#!/bin/sh

# SPDX-License-Identifier: CC0-1.0

# Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
#
# Available under the terms of Creative Commons Zero v1.0 Universal.

### BEGIN INIT INFO
# Provides:          guix-container
# Required-Start:    $local_fs $remote_fs $syslog
# Required-Stop:     $local_fs $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Start Wojtek's Guix container with various services
### END INIT INFO

set -e

. /lib/lsb/init-functions

if [ 0 != $(id -u) ]; then
    log_action_msg "Script '$0' must be run as root"
    exit 1
fi

PIDFILE=/run/guix-container.pid
EXECUTABLE=/usr/local/bin/guix-container
HOST_SYSTEM_ROOT=
MAX_CONTAINER_SPINUP_WAIT=60

ACTION="$1"
shift

OPTIND=1
while getopts p:e:r:s: OPTION_LETTER ; do
    case "$OPTION_LETTER" in
        p)  PIDFILE="$OPTARG"    ;;
        e)  EXECUTABLE="$OPTARG" ;;
        r)  HOST_SYSTEM_ROOT="$OPTARG" ;;
        s)  MAX_CONTAINER_SPINUP_WAIT="$OPTARG" ;;
    esac
done

GUILE_PID=
SUCCESS=
QUIET_EXIT=

is_running() {
    test -e "$PIDFILE" && test -n "$(ps -o pid= --pid $(cat "$PIDFILE"))"
    return $?
}

network_rip() {
    ip link delete veth-guix-out 2>/dev/null || true
}

stop() {
    network_rip
    /sbin/start-stop-daemon                                                 \
        --stop --signal TERM --pidfile "$PIDFILE"  --remove-pidfile --quiet \
        --retry 60  2>/dev/null || true
}

onexit() {
    if [ -z "$SUCCESS" ]; then
        if [ "x$ACTION" = "xstart" -a -n "$GUILE_PID" ]; then
            stop
            kill $GUILE_PID >/dev/null || true
        fi
        if [ -z "$QUIET_EXIT" ]; then
            log_failure_msg
        fi
    else
        if [ -z "$QUIET_EXIT" ]; then
            log_success_msg
        fi
    fi
}

start() {
    LOG_DIR="$HOST_SYSTEM_ROOT"/var/log/guix-container

    KOSZKO_SIDELOAD_REAL="$HOST_SYSTEM_ROOT"/var/www/koszko.org/html
    HYDRILLA_HTTP_REAL="$HOST_SYSTEM_ROOT"/var/www/hydrilla.koszko.org/html
    HYDRILLAREPOS_HTTP_REAL="$HOST_SYSTEM_ROOT"/var/www/hydrillarepos.koszko.org/html
    LOG_REAL="$LOG_DIR"/container
    ETC_REAL="$HOST_SYSTEM_ROOT"/etc/guix-container
    VAR_HYDRILLA_REAL="$HOST_SYSTEM_ROOT"/var/lib/hydrilla
    VAR_GITOLITE_REAL="$HOST_SYSTEM_ROOT"/var/lib/gitolite3

    KOSZKO_SIDELOAD_DIR_SHARE_OPT=--share="$KOSZKO_SIDELOAD_REAL"=/srv/http/koszko.org
    HYDRILLA_HTTP_DIR_SHARE_OPT=--share="$HYDRILLA_HTTP_REAL"=/srv/http/hydrilla.koszko.org
    HYDRILLAREPOS_HTTP_DIR_SHARE_OPT=--share="$HYDRILLAREPOS_HTTP_REAL"=/srv/http/hydrillarepos.koszko.org
    LOG_DIR_SHARE_OPT=--share="$LOG_REAL"=/var/log
    ETC_DIR_SHARE_OPT=--share="$ETC_REAL"=/etc
    VAR_HYDRILLA_DIR_SHARE_OPT=--share="$VAR_HYDRILLA_REAL"=/var/lib/hydrilla
    VAR_GITOLITE_DIR_SHARE_OPT=--share="$VAR_GITOLITE_REAL"=/var/lib/gitolite3

    mkdir --mode=700 -p "$LOG_DIR"
    mkdir --mode=700 -p "$LOG_DIR"/container

    "$EXECUTABLE" "$KOSZKO_SIDELOAD_DIR_SHARE_OPT"                     \
                  "$HYDRILLA_HTTP_DIR_SHARE_OPT"                       \
                  "$HYDRILLAREPOS_HTTP_DIR_SHARE_OPT"                  \
                  "$LOG_DIR_SHARE_OPT"                                 \
                  "$ETC_DIR_SHARE_OPT"                                 \
                  "$VAR_HYDRILLA_DIR_SHARE_OPT"                        \
                  "$VAR_GITOLITE_DIR_SHARE_OPT"                        \
                  >> "$LOG_DIR"/stdout.log 2>> "$LOG_DIR"/stderr.log &

    GUILE_PID=$!
    WAIT_TIME=0
    SHEPHERD_PID=

    while [ $WAIT_TIME -lt "$MAX_CONTAINER_SPINUP_WAIT" ]; do
        sleep 1
        WAIT_TIME=$((WAIT_TIME + 1))
        SHEPHERD_PID=$(ps -o pid= --ppid $GUILE_PID || true)
        if [ -n "$SHEPHERD_PID" ]; then
            mkdir -p "$(dirname "$PIDFILE")"
            printf '%s' $SHEPHERD_PID > "$PIDFILE"
            break
        fi
    done

    if [ -z "$SHEPHERD_PID" ]; then
        exit 1
    fi

    network_rip

    ip link add veth-guix-out type veth peer name veth-guix-in
    ip link set veth-guix-in netns "$SHEPHERD_PID"

    ip link set veth-guix-out up
    ip addr add 10.207.87.1/24 dev veth-guix-out

    nsenter -t "$SHEPHERD_PID" --net ip link set lo up
    nsenter -t "$SHEPHERD_PID" --net ip link set veth-guix-in up
    nsenter -t "$SHEPHERD_PID" --net ip addr add 10.207.87.2/24 dev veth-guix-in
}

trap onexit EXIT

case "$ACTION" in
    start)
        if is_running; then
            log_daemon_msg "Guix container" "already running"
            log_warning_msg
            QUIET_EXIT=1
        else
            log_daemon_msg "Guix container" "starting"
            start
        fi
        ;;
    stop)
        log_daemon_msg "Guix container" "stopping"
        stop
        ;;
    restart)
        QUIET_EXIT=1
        "$0" stop "$@"
        "$0" start "$@"
        ;;
    reload|force-reload)
        QUIET_EXIT=1
        "$0" stop "$@"
        "$0" start "$@"
        ;;
    status)
        status_of_proc -p "$PIDFILE" "$EXECUTABLE" "Guix container"
        QUIET_EXIT=1
        ;;
    *)
        log_action_msg "Usage: $0 {start|stop|status|restart|reload|force-reload}"
        QUIET_EXIT=1
        exit 2
        ;;
esac

SUCCESS=1

exit 0