#!/bin/sh
set -f

LOG=""
DEBUG_LEVEL=1
LOG_D="/run"
ENABLE="enabled"
DISABLE="disabled"
CLOUD_SYSTEM_TARGET="/lib/systemd/system/cloud-init.target"
CLOUD_TARGET_NAME="cloud-init.target"

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

etc_file() {
    local pprefix="${1:-/etc/cloud/cloud-init.}"
    _RET="unset"
    [ -f "${pprefix}.$ENABLE" ] && _RET="$ENABLE" && return 0
    [ -f "${pprefix}.$DISABLE" ] && _RET="$DISABLE" && return 0
    return 0
}

read_proc_cmdline() {
    if [ "$container" = "lxc" ]; then
        _RET=""
        return 0
    fi

    if systemd-detect-virt --container --quiet; then
        _RET=""
        return 0
    fi

    read _RET < /proc/cmdline
}

kernel_cmdline() {
    local cmdline="" tok=""
    if [ -n "${KERNEL_CMDLINE+$KERNEL_CMDLINE}" ]; then
        cmdline=${KERNEL_CMDLINE}
        debug 1 "kernel command line from env KERNEL_CMDLINE: $cmdline"
    elif read_proc_cmdline; then
        read_proc_cmdline && cmdline="$_RET"
        debug 1 "kernel command line from /proc/cmdline: $cmdline"
    fi
    _RET="unset"
    cmdline=" $cmdline "
    tok=${cmdline##* cloud-init=}
    [ "$tok" = "$cmdline" ] && _RET="unset"
    tok=${tok%% *}
    [ "$tok" = "$ENABLE" -o "$tok" = "$DISABLE" ] && _RET="$tok"
    return 0
}

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/${CLOUD_TARGET_NAME}"

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

    local search result="error" ret=""
    for search in kernel_cmdline etc_file default; do
        if $search; then
            debug 1 "$search found $_RET"
            [ "$_RET" = "$ENABLE" -o "$_RET" = "$DISABLE" ] && result=$_RET
        else
            ret=$?
            debug 0 "search $search returned $ret"
        fi
    done
    
    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 $link_path"
            if ln -snf "$CLOUD_SYSTEM_TARGET" "$link_path"; then
                debug 1 "enabled via $link_path -> $CLOUD_SYSTEM_TARGET"
            else
                ret=$?
                debug 0 "[$ret] enable failed:" \
                    "ln $CLOUD_SYSTEM_TARGET $link_path"
            fi
        fi
    elif [ "$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 $link_path"
            fi
        else
            debug 1 "already disabled: no change needed"
        fi
    else
        debug 0 "unexpected result '$result'"
        ret=3
    fi
    return $ret
}

main "$@"

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