package docker
 
 import (
 	"container/list"
 	"fmt"

 	"github.com/dotcloud/docker/utils"

 	"io"

 	"io/ioutil"

 	"log"

 	"os"

 	"os/exec"

 	"path"

 	"sort"

 	"strings"

 )
 

 type Capabilities struct {
 	MemoryLimit bool
 	SwapLimit   bool
 }
 

 type Runtime struct {

 	root           string
 	repository     string
 	containers     *list.List
 	networkManager *NetworkManager

 	graph          *Graph
 	repositories   *TagStore

 	idIndex        *utils.TruncIndex

 	capabilities   *Capabilities

 	kernelVersion  *utils.KernelVersionInfo

 	autoRestart    bool

 	volumes        *Graph

 	srv            *Server

 	Dns            []string

 }
 
 var sysInitPath string
 
 func init() {

 	sysInitPath = utils.SelfPath()

 }
 

 func (runtime *Runtime) List() []*Container {

 	containers := new(History)

 	for e := runtime.containers.Front(); e != nil; e = e.Next() {

 		containers.Add(e.Value.(*Container))

 	}

 	return *containers

 }
 

 func (runtime *Runtime) getContainerElement(id string) *list.Element {
 	for e := runtime.containers.Front(); e != nil; e = e.Next() {

 		container := e.Value.(*Container)

 		if container.ID == id {

 			return e
 		}
 	}
 	return nil
 }
 

 func (runtime *Runtime) Get(name string) *Container {
 	id, err := runtime.idIndex.Get(name)
 	if err != nil {
 		return nil
 	}

 	e := runtime.getContainerElement(id)

 	if e == nil {
 		return nil
 	}
 	return e.Value.(*Container)
 }
 

 func (runtime *Runtime) Exists(id string) bool {
 	return runtime.Get(id) != nil

 }
 

 func (runtime *Runtime) containerRoot(id string) string {
 	return path.Join(runtime.repository, id)

 }
 

 func (runtime *Runtime) Load(id string) (*Container, error) {
 	container := &Container{root: runtime.containerRoot(id)}

 	if err := container.FromDisk(); err != nil {
 		return nil, err
 	}

 	if container.ID != id {
 		return container, fmt.Errorf("Container %s is stored at %s", container.ID, id)

 	}

 	if container.State.Running {
 		container.State.Ghost = true
 	}

 	if err := runtime.Register(container); err != nil {

 		return nil, err
 	}
 	return container, nil
 }
 

 // Register makes a container object usable by the runtime as <container.ID>

 func (runtime *Runtime) Register(container *Container) error {

 	if container.runtime != nil || runtime.Exists(container.ID) {

 		return fmt.Errorf("Container is already loaded")
 	}

 	if err := validateID(container.ID); err != nil {

 		return err
 	}

 	// init the wait lock
 	container.waitLock = make(chan struct{})
 
 	// Even if not running, we init the lock (prevents races in start/stop/kill)

 	container.State.initLock()

 	container.runtime = runtime

 	// Attach to stdout and stderr

 	container.stderr = utils.NewWriteBroadcaster()
 	container.stdout = utils.NewWriteBroadcaster()

 	// Attach to stdin
 	if container.Config.OpenStdin {
 		container.stdin, container.stdinPipe = io.Pipe()
 	} else {

 		container.stdinPipe = utils.NopWriteCloser(ioutil.Discard) // Silently drop stdin

 	}
 	// done

 	runtime.containers.PushBack(container)

 	runtime.idIndex.Add(container.ID)

 	// When we actually restart, Start() do the monitoring.
 	// However, when we simply 'reattach', we have to restart a monitor
 	nomonitor := false
 
 	// FIXME: if the container is supposed to be running but is not, auto restart it?
 	//        if so, then we need to restart monitor and init a new lock
 	// If the container is supposed to be running, make sure of it
 	if container.State.Running {

 		output, err := exec.Command("lxc-info", "-n", container.ID).CombinedOutput()

 		if err != nil {

 			return err

 		}
 		if !strings.Contains(string(output), "RUNNING") {

 			utils.Debugf("Container %s was supposed to be running be is not.", container.ID)

 			if runtime.autoRestart {
 				utils.Debugf("Restarting")
 				container.State.Ghost = false
 				container.State.setStopped(0)
 				if err := container.Start(); err != nil {
 					return err
 				}
 				nomonitor = true
 			} else {
 				utils.Debugf("Marking as stopped")
 				container.State.setStopped(-127)
 				if err := container.ToDisk(); err != nil {
 					return err

 				}
 			}
 		}
 	}
 

 	// If the container is not running or just has been flagged not running
 	// then close the wait lock chan (will be reset upon start)
 	if !container.State.Running {
 		close(container.waitLock)

 	} else if !nomonitor {

 		container.allocateNetwork()
 		go container.monitor()
 	}

 	return nil
 }
 

 func (runtime *Runtime) LogToDisk(src *utils.WriteBroadcaster, dst string) error {

 	log, err := os.OpenFile(dst, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0600)
 	if err != nil {
 		return err
 	}

 	src.AddWriter(log)

 	return nil
 }
 

 func (runtime *Runtime) Destroy(container *Container) error {

 	if container == nil {
 		return fmt.Errorf("The given container is <nil>")
 	}
 

 	element := runtime.getContainerElement(container.ID)

 	if element == nil {

 		return fmt.Errorf("Container %v not found - maybe it was already destroyed?", container.ID)

 	}
 

 	if err := container.Stop(3); err != nil {

 		return err
 	}

 	if mounted, err := container.Mounted(); err != nil {
 		return err
 	} else if mounted {
 		if err := container.Unmount(); err != nil {

 			return fmt.Errorf("Unable to unmount container %v: %v", container.ID, err)

 		}

 	}

 	// Deregister the container before removing its directory, to avoid race conditions

 	runtime.idIndex.Delete(container.ID)

 	runtime.containers.Remove(element)

 	if err := os.RemoveAll(container.root); err != nil {

 		return fmt.Errorf("Unable to remove filesystem for %v: %v", container.ID, err)

 	}
 	return nil
 }
 

 func (runtime *Runtime) restore() error {
 	dir, err := ioutil.ReadDir(runtime.repository)

 	if err != nil {
 		return err
 	}
 	for _, v := range dir {

 		id := v.Name()

 		container, err := runtime.Load(id)

 		if err != nil {

 			utils.Debugf("Failed to load container %v: %v", id, err)

 			continue
 		}

 		utils.Debugf("Loaded container %v", container.ID)

 	}
 	return nil
 }
 

 func (runtime *Runtime) UpdateCapabilities(quiet bool) {

 	if cgroupMemoryMountpoint, err := utils.FindCgroupMountpoint("memory"); err != nil {

 		if !quiet {
 			log.Printf("WARNING: %s\n", err)
 		}
 	} else {
 		_, err1 := ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.limit_in_bytes"))
 		_, err2 := ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.soft_limit_in_bytes"))
 		runtime.capabilities.MemoryLimit = err1 == nil && err2 == nil
 		if !runtime.capabilities.MemoryLimit && !quiet {
 			log.Printf("WARNING: Your kernel does not support cgroup memory limit.")
 		}
 
 		_, err = ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.memsw.limit_in_bytes"))
 		runtime.capabilities.SwapLimit = err == nil
 		if !runtime.capabilities.SwapLimit && !quiet {
 			log.Printf("WARNING: Your kernel does not support cgroup swap limit.")
 		}
 	}
 }
 

 // FIXME: harmonize with NewGraph()

 func NewRuntime(autoRestart bool, dns []string) (*Runtime, error) {

 	runtime, err := NewRuntimeFromDirectory("/var/lib/docker", autoRestart)

 	if err != nil {
 		return nil, err
 	}

 	runtime.Dns = dns

 	if k, err := utils.GetKernelVersion(); err != nil {

 		log.Printf("WARNING: %s\n", err)
 	} else {
 		runtime.kernelVersion = k

 		if utils.CompareKernelVersion(k, &utils.KernelVersionInfo{Kernel: 3, Major: 8, Minor: 0}) < 0 {

 			log.Printf("WARNING: You are running linux kernel version %s, which might be unstable running docker. Please upgrade your kernel to 3.8.0.", k.String())
 		}

 	}

 	runtime.UpdateCapabilities(false)

 	return runtime, nil

 }
 

 func NewRuntimeFromDirectory(root string, autoRestart bool) (*Runtime, error) {

 	runtimeRepo := path.Join(root, "containers")

 	if err := os.MkdirAll(runtimeRepo, 0700); err != nil && !os.IsExist(err) {

 		return nil, err
 	}
 

 	g, err := NewGraph(path.Join(root, "graph"))

 	if err != nil {
 		return nil, err
 	}

 	volumes, err := NewGraph(path.Join(root, "volumes"))
 	if err != nil {
 		return nil, err
 	}

 	repositories, err := NewTagStore(path.Join(root, "repositories"), g)

 	if err != nil {
 		return nil, fmt.Errorf("Couldn't create Tag store: %s", err)
 	}

 	if NetworkBridgeIface == "" {
 		NetworkBridgeIface = DefaultNetworkBridge
 	}

 	netManager, err := newNetworkManager(NetworkBridgeIface)

 	if err != nil {
 		return nil, err
 	}

 	runtime := &Runtime{

 		root:           root,

 		repository:     runtimeRepo,

 		containers:     list.New(),
 		networkManager: netManager,

 		graph:          g,
 		repositories:   repositories,

 		idIndex:        utils.NewTruncIndex(),

 		capabilities:   &Capabilities{},

 		autoRestart:    autoRestart,

 		volumes:        volumes,

 	}
 

 	if err := runtime.restore(); err != nil {

 		return nil, err
 	}

 	return runtime, nil

 }

 
 type History []*Container
 
 func (history *History) Len() int {
 	return len(*history)
 }
 
 func (history *History) Less(i, j int) bool {
 	containers := *history
 	return containers[j].When().Before(containers[i].When())
 }
 
 func (history *History) Swap(i, j int) {
 	containers := *history
 	tmp := containers[i]
 	containers[i] = containers[j]
 	containers[j] = tmp
 }
 
 func (history *History) Add(container *Container) {
 	*history = append(*history, container)
 	sort.Sort(history)
 }