+# TODO: make Devel::Peek optional, only used for daemon
+my @base_mod = qw(Email::MIME Date::Parse Devel::Peek);
+my @over_mod = qw(DBD::SQLite DBI);
+my %mod_groups = (
+ -index => [ @base_mod, @over_mod ],
+ -base => \@base_mod,
+ -search => [ @base_mod, @over_mod, 'Search::Xapian' ],
+);
+
+sub scan_ibx_modules ($$) {
+ my ($mods, $ibx) = @_;
+ if (!$ibx->{indexlevel} || $ibx->{indexlevel} ne 'basic') {
+ $mods->{'Search::Xapian'} = 1;
+ } else {
+ $mods->{$_} = 1 foreach @over_mod;
+ }
+}
+
+sub check_require {
+ my (@mods) = @_;
+ my $err = {};
+ while (my $mod = shift @mods) {
+ if (my $groups = $mod_groups{$mod}) {
+ push @mods, @$groups;
+ } else {
+ eval "require $mod";
+ $err->{$mod} = $@ if $@;
+ }
+ }
+ scalar keys %$err ? $err : undef;
+}
+
+sub missing_mod_msg {
+ my ($err) = @_;
+ my @mods = map { "`$_'" } sort keys %$err;
+ my $last = pop @mods;
+ @mods ? (join(', ', @mods)."' and $last") : $last
+}
+
+sub require_or_die {
+ my $err = check_require(@_) or return;
+ die missing_mod_msg($err)." required for $0\n";
+}
+
+sub indexlevel_ok_or_die ($) {
+ my ($indexlevel) = @_;
+ my $req;
+ if ($indexlevel eq 'basic') {
+ $req = '-index';
+ } elsif ($indexlevel =~ /\A(?:medium|full)\z/) {
+ $req = '-search';
+ } else {
+ die <<"";
+invalid indexlevel=$indexlevel (must be `basic', `medium', or `full')
+
+ }
+ my $err = check_require($req) or return;
+ die missing_mod_msg($err) ." required for indexlevel=$indexlevel\n";
+}
+