package service

import (
	"fmt"
	"math"
	"time"

	"github.com/sundynix/pets-be/internal/ai"
	"github.com/sundynix/pets-be/internal/model"
)

// HomeInsight 首页洞察条一项：Bold 为大号加粗值，Text 为说明
type HomeInsight struct {
	Bold string `json:"bold"`
	Text string `json:"text"`
}

// WeekDay 首页日期条一格
type WeekDay struct {
	Weekday string `json:"weekday"` // 一二三四五六日
	Day     int    `json:"day"`
	Date    string `json:"date"`    // YYYY-MM-DD，供首页点击查当日任务
	Active  bool   `json:"active"`  // 是否今天
	HasDot  bool   `json:"has_dot"` // 当天有任务/记录/提醒
}

// HomeSummary 首页所需的全部动态数据
type HomeSummary struct {
	Greeting     string        `json:"greeting"`
	Insights     []HomeInsight `json:"insights"`
	Week         []WeekDay     `json:"week"`
	Advice       string        `json:"advice"`
	HealthPct    int           `json:"health_pct"`
	HealthStatus string        `json:"health_status"`
}

var weekdayCN = []string{"日", "一", "二", "三", "四", "五", "六"}

// GetHomeSummary 计算首页汇总
func (s *Service) GetHomeSummary(userID, petID string) (*HomeSummary, error) {
	pet, err := s.ownedPet(userID, petID)
	if err != nil {
		return nil, err
	}
	now := time.Now()

	res := &HomeSummary{
		Greeting:     greeting(now, s.userNickname(userID)),
		HealthStatus: pet.HealthStatus,
		Insights:     s.homeInsights(petID, now),
		Week:         s.homeWeek(petID, now),
		Advice:       s.dailyAdvice(pet),
		HealthPct:    s.todayCompletionPct(petID, now),
	}
	return res, nil
}

func (s *Service) userNickname(userID string) string {
	var u model.User
	if err := s.db.Select("nickname").First(&u, userID).Error; err == nil && u.Nickname != "" {
		return u.Nickname
	}
	return "铲屎官"
}

func greeting(t time.Time, name string) string {
	h := t.Hour()
	switch {
	case h < 11:
		return "早上好，" + name
	case h < 14:
		return "中午好，" + name
	case h < 18:
		return "下午好，" + name
	default:
		return "晚上好，" + name
	}
}

func (s *Service) homeInsights(petID string, now time.Time) []HomeInsight {
	insights := make([]HomeInsight, 0, 3)
	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())

	// 1) 最近一条未到期的提醒
	var rem model.Reminder
	if err := s.db.Where("pet_id = ? AND next_due_date >= ?", petID, today).
		Order("next_due_date asc").First(&rem).Error; err == nil && rem.NextDueDate != nil {
		days := int(math.Ceil(rem.NextDueDate.Sub(today).Hours() / 24))
		bold := fmt.Sprintf("%d天后", days)
		if days <= 0 {
			bold = "今天"
		}
		insights = append(insights, HomeInsight{Bold: bold, Text: rem.Title})
	}

	// 2) 本周体重变化
	weekAgo := today.AddDate(0, 0, -7)
	var latest, earliest model.HealthRecord
	if s.db.Where("pet_id = ? AND type = ? AND occurred_at >= ?", petID, model.RecordWeight, weekAgo).
		Order("occurred_at desc").First(&latest).Error == nil {
		if s.db.Where("pet_id = ? AND type = ? AND occurred_at >= ?", petID, model.RecordWeight, weekAgo).
			Order("occurred_at asc").First(&earliest).Error == nil {
			d := latest.NumValue - earliest.NumValue
			insights = append(insights, HomeInsight{Bold: fmt.Sprintf("%+.1fkg", d), Text: "本周体重"})
		}
	}

	// 3) 连续记录天数
	if n := s.streakDays(petID, now); n > 0 {
		insights = append(insights, HomeInsight{Bold: fmt.Sprintf("%d天", n), Text: "连续记录"})
	}
	return insights
}

// streakDays 从今天往前，连续有健康记录的天数
func (s *Service) streakDays(petID string, now time.Time) int {
	streak := 0
	day := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	for i := 0; i < 60; i++ {
		start := day.AddDate(0, 0, -i)
		end := start.AddDate(0, 0, 1)
		var cnt int64
		s.db.Model(&model.HealthRecord{}).
			Where("pet_id = ? AND occurred_at >= ? AND occurred_at < ?", petID, start, end).Count(&cnt)
		if cnt == 0 {
			break
		}
		streak++
	}
	return streak
}

func (s *Service) homeWeek(petID string, now time.Time) []WeekDay {
	// 本周一为起点
	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	offset := (int(today.Weekday()) + 6) % 7 // 周一=0
	monday := today.AddDate(0, 0, -offset)

	dotSet := s.datesWithActivity(petID, monday, monday.AddDate(0, 0, 7))

	week := make([]WeekDay, 7)
	for i := 0; i < 7; i++ {
		d := monday.AddDate(0, 0, i)
		week[i] = WeekDay{
			Weekday: weekdayCN[int(d.Weekday())],
			Day:     d.Day(),
			Date:    d.Format("2006-01-02"),
			Active:  d.Equal(today),
			HasDot:  dotSet[d.Format("2006-01-02")],
		}
	}
	return week
}

// datesWithActivity 区间内有任务/记录/提醒的日期集合
func (s *Service) datesWithActivity(petID string, start, end time.Time) map[string]bool {
	set := map[string]bool{}
	var ts []time.Time
	s.db.Model(&model.DailyTask{}).Where("pet_id = ? AND task_date >= ? AND task_date < ?", petID, start, end).Pluck("task_date", &ts)
	for _, t := range ts {
		set[t.Format("2006-01-02")] = true
	}
	var rs []time.Time
	s.db.Model(&model.HealthRecord{}).Where("pet_id = ? AND occurred_at >= ? AND occurred_at < ?", petID, start, end).Pluck("occurred_at", &rs)
	for _, t := range rs {
		set[t.Format("2006-01-02")] = true
	}
	var reminders []model.Reminder
	s.db.Where("pet_id = ? AND next_due_date >= ? AND next_due_date < ?", petID, start, end).Find(&reminders)
	for _, r := range reminders {
		if r.NextDueDate != nil {
			set[r.NextDueDate.Format("2006-01-02")] = true
		}
	}
	// 30 天计划路线图节点也算「有活动」，让首页周历与计划日历一致
	for _, d := range s.planNodeDates(petID, start, end) {
		set[d.Format("2006-01-02")] = true
	}
	return set
}

func (s *Service) todayCompletionPct(petID string, now time.Time) int {
	// 任务是 PlanTask（DailyTask 已空）。取宠物的 active 30 天计划，算今天那天的完成占比
	var plan model.Plan
	if s.db.Where("pet_id = ? AND kind = ? AND status = ?", petID, model.PlanThirtyDay, "active").
		Order("id desc").First(&plan).Error != nil {
		return 0
	}
	day := dayIndexOf(&plan, now)
	if day < 0 {
		return 0
	}
	var total, done int64
	s.db.Model(&model.PlanTask{}).Where("plan_id = ? AND day = ?", plan.ID, day).Count(&total)
	if total == 0 {
		return 0
	}
	s.db.Model(&model.PlanTask{}).Where("plan_id = ? AND day = ? AND done = ?", plan.ID, day, true).Count(&done)
	return int(math.Round(float64(done) / float64(total) * 100))
}

// dailyAdvice 今日建议：每宠每天缓存一条；启用模型则真调，否则规则化
func (s *Service) dailyAdvice(pet *model.Pet) string {
	day := time.Now().Format("2006-01-02")
	var da model.DailyAdvice
	if err := s.db.Where("pet_id = ? AND day = ?", pet.ID, day).First(&da).Error; err == nil {
		return da.Text
	}

	text := fmt.Sprintf("%s处于%s，建议今天重点观察体重、饮食和排便。若出现连续呕吐、精神明显变差或便血，应尽快就医。", pet.Name, pet.Stage)
	if s.ai != nil && s.ai.Enabled() {
		system := aiSafetyPrompt + "\n\n" + s.petBrief(pet.ID) +
			"\n请用2-3句话给出今天的养宠重点提醒，亲切简洁，直接给建议不要寒暄。"
		if r, err := s.ai.Complete(system, []ai.Message{{Role: "user", Content: "今天的养宠建议"}}, ai.Options{Temperature: -1}); err == nil && r != "" {
			text = r
		}
	}
	_ = s.db.Create(&model.DailyAdvice{PetID: pet.ID, Day: day, Text: text}).Error
	return text
}

// UserSummary 我的页所需计数
type UserSummary struct {
	Pets      int64  `json:"pets"`
	Records   int64  `json:"records"`
	Reminders int64  `json:"reminders"`
	Following int64  `json:"following"` // 我关注了多少人
	Followers int64  `json:"followers"` // 多少人关注我
	ProStatus string `json:"pro_status"`
}

// GetUserSummary 汇总当前用户名下计数
func (s *Service) GetUserSummary(userID string) (*UserSummary, error) {
	var sum UserSummary
	s.db.Model(&model.Pet{}).Where("user_id = ?", userID).Count(&sum.Pets)
	s.db.Model(&model.HealthRecord{}).Where("user_id = ?", userID).Count(&sum.Records)
	s.db.Model(&model.Reminder{}).Where("user_id = ?", userID).Count(&sum.Reminders)
	s.db.Model(&model.Follow{}).Where("follower_id = ?", userID).Count(&sum.Following)
	s.db.Model(&model.Follow{}).Where("followee_id = ?", userID).Count(&sum.Followers)

	sum.ProStatus = model.ProNone
	var m model.ProMembership
	if err := s.db.Where("user_id = ?", userID).First(&m).Error; err == nil {
		sum.ProStatus = m.Status
	}
	return &sum, nil
}