/*
   Copyright 2014 CoreOS, Inc.

   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 system

import (
	"fmt"
	"path"
	"path/filepath"
	"strings"

	"github.com/coreos/coreos-cloudinit/config"
)

type UnitManager interface {
	PlaceUnit(unit Unit) error
	PlaceUnitDropIn(unit Unit, dropIn config.UnitDropIn) error
	EnableUnitFile(unit Unit) error
	RunUnitCommand(unit Unit, command string) (string, error)
	MaskUnit(unit Unit) error
	UnmaskUnit(unit Unit) error
	DaemonReload() error
}

// Unit is a top-level structure which embeds its underlying configuration,
// config.Unit, and provides the system-specific Destination(), Type(), and
// Group().
type Unit struct {
	config.Unit
}

// Type returns the extension of the unit (everything that follows the final
// period).
func (u Unit) Type() string {
	ext := filepath.Ext(u.Name)
	return strings.TrimLeft(ext, ".")
}

// Group returns "network" or "system" depending on whether or not the unit is
// a network unit or otherwise.
func (u Unit) Group() string {
	switch u.Type() {
	case "network", "netdev", "link":
		return "network"
	default:
		return "system"
	}
}

// Destination builds the appropriate absolute file path for the Unit. The root
// argument indicates the effective base directory of the system (similar to a
// chroot).
func (u Unit) Destination(root string) string {
	return path.Join(u.prefix(root), u.Name)
}

// DropInDestination builds the appropriate absolute file path for the
// UnitDropIn. The root argument indicates the effective base directory of the
// system (similar to a chroot) and the dropIn argument is the UnitDropIn for
// which the destination is being calculated.
func (u Unit) DropInDestination(root string, dropIn config.UnitDropIn) string {
	return path.Join(u.prefix(root), fmt.Sprintf("%s.d", u.Name), dropIn.Name)
}

func (u Unit) prefix(root string) string {
	dir := "etc"
	if u.Runtime {
		dir = "run"
	}
	return path.Join(root, dir, "systemd", u.Group())
}