// Package packagetrafficalert 收口套餐真流量预警的规则维护事务脚本与每日扫描用例。
//
// 规则维护是简单写：Handler → Application 事务脚本 → Persistence，事实与审计同事务。
// 每日扫描是复杂写：Application 编排 → Domain 判定 → Port/Infrastructure 原子写入预警事实、
// 可靠通知事件与审计；判定只使用套餐使用记录的真流量快照，不读取虚流量、展示量、卡级累计或通道累计。
package packagetrafficalert

import (
	"context"
	"strconv"
	"strings"

	"gorm.io/gorm"

	"github.com/break/junhong_cmp_fiber/internal/domain/packagetrafficalert"
	"github.com/break/junhong_cmp_fiber/internal/infrastructure/audit"
	"github.com/break/junhong_cmp_fiber/internal/model"
	"github.com/break/junhong_cmp_fiber/internal/model/dto"
	"github.com/break/junhong_cmp_fiber/internal/store/postgres"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/break/junhong_cmp_fiber/pkg/errors"
	"github.com/break/junhong_cmp_fiber/pkg/middleware"
)

// RuleService 套餐真流量预警规则维护事务脚本。
type RuleService struct {
	db          *gorm.DB
	store       *postgres.PackageTrafficAlertStore
	auditWriter *audit.Writer
}

// NewRuleService 创建套餐真流量预警规则事务脚本。
func NewRuleService(db *gorm.DB, store *postgres.PackageTrafficAlertStore, auditWriters ...*audit.Writer) *RuleService {
	service := &RuleService{db: db, store: store}
	if len(auditWriters) > 0 {
		service.auditWriter = auditWriters[0]
	}
	return service
}

// Create 为套餐商品创建唯一预警规则。
// 创建一律校验套餐存在且商品真流量额度大于零：商品 real_data_mb 只用于配置合法性，
// 不作为扫描分母（分母取使用记录的真总量快照）。
func (s *RuleService) Create(ctx context.Context, request *dto.CreatePackageTrafficAlertRuleRequest) (*dto.PackageTrafficAlertRuleItem, error) {
	operatorID, err := requireOperator(ctx)
	if err != nil {
		return nil, err
	}
	if request == nil || request.PackageID == 0 {
		return nil, errors.New(errors.CodeInvalidParam, "套餐商品ID不能为空")
	}
	if !packagetrafficalert.IsValidThresholdPercent(request.ThresholdPercent) {
		return nil, errors.New(errors.CodeInvalidParam, "真流量预警阈值必须大于等于 1 且小于等于 100，允许两位小数")
	}
	enabled := constants.StatusEnabled
	if request.Enabled != nil && !*request.Enabled {
		enabled = constants.StatusDisabled
	}
	rule := &model.PackageTrafficAlertRule{
		PackageID:        request.PackageID,
		ThresholdPercent: packagetrafficalert.NormalizeThresholdPercent(request.ThresholdPercent),
		Enabled:          enabled,
		Remark:           request.Remark,
		BaseModel:        model.BaseModel{Creator: operatorID, Updater: operatorID},
	}
	var response *dto.PackageTrafficAlertRuleItem
	err = s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		pkg, loadErr := s.loadPackage(ctx, tx, request.PackageID)
		if loadErr != nil {
			return loadErr
		}
		if pkg.RealDataMB <= 0 {
			return errors.New(errors.CodeInvalidParam, "该套餐商品真流量额度不大于零，不能启用真流量预警规则")
		}
		store := s.store.WithTx(tx)
		exists, existsErr := store.ExistsRuleByPackageID(ctx, request.PackageID)
		if existsErr != nil {
			return errors.Wrap(errors.CodeDatabaseError, existsErr, "校验套餐预警规则失败")
		}
		if exists {
			return errors.New(errors.CodeInvalidParam, "套餐已存在真流量预警规则")
		}
		if createErr := store.CreateRule(ctx, rule); createErr != nil {
			if isDuplicateKey(createErr) {
				return errors.New(errors.CodeInvalidParam, "套餐已存在真流量预警规则")
			}
			return errors.Wrap(errors.CodeDatabaseError, createErr, "创建套餐真流量预警规则失败")
		}
		item := toRuleItem(rule, pkg.PackageName, pkg.RealDataMB)
		if auditErr := s.appendRuleAudit(ctx, tx, constants.AuditActionPackageTrafficAlertRuleCreated,
			"创建套餐真流量预警规则", rule, pkg.PackageName, nil, ruleAuditSnapshot(rule, pkg.PackageName)); auditErr != nil {
			return auditErr
		}
		response = item
		return nil
	})
	if err != nil {
		return nil, err
	}
	return response, nil
}

// Update 修改阈值、启停与备注。
// 修改不回填既有预警，也不改写已冻结的预警快照；结果状态为启用时同样校验商品真流量额度大于零。
func (s *RuleService) Update(ctx context.Context, ruleID uint, request *dto.UpdatePackageTrafficAlertRuleRequest) (*dto.PackageTrafficAlertRuleItem, error) {
	operatorID, err := requireOperator(ctx)
	if err != nil {
		return nil, err
	}
	if request == nil || ruleID == 0 {
		return nil, errors.New(errors.CodeInvalidParam, "预警规则ID不能为空")
	}
	if request.ThresholdPercent != nil && !packagetrafficalert.IsValidThresholdPercent(*request.ThresholdPercent) {
		return nil, errors.New(errors.CodeInvalidParam, "真流量预警阈值必须大于等于 1 且小于等于 100，允许两位小数")
	}
	var response *dto.PackageTrafficAlertRuleItem
	err = s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		store := s.store.WithTx(tx)
		rule, lockErr := store.LockRuleByID(ctx, ruleID)
		if lockErr != nil {
			return ruleLookupError(lockErr)
		}
		before := ruleAuditSnapshot(rule, "")
		if request.ThresholdPercent != nil {
			rule.ThresholdPercent = packagetrafficalert.NormalizeThresholdPercent(*request.ThresholdPercent)
		}
		if request.Enabled != nil {
			rule.Enabled = constants.StatusEnabled
			if !*request.Enabled {
				rule.Enabled = constants.StatusDisabled
			}
		}
		if request.Remark != nil {
			rule.Remark = *request.Remark
		}
		pkg, pkgErr := s.loadPackage(ctx, tx, rule.PackageID)
		if pkgErr != nil {
			return pkgErr
		}
		if rule.Enabled == constants.StatusEnabled && pkg.RealDataMB <= 0 {
			return errors.New(errors.CodeInvalidParam, "该套餐商品真流量额度不大于零，不能启用真流量预警规则")
		}
		packageName := pkg.PackageName
		if updateErr := store.UpdateRule(ctx, rule, operatorID); updateErr != nil {
			return errors.Wrap(errors.CodeDatabaseError, updateErr, "更新套餐真流量预警规则失败")
		}
		after := ruleAuditSnapshot(rule, packageName)
		if before["enabled"] != after["enabled"] {
			action, summary := constants.AuditActionPackageTrafficAlertRuleEnabled, "启用套餐真流量预警规则"
			if rule.Enabled != constants.StatusEnabled {
				action, summary = constants.AuditActionPackageTrafficAlertRuleDisabled, "停用套餐真流量预警规则"
			}
			if auditErr := s.appendRuleAudit(ctx, tx, action, summary, rule, packageName,
				map[string]any{"enabled": before["enabled"]}, map[string]any{"enabled": after["enabled"]}); auditErr != nil {
				return auditErr
			}
		}
		if before["threshold_percent"] != after["threshold_percent"] || before["remark"] != after["remark"] {
			if auditErr := s.appendRuleAudit(ctx, tx, constants.AuditActionPackageTrafficAlertRuleUpdated,
				"更新套餐真流量预警规则", rule, packageName, before, after); auditErr != nil {
				return auditErr
			}
		}
		response = toRuleItem(rule, packageName, pkg.RealDataMB)
		return nil
	})
	if err != nil {
		return nil, err
	}
	return response, nil
}

// loadPackage 查询套餐商品；不存在时按参数错误返回。
func (s *RuleService) loadPackage(ctx context.Context, tx *gorm.DB, packageID uint) (*model.Package, error) {
	var pkg model.Package
	if err := tx.WithContext(ctx).Where("id = ?", packageID).First(&pkg).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil, errors.New(errors.CodeInvalidParam, "套餐商品不存在")
		}
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "查询套餐商品失败")
	}
	return &pkg, nil
}

// appendRuleAudit 在业务事务内追加预警规则事件。
func (s *RuleService) appendRuleAudit(ctx context.Context, tx *gorm.DB, action, summary string,
	rule *model.PackageTrafficAlertRule, packageName string, before, after map[string]any) error {
	if s.auditWriter == nil {
		return errors.New(errors.CodeInvalidStatus, "套餐真流量预警规则统一审计接缝未配置")
	}
	var resourceID *string
	if rule.ID != 0 {
		value := strconv.FormatUint(uint64(rule.ID), 10)
		resourceID = &value
	}
	displayName := packageName
	if displayName == "" {
		displayName = "套餐 " + strconv.FormatUint(uint64(rule.PackageID), 10)
	}
	// 使用 AppendAndGet：预警规则属于关键配置，「要求成功必达」的审计失败必须回滚事务（ENG-TX-001）。
	if _, err := s.auditWriter.AppendAndGet(ctx, tx, audit.AppendInput{
		ActionCode: action, Summary: summary, Result: constants.AuditResultSuccess,
		Actor:  audit.ActorInput{Kind: constants.AuditActorAccount, ID: strconv.FormatUint(uint64(middleware.GetUserIDFromContext(ctx)), 10)},
		Source: constants.AuditSourceAdminAPI, ScopeType: constants.AuditScopePlatform,
		Resources: []audit.ResourceInput{{
			Type: constants.AuditResourcePackageTrafficAlertRule, ID: resourceID,
			Key: strconv.FormatUint(uint64(rule.PackageID), 10), DisplayName: displayName,
			Relation: constants.AuditResourceRelationPrimary, Role: constants.AuditResourceRolePackageTrafficAlertRuleTarget,
			IdentitySnapshot: ruleAuditIdentity(rule, packageName), BeforeData: before, AfterData: after,
		}},
	}); err != nil {
		return err
	}
	return nil
}

// requireOperator 要求调用方已通过后台鉴权，否则拒绝写入。
func requireOperator(ctx context.Context) (uint, error) {
	operatorID := middleware.GetUserIDFromContext(ctx)
	if operatorID == 0 {
		return 0, errors.New(errors.CodeUnauthorized)
	}
	return operatorID, nil
}

// ruleLookupError 把规则不存在映射为统一资源不可见错误。
func ruleLookupError(err error) error {
	if err == gorm.ErrRecordNotFound {
		return errors.New(errors.CodeForbidden, constants.PlatformManagementForbiddenMessage)
	}
	return errors.Wrap(errors.CodeDatabaseError, err, "查询套餐真流量预警规则失败")
}

// isDuplicateKey 判断数据库错误是否为唯一键冲突。
func isDuplicateKey(err error) bool {
	if err == nil {
		return false
	}
	text := err.Error()
	return strings.Contains(text, "23505") || strings.Contains(text, "duplicate key") || strings.Contains(text, "SQLSTATE 23505")
}

// ruleAuditSnapshot 返回预警规则可审计的可变字段快照。
func ruleAuditSnapshot(rule *model.PackageTrafficAlertRule, packageName string) map[string]any {
	if rule == nil {
		return nil
	}
	snapshot := map[string]any{
		"package_id":        rule.PackageID,
		"threshold_percent": rule.ThresholdPercent,
		"enabled":           rule.Enabled,
		"remark":            rule.Remark,
	}
	if packageName != "" {
		snapshot["package_name"] = packageName
	}
	return snapshot
}

// ruleAuditIdentity 返回预警规则审计身份快照，字段落在注册表白名单内。
func ruleAuditIdentity(rule *model.PackageTrafficAlertRule, packageName string) map[string]any {
	if rule == nil {
		return nil
	}
	identity := map[string]any{
		"id": rule.ID, "package_id": rule.PackageID, "threshold_percent": rule.ThresholdPercent,
		"enabled": rule.Enabled, "remark": rule.Remark,
	}
	if packageName != "" {
		identity["package_name"] = packageName
	}
	return identity
}

// toRuleItem 把规则投影为对外响应项。
func toRuleItem(rule *model.PackageTrafficAlertRule, packageName string, realDataMB int64) *dto.PackageTrafficAlertRuleItem {
	if rule == nil {
		return nil
	}
	return &dto.PackageTrafficAlertRuleItem{
		ID:               rule.ID,
		PackageID:        rule.PackageID,
		PackageName:      packageName,
		RealDataMB:       realDataMB,
		ThresholdPercent: rule.ThresholdPercent,
		Enabled:          rule.Enabled == constants.StatusEnabled,
		EnabledName:      enabledName(rule.Enabled),
		Remark:           rule.Remark,
		UpdatedAt:        rule.UpdatedAt,
	}
}

// enabledName 返回启停状态的中文名称。
func enabledName(enabled int) string {
	if enabled == constants.StatusEnabled {
		return "启用"
	}
	return "停用"
}