#!/bin/sh
set -e

# Defaults
CLASS=
INSTANCE=
REALM=
RECIPIENTS=
SIG="$(hostname -f)"
OPCODE=auto
ZAUTH=

# Read configuration
. /etc/apt-zephyr.conf

send_zephyr ()
{
    zwrite \
	${CLASS:+-c "$CLASS"} \
	${INSTANCE:+-i "$INSTANCE"} \
	${REALM:+-r "$REALM"} \
	${SIG:+-s "$SIG"} \
	${OPCODE:+-O "$OPCODE"} \
	${ZAUTH:--d} \
	${RECIPIENTS:+$RECIPIENTS}
}

package ()
{
    package=$1
    oldver=$2
    cmp=$3
    newver=$4

    if [ "$newver" = '-' ] && [ "$oldver" = '-' ]; then
	echo "Purging $package"
    elif [ "$newver" = '-' ]; then
	echo "Removing $package $oldver"
    elif [ "$oldver" = '-' ]; then
	echo "Installing $package $newver"
    elif [ "$cmp" = '<' ]; then
	echo "Upgrading $package $oldver to $newver"
    elif [ "$cmp" = '=' ]; then
	echo "Reinstalling $package $newver"
    elif [ "$cmp" = '>' ]; then
	echo "Downgrading $package $oldver to $newver"
    else
	echo "I'm confused: $*"
    fi
}

parse_v1 ()
{
    oldpkgs=$(mktemp -t "apt-zephyr-old.XXXXXX") || exit $?
    newpkgs=$(mktemp -t "apt-zephyr-new.XXXXXX") || exit $?
    xargs -r -d '\n' dpkg-deb -W | sort -o "$newpkgs"
    cut -f 1 "$newpkgs" | xargs -r -d '\n' dpkg-query -W | \
	sort -o "$oldpkgs"
    join -t '	' -j 1 -e '-' "$oldpkgs" "$newpkgs" | \
	while IFS='	' read -r package oldver newver; do
	if dpkg --compare-versions "$oldver" lt "$newver"; then
	    package "$package" "$oldver" '<' "$newver"
	elif dpkg --compare-versions "$oldver" eq "$newver"; then
	    package "$package" "$oldver" '=' "$newver"
	else
	    package "$package" "$oldver" '>' "$newver"
	fi
    done
    rm -f "$oldpkgs" "$newpkgs"
}

parse_v2 ()
{
    while read -r line && [ -n "$line" ]; do :; done
    while read -r package oldver cmp newver action; do
	case "$action" in
	    '**CONFIGURE**' | '**REMOVE**')
		package "$package" "$oldver" "$cmp" "$newver"
		;;
	    '**ERROR**')
		echo "ERROR on $package $newver"
		;;
	esac
    done
}

pre_install_pkgs ()
{
    read -r line
    case "$line" in
	'VERSION 2')
	    parse_v2 | send_zephyr
	    ;;
	'VERSION *')
	    echo "$0: unrecognized version: $line" | send_zephyr
	    ;;
	'')
	    ;;
	*)
	    (echo "$line"; cat) | parse_v1 | send_zephyr
	    ;;
    esac
}

post_invoke ()
{
    echo 'Done.' | send_zephyr
}

if [ "$1" = "--pre-install-pkgs" ]; then
    pre_install_pkgs
elif [ "$1" = "--post-invoke" ]; then
    post_invoke
else
    echo "usage: $0 {--pre-install-pkgs | --post-invoke}" >&2
    echo "(Hint: you probably need to update /etc/apt/apt.conf.d/90zephyr.)" >&2
fi

exit 0