event.go

package dag

import (
	"fmt"

	"github.com/corex-mn/corex-base/hash"
	"github.com/corex-mn/corex-base/inter/idx"
)

type Event interface {
	Epoch() idx.Epoch
	Seq() idx.Event
	Frame() idx.Frame
	Creator() idx.ValidatorID
	Lamport() idx.Lamport

	Parents() hash.Events
	SelfParent() *hash.Event
	IsSelfParent(hash hash.Event) bool

	ID() hash.Event

	String() string

	Size() int
}

type MutableEvent interface {
	Event
	SetEpoch(idx.Epoch)
	SetSeq(idx.Event)
	SetFrame(idx.Frame)
	SetCreator(idx.ValidatorID)
	SetLamport(idx.Lamport)

	SetParents(hash.Events)

	SetID(id [24]byte)
}

// BaseEvent is the consensus message in the Lachesis consensus algorithm
// The structure isn't supposed to be used as-is:
// Doesn't contain payload, it should be extended by an app
// Doesn't contain event signature, it should be extended by an app
type BaseEvent struct {
	epoch idx.Epoch
	seq   idx.Event

	frame idx.Frame

	creator idx.ValidatorID

	parents hash.Events

	lamport idx.Lamport

	id hash.Event
}

type MutableBaseEvent struct {
	BaseEvent
}

// Build build immutable event
func (me *MutableBaseEvent) Build(rID [24]byte) *BaseEvent {
	e := me.BaseEvent
	copy(e.id[0:4], e.epoch.Bytes())
	copy(e.id[4:8], e.lamport.Bytes())
	copy(e.id[8:], rID[:])
	return &e
}

// fmtFrame returns frame string representation.
func fmtFrame(frame idx.Frame, isRoot bool) string {
	if isRoot {
		return fmt.Sprintf("%d:y", frame)
	}
	return fmt.Sprintf("%d:n", frame)
}

// String returns string representation.
func (e *BaseEvent) String() string {
	return fmt.Sprintf("{id=%s, p=%s, by=%d, frame=%d}", e.id.ShortID(3), e.parents.String(), e.creator, e.frame)
}

// SelfParent returns event's self-parent, if any
func (e *BaseEvent) SelfParent() *hash.Event {
	if e.seq <= 1 || len(e.parents) == 0 {
		return nil
	}
	return &e.parents[0]
}

// IsSelfParent is true if specified ID is event's self-parent
func (e *BaseEvent) IsSelfParent(hash hash.Event) bool {
	if e.SelfParent() == nil {
		return false
	}
	return *e.SelfParent() == hash
}

func (e *BaseEvent) Epoch() idx.Epoch { return e.epoch }

func (e *BaseEvent) Seq() idx.Event { return e.seq }

func (e *BaseEvent) Frame() idx.Frame { return e.frame }

func (e *BaseEvent) Creator() idx.ValidatorID { return e.creator }

func (e *BaseEvent) Parents() hash.Events { return e.parents }

func (e *BaseEvent) Lamport() idx.Lamport { return e.lamport }

func (e *BaseEvent) ID() hash.Event { return e.id }

func (e *BaseEvent) Size() int { return 4 + 4 + 4 + 4 + len(e.parents)*32 + 4 + 32 }

func (e *MutableBaseEvent) SetEpoch(v idx.Epoch) { e.epoch = v }

func (e *MutableBaseEvent) SetSeq(v idx.Event) { e.seq = v }

func (e *MutableBaseEvent) SetFrame(v idx.Frame) { e.frame = v }

func (e *MutableBaseEvent) SetCreator(v idx.ValidatorID) { e.creator = v }

func (e *MutableBaseEvent) SetParents(v hash.Events) { e.parents = v }

func (e *MutableBaseEvent) SetLamport(v idx.Lamport) { e.lamport = v }

func (e *MutableBaseEvent) SetID(rID [24]byte) {
	copy(e.id[0:4], e.epoch.Bytes())
	copy(e.id[4:8], e.lamport.Bytes())
	copy(e.id[8:], rID[:])
}