package workerruntime

import (
	"context"
	"errors"
	"time"
)

var (
	ErrInvalidStore      = errors.New("invalid worker runtime store")
	ErrInvalidSession    = errors.New("invalid worker runtime session")
	ErrInvalidReport     = errors.New("invalid worker runtime report")
	ErrInvalidQuery      = errors.New("invalid worker runtime query")
	ErrStaleSession      = errors.New("stale worker runtime session")
	ErrStaleReport       = errors.New("stale worker runtime report")
	ErrConflictingReport = errors.New("conflicting worker runtime report")
)

type Session struct {
	WorkerID             string
	InstanceID           string
	SessionID            string
	AckedSnapshotVersion uint64
	AckedOwnershipEpoch  uint64
}

type Counter struct {
	ProxyID  string
	Active   int64
	Reserved int64
	Draining bool
}

// Report is a complete sparse replacement. Missing counters are zero for the
// reported Worker snapshot; callers must increase Sequence for every update.
type Report struct {
	WorkerID        string
	SessionID       string
	Sequence        uint64
	SnapshotVersion uint64
	OwnershipEpoch  uint64
	ObservedAt      time.Time
	Counters        []Counter
}

type OwnedProxy struct {
	ProxyID        string
	WorkerID       string
	OwnershipEpoch uint64
}

type Snapshot struct {
	ProxyID  string
	Active   int64
	Reserved int64
	Draining bool
	Fresh    bool
}

type SessionWriter interface {
	ReplaceSession(context.Context, Session, time.Duration) error
}

type ReportWriter interface {
	ReplaceRuntime(context.Context, Report, time.Duration) error
}

type RuntimeReader interface {
	ReadRuntime(context.Context, []OwnedProxy) ([]Snapshot, error)
}