#!/bin/sh
set -f

LOG=""
DEBUG_LEVEL=1
LOG_D="/run/vyos-router"
ENABLE="enabled"
DISABLE="disabled"
FOUND="found"
NOTFOUND="notfound"
RUN_ENABLED_FILE="$LOG_D/$ENABLE"
VYOS_SYSTEM_TARGET="/lib/systemd/system/vyos.target"
VYOS_TARGET_NAME="vyos.target"

debug() {
    local lvl="$1"
    shift
    [ "$lvl" -gt "$DEBUG_LEVEL" ] && return
    if [ -z "$LOG" ]; then
        local log="$LOG_D/${0##*/}.log"
        { [ -d "$LOG_D" ] || mkdir -p "$LOG_D"; } &&
            { : > "$log"; } >/dev/null 2>&1 && LOG="$log" ||
            LOG="/dev/kmsg"
    fi
    echo "$@" >> "$LOG"
}

default() {
    _RET="$ENABLE"
}

main() {
    local normal_d="$1" early_d="$2" late_d="$3"
    local target_name="multi-user.target" gen_d="$early_d"
    local link_path="$gen_d/${target_name}.wants/${VYOS_TARGET_NAME}"
    local ds="$NOTFOUND"

    debug 1 "$0 normal=$normal_d early=$early_d late=$late_d"
    debug 2 "$0 $*"

    local search result="error" ret=""
    for search in default; do
        if $search; then
            debug 1 "$search found $_RET"
            [ "$_RET" = "$ENABLE" -o "$_RET" = "$DISABLE" ] &&
                result=$_RET && break
        else
            ret=$?
            debug 0 "search $search returned $ret"
        fi
    done

    # enable AND ds=found == enable
    # enable AND ds=notfound == disable
    # disable || <any> == disabled
    if [ "$result" = "$ENABLE" ]; then
        if [ -e "$link_path" ]; then
                debug 1 "already enabled: no change needed"
        else
            [ -d "${link_path%/*}" ] || mkdir -p "${link_path%/*}" ||
                debug 0 "failed to make dir $link_path"
            if ln -snf "$VYOS_SYSTEM_TARGET" "$link_path"; then
                debug 1 "enabled via $link_path -> $VYOS_SYSTEM_TARGET"
            else
                ret=$?
                debug 0 "[$ret] enable failed:" \
                    "ln $VYOS_SYSTEM_TARGET $link_path"
            fi
        fi
        : > "$RUN_ENABLED_FILE"
    elif [ "$result" = "$DISABLE" ]; then
        if [ -f "$link_path" ]; then
            if rm -f "$link_path"; then
                debug 1 "disabled. removed existing $link_path"
            else
                ret=$?
                debug 0 "[$ret] disable failed, remove $link_path"
            fi
        else
            debug 1 "already disabled: no change needed [no $link_path]"
        fi
        if [ -e "$RUN_ENABLED_FILE" ]; then
            rm -f "$RUN_ENABLED_FILE"
        fi
    else
        debug 0 "unexpected result '$result' 'ds=$ds'"
        ret=3
    fi
    return $ret
}

main "$@"

# vi: ts=4 expandtab