// Copyright (C) 2016-2017 Luke Shumaker <lukeshu@sbcglobal.net>
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package sd_login

import (
	"os"
	"strconv"
	"strings"
)

// XXX: logind
func (cgroup _Cgroup) GetSession() Session {
	unit := cgroup.GetUnit()

	session, ok := trimPrefixSuffix(unit, "session-", ".scope")
	if !ok || !valid_session_name(session) {
		return ""
	}

	return Session(session)
}

// XXX: who owns this, systemd or logind?  elogind doesn't implement
// it, but idk
func (cgroup _Cgroup) GetOwnerUser() User {
	slice := cgroup.GetSlice()

	uid_str, ok := trimPrefixSuffix(slice, "user-", ".slice")
	if !ok {
		return -1
	}

	uid, err := strconv.Atoi(uid_str)
	if err != nil {
		return -1
	}

	return User(uid)
}

// XXX: machined
func (cgroup _Cgroup) GetMachine() Machine {
	unit := cgroup.GetUnit()
	if unit == "" {
		return ""
	}

	machine, err := os.Readlink("/run/systemd/machines/unit:" + unit)
	if err != nil {
		return ""
	}
	return Machine(machine)
}

// XXX: systemd
func (cgroup _Cgroup) decodeUnit() string {
	unit, _ := split2(string(cgroup), '/')
	if len(unit) < 3 {
		return ""
	}
	unit = cgUnescape(unit)
	if valid_unit_name(unit)&(unit_name_plain|unit_name_instance) == 0 {
		return ""
	}
	return unit
}

func (cgroup _Cgroup) GetUnit() string {
	unit := cgroup.MaybeSkipSlices().decodeUnit()
	if strings.HasSuffix(unit, ".slice") {
		return ""
	}
	return unit
}
func (cgroup _Cgroup) GetUserUnit() string {
	return cgroup.MustSkipUserPrefix().GetUnit()
}
func (cgroup _Cgroup) GetSlice() string {
	cg := string(cgroup)
	n := 0
	for {
		cg = strings.TrimLeft(cg, "/")
		part, rest := split2(cg, '/')
		if !valid_slice_name(part) {
			if n == 0 {
				return "-.slice"
			}
			return _Cgroup(cg).decodeUnit()
		}
		cg = rest
	}
}
func (cgroup _Cgroup) GetUserSlice() string {
	return cgroup.MustSkipUserPrefix().GetSlice()
}