package model

// TaskState 表示任务状态，与执行尝试状态独立；任务终态不重新打开。
type TaskState string

const (
	TaskWaiting     TaskState = "WAITING"      // 等待派发、延时或退避到期。
	TaskLeased      TaskState = "LEASED"       // 已领取但尚未获得开始授权。
	TaskRunning     TaskState = "RUNNING"      // 已授权处理器开始执行。
	TaskNeedsReview TaskState = "NEEDS_REVIEW" // 结果未知或需要人工核查。
	TaskSucceeded   TaskState = "SUCCEEDED"    // 业务处理器成功结果已保存。
	TaskFailed      TaskState = "FAILED"       // 已知失败且不再继续执行。
	TaskCancelled   TaskState = "CANCELLED"    // 取消已确认，不能理解为业务回滚。
)

func (s TaskState) Terminal() bool {
	return s == TaskSucceeded || s == TaskFailed || s == TaskCancelled
}

// CanTransitionTo 只检查状态图，不能代替数据库事务中的权限、版本、租约、
// 暂停门控、副作用证据和重试预算校验。
func (s TaskState) CanTransitionTo(next TaskState) bool {
	switch s {
	case TaskWaiting:
		return next == TaskLeased || next == TaskCancelled || next == TaskFailed || next == TaskNeedsReview
	case TaskLeased:
		return next == TaskRunning || next == TaskWaiting || next == TaskCancelled || next == TaskFailed || next == TaskNeedsReview
	case TaskRunning:
		return next == TaskSucceeded || next == TaskWaiting || next == TaskFailed || next == TaskNeedsReview || next == TaskCancelled
	case TaskNeedsReview:
		return next == TaskSucceeded || next == TaskFailed
	default:
		return false
	}
}

type AttemptState string

const (
	AttemptLeased    AttemptState = "LEASED"
	AttemptRunning   AttemptState = "RUNNING"
	AttemptSucceeded AttemptState = "SUCCEEDED"
	AttemptFailed    AttemptState = "FAILED"
	AttemptCancelled AttemptState = "CANCELLED"
	AttemptExpired   AttemptState = "EXPIRED"
	AttemptUnknown   AttemptState = "UNKNOWN"
)

// RecoverySafety 表示恢复安全等级，空值或未知值默认需要核查。
type RecoverySafety string

const (
	RecoveryIdempotent    RecoverySafety = "IDEMPOTENT"     // 接入方明确保证可幂等恢复。
	RecoveryReconcileOnly RecoverySafety = "RECONCILE_ONLY" // 恢复前必须查询结果或人工核查。
)

func (s RecoverySafety) CanRecoverAutomatically() bool { return s == RecoveryIdempotent }