package daemon
 
 import (
 	"fmt"
 	"strings"
 

 	"github.com/docker/docker/container"

 	"github.com/docker/docker/errors"

 	"github.com/docker/docker/image"

 	"github.com/docker/docker/pkg/stringid"

 	"github.com/docker/docker/reference"

 	"github.com/docker/engine-api/types"

 )
 

 type conflictType int
 
 const (
 	conflictDependentChild conflictType = (1 << iota)
 	conflictRunningContainer
 	conflictActiveReference
 	conflictStoppedContainer
 	conflictHard = conflictDependentChild | conflictRunningContainer
 	conflictSoft = conflictActiveReference | conflictStoppedContainer
 )
 

 // ImageDelete deletes the image referenced by the given imageRef from this
 // daemon. The given imageRef can be an image ID, ID prefix, or a repository
 // reference (with an optional tag or digest, defaulting to the tag name
 // "latest"). There is differing behavior depending on whether the given
 // imageRef is a repository reference or not.
 //
 // If the given imageRef is a repository reference then that repository
 // reference will be removed. However, if there exists any containers which
 // were created using the same image reference then the repository reference
 // cannot be removed unless either there are other repository references to the
 // same image or force is true. Following removal of the repository reference,
 // the referenced image itself will attempt to be deleted as described below
 // but quietly, meaning any image delete conflicts will cause the image to not
 // be deleted and the conflict will not be reported.
 //
 // There may be conflicts preventing deletion of an image and these conflicts
 // are divided into two categories grouped by their severity:
 //
 // Hard Conflict:
 // 	- a pull or build using the image.

 // 	- any descendant image.

 // 	- any running container using the image.
 //
 // Soft Conflict:
 // 	- any stopped container using the image.
 // 	- any repository tag or digest references to the image.
 //
 // The image cannot be removed if there are any hard conflicts and can be
 // removed if there are soft conflicts only if force is true.
 //
 // If prune is true, ancestor images will each attempt to be deleted quietly,
 // meaning any delete conflicts will cause the image to not be deleted and the
 // conflict will not be reported.
 //
 // FIXME: remove ImageDelete's dependency on Daemon, then move to the graph
 // package. This would require that we no longer need the daemon to determine
 // whether images are being used by a stopped or running container.

 func (daemon *Daemon) ImageDelete(imageRef string, force, prune bool) ([]types.ImageDelete, error) {

 	records := []types.ImageDelete{}
 

 	imgID, err := daemon.GetImageID(imageRef)

 	if err != nil {

 		return nil, daemon.imageNotExistToErrcode(err)

 	}

 	repoRefs := daemon.referenceStore.References(imgID)

 	var removedRepositoryRef bool

 	if !isImageIDPrefix(imgID.String(), imageRef) {

 		// A repository reference was given and should be removed
 		// first. We can only remove this reference if either force is
 		// true, there are multiple repository references to this
 		// image, or there are no containers using the given reference.

 		if !(force || len(repoRefs) > 1) {
 			if container := daemon.getContainerUsingImage(imgID); container != nil {

 				// If we removed the repository reference then
 				// this image would remain "dangling" and since
 				// we really want to avoid that the client must
 				// explicitly force its removal.

 				err := fmt.Errorf("conflict: unable to remove repository reference %q (must force) - container %s is using its referenced image %s", imageRef, stringid.TruncateID(container.ID), stringid.TruncateID(imgID.String()))
 				return nil, errors.NewRequestConflictError(err)

 			}
 		}
 

 		parsedRef, err := reference.ParseNamed(imageRef)

 		if err != nil {
 			return nil, err
 		}
 

 		parsedRef, err = daemon.removeImageRef(parsedRef)
 		if err != nil {
 			return nil, err
 		}
 
 		untaggedRecord := types.ImageDelete{Untagged: parsedRef.String()}

 		daemon.LogImageEvent(imgID.String(), imgID.String(), "untag")

 		records = append(records, untaggedRecord)
 

 		repoRefs = daemon.referenceStore.References(imgID)
 
 		// If this is a tag reference and all the remaining references
 		// to this image are digest references, delete the remaining
 		// references so that they don't prevent removal of the image.
 		if _, isCanonical := parsedRef.(reference.Canonical); !isCanonical {
 			foundTagRef := false
 			for _, repoRef := range repoRefs {
 				if _, repoRefIsCanonical := repoRef.(reference.Canonical); !repoRefIsCanonical {
 					foundTagRef = true
 					break
 				}
 			}
 			if !foundTagRef {
 				for _, repoRef := range repoRefs {
 					if _, err := daemon.removeImageRef(repoRef); err != nil {
 						return records, err
 					}
 
 					untaggedRecord := types.ImageDelete{Untagged: repoRef.String()}
 					records = append(records, untaggedRecord)
 				}
 				repoRefs = []reference.Named{}
 			}
 		}
 
 		// If it has remaining references then the untag finished the remove
 		if len(repoRefs) > 0 {

 			return records, nil
 		}
 

 		removedRepositoryRef = true
 	} else {
 		// If an ID reference was given AND there is exactly one
 		// repository reference to the image then we will want to
 		// remove that reference.
 		// FIXME: Is this the behavior we want?
 		if len(repoRefs) == 1 {

 			c := conflictHard
 			if !force {
 				c |= conflictSoft &^ conflictActiveReference
 			}
 			if conflict := daemon.checkImageDeleteConflict(imgID, c); conflict != nil {

 				return nil, conflict
 			}
 

 			parsedRef, err := daemon.removeImageRef(repoRefs[0])

 			if err != nil {
 				return nil, err
 			}
 

 			untaggedRecord := types.ImageDelete{Untagged: parsedRef.String()}

 			daemon.LogImageEvent(imgID.String(), imgID.String(), "untag")

 			records = append(records, untaggedRecord)
 		}

 	}

 	return records, daemon.imageDeleteHelper(imgID, &records, force, prune, removedRepositoryRef)

 }
 

 // isImageIDPrefix returns whether the given possiblePrefix is a prefix of the
 // given imageID.
 func isImageIDPrefix(imageID, possiblePrefix string) bool {

 	if strings.HasPrefix(imageID, possiblePrefix) {
 		return true
 	}
 
 	if i := strings.IndexRune(imageID, ':'); i >= 0 {
 		return strings.HasPrefix(imageID[i+1:], possiblePrefix)
 	}

 	return false

 }
 
 // getContainerUsingImage returns a container that was created using the given
 // imageID. Returns nil if there is no such container.

 func (daemon *Daemon) getContainerUsingImage(imageID image.ID) *container.Container {

 	return daemon.containers.First(func(c *container.Container) bool {
 		return c.ImageID == imageID
 	})

 }

 // removeImageRef attempts to parse and remove the given image reference from
 // this daemon's store of repository tag/digest references. The given
 // repositoryRef must not be an image ID but a repository name followed by an
 // optional tag or digest reference. If tag or digest is omitted, the default
 // tag is used. Returns the resolved image reference and an error.

 func (daemon *Daemon) removeImageRef(ref reference.Named) (reference.Named, error) {

 	ref = reference.WithDefaultTag(ref)

 	// Ignore the boolean value returned, as far as we're concerned, this
 	// is an idempotent operation and it's okay if the reference didn't
 	// exist in the first place.

 	_, err := daemon.referenceStore.Delete(ref)

 	return ref, err

 }
 
 // removeAllReferencesToImageID attempts to remove every reference to the given
 // imgID from this daemon's store of repository tag/digest references. Returns
 // on the first encountered error. Removed references are logged to this
 // daemon's event service. An "Untagged" types.ImageDelete is added to the
 // given list of records.

 func (daemon *Daemon) removeAllReferencesToImageID(imgID image.ID, records *[]types.ImageDelete) error {

 	imageRefs := daemon.referenceStore.References(imgID)

 
 	for _, imageRef := range imageRefs {

 		parsedRef, err := daemon.removeImageRef(imageRef)

 		if err != nil {
 			return err

 		}

 		untaggedRecord := types.ImageDelete{Untagged: parsedRef.String()}

 		daemon.LogImageEvent(imgID.String(), imgID.String(), "untag")

 		*records = append(*records, untaggedRecord)
 	}
 
 	return nil
 }
 
 // ImageDeleteConflict holds a soft or hard conflict and an associated error.
 // Implements the error interface.
 type imageDeleteConflict struct {
 	hard    bool

 	used    bool

 	imgID   image.ID

 	message string
 }
 
 func (idc *imageDeleteConflict) Error() string {
 	var forceMsg string
 	if idc.hard {
 		forceMsg = "cannot be forced"

 	} else {

 		forceMsg = "must be forced"
 	}
 

 	return fmt.Sprintf("conflict: unable to delete %s (%s) - %s", stringid.TruncateID(idc.imgID.String()), forceMsg, idc.message)

 }
 
 // imageDeleteHelper attempts to delete the given image from this daemon. If
 // the image has any hard delete conflicts (child images or running containers
 // using the image) then it cannot be deleted. If the image has any soft delete
 // conflicts (any tags/digests referencing the image or any stopped container
 // using the image) then it can only be deleted if force is true. If the delete
 // succeeds and prune is true, the parent images are also deleted if they do
 // not have any soft or hard delete conflicts themselves. Any deleted images
 // and untagged references are appended to the given records. If any error or
 // conflict is encountered, it will be returned immediately without deleting
 // the image. If quiet is true, any encountered conflicts will be ignored and
 // the function will return nil immediately without deleting the image.

 func (daemon *Daemon) imageDeleteHelper(imgID image.ID, records *[]types.ImageDelete, force, prune, quiet bool) error {

 	// First, determine if this image has any conflicts. Ignore soft conflicts
 	// if force is true.

 	c := conflictHard
 	if !force {
 		c |= conflictSoft
 	}
 	if conflict := daemon.checkImageDeleteConflict(imgID, c); conflict != nil {

 		if quiet && (!daemon.imageIsDangling(imgID) || conflict.used) {
 			// Ignore conflicts UNLESS the image is "dangling" or not being used in

 			// which case we want the user to know.
 			return nil
 		}
 
 		// There was a conflict and it's either a hard conflict OR we are not
 		// forcing deletion on soft conflicts.
 		return conflict
 	}
 

 	parent, err := daemon.imageStore.GetParent(imgID)
 	if err != nil {
 		// There may be no parent
 		parent = ""
 	}
 

 	// Delete all repository tag/digest references to this image.

 	if err := daemon.removeAllReferencesToImageID(imgID, records); err != nil {

 		return err
 	}
 

 	removedLayers, err := daemon.imageStore.Delete(imgID)
 	if err != nil {

 		return err

 	}
 

 	daemon.LogImageEvent(imgID.String(), imgID.String(), "delete")

 	*records = append(*records, types.ImageDelete{Deleted: imgID.String()})
 	for _, removedLayer := range removedLayers {
 		*records = append(*records, types.ImageDelete{Deleted: removedLayer.ChainID.String()})
 	}

 	if !prune || parent == "" {

 		return nil
 	}
 

 	// We need to prune the parent image. This means delete it if there are
 	// no tags/digests referencing it and there are no containers using it (
 	// either running or stopped).
 	// Do not force prunings, but do so quietly (stopping on any encountered
 	// conflicts).

 	return daemon.imageDeleteHelper(parent, records, false, true, true)

 }
 
 // checkImageDeleteConflict determines whether there are any conflicts
 // preventing deletion of the given image from this daemon. A hard conflict is
 // any image which has the given image as a parent or any running container
 // using the image. A soft conflict is any tags/digest referencing the given
 // image or any stopped container using the image. If ignoreSoftConflicts is
 // true, this function will not check for soft conflict conditions.

 func (daemon *Daemon) checkImageDeleteConflict(imgID image.ID, mask conflictType) *imageDeleteConflict {

 	// Check if the image has any descendant images.

 	if mask&conflictDependentChild != 0 && len(daemon.imageStore.Children(imgID)) > 0 {

 		return &imageDeleteConflict{
 			hard:    true,

 			imgID:   imgID,

 			message: "image has dependent child images",

 		}
 	}
 

 	if mask&conflictRunningContainer != 0 {
 		// Check if any running container is using the image.

 		running := func(c *container.Container) bool {
 			return c.IsRunning() && c.ImageID == imgID
 		}
 		if container := daemon.containers.First(running); container != nil {
 			return &imageDeleteConflict{
 				imgID:   imgID,
 				hard:    true,
 				used:    true,
 				message: fmt.Sprintf("image is being used by running container %s", stringid.TruncateID(container.ID)),

 			}

 		}
 	}

 
 	// Check if any repository tags/digest reference this image.

 	if mask&conflictActiveReference != 0 && len(daemon.referenceStore.References(imgID)) > 0 {

 		return &imageDeleteConflict{

 			imgID:   imgID,

 			message: "image is referenced in one or more repositories",
 		}

 	}

 	if mask&conflictStoppedContainer != 0 {
 		// Check if any stopped containers reference this image.

 		stopped := func(c *container.Container) bool {
 			return !c.IsRunning() && c.ImageID == imgID
 		}
 		if container := daemon.containers.First(stopped); container != nil {
 			return &imageDeleteConflict{
 				imgID:   imgID,
 				used:    true,
 				message: fmt.Sprintf("image is being used by stopped container %s", stringid.TruncateID(container.ID)),

 			}
 		}
 	}

 	return nil
 }

 
 // imageIsDangling returns whether the given image is "dangling" which means
 // that there are no repository references to the given image and it has no
 // child images.

 func (daemon *Daemon) imageIsDangling(imgID image.ID) bool {

 	return !(len(daemon.referenceStore.References(imgID)) > 0 || len(daemon.imageStore.Children(imgID)) > 0)

 }