/*
   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"
	"log"
	"net"
	"os/exec"
	"strings"

	"github.com/coreos/coreos-cloudinit/network"

	"github.com/coreos/coreos-cloudinit/Godeps/_workspace/src/github.com/dotcloud/docker/pkg/netlink"
)

const (
	runtimeNetworkPath = "/run/systemd/network"
)

func RestartNetwork(interfaces []network.InterfaceGenerator) (err error) {
	defer func() {
		if e := restartNetworkd(); e != nil {
			err = e
		}
	}()

	if err = downNetworkInterfaces(interfaces); err != nil {
		return
	}

	if err = maybeProbe8012q(interfaces); err != nil {
		return
	}
	return maybeProbeBonding(interfaces)
}

func downNetworkInterfaces(interfaces []network.InterfaceGenerator) error {
	sysInterfaceMap := make(map[string]*net.Interface)
	if systemInterfaces, err := net.Interfaces(); err == nil {
		for _, iface := range systemInterfaces {
			iface := iface
			sysInterfaceMap[iface.Name] = &iface
		}
	} else {
		return err
	}

	for _, iface := range interfaces {
		if systemInterface, ok := sysInterfaceMap[iface.Name()]; ok {
			log.Printf("Taking down interface %q\n", systemInterface.Name)
			if err := netlink.NetworkLinkDown(systemInterface); err != nil {
				fmt.Printf("Error while downing interface %q (%s). Continuing...\n", systemInterface.Name, err)
			}
		}
	}

	return nil
}

func maybeProbe8012q(interfaces []network.InterfaceGenerator) error {
	for _, iface := range interfaces {
		if iface.Type() == "vlan" {
			log.Printf("Probing LKM %q (%q)\n", "8021q", "8021q")
			return exec.Command("modprobe", "8021q").Run()
		}
	}
	return nil
}

func maybeProbeBonding(interfaces []network.InterfaceGenerator) error {
	for _, iface := range interfaces {
		if iface.Type() == "bond" {
			args := append([]string{"bonding"}, strings.Split(iface.ModprobeParams(), " ")...)
			log.Printf("Probing LKM %q (%q)\n", "bonding", args)
			return exec.Command("modprobe", args...).Run()
		}
	}
	return nil
}

func restartNetworkd() error {
	log.Printf("Restarting networkd.service\n")
	_, err := NewUnitManager("").RunUnitCommand("restart", "systemd-networkd.service")
	return err
}

func WriteNetworkdConfigs(interfaces []network.InterfaceGenerator) error {
	for _, iface := range interfaces {
		filename := fmt.Sprintf("%s.netdev", iface.Filename())
		if err := writeConfig(filename, iface.Netdev()); err != nil {
			return err
		}
		filename = fmt.Sprintf("%s.link", iface.Filename())
		if err := writeConfig(filename, iface.Link()); err != nil {
			return err
		}
		filename = fmt.Sprintf("%s.network", iface.Filename())
		if err := writeConfig(filename, iface.Network()); err != nil {
			return err
		}
	}
	return nil
}

func writeConfig(filename string, config string) error {
	if config == "" {
		return nil
	}
	log.Printf("Writing networkd unit %q\n", filename)
	_, err := WriteFile(&File{Content: config, Path: filename}, runtimeNetworkPath)
	return err
}