#!/bin/sh
#
# Seems like `gbp dch' doesn't work well with non-linear histories. With
# pkg-zsh we do have merges everytime an upstream release is done. That's
# where "Upstream Release ChangeLog" comes into play. It takes a set of
# commit hashes and produces an initial changelog update for those
# situations in which an upstream release tag was merged. After that,
# the situation can be reduced to a linear history again and `gbp dch'
# will do just fine.
#
# This script is pretty dumb, so some manual adjustments might be needed
# for "debian/changelog".

if [ $# = 0 ]; then
    printf 'usage: urcl [OPTIONS] <COMMITHASH(s)...>\n\n'
    printf 'Options:\n\n'
    printf '    -n="..."   Full name to be used for the changelog entry. (Defaults\n'
    printf '               to "$DEBFULLNAME".)\n'
    printf '    -m="..."   Email address for the changelog entry. (Defaults to\n'
    printf '               "$DEBEMAIL".)\n'
    printf '    -p="..."   Package name to use. (Defaults to "$PACKAGE".)\n'
    printf '    -v="..."   Version number to use. (Defaults to "$VERSION".)\n'
    printf '\n'
    exit 0
fi

case "$1" in
    -*) isopt=1;;
    *) isopt=0;;
esac

while [ "$#" -gt 0 ] && [ "$isopt" = 1 ]; do
    case "$1" in
        -n=*) who="${1#-n=}" ;;
        -m=*) ewho="${1#-m=}" ;;
        -p=*) PACKAGE="${1#-p=}" ;;
        -v=*) VERSION="${1#-v=}" ;;
        -*)
            printf 'Unknown option `%s'\''\n.' "$1"
            ;;
    esac
    shift
    case "$1" in
        -*) isopt=1;;
        *) isopt=0;;
    esac
done

if [ x"$who" = x ]; then
    if [ x"$DEBFULLNAME" = x ]; then
        printf '`$DEBFULLNAME'\'' is empty use -n=...\n'
        exit 1
    fi
    who=$DEBFULLNAME
fi
if [ x"$ewho" = x ]; then
    if [ x"$DEBEMAIL" = x ]; then
        printf '`$DEBEMAIL'\'' is empty use -m=...\n'
        exit 1
    fi
    ewho=$DEBEMAIL
fi

if [ x"$PACKAGE" = x ]; then
    printf '`$PACKAGE'\'' is empty use -p=...\n'
    exit 1
fi

if [ x"$VERSION" = x ]; then
    printf '`$VERSION'\'' is empty use -v=...\n'
    exit 1
fi

DATE=$(date -R)

ours="debian/changelog.urcl"
theirs="debian/changelog.old"
cl="debian/changelog"

xecho () {
    printf '%s\n' "$@" >> "$ours"
}

rm -f "$ours" "$theirs"

xecho "$PACKAGE ($VERSION) UNRELEASED; urgency=low"
xecho

for rev; do
    data=$(git log -1 --abbrev=8 --pretty=format:'  * [%h] %s' "$rev")
    [ $? = 0 ] && xecho "$data"
done

xecho
xecho " -- ${who} <${ewho}>  $DATE"
xecho

cp "$cl" "$theirs"
cat "$ours" > "$cl"
cat "$theirs" >> "$cl"
rm -f "$ours" "$theirs"
${VISUAL:-${EDITOR:-vi}} "$cl"