protocol

type Blockchain interface {
	// SubscribeEvents subscribes new blockchain event
	SubscribeEvents() blockchain.Subscription
	Header() *types.Header

	// deprecated methods. Those are old version protocols, keep it only for backward compatible
	CurrentTD() *big.Int
	GetTD(hash types.Hash) (*big.Int, bool)
	GetReceiptsByHash(types.Hash) ([]*types.Receipt, error)
	GetBodyByHash(types.Hash) (*types.Body, bool)
	GetHeaderByHash(types.Hash) (*types.Header, bool)
	GetHeaderByNumber(n uint64) (*types.Header, bool)
	CalculateGasLimit(number uint64) (uint64, error)

	// advance chain methods
	WriteBlock(block *types.Block, source string) error
	VerifyFinalizedBlock(block *types.Block) error

	// GetBlockByNumber returns block by number
	GetBlockByNumber(uint64, bool) (*types.Block, bool)
}

type NoForkPeer struct {
	// identifier
	ID peer.ID
	// peer's latest block number
	Number uint64
}

type PeerMap struct {
	sync.Map
}

type Progression interface {
	// StartProgression starts progression
	StartProgression(syncingPeer string, startingBlock uint64, subscription blockchain.Subscription)
	// UpdateHighestProgression updates highest block number
	UpdateHighestProgression(highestBlock uint64)
	// GetProgression returns Progression
	GetProgression() *progress.Progression
	// StopProgression finishes progression
	StopProgression()
}

type Status struct {
	Difficulty *big.Int   // Current difficulty
	Hash       types.Hash // Latest block hash
	Number     uint64     // Latest block number
}

type SyncPeerClient interface {
	// Start processes for SyncPeerClient
	Start() error
	// Close terminates running processes for SyncPeerClient
	Close()
	// GetPeerStatus fetches peer status
	GetPeerStatus(id peer.ID) (*NoForkPeer, error)
	// GetConnectedPeerStatuses fetches the statuses of all connecting peers
	GetConnectedPeerStatuses() []*NoForkPeer
	// GetBlocks returns a stream of blocks from given height to peer's latest
	GetBlocks(ctx context.Context, peerID peer.ID, from uint64, to uint64) ([]*types.Block, error)
	// GetPeerStatusUpdateCh returns a channel of peer's status update
	GetPeerStatusUpdateCh() <-chan *NoForkPeer
	// GetPeerConnectionUpdateEventCh returns peer's connection change event
	GetPeerConnectionUpdateEventCh() <-chan *event.PeerEvent
	// DisablePublishingPeerStatus disables publishing status in syncer topic
	DisablePublishingPeerStatus()
	// EnablePublishingPeerStatus enables publishing status in syncer topic
	EnablePublishingPeerStatus()

	// broadcast block to all its connected peers
	Broadcast(block *types.Block) error
}

type SyncPeerService interface {
	// Start starts server
	Start()
	// Close terminates running processes for SyncPeerService
	Close() error

	// SetSyncer sets referent syncer
	SetSyncer(syncer *noForkSyncer)
}

type Syncer interface {
	// Start starts syncer processes
	Start() error
	// Close terminates syncer process
	Close() error
	// GetSyncProgression returns sync progression
	GetSyncProgression() *progress.Progression
	// HasSyncPeer returns whether syncer has the peer syncer can sync with
	HasSyncPeer() bool
	// IsSyncing returns whether syncer is syncing
	IsSyncing() bool
	// Sync starts routine to sync blocks
	Sync(func(*types.Block) bool) error
}