package ownership

import (
	"errors"
	"time"
)

var (
	ErrInvalidOwnership     = errors.New("invalid proxy ownership request")
	ErrOwnershipUnavailable = errors.New("proxy is unavailable for ownership")
	ErrAlreadyOwned         = errors.New("proxy is already owned")
	ErrStaleAssignment      = errors.New("proxy ownership assignment is stale")
	ErrNotDraining          = errors.New("proxy ownership is not draining")
	ErrDrainNotReady        = errors.New("proxy still has active or reserved runtime")
)

type Assignment struct {
	ProxyID   string
	WorkerID  string
	Epoch     uint64
	Version   uint64
	ExpiresAt time.Time
	Draining  bool
}

// Repository is the shared authority for ownership changes. Implementations
// that also support extraction must serialize both operations transactionally.
type Repository interface {
	Assign(now time.Time, proxyID, workerID string, ttl time.Duration) (Assignment, error)
	Renew(now time.Time, proxyID, workerID string, epoch uint64, ttl time.Duration) (Assignment, error)
	BeginDrain(proxyID, workerID string, epoch uint64) (Assignment, error)
	AcknowledgeDrain(proxyID, workerID string, epoch uint64, active, reserved int64) error
	Get(proxyID string) (Assignment, bool)
	Expire(now time.Time) []Assignment
}