sweep

type CoinSelectionLocker interface {
	// WithCoinSelectLock will execute the passed function closure in a
	// synchronized manner preventing any coin selection operations from
	// proceeding while the closure is executing. This can be seen as the
	// ability to execute a function closure under an exclusive coin
	// selection lock.
	WithCoinSelectLock(func() error) error
}

type DeliveryAddr struct {
	// Addr is the address to pay to.
	Addr btcutil.Address

	// Amt is the amount to pay to the given address.
	Amt btcutil.Amount
}

type FeePreference struct {
	// ConfTarget if non-zero, signals a fee preference expressed in the
	// number of desired blocks between first broadcast, and confirmation.
	ConfTarget uint32

	// FeeRate if non-zero, signals a fee pre fence expressed in the fee
	// rate expressed in sat/kw for a particular transaction.
	FeeRate chainfee.SatPerKWeight
}

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

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

type OutpointLocker interface {
	// LockOutpoint locks a target outpoint, rendering it unusable for coin
	// selection.
	LockOutpoint(o wire.OutPoint)

	// UnlockOutpoint unlocks a target outpoint, allowing it to be used for
	// coin selection once again.
	UnlockOutpoint(o wire.OutPoint)
}

type Params struct {
	// Fee is the fee preference of the client who requested the input to be
	// swept. If a confirmation target is specified, then we'll map it into
	// a fee rate whenever we attempt to cluster inputs for a sweep.
	Fee FeePreference

	// Force indicates whether the input should be swept regardless of
	// whether it is economical to do so.
	Force bool

	// ExclusiveGroup is an identifier that, if set, prevents other inputs
	// with the same identifier from being batched together.
	ExclusiveGroup *uint64
}

type ParamsUpdate struct {
	// Fee is the fee preference of the client who requested the input to be
	// swept. If a confirmation target is specified, then we'll map it into
	// a fee rate whenever we attempt to cluster inputs for a sweep.
	Fee FeePreference

	// Force indicates whether the input should be swept regardless of
	// whether it is economical to do so.
	Force bool
}

type PendingInput struct {
	// OutPoint is the identify outpoint of the input being swept.
	OutPoint wire.OutPoint

	// WitnessType is the witness type of the input being swept.
	WitnessType input.WitnessType

	// Amount is the amount of the input being swept.
	Amount btcutil.Amount

	// LastFeeRate is the most recent fee rate used for the input being
	// swept within a transaction broadcast to the network.
	LastFeeRate chainfee.SatPerKWeight

	// BroadcastAttempts is the number of attempts we've made to sweept the
	// input.
	BroadcastAttempts int

	// NextBroadcastHeight is the next height of the chain at which we'll
	// attempt to broadcast a transaction sweeping the input.
	NextBroadcastHeight uint32

	// Params contains the sweep parameters for this pending request.
	Params Params
}

type Result struct {
	// Err is the final result of the sweep. It is nil when the input is
	// swept successfully by us. ErrRemoteSpend is returned when another
	// party took the input.
	Err error

	// Tx is the transaction that spent the input.
	Tx *wire.MsgTx
}

type SweeperStore interface {
	// IsOurTx determines whether a tx is published by us, based on its
	// hash.
	IsOurTx(hash chainhash.Hash) (bool, error)

	// NotifyPublishTx signals that we are about to publish a tx.
	NotifyPublishTx(*wire.MsgTx) error

	// ListSweeps lists all the sweeps we have successfully published.
	ListSweeps() ([]chainhash.Hash, error)
}

type UtxoSource interface {
	// ListUnspentWitness returns all UTXOs from the default wallet account
	// that have between minConfs and maxConfs number of confirmations.
	ListUnspentWitnessFromDefaultAccount(minConfs, maxConfs int32) (
		[]*lnwallet.Utxo, error)
}

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

type UtxoSweeperConfig struct {
	// GenSweepScript generates a P2WKH script belonging to the wallet where
	// funds can be swept.
	GenSweepScript func() ([]byte, error)

	// FeeEstimator is used when crafting sweep transactions to estimate
	// the necessary fee relative to the expected size of the sweep
	// transaction.
	FeeEstimator chainfee.Estimator

	// Wallet contains the wallet functions that sweeper requires.
	Wallet Wallet

	// NewBatchTimer creates a channel that will be sent on when a certain
	// time window has passed. During this time window, new inputs can still
	// be added to the sweep tx that is about to be generated.
	NewBatchTimer func() <-chan time.Time

	// Notifier is an instance of a chain notifier we'll use to watch for
	// certain on-chain events.
	Notifier chainntnfs.ChainNotifier

	// Store stores the published sweeper txes.
	Store SweeperStore

	// Signer is used by the sweeper to generate valid witnesses at the
	// time the incubated outputs need to be spent.
	Signer input.Signer

	// MaxInputsPerTx specifies the default maximum number of inputs allowed
	// in a single sweep tx. If more need to be swept, multiple txes are
	// created and published.
	MaxInputsPerTx int

	// MaxSweepAttempts specifies the maximum number of times an input is
	// included in a publish attempt before giving up and returning an error
	// to the caller.
	MaxSweepAttempts int

	// NextAttemptDeltaFunc returns given the number of already attempted
	// sweeps, how many blocks to wait before retrying to sweep.
	NextAttemptDeltaFunc func(int) int32

	// MaxFeeRate is the the maximum fee rate allowed within the
	// UtxoSweeper.
	MaxFeeRate chainfee.SatPerKWeight

	// FeeRateBucketSize is the default size of fee rate buckets we'll use
	// when clustering inputs into buckets with similar fee rates within the
	// UtxoSweeper.
	//
	// Given a minimum relay fee rate of 1 sat/vbyte, a fee rate bucket size
	// of 10 would result in the following fee rate buckets up to the
	// maximum fee rate:
	//
	//   #1: min = 1 sat/vbyte, max (exclusive) = 11 sat/vbyte
	//   #2: min = 11 sat/vbyte, max (exclusive) = 21 sat/vbyte...
	FeeRateBucketSize int
}

type Wallet interface {
	// PublishTransaction performs cursory validation (dust checks, etc) and
	// broadcasts the passed transaction to the Bitcoin network.
	PublishTransaction(tx *wire.MsgTx, label string) error

	// ListUnspentWitnessFromDefaultAccount returns all unspent outputs
	// which are version 0 witness programs from the default wallet account.
	// The 'minConfs' and 'maxConfs' parameters indicate the minimum
	// and maximum number of confirmations an output needs in order to be
	// returned by this method.
	ListUnspentWitnessFromDefaultAccount(minConfs, maxConfs int32) (
		[]*lnwallet.Utxo, error)

	// WithCoinSelectLock will execute the passed function closure in a
	// synchronized manner preventing any coin selection operations from
	// proceeding while the closure is executing. This can be seen as the
	// ability to execute a function closure under an exclusive coin
	// selection lock.
	WithCoinSelectLock(f func() error) error

	// RemoveDescendants removes any wallet transactions that spends
	// outputs created by the specified transaction.
	RemoveDescendants(*wire.MsgTx) error

	// FetchTx returns the transaction that corresponds to the transaction
	// hash passed in. If the transaction can't be found then a nil
	// transaction pointer is returned.
	FetchTx(chainhash.Hash) (*wire.MsgTx, error)

	// CancelRebroadcast is used to inform the rebroadcaster sub-system
	// that it no longer needs to try to rebroadcast a transaction. This is
	// used to ensure that invalid transactions (inputs spent) aren't
	// retried in the background.
	CancelRebroadcast(tx chainhash.Hash)
}

type WalletSweepPackage struct {
	// SweepTx is a fully signed, and valid transaction that is broadcast,
	// will sweep ALL confirmed coins in the wallet with a single
	// transaction.
	SweepTx *wire.MsgTx

	// CancelSweepAttempt allows the caller to cancel the sweep attempt.
	//
	// NOTE: If the sweeping transaction isn't or cannot be broadcast, then
	// this closure MUST be called, otherwise all selected utxos will be
	// unable to be used.
	CancelSweepAttempt func()
}