consensus/protocol/horizon/horizon.go

package horizon

import (
	"github.com/luxfi/consensus/core/dag"
)

type VertexID [32]byte

type Meta interface {
	ID() VertexID
	Author() string
	Round() uint64
	Parents() []VertexID
}

type View interface {
	Get(VertexID) (Meta, bool)
	ByRound(round uint64) []Meta
	Supports(from VertexID, author string, round uint64) bool
}

type Params struct{ N, F int }

// TransitiveClosure computes the transitive closure of a vertex in the DAG
func TransitiveClosure[V comparable](store dag.Store[V], vertex V) []V {
	// TODO: Implement transitive closure computation
	return []V{vertex}
}

// Certificate represents a proof that a vertex has achieved consensus
type Certificate[V comparable] struct {
	Vertex    V
	Proof     []V
	Threshold int
}

// ValidateCertificate checks if a certificate is valid given a validator function
func ValidateCertificate[V comparable](store dag.Store[V], cert Certificate[V], isValid func(V) bool) bool {
	// TODO: Implement certificate validation
	validCount := 0
	for _, proof := range cert.Proof {
		if isValid(proof) {
			validCount++
		}
	}
	return validCount >= cert.Threshold
}

// SkipList represents a skip list data structure for efficient DAG traversal
type SkipList[V comparable] struct {
	Levels map[V][]V
}

// BuildSkipList constructs a skip list from DAG vertices for efficient navigation
func BuildSkipList[V comparable](store dag.Store[V], vertices []V) *SkipList[V] {
	// TODO: Implement skip list construction
	sl := &SkipList[V]{
		Levels: make(map[V][]V),
	}

	// Simple placeholder: each vertex points to its first parent
	for _, v := range vertices {
		if block, exists := store.Get(v); exists {
			parents := block.Parents()
			if len(parents) > 0 {
				sl.Levels[v] = []V{parents[0]}
			} else {
				sl.Levels[v] = []V{}
			}
		}
	}

	return sl
}

// FindPath finds a path between two vertices in the DAG
func FindPath[V comparable](store dag.Store[V], from, to V) ([]V, bool) {
	// TODO: Implement path finding algorithm
	// Simple placeholder: return single vertex path if vertices exist
	if _, exists1 := store.Get(from); exists1 {
		if _, exists2 := store.Get(to); exists2 {
			return []V{from, to}, true
		}
	}
	return nil, false
}