// Copyright 2015 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/rancher/os/config/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())
}