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

 	"github.com/dotcloud/docker/auth"

 	"io"

 	"io/ioutil"

 	"log"

 	"os"

 	"os/exec"

 	"path"

 	"sort"

 	"strings"

 	"time"

 )
 

 type Capabilities struct {
 	MemoryLimit bool
 	SwapLimit   bool
 }
 

 type Runtime struct {

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

 	graph          *Graph
 	repositories   *TagStore

 	authConfig     *auth.AuthConfig

 	idIndex        *TruncIndex

 	capabilities   *Capabilities

 	kernelVersion  *KernelVersionInfo

 	autoRestart    bool

 	volumes        *Graph

 }
 
 var sysInitPath string
 
 func init() {
 	sysInitPath = 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) mergeConfig(userConf, imageConf *Config) {
 	if userConf.Hostname != "" {
 		userConf.Hostname = imageConf.Hostname
 	}
 	if userConf.User != "" {
 		userConf.User = imageConf.User
 	}
 	if userConf.Memory == 0 {
 		userConf.Memory = imageConf.Memory
 	}
 	if userConf.MemorySwap == 0 {
 		userConf.MemorySwap = imageConf.MemorySwap
 	}
 	if userConf.PortSpecs == nil || len(userConf.PortSpecs) == 0 {
 		userConf.PortSpecs = imageConf.PortSpecs
 	}
 	if !userConf.Tty {
 		userConf.Tty = userConf.Tty
 	}
 	if !userConf.OpenStdin {
 		userConf.OpenStdin = imageConf.OpenStdin
 	}
 	if !userConf.StdinOnce {
 		userConf.StdinOnce = imageConf.StdinOnce
 	}
 	if userConf.Env == nil || len(userConf.Env) == 0 {
 		userConf.Env = imageConf.Env
 	}
 	if userConf.Cmd == nil || len(userConf.Cmd) == 0 {
 		userConf.Cmd = imageConf.Cmd
 	}
 	if userConf.Dns == nil || len(userConf.Dns) == 0 {
 		userConf.Dns = imageConf.Dns
 	}
 }
 

 func (runtime *Runtime) Create(config *Config) (*Container, error) {

 	// Lookup image

 	img, err := runtime.repositories.LookupImage(config.Image)

 	if err != nil {
 		return nil, err
 	}

 
 	if img.Config != nil {

 		runtime.mergeConfig(config, img.Config)

 	}
 
 	if config.Cmd == nil {
 		return nil, fmt.Errorf("No command specified")
 	}
 

 	// Generate id
 	id := GenerateId()
 	// Generate default hostname

 	// FIXME: the lxc template no longer needs to set a default hostname

 	if config.Hostname == "" {
 		config.Hostname = id[:12]
 	}

 	container := &Container{
 		// FIXME: we should generate the ID here instead of receiving it as an argument

 		Id:              id,

 		Created:         time.Now(),
 		Path:            config.Cmd[0],
 		Args:            config.Cmd[1:], //FIXME: de-duplicate from config
 		Config:          config,
 		Image:           img.Id, // Always use the resolved image id

 		NetworkSettings: &NetworkSettings{},
 		// FIXME: do we need to store this in the container?
 		SysInitPath: sysInitPath,
 	}

 	container.root = runtime.containerRoot(container.Id)

 	// Step 1: create the container directory.
 	// This doubles as a barrier to avoid race conditions.
 	if err := os.Mkdir(container.root, 0700); err != nil {
 		return nil, err
 	}

 
 	// If custom dns exists, then create a resolv.conf for the container
 	if len(config.Dns) > 0 {
 		container.ResolvConfPath = path.Join(container.root, "resolv.conf")
 		f, err := os.Create(container.ResolvConfPath)
 		if err != nil {
 			return nil, err
 		}
 		defer f.Close()
 		for _, dns := range config.Dns {
 			if _, err := f.Write([]byte("nameserver " + dns + "\n")); err != nil {
 				return nil, err
 			}
 		}
 	} else {
 		container.ResolvConfPath = "/etc/resolv.conf"
 	}
 

 	// Step 2: save the container json
 	if err := container.ToDisk(); err != nil {
 		return nil, err
 	}
 	// Step 3: register the container

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

 		return nil, err

 	}

 	return container, nil
 }

 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 = newWriteBroadcaster()
 	container.stdout = newWriteBroadcaster()
 	// Attach to stdin
 	if container.Config.OpenStdin {
 		container.stdin, container.stdinPipe = io.Pipe()
 	} else {
 		container.stdinPipe = 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 {
 		if output, err := exec.Command("lxc-info", "-n", container.Id).CombinedOutput(); err != nil {
 			return err
 		} else {
 			if !strings.Contains(string(output), "RUNNING") {
 				Debugf("Container %s was supposed to be running be is not.", container.Id)
 				if runtime.autoRestart {
 					Debugf("Restarting")
 					container.State.Ghost = false
 					container.State.setStopped(0)
 					if err := container.Start(); err != nil {
 						return err
 					}
 					nomonitor = true
 				} else {
 					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 *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 {
 	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(10); 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
 }
 

 // Commit creates a new filesystem image from the current state of a container.
 // The image can optionally be tagged into a repository

 func (runtime *Runtime) Commit(id, repository, tag, comment, author string, config *Config) (*Image, error) {

 	container := runtime.Get(id)
 	if container == nil {
 		return nil, fmt.Errorf("No such container: %s", id)
 	}
 	// FIXME: freeze the container before copying it to avoid data corruption?
 	// FIXME: this shouldn't be in commands.
 	rwTar, err := container.ExportRw()
 	if err != nil {
 		return nil, err
 	}
 	// Create a new image from the container's base layers + a new layer from container changes

 	img, err := runtime.graph.Create(rwTar, container, comment, author, config)

 	if err != nil {
 		return nil, err
 	}
 	// Register the image if needed
 	if repository != "" {

 		if err := runtime.repositories.Set(repository, tag, img.Id, true); err != nil {

 			return img, err
 		}
 	}
 	return img, 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 {

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

 			continue
 		}

 		Debugf("Loaded container %v", container.Id)

 	}
 	return nil
 }
 

 func (runtime *Runtime) UpdateCapabilities(quiet bool) {
 	if cgroupMemoryMountpoint, err := 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) (*Runtime, error) {
 	runtime, err := NewRuntimeFromDirectory("/var/lib/docker", autoRestart)

 	if err != nil {
 		return nil, err
 	}
 

 	if k, err := GetKernelVersion(); err != nil {
 		log.Printf("WARNING: %s\n", err)
 	} else {
 		runtime.kernelVersion = k
 		if CompareKernelVersion(k, &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
 	}

 	authConfig, err := auth.LoadConfig(root)
 	if err != nil && authConfig == nil {
 		// If the auth file does not exist, keep going
 		return nil, err
 	}

 	runtime := &Runtime{

 		root:           root,

 		repository:     runtimeRepo,

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

 		graph:          g,
 		repositories:   repositories,

 		authConfig:     authConfig,

 		idIndex:        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)
 }