package domain

import (
	"errors"
	"time"
)

var ErrInvalidAuthorizationTransition = errors.New("invalid authorization status transition")

type AuthorizationStatus string

const (
	AuthorizationStatusActive    AuthorizationStatus = "ACTIVE"
	AuthorizationStatusClaimed   AuthorizationStatus = "CLAIMED"
	AuthorizationStatusFenced    AuthorizationStatus = "FENCED"
	AuthorizationStatusConsumed  AuthorizationStatus = "CONSUMED"
	AuthorizationStatusExpired   AuthorizationStatus = "EXPIRED"
	AuthorizationStatusAbandoned AuthorizationStatus = "ABANDONED"
)

type OrderAuthorization struct {
	ID            string
	TaskID        string
	TaskVersion   int
	StartKey      string
	GoodsID       string
	SKUColor      string
	SKUSize       string
	Quantity      int
	TotalPriceCap string
	Status        AuthorizationStatus
	CreatedBy     string
	CreatedAt     time.Time
	ExpiresAt     time.Time
}

// CanTransitionTo 围栏后的授权只能消费，不能回到可领取或可过期状态，以防重复采购。
func (status AuthorizationStatus) CanTransitionTo(next AuthorizationStatus) bool {
	_, allowed := authorizationTransitions[status][next]
	return allowed
}

// TransitionAuthorization 返回下一状态；未定义的授权状态转移一律失败。
func TransitionAuthorization(current, next AuthorizationStatus) (AuthorizationStatus, error) {
	if !current.CanTransitionTo(next) {
		return current, ErrInvalidAuthorizationTransition
	}

	return next, nil
}

var authorizationTransitions = map[AuthorizationStatus]map[AuthorizationStatus]struct{}{
	AuthorizationStatusActive: {
		AuthorizationStatusClaimed:   {},
		AuthorizationStatusExpired:   {},
		AuthorizationStatusAbandoned: {},
	},
	AuthorizationStatusClaimed: {
		AuthorizationStatusFenced:    {},
		AuthorizationStatusExpired:   {},
		AuthorizationStatusAbandoned: {},
	},
	AuthorizationStatusFenced: {
		AuthorizationStatusConsumed: {},
	},
}