snowman

type Block interface {
	choices.Decidable

	// Parent returns the ID of this block's parent.
	Parent() ids.ID

	// Verify that the state transition this block would make if accepted is
	// valid. If the state transition is invalid, a non-nil error should be
	// returned.
	//
	// It is guaranteed that the Parent has been successfully verified.
	//
	// If nil is returned, it is guaranteed that either Accept or Reject will be
	// called on this block, unless the VM is shut down.
	Verify(context.Context) error

	// Bytes returns the binary representation of this block.
	//
	// This is used for sending blocks to peers. The bytes should be able to be
	// parsed into the same block on another node.
	Bytes() []byte

	// Height returns the height of this block in the chain.
	Height() uint64

	// Time this block was proposed at. This value should be consistent across
	// all nodes. If this block hasn't been successfully verified, any value can
	// be returned. If this block is the last accepted block, the timestamp must
	// be returned correctly. Otherwise, accepted blocks can return any value.
	Timestamp() time.Time
}

type Consensus interface {
	health.Checker

	// Takes in the context, snowball parameters, and the last accepted block.
	Initialize(
		ctx *snow.ConsensusContext,
		params snowball.Parameters,
		lastAcceptedID ids.ID,
		lastAcceptedHeight uint64,
		lastAcceptedTime time.Time,
	) error

	// Returns the number of blocks processing
	NumProcessing() int

	// Adds a new decision. Assumes the dependency has already been added.
	// Returns if a critical error has occurred.
	Add(context.Context, Block) error

	// Decided returns true if the block has been decided.
	Decided(Block) bool

	// Processing returns true if the block ID is currently processing.
	Processing(ids.ID) bool

	// IsPreferred returns true if the block is currently on the preferred
	// chain.
	IsPreferred(Block) bool

	// Returns the ID and height of the last accepted decision.
	LastAccepted() (ids.ID, uint64)

	// Returns the ID of the tail of the strongly preferred sequence of
	// decisions.
	Preference() ids.ID

	// Returns the ID of the strongly preferred decision with the provided
	// height. Only the last accepted decision and processing decisions are
	// tracked.
	PreferenceAtHeight(height uint64) (ids.ID, bool)

	// RecordPoll collects the results of a network poll. Assumes all decisions
	// have been previously added. Returns if a critical error has occurred.
	RecordPoll(context.Context, bag.Bag[ids.ID]) error
}

type Factory interface {
	New() Consensus
}

type OracleBlock interface {
	// Options returns the possible children of this block in the order this
	// validator prefers the blocks.
	Options(context.Context) ([2]Block, error)
}

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

type TopologicalFactory struct{}