pool

type Config struct {
	// Min indicates what is minimum number of transactions that is required
	// before returning.
	Min int

	// Callback is a function called when the pool doesn't have enough
	// transactions at the moment of calling and must therefore wait for new
	// transactions to come. It allows one to take action to stop the gathering
	// if necessary.
	Callback func()
}

type Filter interface {
	// Accept returns an error when the transaction is going to be rejected.
	Accept(tx txn.Transaction, leeway validation.Leeway) error
}

type Gatherer interface {
	// AddFilter adds the filter to the list that a transaction will go through
	// before being accepted by the gatherer.
	AddFilter(Filter)

	// Add adds the transaction to the list of pending transactions.
	Add(tx txn.Transaction) error

	// Remove removes a transaction from the list of pending ones.
	Remove(tx txn.Transaction) error

	// Wait waits for a notification with sufficient transactions to return the
	// array, or nil if the context ends.
	Wait(ctx context.Context, cfg Config) []txn.Transaction

	// Close closes current operations and cleans the resources.
	Close()

	// Stats gets the transaction statistics.
	Stats() Stats

	// ResetStats resets the transaction statistics.
	ResetStats()
}

type Pool interface {
	// SetPlayers updates the list of participants that should eventually
	// receive the transactions.
	SetPlayers(mino.Players) error

	AddFilter(Filter)

	// Add adds the transaction to the pool.
	Add(txn.Transaction) error

	// Remove removes the transaction from the pool.
	Remove(txn.Transaction) error

	// Gather is a blocking function to gather transactions from the pool. The
	// configuration allows one to specify criterion before returning.
	Gather(context.Context, Config) []txn.Transaction

	// Stats gets the transactions statistics
	Stats() Stats

	// ResetStats resets the transaction statistics.
	ResetStats()

	// Close closes the pool and cleans the resources.
	Close() error
}

type Stats struct {
	// OldestTx is the time at which the oldest transaction was added to the pool.
	OldestTx time.Time

	// TxCount is the number of transactions available in the pool.
	TxCount int
}