charmstore

type EntityCache interface {
	// GetResource returns the resource data for the identified resource.
	GetResource(name string) (resource.Resource, error)

	// SetResource stores the resource in the local cache.
	SetResource(res charmresource.Resource, reader io.Reader) (resource.Resource, error)

	// OpenResource returns metadata about the resource, and a reader
	// for the resource.
	OpenResource(name string) (resource.Resource, io.ReadCloser, error)
}

type GetResourceArgs struct {
	// Client is the charm store client to use.
	Client StoreResourceGetter

	// EntityCache is the charm store cache to use. It is optional.
	Cache EntityCache

	// CharmID indicates the charm for which to get the resource.
	CharmID charmstore.CharmID

	// Name is the name of the resource.
	Name string
}

type StoreResourceGetter interface {
	// GetResource returns a reader for the resource's data. That data
	// is streamed from the charm store. The charm's revision, if any,
	// is ignored. If the identified resource is not in the charm store
	// then errors.NotFound is returned.
	//
	// But if you write any code that assumes a NotFound error returned
	// from this methid means that the resource was not found, you fail
	// basic logic.
	GetResource(charmstore.ResourceRequest) (charmstore.ResourceData, error)
}