (<READ>) {
    chomp;
    die unless /^\//;
    push @storeExprs, $_;
}
close READ or die "nix-instantiate failed: $?";


# Build the derivations.
print STDERR "creating archives...\n";

my @narPaths;

my @tmp = @storeExprs;
while (scalar @tmp > 0) {
    my $n = scalar @tmp;
    if ($n > 256) { $n = 256 };
    my @tmp2 = @tmp[0..$n - 1];
    @tmp = @tmp[$n..scalar @tmp - 1];

    my $pid = open(READ, "$binDir/nix-store --realise @tmp2|")
        or die "cannot run nix-store";
    while (<READ>) {
        chomp;
        die unless (/^\//);
        push @narPaths, "$_";
    }
    close READ or die "nix-store failed: $?";
}


# Create the manifest.
print STDERR "creating manifest...\n";

my %narFiles;
my %patches;

my @narArchives;
for (my $n = 0; $n < scalar @storePaths; $n++) {
    my $storePath = $storePaths[$n];
    my $narDir = $narPaths[$n];
    
    $storePath =~ /\/([^\/]*)$/;
    my $basename = $1;
    defined $basename or die;

    open HASH, "$narDir/narbz2-hash" or die "cannot open narbz2-hash";
    my $narbz2Hash = <HASH>;
    chomp $narbz2Hash;
    $narbz2Hash =~ /^[0-9a-z]+$/ or die "invalid hash";
    close HASH;

    my $narName = "$narbz2Hash.nar.bz2";

    my $narFile = "$narDir/$narName";
    (-f $narFile) or die "narfile for $storePath not found";
    push @narArchives, $narFile;

    my $narbz2Size = stat($narFile)->size;

    my $references = `$binDir/nix-store --query --references '$storePath'`;
    die "cannot query references for `$storePath'" if $? != 0;
    $references = join(" ", split(" ", $references));

    my $deriver = `$binDir/nix-store --query --deriver '$storePath'`;
    die "cannot query deriver for `$storePath'" if $? != 0;
    chomp $deriver;
    $deriver = "" if $deriver eq "unknown-deriver";

    my $narHash = `$binDir/nix-store --query --hash '$storePath'`;
    die "cannot query hash for `$storePath'" if $? != 0;
    chomp $narHash;

    # 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 eq "sha256:0000000000000000000000000000000000000000000000000000") {
        $narHash = `$binDir/nix-hash --type sha256 '$storePath'`;
        die "cannot hash `$storePath'" if $? != 0;
        chomp $narHash;
        $narHash = "sha256:$narHash";
    }

    my $narSize = `$binDir/nix-store --query --size '$storePath'`;
    die "cannot query size for `$storePath'" if $? != 0;
    chomp $narSize;

    my $url;
    if ($localCopy) {
        $url = "$targetArchivesUrl/$narName";
    } else {
        $url = "$archivesGetURL/$narName";
    }
    $narFiles{$storePath} = [
        { url => $url
        , hash => "$hashAlgo:$narbz2Hash"
        , size => $narbz2Size
        , narHash => "$narHash"
        , narSize => $narSize
        , references => $references
        , deriver => $deriver
        }
    ];
}

writeManifest $manifest, \%narFiles, \%patches;


sub copyFile {
    my $src = shift;
    my $dst = shift;
    my $tmp = "$dst.tmp.$$";
    system("@coreutils@/cp", $src, $tmp) == 0 or die "cannot copy file";
    rename($tmp, $dst) or die "cannot rename file: $!";
}


# Upload/copy the archives.
print STDERR "uploading/copying archives...\n";

sub archiveExists {
    my $name = shift;
    print STDERR "  HEAD on $archivesGetURL/$name\n";
    return system("$curl --head $archivesGetURL/$name > /dev/null") == 0;
}

foreach my $narArchive (@narArchives) {

    $narArchive =~ /\/([^\/]*)$/;
    my $basename = $1;

    if ($localCopy) {
        # Since nix-push creates $dst atomically, if it exists we
        # don't have to copy again.
        my $dst = "$localArchivesDir/$basename";
        if (! -f "$localArchivesDir/$basename") {
            print STDERR "  $narArchive\n";
            copyFile $narArchive, $dst;
        }
    }
    else {
        if (!archiveExists("$basename")) {
            print STDERR "  $narArchive\n";
            system("$curl --show-error --upload-file " .
                   "'$narArchive' '$archivesPutURL/$basename' > /dev/null") == 0 or
                   die "curl failed on $narArchive: $?";
        }
    }
}


# Upload the manifest.
print STDERR "uploading manifest...\n";
if ($localCopy) {
    copyFile $manifest, $localManifestFile;
    copyFile "$manifest.bz2", "$localManifestFile.bz2";
} else {
    system("$curl --show-error --upload-file " .
           "'$manifest' '$manifestPutURL' > /dev/null") == 0 or
           die "curl failed on $manifest: $?";
    system("$curl --show-error --upload-file " .
           "'$manifest'.bz2 '$manifestPutURL'.bz2 > /dev/null") == 0 or
           die "curl failed on $manifest: $?";
}