package business

import (
	"context"
	"fmt"
	"github.com/go-kratos/kratos/v3/errors"
	"kra/internal/biz/system"
	"math/big"
	"regexp"
	"strconv"
	"strings"
	"time"
	"unicode/utf16"
)

var alertDecimal = regexp.MustCompile(`^[0-9]{1,12}(\.[0-9]{1,2})?$`)

var (
	ErrAlertRuleNotFound  = errors.NotFound("SW_ALERT_RULE_NOT_FOUND", "规则不存在")
	ErrAlertRuleScope     = errors.Forbidden("SW_ALERT_RULE_SCOPE", "无权限操作该规则")
	ErrAlertRuleLevel     = errors.Forbidden("SW_ALERT_RULE_LEVEL", "仅1级商务可操作预警规则")
	ErrAlertRuleInput     = errors.BadRequest("SW_ALERT_RULE_INPUT", "预警规则参数不正确")
	ErrAlertRulePeriod    = errors.BadRequest("SW_ALERT_RULE_PERIOD", "统计周期必须大于0")
	ErrAlertRuleDirection = errors.BadRequest("SW_ALERT_RULE_DIRECTION", "环比方向必须为上升或下降")
	ErrAlertRuleThreshold = errors.BadRequest("SW_ALERT_RULE_THRESHOLD", "环比阈值必须大于0且不超过9999")
	ErrAlertRuleUnlogin   = errors.BadRequest("SW_ALERT_RULE_UNLOGIN", "未登录天数必须大于0")
)

type LevelOneScope struct {
	All, Empty bool
	UserID     uint
}

func LevelOneOwner(actor system.Actor, a *Account) LevelOneScope {
	if actor.AuthorityID == 888 {
		return LevelOneScope{All: true}
	}
	if a == nil {
		return LevelOneScope{Empty: true}
	}
	if a.Level == 1 {
		return LevelOneScope{UserID: a.ID}
	}
	if a.Level < 2 || a.Level > 3 {
		return LevelOneScope{Empty: true}
	}
	parts := strings.Split(a.IDPath, ",")
	if len(parts) < 2 {
		return LevelOneScope{Empty: true}
	}
	id, err := strconv.ParseUint(strings.TrimSpace(parts[1]), 10, 64)
	if err != nil || id == 0 {
		return LevelOneScope{Empty: true}
	}
	return LevelOneScope{UserID: uint(id)}
}

type AlertRule struct {
	ConditionMode                             int
	AmountDirection                           int
	AmountThreshold                           *string
	ID                                        uint64
	Name, Type                                string
	Metric                                    int
	StatPeriodDays, MomDirection, UnloginDays *int
	MomThreshold                              *string
	MonitorScope                              int
	WarningColor                              string
	CreatorID                                 uint
	CreatorName                               string
	Enabled, IsDeleted                        int
	CreatedAt, UpdatedAt                      time.Time
}
type AlertRuleFilter struct {
	Name, Type string
	Metric     *int
}
type AlertRuleRepo interface {
	List(context.Context, LevelOneScope, AlertRuleFilter, ...ListOption) ([]*AlertRule, int64, error)
	Find(context.Context, uint64) (*AlertRule, error)
	Create(context.Context, *AlertRule) error
	Update(context.Context, *AlertRule) error
	SetDeleted(context.Context, uint64) error
	SetEnabled(context.Context, uint64, int) error
	TypesFromRecords(context.Context, LevelOneScope) ([]string, error)
}
type AlertRuleUsecase struct {
	repo     AlertRuleRepo
	accounts *AccountUsecase
}

func NewAlertRuleUsecase(repo AlertRuleRepo, accounts *AccountUsecase) *AlertRuleUsecase {
	return &AlertRuleUsecase{repo: repo, accounts: accounts}
}

func (uc *AlertRuleUsecase) List(ctx context.Context, filter AlertRuleFilter, options ...ListOption) ([]*AlertRule, int64, error) {
	actor, a, err := uc.accounts.actor(ctx)
	if err != nil {
		return nil, 0, err
	}
	return uc.repo.List(ctx, LevelOneOwner(actor, a), filter, options...)
}
func (uc *AlertRuleUsecase) Find(ctx context.Context, id uint64) (*AlertRule, error) {
	actor, a, err := uc.accounts.actor(ctx)
	if err != nil {
		return nil, err
	}
	rule, err := uc.repo.Find(ctx, id)
	if err != nil {
		return nil, err
	}
	scope := LevelOneOwner(actor, a)
	if !scope.All && (scope.Empty || scope.UserID != rule.CreatorID) {
		return nil, ErrAlertRuleScope
	}
	return rule, nil
}
func (uc *AlertRuleUsecase) Types(ctx context.Context) ([]string, error) {
	actor, a, err := uc.accounts.actor(ctx)
	if err != nil {
		return nil, err
	}
	values, err := uc.repo.TypesFromRecords(ctx, LevelOneOwner(actor, a))
	if err != nil {
		return nil, err
	}
	result := []string{}
	seen := map[string]bool{}
	for _, value := range values {
		value = strings.TrimSpace(value)
		if value != "" && !seen[value] {
			seen[value] = true
			result = append(result, value)
		}
	}
	return result, nil
}
func validateAlertRule(r *AlertRule) error {
	if r == nil {
		return ErrAlertRuleInput
	}
	r.Type = strings.TrimSpace(r.Type)
	if r.ConditionMode == 0 {
		r.ConditionMode = 1
	}
	if r.ConditionMode != 1 && r.ConditionMode != 2 {
		return ErrAlertRuleInput
	}
	// 非当前指标的输入不参与业务配置，避免隐藏字段绕过校验写入存储。
	if r.Metric == 3 {
		r.StatPeriodDays = nil
		r.MomDirection = nil
		r.MomThreshold = nil
	} else {
		r.UnloginDays = nil
	}
	if r.ConditionMode == 2 {
		r.MomDirection = nil
		r.MomThreshold = nil
	} else {
		r.AmountThreshold = nil
		r.AmountDirection = 1
	}
	if r.ConditionMode == 2 {
		if r.Metric != 2 || r.StatPeriodDays == nil || *r.StatPeriodDays <= 0 {
			return ErrAlertRuleInput
		}
		if r.AmountDirection != 1 && r.AmountDirection != 2 {
			return ErrAlertRuleInput
		}
		if r.AmountThreshold == nil || !alertDecimal.MatchString(*r.AmountThreshold) {
			return ErrAlertRuleInput
		}
		n, ok := new(big.Rat).SetString(*r.AmountThreshold)
		if !ok || n.Sign() <= 0 || n.Cmp(big.NewRat(99999999999999, 100)) > 0 || !new(big.Rat).Mul(n, big.NewRat(100, 1)).IsInt() {
			return ErrAlertRuleInput
		}
		amount := n.FloatString(2)
		r.AmountThreshold = &amount
		if r.Type == "" || len(utf16.Encode([]rune(r.Type))) > 50 {
			return ErrAlertRuleInput
		}
		return nil
	}
	if r.Type == "" || len(utf16.Encode([]rune(r.Type))) > 50 {
		return ErrAlertRuleInput
	}
	switch r.Metric {
	case 1, 2:
		if r.StatPeriodDays == nil || *r.StatPeriodDays <= 0 {
			return ErrAlertRulePeriod
		}
		if r.MomDirection == nil || (*r.MomDirection != 1 && *r.MomDirection != 2) {
			return ErrAlertRuleDirection
		}
		if r.MomThreshold == nil || !alertDecimal.MatchString(*r.MomThreshold) {
			return ErrAlertRuleThreshold
		}
		n, ok := new(big.Rat).SetString(*r.MomThreshold)
		if !ok || n.Sign() <= 0 || n.Cmp(big.NewRat(9999, 1)) > 0 {
			return ErrAlertRuleThreshold
		}
	case 3:
		if r.UnloginDays == nil || *r.UnloginDays <= 0 {
			return ErrAlertRuleUnlogin
		}
	default:
		return ErrAlertRuleInput
	}
	return nil
}
func (uc *AlertRuleUsecase) Save(ctx context.Context, input *AlertRule) (uint64, error) {
	actor, a, err := uc.accounts.actor(ctx)
	if err != nil {
		return 0, err
	}
	if actor.AuthorityID != 888 && a.Level != 1 {
		return 0, ErrAlertRuleLevel
	}
	if input == nil {
		return 0, ErrAlertRuleInput
	}
	rule := *input
	if err := validateAlertRule(&rule); err != nil {
		return 0, err
	}
	rule.MonitorScope = 1
	if rule.ID == 0 {
		rule.CreatorID, rule.Enabled, rule.IsDeleted = actor.UserID, 1, 0
		if err := uc.repo.Create(ctx, &rule); err != nil {
			return 0, err
		}
		return rule.ID, nil
	}
	existing, err := uc.repo.Find(ctx, rule.ID)
	if err != nil {
		return 0, err
	}
	if actor.AuthorityID != 888 && existing.CreatorID != actor.UserID {
		return 0, ErrAlertRuleScope
	}
	// 原接口忽略未提供的可选指标字段，切换指标后保留历史配置值。
	if rule.StatPeriodDays == nil {
		rule.StatPeriodDays = existing.StatPeriodDays
	}
	if rule.MomDirection == nil {
		rule.MomDirection = existing.MomDirection
	}
	if rule.MomThreshold == nil {
		rule.MomThreshold = existing.MomThreshold
	}
	if rule.UnloginDays == nil {
		rule.UnloginDays = existing.UnloginDays
	}
	if err := uc.repo.Update(ctx, &rule); err != nil {
		return 0, err
	}
	return rule.ID, nil
}
func (uc *AlertRuleUsecase) checkWrite(ctx context.Context, id uint64) error {
	actor, a, err := uc.accounts.actor(ctx)
	if err != nil {
		return err
	}
	if actor.AuthorityID != 888 && a.Level != 1 {
		return ErrAlertRuleLevel
	}
	rule, err := uc.repo.Find(ctx, id)
	if err != nil {
		return err
	}
	if actor.AuthorityID != 888 && rule.CreatorID != actor.UserID {
		return ErrAlertRuleScope
	}
	return nil
}
func (uc *AlertRuleUsecase) Delete(ctx context.Context, id uint64) error {
	if err := uc.checkWrite(ctx, id); err != nil {
		return err
	}
	return uc.repo.SetDeleted(ctx, id)
}
func (uc *AlertRuleUsecase) Toggle(ctx context.Context, id uint64, enabled int) error {
	if enabled != 0 && enabled != 1 {
		return ErrAlertRuleInput
	}
	if err := uc.checkWrite(ctx, id); err != nil {
		return err
	}
	return uc.repo.SetEnabled(ctx, id, enabled)
}

func AlertRuleTypeLabel(value string) string {
	switch value {
	case "register_anomaly":
		return "注册异常"
	case "recharge_anomaly":
		return "充值异常"
	case "login_anomaly":
		return "登录异常"
	}
	return value
}
func AlertMetricLabel(metric int) string {
	return map[int]string{1: "注册量", 2: "充值金额", 3: "登录天数"}[metric]
}
func AlertDirectionLabel(direction *int) string {
	if direction == nil {
		return ""
	}
	return map[int]string{1: "上升", 2: "下降"}[*direction]
}
func optionalInt(value *int) string {
	if value == nil {
		return "null"
	}
	return strconv.Itoa(*value)
}
func (r *AlertRule) Description() string {
	if r.Metric == 2 && r.ConditionMode == 2 && r.AmountThreshold != nil {
		direction := "满"
		if r.AmountDirection == 2 {
			direction = "未满"
		}
		return fmt.Sprintf("渠道近 %s 天充值金额%s %s 元时触发预警（汇总子渠道）", optionalInt(r.StatPeriodDays), direction, *r.AmountThreshold)
	}
	if r.Metric == 3 {
		return "渠道连续 " + optionalInt(r.UnloginDays) + " 天未登录时触发预警"
	}
	if r.Metric != 1 && r.Metric != 2 {
		return ""
	}
	threshold := "null"
	if r.MomThreshold != nil {
		threshold = *r.MomThreshold
	}
	direction := AlertDirectionLabel(r.MomDirection)
	if direction == "" {
		direction = "null"
	}
	return fmt.Sprintf("渠道近 %s 天%s较上一同期环比%s %s%% 时触发", optionalInt(r.StatPeriodDays), AlertMetricLabel(r.Metric), direction, threshold)
}