package service

import (
	"math"
	"strings"
	"time"

	"gorm.io/datatypes"
	"gorm.io/gorm"

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

// TogglePlanTask 切换计划明细完成状态（校验归属）
func (s *Service) TogglePlanTask(userID, taskID uint) error {
	var pt model.PlanTask
	if err := s.db.First(&pt, taskID).Error; err != nil {
		return ErrNotFound
	}
	var plan model.Plan
	if err := s.db.Where("id = ? AND user_id = ?", pt.PlanID, userID).First(&plan).Error; err != nil {
		return ErrNotFound
	}
	return s.db.Model(&model.PlanTask{}).Where("id = ?", taskID).Update("done", !pt.Done).Error
}

// GetPlan 取宠物的 30 天计划（含明细）
func (s *Service) GetPlan(userID, petID uint) (*model.Plan, error) {
	if _, err := s.ownedPet(userID, petID); err != nil {
		return nil, err
	}
	var plan model.Plan
	err := s.db.Preload("Tasks").
		Where("pet_id = ? AND kind = ?", petID, model.PlanThirtyDay).
		Order("id desc").First(&plan).Error
	if err == gorm.ErrRecordNotFound {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, err
	}
	// 真实完成度：已完成明细 / 总明细
	if n := len(plan.Tasks); n > 0 {
		done := 0
		for _, t := range plan.Tasks {
			if t.Done {
				done++
			}
		}
		plan.CompletionPct = int(math.Round(float64(done) / float64(n) * 100))
	} else {
		plan.CompletionPct = 0
	}
	return &plan, nil
}

// CalendarResult 日历视图
type CalendarResult struct {
	Year       int   `json:"year"`
	Month      int   `json:"month"`
	TaskedDays []int `json:"tasked_days"`
	Today      int   `json:"today"`
}

// Calendar 某月有任务/提醒的日期
func (s *Service) Calendar(userID, petID uint, year, month int) (*CalendarResult, error) {
	if _, err := s.ownedPet(userID, petID); err != nil {
		return nil, err
	}
	loc := time.Now().Location()
	start := time.Date(year, time.Month(month), 1, 0, 0, 0, 0, loc)
	end := start.AddDate(0, 1, 0)

	daySet := map[int]struct{}{}

	var taskDates []time.Time
	s.db.Model(&model.DailyTask{}).
		Where("pet_id = ? AND task_date >= ? AND task_date < ?", petID, start, end).
		Pluck("task_date", &taskDates)
	for _, t := range taskDates {
		daySet[t.Day()] = struct{}{}
	}

	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 {
			daySet[r.NextDueDate.Day()] = struct{}{}
		}
	}

	days := make([]int, 0, len(daySet))
	for d := range daySet {
		days = append(days, d)
	}

	today := 0
	now := time.Now()
	if now.Year() == year && int(now.Month()) == month {
		today = now.Day()
	}
	return &CalendarResult{Year: year, Month: month, TaskedDays: days, Today: today}, nil
}

// CreateAIPlan 基于用户描述做规则化提取，生成待确认的 AI 计划
func (s *Service) CreateAIPlan(userID, petID uint, input string) (*model.Plan, error) {
	pet, err := s.ownedPet(userID, petID)
	if err != nil {
		return nil, err
	}

	// 默认（规则化）提取与任务
	var extracted any = extractAIInfo(input, pet.Stage)
	tasks := []model.PlanTask{
		{DayLabel: "Day 1-2", Title: "观察食欲和便便", Description: "每日记录饮食、便便、精神状态。"},
		{DayLabel: "Day 3-5", Title: "记录换粮比例", Description: "逐步提高新粮比例，留意软便。"},
		{DayLabel: "Day 6-7", Title: "生成复盘建议", Description: "汇总一周状态，输出复盘。"},
	}

	// 启用模型则用真实提取覆盖
	if ex, ok := s.aiPlanExtract(pet, input); ok {
		extracted = map[string]string{
			"stage": ex.Stage, "risk": ex.Risk, "priority": ex.Priority, "reminder": ex.Reminder,
		}
		tasks = tasks[:0]
		for _, t := range ex.Tasks {
			tasks = append(tasks, model.PlanTask{DayLabel: t.DayLabel, Title: t.Title, Description: t.Description})
		}
	}

	b, _ := jsonMarshalAny(extracted)
	plan := model.Plan{
		PetID: petID, UserID: userID, Kind: model.PlanAI, Stage: pet.Stage,
		UserInput: input, Extracted: datatypes.JSON(b), Status: "draft", Tasks: tasks,
	}
	if err := s.db.Create(&plan).Error; err != nil {
		return nil, err
	}
	return &plan, nil
}

// ApplyAIPlan 确认并应用 AI 计划
func (s *Service) ApplyAIPlan(userID, planID uint) (*model.Plan, error) {
	var plan model.Plan
	if err := s.db.Where("id = ? AND user_id = ?", planID, userID).First(&plan).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil, ErrNotFound
		}
		return nil, err
	}
	now := time.Now()
	end := now.AddDate(0, 0, 7)
	if err := s.db.Model(&plan).Updates(map[string]any{
		"status": "active", "start_date": now, "end_date": end,
	}).Error; err != nil {
		return nil, err
	}
	if err := s.db.Preload("Tasks").First(&plan, plan.ID).Error; err != nil {
		return nil, err
	}
	return &plan, nil
}

// extractAIInfo 规则化提取（后续可替换为大模型）
func extractAIInfo(input, stage string) map[string]string {
	risk := "暂无明显风险"
	priority := "日常观察"
	reminder := "常规提醒"
	if strings.Contains(input, "换粮") || strings.Contains(input, "软便") {
		risk = "换粮软便"
		priority = "排便观察"
	}
	if strings.Contains(input, "疫苗") {
		reminder = "第二针疫苗"
	}
	if stage == "" {
		stage = "幼年期"
	}
	return map[string]string{
		"stage":    stage + " / 疫苗期",
		"risk":     risk,
		"priority": priority,
		"reminder": reminder,
	}
}