#! @perl@ -w @perlFlags@

use DBI;
use File::Basename;
use IO::Select;
use Nix::Config;
use Nix::Store;
use WWW::Curl::Easy;
use WWW::Curl::Multi;
use strict;


Nix::Config::readConfig;

my @binaryCacheUrls = map { s/\/+$//; $_ } split(/ /,
    ($ENV{"NIX_BINARY_CACHES"} // $Nix::Config::config{"binary-caches"} // "http://nixos.org/binary-cache"));

my $maxParallelRequests = int($Nix::Config::config{"binary-caches-parallel-connections"} // 150);
$maxParallelRequests = 1 if $maxParallelRequests < 1;

my ($dbh, $insertNAR, $queryNAR, $insertNARExistence, $queryNARExistence);
my %cacheIds;

my $curlm = WWW::Curl::Multi->new;
my $activeRequests = 0;
my $curlIdCount = 1;
my %requests;
my %scheduled;
my $caBundle = $ENV{"CURL_CA_BUNDLE"} // $ENV{"OPENSSL_X509_CERT_FILE"};


sub addRequest {
    my ($storePath, $url, $head) = @_;
    
    my $curl = WWW::Curl::Easy->new;
    my $curlId = $curlIdCount++;
    $requests{$curlId} = { storePath => $storePath, url => $url, handle => $curl, content => "" };

    $curl->setopt(CURLOPT_PRIVATE, $curlId);
    $curl->setopt(CURLOPT_URL, $url);
    $curl->setopt(CURLOPT_WRITEDATA, \$requests{$curlId}->{content});
    $curl->setopt(CURLOPT_FOLLOWLOCATION, 1);
    $curl->setopt(CURLOPT_CAINFO, $caBundle) if defined $caBundle;
    $curl->setopt(CURLOPT_USERAGENT, "Nix/$Nix::Config::version");
    $curl->setopt(CURLOPT_NOBODY, 1) if $head;

    if ($activeRequests >= $maxParallelRequests) {
        $scheduled{$curlId} = 1;
    } else {
        $curlm->add_handle($curl);
        $activeRequests++;
    }

    return $requests{$curlId};
}


sub processRequests {
    while ($activeRequests) {
        my ($rfds, $wfds, $efds) = $curlm->fdset();
        #print STDERR "R = @{$rfds}, W = @{$wfds}, E = @{$efds}\n";

        # Sleep until we can read or write some data.
        if (scalar @{$rfds} + scalar @{$wfds} + scalar @{$efds} > 0) {
            IO::Select->select(IO::Select->new(@{$rfds}), IO::Select->new(@{$wfds}), IO::Select->new(@{$efds}), 0.1);
        }
        
        if ($curlm->perform() != $activeRequests) {
            while (my ($id, $result) = $curlm->info_read) {
                if ($id) {
                    my $handle = $requests{$id}->{handle};
                    $requests{$id}->{result} = $result;
                    $requests{$id}->{httpStatus} = $handle->getinfo(CURLINFO_HTTP_CODE);
                    #print STDERR "\nRequest completed ($id, $result, $requests{$id}->{httpStatus})\n";
                    $activeRequests--;
                    delete $requests{$id}->{handle};

                    if (scalar(keys %scheduled) > 0) {
                        my $id2 = (keys %scheduled)[0];
                        $curlm->add_handle($requests{$id2}->{handle});
                        $activeRequests++;
                        delete $scheduled{$id2};
                    }
                    
                }
            }
        }
    }
}


sub initCache {
    my $dbPath = "$Nix::Config::stateDir/binary-cache-v1.sqlite";

    # Open/create the database.
    $dbh = DBI->connect("dbi:SQLite:dbname=$dbPath", "", "")
        or die "cannot open database `$dbPath'";
    $dbh->{RaiseError} = 1;
    $dbh->{PrintError} = 0;

    $dbh->do("pragma synchronous = off"); # we can always reproduce the cache
    $dbh->do("pragma journal_mode = truncate");

    # Initialise the database schema, if necessary.
    $dbh->do(<<EOF);
        create table if not exists BinaryCaches (
            id        integer primary key autoincrement not null,
            url       text unique not null
        );
EOF
    
    $dbh->do(<<EOF);
        create table if not exists NARs (
            cache            integer not null,
            storePath        text not null,
            url              text not null,
            compression      text not null,
            fileHash         text,
            fileSize         integer,
            narHash          text,
            narSize          integer,
            refs             text,
            deriver          text,
            system           text,
            timestamp        integer not null,
            primary key (cache, storePath),
            foreign key (cache) references BinaryCaches(id) on delete cascade
        );
EOF

    $dbh->do(<<EOF);
        create table if not exists NARExistence (
            cache            integer not null,
            storePath        text not null,
            exist            integer not null,
            timestamp        integer not null,
            primary key (cache, storePath),
            foreign key (cache) references BinaryCaches(id) on delete cascade
        );
EOF

    $insertNAR = $dbh->prepare(
        "insert or replace into NARs(cache, storePath, url, compression, fileHash, fileSize, narHash, " .
        "narSize, refs, deriver, system, timestamp) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)") or die;

    $queryNAR = $dbh->prepare("select * from NARs where cache = ? and storePath = ?") or die;

    $insertNARExistence = $dbh->prepare(
        "insert or replace into NARExistence(cache, storePath, exist, timestamp) values (?, ?, ?, ?)") or die;

    $queryNARExistence = $dbh->prepare("select exist from NARExistence where cache = ? and storePath = ?") or die;
}



sub negativeHit {
    my ($storePath, $binaryCacheUrl) = @_;
    $queryNARExistence->execute(getCacheId($binaryCacheUrl), basename($storePath));
    my $res = $queryNARExistence->fetchrow_hashref();
    return defined $res && $res->{exist} == 0;
}


sub positiveHit {
    my ($storePath, $binaryCacheUrl) = @_;
    return 1 if defined getCachedInfoFrom($storePath, $binaryCacheUrl);
    $queryNARExistence->execute(getCacheId($binaryCacheUrl), basename($storePath));
    my $res = $queryNARExistence->fetchrow_hashref();
    return defined $res && $res->{exist} == 1;
}


sub processNARInfo {
    my ($storePath, $binaryCacheUrl, $request) = @_;
    
    my $cacheId = getCacheId($binaryCacheUrl);

    if ($request->{result} != 0 || $request->{httpStatus} != 200) {
        if ($request->{httpStatus} != 404) {
            print STDERR "could not download ‘$request->{url}’ (" .
                ($request->{result} != 0 ? "Curl error $request->{result}" : "HTTP status $request->{httpStatus}") . ")\n";
        } else {
            $insertNARExistence->execute($cacheId, basename($storePath), 0, time());
        }
        return undef;
    }
    
    my ($storePath2, $url, $fileHash, $fileSize, $narHash, $narSize, $deriver, $system);
    my $compression = "bzip2";
    my @refs;
    foreach my $line (split "\n", $request->{content}) {
        $line =~ /^(.*): (.*)$/ or return undef;
        if ($1 eq "StorePath") { $storePath2 = $2; }
        elsif ($1 eq "URL") { $url = $2; }
        elsif ($1 eq "Compression") { $compression = $2; }
        elsif ($1 eq "FileHash") { $fileHash = $2; }
        elsif ($1 eq "FileSize") { $fileSize = int($2); }
        elsif ($1 eq "NarHash") { $narHash = $2; }
        elsif ($1 eq "NarSize") { $narSize = int($2); }
        elsif ($1 eq "References") { @refs = split / /, $2; }
        elsif ($1 eq "Deriver") { $deriver = $2; }
        elsif ($1 eq "System") { $system = $2; }
    }
    return undef if $storePath ne $storePath2;
    if ($storePath ne $storePath2 || !defined $url || !defined $narHash) {
        print STDERR "bad NAR info file ‘$request->{url}’\n";
        return undef;
    }
    
    # Cache the result.
    $insertNAR->execute(
        $cacheId, basename($storePath), $url, $compression, $fileHash, $fileSize,
        $narHash, $narSize, join(" ", @refs), $deriver, $system, time());
    
    return
        { url => $url
        , compression => $compression
        , fileHash => $fileHash
        , fileSize => $fileSize
        , narHash => $narHash
        , narSize => $narSize
        , refs => [ @refs ]
        , deriver => $deriver
        , system => $system
        };
}


sub getCacheId {
    my ($binaryCacheUrl) = @_;
    
    my $cacheId = $cacheIds{$binaryCacheUrl};
    return $cacheId if defined $cacheId;
    
    # FIXME: not atomic.
    my @res = @{$dbh->selectcol_arrayref("select id from BinaryCaches where url = ?", {}, $binaryCacheUrl)};
    if (scalar @res == 1) {
        $cacheId = $res[0];
    } else {
        $dbh->do("insert into BinaryCaches(url) values (?)",
                 {}, $binaryCacheUrl);
        $cacheId = $dbh->last_insert_id("", "", "", "");
    }

    $cacheIds{$binaryCacheUrl} = $cacheId;
    return $cacheId;
}


sub getCachedInfoFrom {
    my ($storePath, $binaryCacheUrl) = @_;

    $queryNAR->execute(getCacheId($binaryCacheUrl), basename($storePath));
    my $res = $queryNAR->fetchrow_hashref();
    return undef unless defined $res;
    
    return 
        { url => $res->{url}
        , compression => $res->{compression}
        , fileHash => $res->{fileHash}
        , fileSize => $res->{fileSize}
        , narHash => $res->{narHash}
        , narSize => $res->{narSize}
        , refs => [ split " ", $res->{refs} ]
        , deriver => $res->{deriver}
        } if defined $res;
}


sub printInfo {
    my ($storePath, $info) = @_;
    print "$storePath\n";
    print $info->{deriver} ? "$Nix::Config::storeDir/$info->{deriver}" : "", "\n";
    print scalar @{$info->{refs}}, "\n";
    print "$Nix::Config::storeDir/$_\n" foreach @{$info->{refs}};
    print $info->{fileSize} || 0, "\n";
    print $info->{narSize} || 0, "\n";
}


sub infoUrl {
    my ($binaryCacheUrl, $storePath) = @_;
    my $pathHash = substr(basename($storePath), 0, 32);
    my $infoUrl = "$binaryCacheUrl/$pathHash.narinfo";
}


sub printInfoParallel {
    my @paths = @_;

    # First print all paths for which we have cached info.
    my @left;
    foreach my $storePath (@paths) {
        my $found = 0;
        foreach my $binaryCacheUrl (@binaryCacheUrls) {
            my $info = getCachedInfoFrom($storePath, $binaryCacheUrl);
            if (defined $info) {
                printInfo($storePath, $info);
                $found = 1;
                last;
            }
        }
        push @left, $storePath if !$found;
    }

    return if scalar @left == 0;

    foreach my $binaryCacheUrl (@binaryCacheUrls) {

        my @left2;
        %requests = ();
        foreach my $storePath (@left) {
            if (negativeHit($storePath, $binaryCacheUrl)) {
                push @left2, $storePath;
                next;
            }
            addRequest($storePath, infoUrl($binaryCacheUrl, $storePath));
        }

        processRequests;

        foreach my $request (values %requests) {
            my $info = processNARInfo($request->{storePath}, $binaryCacheUrl, $request);
            if (defined $info) {
                printInfo($request->{storePath}, $info);
            } else {
                push @left2, $request->{storePath};
            }
        }

        @left = @left2;
    }
}


sub printSubstitutablePaths {
    my @paths = @_;

    # First look for paths that have cached info.
    my @left;
    foreach my $storePath (@paths) {
        my $found = 0;
        foreach my $binaryCacheUrl (@binaryCacheUrls) {
            if (positiveHit($storePath, $binaryCacheUrl)) {
                print "$storePath\n";
                $found = 1;
                last;
            }
        }
        push @left, $storePath if !$found;
    }

    return if scalar @left == 0;

    # For remaining paths, do HEAD requests.
    foreach my $binaryCacheUrl (@binaryCacheUrls) {
        my $cacheId = getCacheId($binaryCacheUrl);

        my @left2;
        %requests = ();
        foreach my $storePath (@left) {
            if (negativeHit($storePath, $binaryCacheUrl)) {
                push @left2, $storePath;
                next;
            }
            addRequest($storePath, infoUrl($binaryCacheUrl, $storePath), 1);
        }
        
        processRequests;

        foreach my $request (values %requests) {
            if ($request->{result} != 0 || $request->{httpStatus} != 200) {
                if ($request->{httpStatus} != 404) {
                    print STDERR "could not check ‘$request->{url}’ (" .
                        ($request->{result} != 0 ? "Curl error $request->{result}" : "HTTP status $request->{httpStatus}") . ")\n";
                } else {
                    $insertNARExistence->execute($cacheId, basename($request->{storePath}), 0, time());
                }
                push @left2, $request->{storePath};
            } else {
                $insertNARExistence->execute($cacheId, basename($request->{storePath}), 1, time());
                print "$request->{storePath}\n";
            }
        }

        @left = @left2;
    }
}


sub downloadBinary {
    my ($storePath) = @_;
    
    foreach my $binaryCacheUrl (@binaryCacheUrls) {
        my $info = getCachedInfoFrom($storePath, $binaryCacheUrl);

        unless (defined $info) {
            next if negativeHit($storePath, $binaryCacheUrl);
            my $request = addRequest($storePath, infoUrl($binaryCacheUrl, $storePath));
            processRequests;
            $info = processNARInfo($storePath, $binaryCacheUrl, $request);
        }

        next unless defined $info;
        
        my $decompressor;
        if ($info->{compression} eq "bzip2") { $decompressor = "$Nix::Config::bzip2 -d"; }
        elsif ($info->{compression} eq "xz") { $decompressor = "$Nix::Config::xz -d"; }
        else {
            print STDERR "unknown compression method ‘$info->{compression}’\n";
            next;
        }
        print STDERR "\n*** Downloading ‘$info->{url}’ into ‘$storePath’...\n";
        if (system("$Nix::Config::curl --fail --location $binaryCacheUrl/$info->{url} | $decompressor | $Nix::Config::binDir/nix-store --restore $storePath") != 0) {
            die "download of `$info->{url}' failed" . ($! ? ": $!" : "") . "\n" unless $? == 0;
            next;
        }
        # The hash in the manifest can be either in base-16 or
        # base-32.  Handle both.
        $info->{narHash} =~ /^sha256:(.*)$/ or die "invalid hash";
        my $hash = $1;
        my $hash2 = hashPath("sha256", 1, $storePath);
        die "hash mismatch in downloaded path ‘$storePath’; expected $hash, got $hash2\n"
            if $hash ne $hash2;
        print STDERR "\n";
        return 1;
    }

    return 0;
}


initCache();


if ($ARGV[0] eq "--query") {

    while (<STDIN>) {
        chomp;
        my ($cmd, @args) = split " ", $_;
        
        if ($cmd eq "have") {
            printSubstitutablePaths(@args);
            print "\n";
        }

        elsif ($cmd eq "info") {
            printInfoParallel(@args);
            print "\n";
        }

        else { die "unknown command `$cmd'"; }

        flush STDOUT;
    }

}

elsif ($ARGV[0] eq "--substitute") {
    my $storePath = $ARGV[1] or die;
    if (!downloadBinary($storePath)) {
        print STDERR "could not download ‘$storePath’ from any binary cache\n";
    }
}

else {
    die;
}