package exchange

import (
	"context"
	stderrors "errors"
	"strings"
	"time"

	"github.com/break/junhong_cmp_fiber/internal/model"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/break/junhong_cmp_fiber/pkg/errors"
	"github.com/break/junhong_cmp_fiber/pkg/middleware"
	"gorm.io/gorm"
)

const (
	// exchangeMigrationFailureReasonMaxRunes 是失败原因的最大字符数，与 tb_exchange_order.migration_failure_reason 列宽一致。
	exchangeMigrationFailureReasonMaxRunes = 500
	// exchangeMigrationInfrastructureFailureReason 是基础设施类迁移失败的固定安全摘要。
	// 数据库与内部错误的原文可能包含连接串、SQL 或载荷，不得进入可被列表和详情读取的字段。
	exchangeMigrationInfrastructureFailureReason = "迁移执行失败，请稍后重试或联系技术支持"
)

// isExchangeMigrationFailure 判断错误链上是否带业务数据迁移失败码。
// executeMigrationWithTx 的每个子步骤都以 CodeExchangeMigrationFailed 收口，
// 因此该判定等价于「本次确认完成在业务数据迁移步骤失败」；其他步骤失败不写迁移失败状态。
// 与 asset_audit.BuildErrorInfo 一致地按标准库错误链接口穿透，链中出现非 AppError 包装时继续向上查找。
func isExchangeMigrationFailure(err error) bool {
	for err != nil {
		if appErr, ok := err.(*errors.AppError); ok && appErr.Code == errors.CodeExchangeMigrationFailed {
			return true
		}
		err = stderrors.Unwrap(err)
	}
	return false
}

// isExchangeMigrationRetryAuthorized 判断当前调用者是否可以确认完成该换货单。
// 只有迁移状态为 failed 的重试才要求超级管理员或平台用户；其他状态沿用既有完成门禁，
// 不削弱代理与企业账号既有的确认完成权限。
func isExchangeMigrationRetryAuthorized(ctx context.Context, migrationStatus string) bool {
	if migrationStatus != constants.ExchangeMigrationStatusFailed {
		return true
	}
	userType := middleware.GetUserTypeFromContext(ctx)
	return userType == constants.UserTypeSuperAdmin || userType == constants.UserTypePlatform
}

// exchangeMigrationFailureReason 生成可安全展示的迁移失败原因。
// 只拼接 AppError 链上的中文 Message，丢弃非 AppError 的底层 cause；
// 数据库、内部错误等基础设施失败降级为固定安全摘要，禁止把数据库、外部服务或敏感载荷原文写入该字段。
func exchangeMigrationFailureReason(err error) string {
	var parts []string
	for current := err; current != nil; current = stderrors.Unwrap(current) {
		appErr, ok := current.(*errors.AppError)
		if !ok {
			// 丢弃非 AppError 的底层 cause，禁止把数据库/外部原文写入可展示字段。
			continue
		}
		if isExchangeMigrationInfrastructureCode(appErr.Code) {
			return exchangeMigrationInfrastructureFailureReason
		}
		parts = append(parts, appErr.Message)
	}
	if len(parts) == 0 {
		return exchangeMigrationInfrastructureFailureReason
	}
	return truncateExchangeMigrationFailureReason(strings.Join(parts, "："))
}

func isExchangeMigrationInfrastructureCode(code int) bool {
	return code == errors.CodeDatabaseError || code == errors.CodeInternalError
}

// truncateExchangeMigrationFailureReason 按 rune 截断失败原因，保留 499 个字符并以省略号结尾，
// 总长度不超过列宽 500，便于后端与前端识别原因已被裁剪。
func truncateExchangeMigrationFailureReason(reason string) string {
	runes := []rune(reason)
	if len(runes) <= exchangeMigrationFailureReasonMaxRunes {
		return reason
	}
	return string(runes[:exchangeMigrationFailureReasonMaxRunes-1]) + "…"
}

// markExchangeMigrationFailedWithTx 在同一短事务内条件更新迁移失败状态与安全化失败原因。
// 条件为换货单仍是物流换货的「已发货待确认」状态：并发确认已完成换货时命中 0 行，
// 此时不写状态，避免把已经 migrated 的换货单改回 failed；失败原因只随状态一并写入。
func (s *Service) markExchangeMigrationFailedWithTx(ctx context.Context, tx *gorm.DB, order *model.ExchangeOrder, businessErr error) error {
	result := tx.WithContext(ctx).Model(&model.ExchangeOrder{}).
		Where("id = ? AND status = ?", order.ID, constants.ExchangeStatusShipped).
		Where("COALESCE(NULLIF(flow_type, ''), ?) = ?", constants.ExchangeFlowTypeShipping, constants.ExchangeFlowTypeShipping).
		Updates(map[string]any{
			"migration_status":         constants.ExchangeMigrationStatusFailed,
			"migration_failure_reason": exchangeMigrationFailureReason(businessErr),
			"updater":                  middleware.GetUserIDFromContext(ctx),
			"updated_at":               time.Now(),
		})
	if result.Error != nil {
		return errors.Wrap(errors.CodeDatabaseError, result.Error, "更新换货单迁移失败状态失败")
	}
	if result.RowsAffected == 0 {
		return nil
	}
	order.MigrationStatus = constants.ExchangeMigrationStatusFailed
	return nil
}

// recordExchangeMigrationFailure 在主事务回滚后以独立短事务保存迁移失败状态、安全化原因与失败审计。
// 该短事务不与已回滚的主事务共用连接或事务，符合 ENG-TX-001 的 failed 事实例外；
// 短事务自身异常复用既有换货失败审计的次级故障记录方式，不改变对外返回的原始迁移失败。
//
// 本函数刻意镜像既有失败审计接缝（audit.go 的 recordCardExchangeFailure/recordCardExchangeAuditSecondaryFailure
// 与 device_audit.go 的 recordExchangeOrderFailure）：后者只写审计、不写换货单状态，而本用例需要在同一短事务内
// 同时落 failed 状态与失败原因，故未改动既有接缝。后续修改既有卡/设备失败审计接缝时须同步此处，
// 保持资产类型分派、动作码转换（deviceExchangeActionCode）、摘要改写与次级故障记录方式一致。
func (s *Service) recordExchangeMigrationFailure(ctx context.Context, order *model.ExchangeOrder, businessErr error) {
	if order == nil {
		return
	}
	isDevice := order.OldAssetType == constants.ExchangeAssetTypeDevice
	if !isDevice && order.OldAssetType != constants.ExchangeAssetTypeIotCard {
		return
	}
	actionCode, summary, seamMessage := constants.AuditActionCardExchangeCompleted, "完成卡换货失败", "卡换货统一审计接缝未配置"
	if isDevice {
		actionCode = deviceExchangeActionCode(actionCode)
		summary = strings.ReplaceAll(summary, "卡", "设备")
		seamMessage = "设备换货统一审计接缝未配置"
	}
	if s.db == nil || s.auditWriter == nil {
		recordCardExchangeAuditSecondaryFailure(ctx, actionCode, order.ExchangeNo, businessErr, errors.New(errors.CodeInvalidStatus, seamMessage))
		return
	}
	if err := s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		if updateErr := s.markExchangeMigrationFailedWithTx(ctx, tx, order, businessErr); updateErr != nil {
			return updateErr
		}
		if isDevice {
			oldDevice, newDevice := s.loadDeviceExchangeAuditDevices(ctx, order)
			return s.appendDeviceExchangeAudit(ctx, tx, actionCode, summary, cardExchangeFailureResult(businessErr), order, oldDevice, newDevice,
				nil, nil, nil, nil, nil, nil, nil, businessErr)
		}
		oldCard, newCard := s.loadCardExchangeAuditCards(ctx, order)
		return s.appendCardExchangeAudit(ctx, tx, actionCode, summary, cardExchangeFailureResult(businessErr), order, oldCard, newCard,
			nil, nil, nil, nil, nil, nil, nil, businessErr)
	}); err != nil {
		recordCardExchangeAuditSecondaryFailure(ctx, actionCode, order.ExchangeNo, businessErr, err)
	}
}