package domain

import (
	"errors"
	"time"
)

var ErrInvalidAttemptTransition = errors.New("invalid purchase attempt status transition")

// AttemptStatus 只描述单趟领取的可恢复执行。真实提交结果独立由唯一围栏记录调和。
type AttemptStatus string

const (
	AttemptStatusClaimed   AttemptStatus = "CLAIMED"
	AttemptStatusOrdering  AttemptStatus = "ORDERING"
	AttemptStatusFailed    AttemptStatus = "FAILED"
	AttemptStatusFenced    AttemptStatus = "FENCED"
	AttemptStatusAbandoned AttemptStatus = "ABANDONED"
)

// AttemptFailureCode 是服务端可审计的固定失败摘要，不能承载页面正文或其他自由文本。
type AttemptFailureCode string

const (
	AttemptFailureAuthorizationExpired AttemptFailureCode = "AUTHORIZATION_EXPIRED"
	AttemptFailureLeaseLost            AttemptFailureCode = "LEASE_LOST"
	AttemptFailureGate1Rejected        AttemptFailureCode = "GATE_1_REJECTED"
	AttemptFailureQuantityMismatch     AttemptFailureCode = "QUANTITY_MISMATCH"
	AttemptFailureGate2Rejected        AttemptFailureCode = "GATE_2_REJECTED"
	AttemptFailureGate3Rejected        AttemptFailureCode = "GATE_3_REJECTED"
	AttemptFailureFenceRejected        AttemptFailureCode = "FENCE_REJECTED"
	AttemptFailureSafeAborted          AttemptFailureCode = "SAFE_ABORTED"
)

type PurchaseAttempt struct {
	ID              string
	TaskID          string
	AuthorizationID string
	ClaimGeneration int
	Status          AttemptStatus
	Gate1UnitPrice  *string
	Gate2UnitPrice  *string
	QuantityRead    *int
	ConfirmAmount   *string
	FailureCode     *AttemptFailureCode
	StartedAt       time.Time
	FinishedAt      *time.Time
}

// CanTransitionTo 只允许围栏前的领取恢复为安全失败；围栏后不再提供回退或重试路径。
func (status AttemptStatus) CanTransitionTo(next AttemptStatus) bool {
	_, allowed := attemptTransitions[status][next]
	return allowed
}

func TransitionAttempt(current, next AttemptStatus) (AttemptStatus, error) {
	if !current.CanTransitionTo(next) {
		return current, ErrInvalidAttemptTransition
	}
	return next, nil
}

var attemptTransitions = map[AttemptStatus]map[AttemptStatus]struct{}{
	AttemptStatusClaimed: {
		AttemptStatusOrdering:  {},
		AttemptStatusFailed:    {},
		AttemptStatusAbandoned: {},
	},
	AttemptStatusOrdering: {
		AttemptStatusFenced:    {},
		AttemptStatusFailed:    {},
		AttemptStatusAbandoned: {},
	},
}