package service

import (
	"encoding/json"
	"errors"
	"fmt"
	"strings"

	"gorm.io/gorm"

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

// CareSpecies / CareStages 支持的物种与阶段（阶段字符串与 onboarding 一致）
var CareSpecies = []string{model.SpeciesCat, model.SpeciesDog}
var CareStages = []string{"刚到家 0-30 天", "幼年期", "成年期", "老年期"}

// SpeciesOf 由宠物类型（猫猫/狗狗）映射到模板物种键
func SpeciesOf(petType string) string {
	if strings.Contains(petType, "狗") {
		return model.SpeciesDog
	}
	return model.SpeciesCat
}

func validSpecies(s string) bool { return s == model.SpeciesCat || s == model.SpeciesDog }
func validStage(s string) bool {
	for _, x := range CareStages {
		if x == s {
			return true
		}
	}
	return false
}

// careTemplateItems 取某组合的模板明细：DB 优先，无则回退内置默认
func (s *Service) careTemplateItems(species, stage string) []model.CareTemplateItem {
	var tpl model.CareTemplate
	err := s.db.
		Preload("Items", func(db *gorm.DB) *gorm.DB { return db.Order("kind, sort, id") }).
		Where("species = ? AND stage = ?", species, stage).First(&tpl).Error
	if err == nil && len(tpl.Items) > 0 {
		return tpl.Items
	}
	return builtinCareItems(species, stage)
}

// GetCareTemplate 后台读取：返回某组合的明细（DB 优先，无则内置默认）
func (s *Service) GetCareTemplate(species, stage string) (map[string]any, error) {
	if !validSpecies(species) || !validStage(stage) {
		return nil, errors.New("invalid species or stage")
	}
	return map[string]any{
		"species": species,
		"stage":   stage,
		"items":   s.careTemplateItems(species, stage),
	}, nil
}

// SaveCareTemplate 后台保存：整表替换该组合的明细
func (s *Service) SaveCareTemplate(species, stage string, items []model.CareTemplateItem) error {
	if !validSpecies(species) || !validStage(stage) {
		return errors.New("invalid species or stage")
	}
	return s.db.Transaction(func(tx *gorm.DB) error {
		var tpl model.CareTemplate
		err := tx.Where("species = ? AND stage = ?", species, stage).First(&tpl).Error
		if errors.Is(err, gorm.ErrRecordNotFound) {
			tpl = model.CareTemplate{Species: species, Stage: stage}
			if err := tx.Create(&tpl).Error; err != nil {
				return err
			}
		} else if err != nil {
			return err
		}
		if err := tx.Where("template_id = ?", tpl.ID).Delete(&model.CareTemplateItem{}).Error; err != nil {
			return err
		}
		clean := make([]model.CareTemplateItem, 0, len(items))
		for i := range items {
			it := items[i]
			if strings.TrimSpace(it.Title) == "" {
				continue
			}
			it.ID = ""
			it.TemplateID = tpl.ID
			it.Sort = i
			clean = append(clean, it)
		}
		if len(clean) > 0 {
			if err := tx.Create(&clean).Error; err != nil {
				return err
			}
		}
		return nil
	})
}

// GenerateCareTemplate 后台「AI 生成草稿」：不落库，仅返回建议明细。
// AI 未开启或失败时回退内置默认，保证总有可用草稿。
func (s *Service) GenerateCareTemplate(species, stage string) ([]model.CareTemplateItem, error) {
	if !validSpecies(species) || !validStage(stage) {
		return nil, errors.New("invalid species or stage")
	}
	if !s.ai.Enabled() {
		return builtinCareItems(species, stage), nil
	}
	spName := "猫"
	if species == model.SpeciesDog {
		spName = "狗"
	}
	system := aiSafetyPrompt + `

你现在为后台生成一套「养护模板」，用于新宠建档时自动生成任务/计划/提醒。
只输出 JSON，结构如下（不要多余文字）：
{
  "tasks": [{"title":"","description":"","priority":"重要或空","sheet_type":"weight|poop|food|symptom|vaccine|medicine 或空"}],
  "plan":  [{"day":0,"day_label":"今天","title":"","description":"","sheet_type":"weight|vaccine|medicine|report|taskDetail 或空"}],
  "reminders":[{"reminder_type":"vaccine|deworm|weight|monthlyReport","title":"","offset_days":18,"frequency":"到期用天数则填0并写频率，如每周二五"}]
}
要求：tasks 3 条、plan 4 条、reminders 3-4 条；贴合该物种与阶段的真实照护节奏（如成年比幼年疫苗/驱虫间隔更长，狗驱虫比猫更频繁）。`
	user := fmt.Sprintf("为【%s · %s】生成一套养护模板。", spName, stage)

	out, err := s.ai.Complete(system, []ai.Message{{Role: "user", Content: user}}, ai.Options{JSON: true, Temperature: -1})
	if err != nil {
		return builtinCareItems(species, stage), nil
	}
	items, ok := parseCareItems(out)
	if !ok || len(items) == 0 {
		return builtinCareItems(species, stage), nil
	}
	return items, nil
}

// parseCareItems 解析 AI 返回的分组 JSON → 扁平明细
func parseCareItems(out string) ([]model.CareTemplateItem, bool) {
	var raw struct {
		Tasks []struct {
			Title, Description, Priority, SheetType string
		} `json:"tasks"`
		Plan []struct {
			Day                              int
			DayLabel, Title, Description, SheetType string
		} `json:"plan"`
		Reminders []struct {
			ReminderType, Title, Frequency string
			OffsetDays                     int
		} `json:"reminders"`
	}
	if err := json.Unmarshal([]byte(extractJSON(out)), &raw); err != nil {
		return nil, false
	}
	var items []model.CareTemplateItem
	for _, t := range raw.Tasks {
		if t.Title == "" {
			continue
		}
		items = append(items, careTask(t.Title, t.Description, t.Priority, t.SheetType))
	}
	for _, p := range raw.Plan {
		if p.Title == "" {
			continue
		}
		items = append(items, carePlan(p.Day, p.DayLabel, p.Title, p.Description, p.SheetType))
	}
	for _, r := range raw.Reminders {
		if r.Title == "" {
			continue
		}
		items = append(items, careReminder(r.ReminderType, r.Title, r.OffsetDays, r.Frequency))
	}
	return items, len(items) > 0
}

// SeedCareTemplates 启动幂等 seed：库中无任何模板时写入 8 套内置默认
func (s *Service) SeedCareTemplates() error {
	var count int64
	if err := s.db.Model(&model.CareTemplate{}).Count(&count).Error; err != nil {
		return err
	}
	if count > 0 {
		return nil
	}
	for _, sp := range CareSpecies {
		for _, stage := range CareStages {
			tpl := model.CareTemplate{Species: sp, Stage: stage, Items: builtinCareItems(sp, stage)}
			if err := s.db.Create(&tpl).Error; err != nil {
				return err
			}
		}
	}
	return nil
}

// ---- 明细构造小工具 ----

func careTask(title, desc, priority, sheet string) model.CareTemplateItem {
	return model.CareTemplateItem{Kind: model.CareKindTask, Title: title, Description: desc, Priority: priority, SheetType: sheet}
}
func carePlan(day int, label, title, desc, sheet string) model.CareTemplateItem {
	return model.CareTemplateItem{Kind: model.CareKindPlan, Day: day, DayLabel: label, Title: title, Description: desc, SheetType: sheet}
}
func careReminder(rtype, title string, offset int, freq string) model.CareTemplateItem {
	return model.CareTemplateItem{Kind: model.CareKindReminder, ReminderType: rtype, Title: title, OffsetDays: offset, Frequency: freq}
}

// builtinCareItems 内置默认模板（8 套），既作开箱数据也作兜底
func builtinCareItems(species, stage string) []model.CareTemplateItem {
	isDog := species == model.SpeciesDog
	dewormAdult := 90
	if isDog {
		dewormAdult = 60 // 狗驱虫间隔通常比猫短
	}

	switch stage {
	case "刚到家 0-30 天":
		return []model.CareTemplateItem{
			careTask("记录一次体重", "到家后每周记录，建立基线", "重要", "weight"),
			careTask("观察饮水与排便", "换环境应激常见软便，连续观察几天", "", "poop"),
			careTask("布置安静休息角", "固定饮食、厕所与休息区，减少应激", "", ""),
			carePlan(0, "今天", "安顿与环境适应", "固定饮食、厕所、休息区位置", "taskDetail"),
			carePlan(3, "第3天", "观察排便与食欲", "记录应激缓解情况", "poop"),
			carePlan(7, "第7天", "第一次体重记录", "作为后续趋势基线", "weight"),
			carePlan(14, "第14天", "预约首次体检/疫苗", "确认医院与时间", "vaccine"),
			careReminder("vaccine", "首次疫苗接种", 14, ""),
			careReminder("deworm", "首次体内外驱虫", 7, ""),
			careReminder("weight", "体重记录", 0, "每周一次"),
			careReminder("monthlyReport", "月度报告", 0, "每月 1 日"),
		}
	case "幼年期":
		vaccineTitle := "第 2 针疫苗"
		if isDog {
			vaccineTitle = "下一针联苗"
		}
		return []model.CareTemplateItem{
			careTask("记录一次体重", "幼年期每周至少记录 2 次", "重要", "weight"),
			careTask("观察饮水与排便", "换粮、应激都可能影响排便状态", "", "poop"),
			careTask("检查疫苗预约", "按免疫程序别漏针", "重要", "vaccine"),
			carePlan(0, "今天", "观察排便状态", "记录颜色、形态、次数", "taskDetail"),
			carePlan(1, "明天", "检查疫苗预约", "确认下一针医院与时间", "vaccine"),
			carePlan(7, "第7天", "体重趋势检查", "每周称重，观察稳定增长", "weight"),
			carePlan(14, "第14天", "复盘饮食与便便", "换粮记录与异常一起看", "taskDetail"),
			careReminder("vaccine", vaccineTitle, 18, ""),
			careReminder("deworm", "体内外驱虫", 12, ""),
			careReminder("weight", "体重记录", 0, "每周二、周五"),
			careReminder("monthlyReport", "月度报告", 0, "每月 1 日"),
		}
	case "老年期":
		return []model.CareTemplateItem{
			careTask("记录一次体重", "老年期体重波动要重视", "重要", "weight"),
			careTask("观察精神与食欲", "明显变差要尽快就医", "重要", "symptom"),
			careTask("关注饮水量", "多饮多尿可能是慢病信号", "", ""),
			carePlan(0, "今天", "老年健康自查", "精神、食欲、饮水一起看", "taskDetail"),
			carePlan(7, "第7天", "体重与饮水记录", "留意慢病早期信号", "weight"),
			carePlan(14, "第14天", "用药与体检回顾", "慢病管理与用药记录", "medicine"),
			carePlan(30, "第30天", "生成月度报告", "整理给医生看的记录", "report"),
			careReminder("vaccine", "年度疫苗加强", 30, ""),
			careReminder("deworm", "体内外驱虫", dewormAdult, ""),
			careReminder("weight", "体重记录", 0, "每两周一次"),
			careReminder("monthlyReport", "月度报告 / 建议体检", 0, "每月 1 日"),
		}
	default: // 成年期
		return []model.CareTemplateItem{
			careTask("记录一次体重", "成年期每月称重一次即可", "", "weight"),
			careTask("观察饮水与排便", "发现软便可连续观察几天", "", "poop"),
			careTask("梳毛与口腔检查", "关注牙结石与皮肤状态", "", ""),
			carePlan(0, "今天", "全面健康自查", "体重、精神、食欲、被毛过一遍", "taskDetail"),
			carePlan(7, "第7天", "体重趋势检查", "对比上月，观察是否稳定", "weight"),
			carePlan(14, "第14天", "驱虫记录复盘", "确认体内外驱虫是否到期", "medicine"),
			carePlan(30, "第30天", "生成月度报告", "回顾本月记录，导出成长卡片", "report"),
			careReminder("vaccine", "年度疫苗加强", 30, ""),
			careReminder("deworm", "体内外驱虫", dewormAdult, ""),
			careReminder("weight", "体重记录", 0, "每月一次"),
			careReminder("monthlyReport", "月度报告", 0, "每月 1 日"),
		}
	}
}