const (
	Unknown = State(iota)
	Created
	Online
	Banned
	Offline
	Destroyed
)

var (
	// ErrOperationNotReady specified error when operation is not ready
	ErrOperationNotReady = fmt.Errorf("operation is not ready yet")
)

type Config interface {
	DialTimeout() time.Duration
	Trace() trace.Driver
	ConnectionTTL() time.Duration
	GrpcDialOptions() []grpc.DialOption
	Meta() meta.Meta
	UseDNSResolver() bool
}

type Conn interface {
	grpc.ClientConnInterface

	Endpoint() endpoint.Endpoint

	LastUsage() time.Time

	IsState(states ...State) bool
	GetState() State
	SetState(State) State

	Release(ctx context.Context)
}

type Creator interface {
	Create(endpoint endpoint.Endpoint) Conn // creates new detached conn applying pool config
}

type Getter interface {
	Get(endpoint endpoint.Endpoint) Conn
}

type Pessimizer interface {
	Pessimize(ctx context.Context, cc Conn, cause error)
}

type Pool interface {
	Creator
	Getter
	Taker
	Releaser
	Pessimizer
}

type PoolConfig interface {
	ConnectionTTL() time.Duration
	GrpcDialOptions() []grpc.DialOption
}

type Releaser interface {
	Release(ctx context.Context) error
}

type State int8

type Taker interface {
	Take(ctx context.Context) error
}