db

type Action struct {
	// Type of the action.
	Type ActionType
	// InstanceID of the instance in action.
	InstanceID InstanceID
	// CollectionName of the instance in action.
	CollectionName string
	// Previous is the instance before the action.
	Previous []byte
	// Current is the instance after the action was done.
	Current []byte
}

type ActionType int

type Event interface {
	// Time (wall-clock) the event was created.
	Time() []byte
	// InstanceID is the associated instance's unique identifier.
	InstanceID() InstanceID
	// Collection is the associated instance's collection name.
	Collection() string
	// Marshal the event to JSON.
	Marshal() ([]byte, error)
}

type EventCodec interface {
	// Reduce applies generated events into state.
	Reduce(events []Event, datastore ds.TxnDatastore, baseKey ds.Key, indexFunc IndexFunc) ([]ReduceAction, error)
	// Create corresponding events to be dispatched.
	Create(ops []Action) ([]Event, format.Node, error)
	// EventsFromBytes deserializes a format.Node bytes payload into Events.
	EventsFromBytes(data []byte) ([]Event, error)
}

type IndexFunc func(collection string, key ds.Key, oldData, newData []byte, txn ds.Txn) error

type InstanceID string

type ReduceAction struct {
	// Type of the reduced action.
	Type ActionType
	// Collection in which action was made.
	Collection string
	// InstanceID of the instance in reduced action.
	InstanceID InstanceID
}