#!/usr/bin/perl -w
# dgit repos policy hook script for Debian
#
# usages:
#   dgit-repos-policy-debian DISTRO DGIT-REPOS-DIR ACTION...
# ie.
#   dgit-repos-policy-debian ... check-list [...]
#   dgit-repos-policy-debian ... check-package PACKAGE [...]
#   dgit-repos-policy-debian ... push PACKAGE \
#         VERSION SUITE TAGNAME DELIBERATELIES [...]
#
# cwd for push is a temporary repo where the to-be-pushed objects have
#  been received; TAGNAME is the version-based tag
#
# if push requested FRESHREPO, push-confirm happens in said fresh repo
#
# policy hook for a particular package will be invoked only once at
# a time

use strict;
use POSIX;
use JSON;
use File::Temp;

use Debian::Dgit qw(:DEFAULT :policyflags);

our $distro = shift @ARGV // die "need DISTRO";
our $repos = shift @ARGV // die "need DGIT-REPOS-DIR";
our $action = shift @ARGV // die "need ACTION";

our $publicmode = 02775;
our $policydb = "dbi:SQLite:$repos/policy";
our $new_upload_propagation_slop = 3600*4 + 100;

our $poldbh;
our $pkg;
our $pkgdir;
our ($pkg_exists,$pkg_secret);

# We assume that it is not possible for NEW to have a version older
# than sid.

# Whenever pushing, we check for
#   source-package-local tainted history
#   global tainted history
#   can be overridden by --deliberately except for an admin prohib taint
# 
# ALL of the following apply only if history is secret:
# 
# if NEW has no version, or a version which is not in our history[1]
#   (always)
#   check all suites
#   if any suite's version is in our history[1], publish our history
#   otherwise discard our history,
#     tainting --deliberately-include-questionable-history
# 
# if NEW has a version which is in our history[1]
#   (on push only)
#   require explicit specification of one of
#     --deliberately-include-questionable-history
#     --deliberately-not-fast-forward
#       (latter will taint old NEW version --d-i-q-h)
#   (otherwise)
#   leave it be
# 
# [1] looking for the relevant git tag for the version number and not
#    caring what that tag refers to.
#
# A wrinkle: if we approved a push recently, we treat NEW as having
# a version which is in our history.  This is because the package may
# still be being uploaded.  (We record this using the timestamp of the
# package's git repo directory.)


sub poldb_setup () {
    $poldbh = DBI->connect($policydb,'','', {
	RaiseError=>1, PrintError=>1, AutoCommit=>0
			   });
    $poldbh->do("PRAGMA foreign_keys = ON");

    $poldbh->do(<<END);
	CREATE TABLE IF NOT EXISTS taints (
	    taint_id   INTEGER NOT NULL PRIMARY KEY ASC AUTOINCREMENT,
	    package    TEXT    NOT NULL,
	    gitobjid   TEXT    NOT NULL,
	    comment    TEXT    NOT NULL,
	    time       INTEGER,
	    gitobjtype TEXT,
	    gitobjdata TEXT
	    )
END
    $poldbh->do(<<END);
	CREATE INDEX IF NOT EXISTS taints_by_package
	    ON taints (package, gitobject)
END
    # any one of of the listed deliberatelies will override its taint
    $poldbh->do(<<END);
	CREATE TABLE IF NOT EXISTS taintoverrides (
	    taint_id  INTEGER NOT NULL
		      REFERENCES taints (taint_id)
			  ON UPDATE RESTRICT
			  ON DELETE CASCADE
		      DEFERRABLE INITIALLY DEFERRED,
	    deliberately TEXT NOT NULL,
	    PRIMARY KEY (taint_id, deliberately)
	)
END
}

sub poldb_commit () {
    $poldbh->commit;
}

sub apiquery ($) {
    my ($subpath) = @_;
    local $/=undef;
    $!=0; $?=0; my $json = `dgit -d $distro archive-api-query $subpath`;
    defined $json or die "$subpath $! $?";
    return decode_json $json;
}

sub specific_suite_has_vsn_in_our_history ($) {
    my ($suite) = @_;
    my $in_new = apiquery "/dsc_in_suite/$suite/$pkg";
    foreach my $entry (@$in_new) {
	my $vsn = $entry->{version};
	die "$pkg ?" unless defined $vsn;
	my $tag = debiantag $vsn;
	$?=0; my $r = system qw(git show-ref --verify --quiet), $tag;
	return 1 if !$r;
	next if $r==256;
	die "$pkg tag $tag $? $!";
    }
    return 0;
}

sub new_has_vsn_in_our_history () {
    stat $pkgdir or die "$pkgdir $!";
    my $mtime = ((stat _)[9]);
    my $age = time -  $mtime;
    return 1 if $age < $new_upload_propagation_slop;
    return specific_suite_has_vsn_in_our_history('new');
}

sub good_suite_has_vsn_in_our_history () {
    my $suites = apiquery "/suites";
    foreach my $suitei (@$suites) {
	my $suite = $suitei->{name};
	die unless defined $suite;
	next if $suite =~ m/\bnew$/;
	return 1 if specific_suite_has_vsn_in_our_history($suite);
    }
    return 0;
}

sub getpackage () {
    die unless @ARGV > 1;
    $pkg = shift @ARGV;
    die if $pkg =~ m#[^-+.0-9a-z]#;
    die unless $pkg =~ m#^[^-]#;

    $pkgdir = "$repos/$pkg";
    if (!stat $pkgdir) {
	die "$pkgdir $!" unless $!==ENOENT;
	$pkg_exists = 0;
    }
    $pkg_exists = 1;
    $pkg_secret = !!(~(stat _)[2] & 05);
}

sub add_taint_by_tag ($$$) {
    my ($tagname, $refobjid, $refobjtype) = @_;

    my $tf = new File::Temp or die $!;
    print $tf "$refobjid^0\n" or die $!;

    my $gcfpid = open GCF, "-|";
    defined $gcfpid or die $!;
    if (!$gcfpid) {
	open STDIN, "<&", $tf or die $!;
	exec 'git', 'cat-file';
	die $!;
    }

    close $tf or die $!;
    $_ = <GCF>;
    m/^(\w+) (\w+) (\d+)\n/ or die "$objline ?";
    my $gitobjid = $1;
    my $gitobjtype = $2;
    my $bytes = $3;

    my $gitobjdata;
    if ($gitobjtype eq 'commit' or $gitobjtype eq 'tag') {
	$!=0; read GCF, $gitobjdata, $bytes == $bytes
	    or die "$gitobjid $bytes $!";
    }
    close GCF;

    my $reason =
	"tag $tagname referred to this object in git tree but all".
	" previously pushed versions were found to have been".
	" removed from NEW (ie, rejected) (or never arrived)";

    $poldbh->do("INSERT INTO taints".
		" (package, gitobjid, gitobjtype, gitobjdata, time, comment)",
		" VALUES (?,?,?,?,?,?)", {},
		$pkg, $gitobjid, $gitobjtype, $gitobjdata, time, $reason);

    my $taint_id = $poldbh->last_insert_id(undef,undef,"taints","taint_id");
    die unless defined $taint_id;

    $poldbh->do("INSERT INTO taintoverrides".
		" (taint_id, 'include-questionable-history')",
		" VALUES (?)", {},
		$taint_id);
}


sub action__check_package () {
    getpackage();
    return 0 unless $pkg_exists;
    return 0 unless $pkg_secret;

    chdir $pkgdir or die "$pkgdir $!";
    return if new_has_vsn_in_our_history();

    if (good_suite_has_vsn_in_our_history) {
	chmod $publicmode, "." or die $!;
	return 0;
    }

    git_for_each_ref('refs/tags', sub {
	my ($objid,$objtype,$fullrefname,$tagname) = @_;
	add_taint_by_tag($tagname,$objid,$objtype);
    });
    $?=0; $!=0; close TAGL or die "git for-each-ref $? $!";

    return FRESHREPO;
}

sub action_push () {
    # we suppose that NEW has a version which is already in our
    # history, as otherwise the repo would have been blown away

    getpackage();
    return 0 unless $pkg_exists;
    return 0 unless $pkg_secret;

    xxx up to here
}



if (defined $pkg) {
    selectpackage;
}

my $fn = ${*::}{"action__$cmd"};
$fn or die "unknown ACTION";

poldb_setup();

my $rcode = $fn->();
die unless defined $rcode;

poldb_commit();
exit $rcode;