package service

import (
	"errors"
	"strconv"
	"strings"

	"affiliate_dash/internal/model"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

// TenantService 负责商户成员关系与请求租户解析。
type TenantService struct {
	db *gorm.DB
}

func NewTenantService(db *gorm.DB) *TenantService {
	return &TenantService{db: db}
}

func (s *TenantService) ResolveMember(userID uint, merchantRef string) (*model.MerchantMember, error) {
	if userID == 0 {
		return nil, errors.New("无效的用户身份")
	}
	tx := s.db.Preload("Merchant").
		Where("merchant_members.user_id = ? AND merchant_members.status = ?", userID, 1).
		Joins("JOIN merchants ON merchants.id = merchant_members.merchant_id AND merchants.status = ?", model.MerchantStatusActive)
	if merchantRef != "" {
		if id, err := strconv.ParseUint(merchantRef, 10, 64); err == nil {
			tx = tx.Where("merchant_members.merchant_id = ?", uint(id))
		} else {
			tx = tx.Where("merchants.code = ?", merchantRef)
		}
	}
	var member model.MerchantMember
	err := tx.Order("merchant_members.is_default DESC, merchant_members.id ASC").First(&member).Error
	if err == nil {
		return &member, nil
	}
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, errors.New("当前账号无权访问该商户")
	}
	return nil, err
}

// ResolveMerchantForAdmin 允许平台管理员显式进入任一启用商户的后台管理上下文。
func (s *TenantService) ResolveMerchantForAdmin(merchantRef string) (*model.Merchant, error) {
	if strings.TrimSpace(merchantRef) == "" {
		return nil, errors.New("请选择商户")
	}
	tx := s.db.Where("status = ?", model.MerchantStatusActive)
	if id, err := strconv.ParseUint(merchantRef, 10, 64); err == nil {
		tx = tx.Where("id = ?", uint(id))
	} else {
		tx = tx.Where("code = ?", merchantRef)
	}
	var merchant model.Merchant
	if err := tx.First(&merchant).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("商户不存在或已禁用")
		}
		return nil, err
	}
	return &merchant, nil
}

func (s *TenantService) EnsureSelfMember(userID uint, role string, status int) error {
	var merchant model.Merchant
	if err := s.db.Where("code = ?", model.MerchantCodeSelfOperated).First(&merchant).Error; err != nil {
		return err
	}
	return s.EnsureMember(merchant.ID, userID, role, status, role == model.MemberRoleOwner)
}

func (s *TenantService) EnsureMember(merchantID, userID uint, role string, status int, isDefault bool) error {
	if merchantID == 0 || userID == 0 {
		return errors.New("商户和用户不能为空")
	}
	if !isValidMemberRole(role) {
		return errors.New("无效的商户成员角色")
	}
	member := model.MerchantMember{
		MerchantID: merchantID,
		UserID:     userID,
		Role:       role,
		Status:     status,
		IsDefault:  isDefault,
	}
	return s.db.Clauses(clause.OnConflict{
		Columns: []clause.Column{{Name: "merchant_id"}, {Name: "user_id"}},
		DoUpdates: clause.Assignments(map[string]interface{}{
			"role":       role,
			"status":     status,
			"is_default": isDefault,
		}),
	}).Create(&member).Error
}

func isValidMemberRole(role string) bool {
	switch role {
	case model.MemberRoleOwner, model.MemberRoleViewer:
		return true
	default:
		return false
	}
}

// MerchantRolePermissions 返回保留角色或商户自定义角色的权限集合。
// 负责人始终拥有该商户的全部后台权限，避免被自定义角色配置锁死。
func (s *TenantService) MerchantRolePermissions(merchantID uint, role string) (map[string]struct{}, error) {
	permissions := builtinMerchantRolePermissions(role)
	if permissions != nil {
		return permissions, nil
	}
	var merchantRole model.MerchantRole
	if err := s.db.Where("merchant_id = ? AND code = ? AND status = ?", merchantID, role, 1).First(&merchantRole).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("商户角色不存在或已禁用")
		}
		return nil, err
	}
	return ParseScopes(merchantRole.Permissions), nil
}

func builtinMerchantRolePermissions(role string) map[string]struct{} {
	all := func(values ...string) map[string]struct{} { return ParseScopes(strings.Join(values, ",")) }
	switch role {
	case model.MemberRoleOwner:
		return all(model.PermissionMembersManage, model.PermissionProductsManage, model.PermissionOrdersManage, model.PermissionWalletView, model.PermissionWalletLedger, model.PermissionRechargeManage, model.PermissionAPIManage, model.PermissionCallbacksManage)
	case model.MemberRoleViewer:
		return map[string]struct{}{}
	default:
		return nil
	}
}

func MemberCanManage(memberRole string) bool {
	return memberRole == model.MemberRoleOwner || memberRole == model.MemberRoleOperator
}

func MemberCanManageFinance(memberRole string) bool {
	return memberRole == model.MemberRoleOwner || memberRole == model.MemberRoleFinance
}

func ParseScopes(scopes string) map[string]struct{} {
	out := make(map[string]struct{})
	for _, scope := range strings.FieldsFunc(scopes, func(r rune) bool {
		return r == ',' || r == ' ' || r == '\n' || r == '\t'
	}) {
		if scope != "" {
			out[scope] = struct{}{}
		}
	}
	return out
}

func HasAnyScope(scopes string, wanted ...string) bool {
	set := ParseScopes(scopes)
	if _, ok := set["*"]; ok {
		return true
	}
	for _, scope := range wanted {
		if _, ok := set[scope]; ok {
			return true
		}
	}
	return false
}

func NormalizeMerchantFeatures(features string) string {
	set := ParseScopes(features)
	if len(set) == 0 {
		set = ParseScopes(model.DefaultMerchantFeatures)
	}
	valid := map[string]struct{}{
		model.MerchantFeatureProducts:  {},
		model.MerchantFeatureOrders:    {},
		model.MerchantFeatureWallet:    {},
		model.MerchantFeatureAPI:       {},
		model.MerchantFeatureCallbacks: {},
	}
	ordered := []string{
		model.MerchantFeatureProducts,
		model.MerchantFeatureOrders,
		model.MerchantFeatureWallet,
		model.MerchantFeatureAPI,
		model.MerchantFeatureCallbacks,
	}
	out := make([]string, 0, len(ordered))
	for _, feature := range ordered {
		if _, ok := set[feature]; ok {
			if _, allowed := valid[feature]; allowed {
				out = append(out, feature)
			}
		}
	}
	if len(out) == 0 {
		return model.DefaultMerchantFeatures
	}
	return strings.Join(out, ",")
}

func MerchantHasFeature(features string, wanted ...string) bool {
	set := ParseScopes(features)
	for _, feature := range wanted {
		if _, ok := set[feature]; ok {
			return true
		}
	}
	return false
}