package refund

import (
	"context"
	"strconv"
	"strings"

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

	approvalapp "github.com/break/junhong_cmp_fiber/internal/application/approval"
	employeecollectionapp "github.com/break/junhong_cmp_fiber/internal/application/employeecollection"
	refundapproval "github.com/break/junhong_cmp_fiber/internal/application/refundapproval"
	"github.com/break/junhong_cmp_fiber/internal/infrastructure/commissiondelivery"
	"github.com/break/junhong_cmp_fiber/internal/infrastructure/messaging/outbox"
	"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"
)

// Handle 幂等处理退款的渠道无关审批终态。
func (s *Service) Handle(ctx context.Context, event approvalapp.TerminalDecisionEvent) error {
	if s == nil || s.db == nil || event.BusinessType != constants.ApprovalBusinessTypeRefund ||
		event.BusinessID == 0 || event.InstanceID == 0 {
		return errors.New(errors.CodeInvalidParam, "退款审批终态参数无效")
	}
	switch event.Decision {
	case constants.ApprovalDecisionApproved:
		return s.applyApprovedDecision(ctx, event)
	case constants.ApprovalDecisionRejected, constants.ApprovalDecisionCancelled, constants.ApprovalDecisionDeleted:
		return s.applyClosedDecision(ctx, event)
	case constants.ApprovalDecisionRevokedAfterApproved:
		return s.applyRevokedAfterApproved(ctx, event)
	default:
		return errors.New(errors.CodeInvalidParam, "不支持的退款审批终态")
	}
}

// applyRevokedAfterApproved 处理企业微信通过后撤销。
//
// 不回滚已失效的套餐权益、不取消已提交的渠道退款、也不恢复订单退款状态：这些事实在通过时
// 已经成立。系统只标记审批异常并禁止后续自动重提，交由超级管理员线下处理。
func (s *Service) applyRevokedAfterApproved(ctx context.Context, event approvalapp.TerminalDecisionEvent) error {
	ctx = auditcontext.With(ctx, auditcontext.Context{CorrelationID: event.CorrelationID, ParentEventID: event.EventID})
	var refund model.RefundRequest
	err := s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		target, _, err := refundapproval.ResolveRefundInTx(ctx, tx, event.BusinessID, event.InstanceID)
		if err != nil {
			return err
		}
		if err := tx.WithContext(ctx).Clauses(clause.Locking{Strength: "UPDATE"}).First(&refund, target.ID).Error; err != nil {
			return errors.Wrap(errors.CodeDatabaseError, err, "锁定退款申请失败")
		}
		if refund.AnomalyFlag == 1 {
			return nil
		}
		beforeRefund := refundAuditState(&refund)
		result := tx.WithContext(ctx).Model(&model.RefundRequest{}).
			Where("id = ? AND anomaly_flag = 0", refund.ID).
			Updates(map[string]any{
				"anomaly_flag":   1,
				"anomaly_reason": "企业微信通过后撤销，需超级管理员线下处理",
				"failure_reason": constants.RefundFailureRevokedAfterApproved,
				"updated_at":     event.OccurredAt,
			})
		if result.Error != nil {
			return errors.Wrap(errors.CodeDatabaseError, result.Error, "标记退款审批异常失败")
		}
		if result.RowsAffected != 1 {
			return nil
		}
		refund.AnomalyFlag = 1
		refund.AnomalyReason = "企业微信通过后撤销，需超级管理员线下处理"
		refund.FailureReason = constants.RefundFailureRevokedAfterApproved
		return s.appendRefundAudit(ctx, tx, refund.ID, constants.AuditActionRefundAnomalyFlagged, "标记退款审批异常",
			"refund:"+strconv.FormatUint(uint64(refund.ID), 10)+":revoked", beforeRefund, nil, "退款审批通过后撤销")
	})
	if err != nil {
		return err
	}
	return nil
}

func (s *Service) applyApprovedDecision(ctx context.Context, event approvalapp.TerminalDecisionEvent) error {
	ctx = auditcontext.With(ctx, auditcontext.Context{CorrelationID: event.CorrelationID, ParentEventID: event.EventID})
	var refund model.RefundRequest
	var order model.Order
	changed := false
	err := s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		// 业务标识解析：审批尝试记录优先，退款申请兜底（兼容尚未接入尝试模式的存量申请）。
		target, attempt, err := refundapproval.ResolveRefundInTx(ctx, tx, event.BusinessID, event.InstanceID)
		if err != nil {
			return err
		}
		if err := tx.WithContext(ctx).Clauses(clause.Locking{Strength: "UPDATE"}).First(&refund, target.ID).Error; err != nil {
			if err == gorm.ErrRecordNotFound {
				return errors.New(errors.CodeForbidden, "无权限操作该资源或资源不存在")
			}
			return errors.Wrap(errors.CodeDatabaseError, err, "锁定退款申请失败")
		}
		if refund.Status != model.RefundStatusPending && refund.Status != model.RefundStatusApproved &&
			refund.Status != model.RefundStatusChannelProcessing {
			return errors.New(errors.CodeInvalidStatus, "退款申请状态不允许审批通过")
		}
		if err := tx.WithContext(ctx).Clauses(clause.Locking{Strength: "UPDATE"}).Where("id = ?", refund.OrderID).First(&order).Error; err != nil {
			return errors.Wrap(errors.CodeDatabaseError, err, "锁定退款关联订单失败")
		}
		beforeRefund := refundAuditState(&refund)
		beforeOrder := map[string]any{"payment_status": order.PaymentStatus}
		approvedAmount := refund.RequestedRefundAmount
		if err := validateApprovedRefundAmount(approvedAmount, refund.RequestedRefundAmount, &order); err != nil {
			return err
		}
		if err := s.preparePaymentRefundCredentials(ctx, tx, order.ID); err != nil {
			return err
		}
		// 原路退款只登记待执行事实：退款单转入原路处理中，订单在渠道明确成功前保持已支付。
		// 客户收款信息与退回原钱包在审批通过时即完成，订单同时置为已退款。
		originalRoute := refund.Method == constants.RefundMethodOriginalRoute
		if refund.Status == model.RefundStatusPending {
			changed = true
			targetStatus := model.RefundStatusApproved
			if originalRoute {
				targetStatus = model.RefundStatusChannelProcessing
			}
			result := tx.WithContext(ctx).Model(&model.RefundRequest{}).
				Where("id = ? AND status = ?", refund.ID, model.RefundStatusPending).
				Updates(map[string]any{
					"status": targetStatus, "processed_at": event.OccurredAt,
					"approved_refund_amount": approvedAmount, "remark": "企业微信审批通过",
					"failure_reason": "", "failure_message": "",
					"updated_at": event.OccurredAt,
				})
			if result.Error != nil {
				return errors.Wrap(errors.CodeDatabaseError, result.Error, "完成退款审批申请失败")
			}
			if result.RowsAffected != 1 {
				return errors.New(errors.CodeConflict, "退款申请状态已变化")
			}
			refund.Status = targetStatus
		}
		if !originalRoute {
			switch order.PaymentStatus {
			case model.PaymentStatusPaid:
				changed = true
				result := tx.WithContext(ctx).Model(&model.Order{}).
					Where("id = ? AND payment_status = ?", order.ID, model.PaymentStatusPaid).
					Updates(map[string]any{"payment_status": model.PaymentStatusRefunded, "updated_at": event.OccurredAt})
				if result.Error != nil {
					return errors.Wrap(errors.CodeDatabaseError, result.Error, "更新订单退款状态失败")
				}
				if result.RowsAffected != 1 {
					return errors.New(errors.CodeConflict, "订单退款状态已变化")
				}
				order.PaymentStatus = model.PaymentStatusRefunded
			case model.PaymentStatusRefunded:
			default:
				return errors.New(errors.CodeInvalidStatus, "订单状态不允许完成退款")
			}
		} else {
			if order.PaymentStatus != model.PaymentStatusPaid && order.PaymentStatus != model.PaymentStatusRefunded {
				return errors.New(errors.CodeInvalidStatus, "订单状态不允许原路退款")
			}
			if err := s.prepareChannelRefundInTx(ctx, tx, &refund, attempt); err != nil {
				return err
			}
		}
		if err := s.refundWalletPayment(ctx, tx, &refund, &order, approvedAmount, event.SubmitterAccountID); err != nil {
			return err
		}
		// 员工代收款冲销：接入点只在既有退款成功事务内，以 bill_id+refund_id 唯一事实幂等，
		// 不依赖下方 changed 门；来源订单未建账时直接跳过，不阻断退款。
		if s.refundOffset == nil {
			return errors.New(errors.CodeInternalError, "员工代收款退款冲销能力未配置")
		}
		if err := s.refundOffset.ApplyInTx(ctx, tx, employeecollectionapp.RefundOffsetSource{
			RefundID: refund.ID, OrderID: order.ID, RefundAmount: approvedAmount,
		}); err != nil {
			return err
		}
		if !originalRoute {
			if err := s.appendCompletedNotification(ctx, tx, &refund); err != nil {
				return err
			}
		}
		if err := commissiondelivery.AppendRefundCommissionDeduct(ctx, tx, outbox.NewRepository(), refund.ID, refund.OrderID); err != nil {
			return err
		}
		if err := commissiondelivery.AppendRefundAssetProcess(ctx, tx, outbox.NewRepository(), refund.ID, refund.OrderID); err != nil {
			return err
		}
		if !changed {
			return nil
		}
		return s.appendRefundAudit(ctx, tx, refund.ID, constants.AuditActionRefundApproved, "通过退款审批",
			"refund:"+strconv.FormatUint(uint64(refund.ID), 10)+":approved", beforeRefund, beforeOrder, "退款已通过")
	})
	if err != nil {
		s.recordRefundFailure(ctx, constants.AuditActionRefundApproved, "通过退款审批失败", &refund, &order, err)
		return err
	}
	return nil
}

// prepareChannelRefundInTx 在企微通过事务内登记原路退款的待执行事实。
//
// 只写本地事实与可靠事件：请求号在提交时已冻结到审批尝试记录，这里把它落到退款单并转入
// 原路处理中；真正的渠道调用由可靠事件驱动的事务外消费者执行（ENG-TX-001）。
func (s *Service) prepareChannelRefundInTx(ctx context.Context, tx *gorm.DB, refund *model.RefundRequest, attempt *model.RefundRequestAttempt) error {
	if s.channelRefund == nil {
		return errors.New(errors.CodeInternalError, "渠道原路退款能力未配置")
	}
	return s.channelRefund.PrepareInTx(ctx, tx, refund, attempt)
}

func (s *Service) applyClosedDecision(ctx context.Context, event approvalapp.TerminalDecisionEvent) error {
	ctx = auditcontext.With(ctx, auditcontext.Context{CorrelationID: event.CorrelationID, ParentEventID: event.EventID})
	reason := map[string]string{
		constants.ApprovalDecisionRejected:  "企业微信审批已拒绝",
		constants.ApprovalDecisionCancelled: "企业微信审批已撤销",
		constants.ApprovalDecisionDeleted:   "企业微信审批已删除",
	}[event.Decision]
	var refund model.RefundRequest
	var order model.Order
	err := s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		if err := tx.WithContext(ctx).Clauses(clause.Locking{Strength: "UPDATE"}).Where("id = ?", event.BusinessID).First(&refund).Error; err != nil {
			return errors.Wrap(errors.CodeDatabaseError, err, "锁定退款申请失败")
		}
		if refund.ApprovalInstanceID == nil || *refund.ApprovalInstanceID != event.InstanceID {
			return errors.New(errors.CodeConflict, "退款申请关联的审批实例不一致")
		}
		if refund.Status == model.RefundStatusRejected {
			return nil
		}
		if refund.Status != model.RefundStatusPending {
			return errors.New(errors.CodeInvalidStatus, "退款申请状态不允许结束审批")
		}
		if err := tx.WithContext(ctx).First(&order, refund.OrderID).Error; err != nil {
			return errors.Wrap(errors.CodeDatabaseError, err, "查询退款关联订单失败")
		}
		beforeRefund := refundAuditState(&refund)
		result := tx.WithContext(ctx).Model(&model.RefundRequest{}).
			Where("id = ? AND status = ?", refund.ID, model.RefundStatusPending).
			Updates(map[string]any{
				"status": model.RefundStatusRejected, "processed_at": event.OccurredAt,
				"reject_reason": strings.TrimSpace(reason), "updated_at": event.OccurredAt,
			})
		if result.Error != nil {
			return errors.Wrap(errors.CodeDatabaseError, result.Error, "结束退款审批申请失败")
		}
		if result.RowsAffected != 1 {
			return errors.New(errors.CodeConflict, "退款申请状态已变化")
		}
		return s.appendRefundAudit(ctx, tx, refund.ID, constants.AuditActionRefundRejected, "拒绝退款审批",
			"refund:"+strconv.FormatUint(uint64(refund.ID), 10)+":rejected", beforeRefund, nil, "退款已拒绝")
	})
	if err != nil {
		s.recordRefundFailure(ctx, constants.AuditActionRefundRejected, "拒绝退款审批失败", &refund, &order, err)
	}
	return err
}

// ProcessCommissionDeduction 处理退款佣金回溯后处理。
// 返回非 nil 表示后处理尚未闭合（准入未满足、冻结实收非正或订单佣金未终态），
// 由 Outbox 与周期性补偿任务重试；返回 nil 表示已闭合并已落库全部应有事实。
func (s *Service) ProcessCommissionDeduction(ctx context.Context, refundID uint) error {
	return s.clawbackCommission(ctx, refundID)
}

func (s *Service) ProcessAssetPostProcessing(ctx context.Context, refundID uint) error {
	s.handleRefundAssetProcessing(ctx, refundID)
	var refund model.RefundRequest
	if err := s.db.WithContext(ctx).Select("asset_reset").First(&refund, refundID).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "复核退款资产后处理状态失败")
	}
	if !refund.AssetReset {
		return errors.New(errors.CodeServiceUnavailable, "退款资产后处理尚未完成")
	}
	return nil
}

var _ approvalapp.BusinessDecisionHandler = (*Service)(nil)