blobstore

type ManagedResource struct {
	EnvUUID string
	User    string
	Path    string
}

type ManagedStorage interface {
	// GetForEnvironment returns a reader for data at path, namespaced to the environment.
	// If the data is still being uploaded and is not fully written yet,
	// an ErrUploadPending error is returned. This means the path is valid but the caller
	// should try again to retrieve the data.
	GetForEnvironment(envUUID, path string) (r io.ReadCloser, length int64, err error)

	// PutForEnvironment stores data from reader at path, namespaced to the environment.
	PutForEnvironment(envUUID, path string, r io.Reader, length int64) error

	// RemoveForEnvironment deletes data at path, namespaced to the environment.
	RemoveForEnvironment(envUUID, path string) error

	// PutForEnvironmentRequest requests that data, which may already exist in storage,
	// be saved at path, namespaced to the environment. It allows callers who can
	// demonstrate proof of ownership of the data to store a reference to it without
	// having to upload it all. If no such data exists, a NotFound error is returned
	// and a call to EnvironmentPut is required. If matching data is found, the caller
	// is returned a response indicating the random byte range to for which they must
	// provide checksums to complete the process.
	PutForEnvironmentRequest(envUUID, path string, hash ResourceHash) (*RequestResponse, error)

	// ProofOfAccessResponse is called to respond to a Put..Request call in order to
	// prove ownership of data for which a storage reference is created.
	ProofOfAccessResponse(putResponse) error
}

type PutRequest struct {
	// contains filtered or unexported fields
}

type RequestResponse struct {
	RequestId   int64
	RangeStart  int64
	RangeLength int64
}

type Resource struct {
	ResourceHash
	Path   string
	Length int64
}

type ResourceCatalog interface {
	// Get fetches a Resource with the given id.
	Get(id string) (*Resource, error)

	// Find returns the resource id for the Resource with the given hashes.
	Find(rh *ResourceHash) (id string, err error)

	// Put ensures a Resource entry exists for the given ResourceHash, returning the id, path,
	// and a flag indicating if this is a new record.
	// If the Resource exists, its reference count is incremented, otherwise a new entry is created.
	Put(rh *ResourceHash, length int64) (id, path string, isNew bool, err error)

	// UploadComplete records that the underlying resource described by the Resource entry with id
	// is now fully uploaded and the resource is available for use.
	UploadComplete(id string) error

	// Remove decrements the reference count for a Resource with the given id, deleting it
	// if the reference count reaches zero. The path of the Resource is returned.
	// If the Resource is deleted, wasDeleted is returned as true.
	Remove(id string) (wasDeleted bool, path string, err error)
}

type ResourceHash struct {
	MD5Hash    string
	SHA256Hash string
}

type ResourceStorage interface {
	// Get returns a reader for the resource located at path.
	Get(path string) (io.ReadCloser, error)

	// Put writes data from the specified reader to path and returns a checksum of the data written.
	Put(path string, r io.Reader, length int64) (checksum string, err error)

	// Remove deletes the data at the specified path.
	Remove(path string) error
}