#!/bin/bash

fatal()
{
        [ -z "$1" ] && echo "$@"
        exit 1
}

while :; do
        case $1 in
                --debug)
                set -x
                ;;
                --spec)
                shift
                SPEC=$1
                ;;
                *)
                [ -z "$1" ] && break
                ;;
        esac
        shift
done

rules=
rules_in=
[ -f .gear/rules.in ] && rules_in=".gear/rules.in"
[ -f .gear-rules ] && rules_in=".gear-rules.in"

[ -f "$rules_in" ] || exit

rules="${rules_in%*.in}"

[ -z "$SPEC" ] && SPEC=`ls *.spec 2>/dev/null`
[ -f "$SPEC" ] || fatal "spec $SPEC not found"

vars="$(awk '
{
        line = $0;
        while(match(line, /@([a-z]+)@/, f))
        {
                if(!x[f[1]])
                {
                        print f[1];
                        x[f[1]] = 1;
                }
                line = substr(line, RSTART + RLENGTH)
        }
}' $rules_in)"

tmpspec=`mktemp --tmpdir spec-XXXXX`
trap "rm -f $tmpspec" INT TERM

install -p -m644 "$rules_in" "$rules" || fatal

for var in $vars; do
        cat $SPEC > $tmpspec
        echo "%$var" >> $tmpspec
        val="$(rpm -bE $tmpspec | tail -1)"

        [ -z "$val" ] && fatal "$var not expanded"

        echo "substitute $var --> $val"
        perl -i -npe "s/\@\Q$var\E@/$val/g" $rules
done

rm -f $tmpspec