package distributionwithdrawal

import (
	"context"
	"time"

	"gorm.io/gorm"

	approvalapp "github.com/break/junhong_cmp_fiber/internal/application/approval"
	shopapp "github.com/break/junhong_cmp_fiber/internal/application/shop"
	"github.com/break/junhong_cmp_fiber/internal/model"
	"github.com/break/junhong_cmp_fiber/pkg/auditcontext"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/break/junhong_cmp_fiber/pkg/errors"
)

// SubordinateCacheInvalidator 在审批通过事务提交后清理上级店铺下级集合缓存。
type SubordinateCacheInvalidator interface {
	InvalidateSubordinateCache(ctx context.Context, shopID uint)
}

// DistributionApprovalHandler 将渠道无关企业微信终态应用到代理扫码注册记录。
// 通过才在单一事务内创建启用店铺、代理主账号、所需钱包、上级层级与业务员快照；
// 驳回只标记注册记录，不创建任何实体；重复或乱序回调不重复创建账号、层级或钱包。
type DistributionApprovalHandler struct {
	db    *gorm.DB
	audit AuditWriter
	cache SubordinateCacheInvalidator
}

// NewDistributionApprovalHandler 创建代理分销注册审批终态消费者。
func NewDistributionApprovalHandler(
	db *gorm.DB,
	audit AuditWriter,
	cache SubordinateCacheInvalidator,
) *DistributionApprovalHandler {
	return &DistributionApprovalHandler{db: db, audit: audit, cache: cache}
}

// Handle 幂等消费标准审批终态。
// 业务标识为待审批注册记录主键；先锁定注册记录并校验审批实例一致，再按条件更新推进状态。
func (h *DistributionApprovalHandler) Handle(ctx context.Context, event approvalapp.TerminalDecisionEvent) error {
	if h == nil || h.db == nil || h.audit == nil {
		return errors.New(errors.CodeInternalError, "代理分销注册审批终态能力未配置")
	}
	if event.BusinessType != constants.ApprovalBusinessTypeAgentDistribution ||
		event.BusinessID == 0 || event.InstanceID == 0 {
		return errors.New(errors.CodeInvalidParam, "代理分销注册审批终态参数无效")
	}
	ctx = auditcontext.With(ctx, auditcontext.Context{
		CorrelationID: event.CorrelationID, ParentEventID: event.EventID,
	})
	parentShopID := uint(0)
	err := h.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		registration, err := lockRegistrationForUpdate(ctx, tx, event.BusinessID)
		if err != nil {
			return err
		}
		if registration.ApprovalInstanceID == nil || *registration.ApprovalInstanceID != event.InstanceID {
			return errors.New(errors.CodeConflict, "扫码注册记录关联的审批实例不一致")
		}
		if registration.Status != constants.AgentDistributionRegistrationStatusPending {
			// 已是终态：重复或乱序回调不再改变事实。
			return nil
		}
		switch event.Decision {
		case constants.ApprovalDecisionApproved:
			parentShopID = registration.ParentShopID
			return h.applyApproved(ctx, tx, registration, event)
		case constants.ApprovalDecisionRejected,
			constants.ApprovalDecisionCancelled,
			constants.ApprovalDecisionDeleted:
			return h.applyRejected(ctx, tx, registration, event)
		case constants.ApprovalDecisionRevokedAfterApproved:
			// 注册记录无已建立的对外资金事实；通过后撤销按驳回处理并保留渠道决策痕迹。
			return h.applyRejected(ctx, tx, registration, event)
		default:
			return errors.New(errors.CodeInvalidParam, "不支持的代理分销注册审批终态")
		}
	})
	if err != nil {
		return err
	}
	if parentShopID != 0 && h.cache != nil {
		// 缓存清理必须在事务提交后执行，避免回滚后缓存与库内事实不一致。
		h.cache.InvalidateSubordinateCache(ctx, parentShopID)
	}
	return nil
}

// applyApproved 在同一事务内建立店铺、账号、钱包、层级与业务员快照。
// 上级店铺必须仍然存在且启用；手机号或用户名已被并发注册占用时整体回滚，不留半套实体。
func (h *DistributionApprovalHandler) applyApproved(
	ctx context.Context,
	tx *gorm.DB,
	registration *model.AgentDistributionRegistration,
	event approvalapp.TerminalDecisionEvent,
) error {
	parent, err := loadEnabledParentShop(ctx, tx, registration.ParentShopID)
	if err != nil {
		return err
	}
	level := parent.Level + 1
	if level > constants.ShopMaxLevel {
		return errors.New(errors.CodeShopLevelExceeded, "店铺层级不能超过 7 级")
	}
	role, err := loadEnabledCustomerRole(ctx, tx)
	if err != nil {
		return err
	}
	shop := &model.Shop{
		ShopName: registration.ShopName, ShopCode: registration.ShopCode,
		ParentID: &parent.ID, Level: level,
		ContactName: registration.ContactName, Province: registration.Province,
		City: registration.City, District: registration.District, Address: registration.Address,
		Status: constants.ShopStatusEnabled,
	}
	shop.BusinessOwnerAccountID = parent.BusinessOwnerAccountID
	shop.Creator = registration.ID
	shop.Updater = registration.ID
	// 新店铺生成自己的分销码：注册记录上的分销码是上级店铺快照，复用会与父店铺同码并命中唯一索引。
	if err := shopapp.CreateShopWithDistributionCode(ctx, tx, shop); err != nil {
		return err
	}
	account := &model.Account{
		Username: registration.Username, Phone: registration.Phone,
		Password: registration.PasswordHash, UserType: constants.UserTypeAgent,
		ShopID: &shop.ID, Status: constants.StatusEnabled, IsPrimary: true,
	}
	account.Creator = registration.ID
	account.Updater = registration.ID
	if err := tx.WithContext(ctx).Create(account).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "创建扫码注册代理账号失败")
	}
	if err := tx.WithContext(ctx).Create(&model.AccountRole{
		AccountID: account.ID, RoleID: role.ID, Status: constants.StatusEnabled,
		Creator: registration.ID, Updater: registration.ID,
	}).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "为扫码注册代理账号分配角色失败")
	}
	if err := tx.WithContext(ctx).Create(&model.ShopRole{
		ShopID: shop.ID, RoleID: role.ID, Status: constants.StatusEnabled,
		Creator: registration.ID, Updater: registration.ID,
	}).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "设置扫码注册店铺默认角色失败")
	}
	if err := tx.WithContext(ctx).Create([]*model.AgentWallet{
		{
			ShopID: shop.ID, WalletType: constants.AgentWalletTypeMain,
			CreditEnabled: role.DefaultCreditEnabled, CreditLimit: role.DefaultCreditLimit,
			Currency: "CNY", Status: constants.AgentWalletStatusNormal, ShopIDTag: shop.ID,
		},
		{
			ShopID: shop.ID, WalletType: constants.AgentWalletTypeCommission,
			CreditEnabled: false, CreditLimit: 0,
			Currency: "CNY", Status: constants.AgentWalletStatusNormal, ShopIDTag: shop.ID,
		},
	}).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "初始化扫码注册店铺钱包失败")
	}
	if err := markRegistrationApproved(ctx, tx, registration); err != nil {
		return err
	}
	// 建店与业务员归属的访问审计不在本用例职责内：该动作面向后台账号入口，
	// 由审批消费任务触发的建店无法提供其要求的操作者/数据范围投影，
	// 强行写入会以「账号权限或组织审计操作者不完整」失败并中止事务。
	// 新建店铺已作为 CreatedShop 资源记录在本用例的分销审计中。
	return h.audit.WriteDistributionWithdrawal(ctx, tx, AuditChange{
		EventID:       "agent-distribution:" + uintText(registration.ID) + ":approved",
		ActionCode:    constants.AuditActionAgentDistributionRegistrationApproved,
		Summary:       "企业微信通过扫码注册，已创建店铺与代理账号",
		CorrelationID: event.CorrelationID, Registration: registration,
		ParentShop: parent, CreatedShop: shop,
		AppliedDistributionCode: registration.DistributionCode,
		AfterData:               registrationAuditSnapshot(registration),
	})
}

// applyRejected 只标记注册记录终态，不创建店铺、账号、钱包或层级。
func (h *DistributionApprovalHandler) applyRejected(
	ctx context.Context,
	tx *gorm.DB,
	registration *model.AgentDistributionRegistration,
	event approvalapp.TerminalDecisionEvent,
) error {
	now := time.Now().UTC()
	reason := rejectionReason(event.Decision)
	result := tx.WithContext(ctx).Model(&model.AgentDistributionRegistration{}).
		Where("id = ? AND status = ?", registration.ID, constants.AgentDistributionRegistrationStatusPending).
		Updates(map[string]any{
			"status":        constants.AgentDistributionRegistrationStatusRejected,
			"reject_reason": reason, "decided_at": now, "updater": 0,
		})
	if result.Error != nil {
		return errors.Wrap(errors.CodeDatabaseError, result.Error, "标记扫码注册记录已驳回失败")
	}
	if result.RowsAffected != 1 {
		return errors.New(errors.CodeConflict, "扫码注册记录状态已变化")
	}
	before := registration.Status
	registration.Status = constants.AgentDistributionRegistrationStatusRejected
	registration.RejectReason = reason
	registration.DecidedAt = &now
	return h.audit.WriteDistributionWithdrawal(ctx, tx, AuditChange{
		EventID:       "agent-distribution:" + uintText(registration.ID) + ":rejected",
		ActionCode:    constants.AuditActionAgentDistributionRegistrationRejected,
		Summary:       "企业微信未通过扫码注册，未创建任何实体",
		CorrelationID: event.CorrelationID, Registration: registration,
		BeforeData: map[string]any{"status": before},
		AfterData:  registrationAuditSnapshot(registration),
	})
}

// markRegistrationApproved 以待审批状态条件更新标记注册记录已通过，重复回调不重复推进。
func markRegistrationApproved(
	ctx context.Context,
	tx *gorm.DB,
	registration *model.AgentDistributionRegistration,
) error {
	now := time.Now().UTC()
	result := tx.WithContext(ctx).Model(&model.AgentDistributionRegistration{}).
		Where("id = ? AND status = ?", registration.ID, constants.AgentDistributionRegistrationStatusPending).
		Updates(map[string]any{
			"status":     constants.AgentDistributionRegistrationStatusApproved,
			"decided_at": now, "updater": 0,
		})
	if result.Error != nil {
		return errors.Wrap(errors.CodeDatabaseError, result.Error, "标记扫码注册记录已通过失败")
	}
	if result.RowsAffected != 1 {
		return errors.New(errors.CodeConflict, "扫码注册记录状态已变化")
	}
	registration.Status = constants.AgentDistributionRegistrationStatusApproved
	registration.DecidedAt = &now
	return nil
}

// rejectionReason 把渠道决策映射为可查询的中文驳回原因。
func rejectionReason(decision string) string {
	switch decision {
	case constants.ApprovalDecisionCancelled:
		return "企业微信审批已撤销"
	case constants.ApprovalDecisionDeleted:
		return "企业微信审批已删除"
	case constants.ApprovalDecisionRevokedAfterApproved:
		return "企业微信审批通过后撤销"
	default:
		return "企业微信审批已驳回"
	}
}

// loadEnabledParentShop 校验分销码所属店铺仍存在且启用。
func loadEnabledParentShop(ctx context.Context, tx *gorm.DB, shopID uint) (*model.Shop, error) {
	var parent model.Shop
	if err := tx.WithContext(ctx).First(&parent, shopID).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil, errors.New(errors.CodeNotFound, "上级店铺不存在")
		}
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "查询上级店铺失败")
	}
	if parent.Status != constants.ShopStatusEnabled {
		return nil, errors.New(errors.CodeInvalidStatus, "上级店铺已停用，不允许注册下级")
	}
	return &parent, nil
}

// loadEnabledCustomerRole 读取启用的客户角色，用于新建代理店铺的默认角色与信用额度。
func loadEnabledCustomerRole(ctx context.Context, tx *gorm.DB) (*model.Role, error) {
	var role model.Role
	if err := tx.WithContext(ctx).
		Where("role_type = ? AND status = ?", constants.RoleTypeCustomer, constants.StatusEnabled).
		Order("id ASC").First(&role).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil, errors.New(errors.CodeInvalidStatus, "缺少启用的客户角色，无法创建代理店铺")
		}
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "查询启用客户角色失败")
	}
	return &role, nil
}