protocol

type Client interface {
	// GetResource gets resource by argument.
	GetResource(url string, md Metadata) Resource
}

type ClientBuilder interface {
	// NewProtocolClient creates an instance of Client.
	// Here have a suggestion that every implementation should have
	// opts with WithMapInterface(map[string]interface),
	// which may be easier for configuration with config file.
	NewProtocolClient(opts ...func(client Client) error) (Client, error)
}

type ClientRegister interface {
	// ClientRegister registers pair <protocol, ClientBuilder>.
	RegisterProtocol(protocol string, builder ClientBuilder)

	// GetClientBuilder gets the ClientBuilder by protocol.
	GetClientBuilder(protocol string) (ClientBuilder, error)
}

type DataEncoder interface {
	// Encode data.
	Encode(io.Reader) (io.Reader, error)

	// Decode data.
	Decode(io.Reader) (io.Reader, error)
}

type DataType interface {
	// String return the type string.
	String() string

	// Encoder return the encoder of the type.
	Encoder() DataEncoder
}

type DistributionData interface {
	// Type gets the data type.
	Type() DataType

	// Size gets the size of data.
	Size() int64

	// Metadata gets the metadata.
	Metadata() interface{}

	// Content gets the content of data.
	Content(ctx context.Context) (io.Reader, error)
}

type MapInterfaceOptFunc func(map[string]interface{}) func(Client) error

type Metadata interface {
	Get(key string) (interface{}, error)
	Set(key string, value interface{})
	Del(key string)
	All() interface{}
}

type Resource interface {
	// Read gets range data from the binding resource.
	Read(ctx context.Context, off int64, size int64) (io.ReadCloser, error)

	// Length gets the length of binding resource.
	Length(ctx context.Context) (int64, error)

	// Metadata gets the metadata of binding resource.
	Metadata(ctx context.Context) (Metadata, error)

	// Expire gets if the binding resource is expired.
	Expire(ctx context.Context) (bool, interface{}, error)

	// Call allows user defined request.
	Call(ctx context.Context, request interface{}) (response interface{}, err error)

	// Close the resource.
	io.Closer
}