package home

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"strings"
	"sync"
	"time"
	"unicode/utf8"

	"github.com/google/uuid"

	"github.com/yuxingu/digital-psychology/apps/api/internal/llm/deepseek"
	"github.com/yuxingu/digital-psychology/apps/api/internal/model"
	"github.com/yuxingu/digital-psychology/apps/api/internal/yijing"
)

// ColorChip is one palette swatch.
type ColorChip struct {
	Name string `json:"name"`
	Hex  string `json:"hex"`
}

// DailyTips is homepage self-card lifestyle tips.
type DailyTips struct {
	ClothingIndex int         `json:"clothing_index"`
	Clothing      string      `json:"clothing"`
	ColorNote     string      `json:"color_note"`
	Palette       []ColorChip `json:"palette"`
	Wellness      string      `json:"wellness"`
	Source        string      `json:"source"` // llm | fallback
	GuaName       string      `json:"gua_name,omitempty"`
	DayPart       string      `json:"day_part,omitempty"`
	NeedBirth     bool        `json:"need_birth"`
}

type tipsCacheEntry struct {
	tips DailyTips
	exp  time.Time
}

var tipsCache sync.Map // key string → tipsCacheEntry

// DailyTips returns personalized tips; falls back when LLM / profile unavailable.
func (s *Service) DailyTips(ctx context.Context, userID uuid.UUID) (*DailyTips, error) {
	now := time.Now()
	self, ok := s.findSelf(ctx, userID)
	if !ok {
		fb := fallbackTips(now, "", nil)
		fb.NeedBirth = true
		return fb, nil
	}

	birth := self.BirthDate.Format("2006-01-02")
	yc := yijing.Seed(birth, self.BirthTime, now)
	cacheKey := fmt.Sprintf("%s:%s:%s:%d", userID, birth, now.Format("2006-01-02"), now.Hour()/3)
	if v, hit := tipsCache.Load(cacheKey); hit {
		e := v.(tipsCacheEntry)
		if time.Now().Before(e.exp) {
			out := e.tips
			return &out, nil
		}
	}

	if s.LLM == nil || !s.LLM.Enabled() {
		fb := fallbackTips(now, birth, self.BirthTime)
		fb.GuaName = yc.GuaName
		fb.DayPart = yc.DayPart
		return fb, nil
	}

	tips, err := s.generateLLMTips(ctx, yc)
	if err != nil {
		log.Printf("home daily-tips llm: %v", err)
		fb := fallbackTips(now, birth, self.BirthTime)
		fb.GuaName = yc.GuaName
		fb.DayPart = yc.DayPart
		return fb, nil
	}
	tips.Source = "llm"
	tips.GuaName = yc.GuaName
	tips.DayPart = yc.DayPart
	tips.NeedBirth = false
	tipsCache.Store(cacheKey, tipsCacheEntry{tips: *tips, exp: now.Add(45 * time.Minute)})
	return tips, nil
}

func (s *Service) findSelf(ctx context.Context, userID uuid.UUID) (*model.Profile, bool) {
	if s.Profiles == nil || userID == uuid.Nil {
		return nil, false
	}
	items, err := s.Profiles.ListByUser(ctx, userID)
	if err != nil {
		return nil, false
	}
	for i := range items {
		if items[i].Relation == "self" {
			return &items[i], true
		}
	}
	return nil, false
}

func (s *Service) generateLLMTips(ctx context.Context, yc yijing.Context) (*DailyTips, error) {
	sys := `你是愈心谷的生活节律助手。根据用户出生信息与当前时刻的易经卦象种子，给出温和的生活建议。
硬性要求：
- 禁止占卜/算命/改命恐吓/吉凶祸福话术
- 禁止医疗疗效承诺
- 用探索向、身心节律语气；可参考卦象意象，不要说「必有」类断言
- 只输出 JSON，不要 markdown：
{"clothing_index":70,"clothing":"一句穿衣建议","color_note":"一句颜色说明","palette":[{"name":"色名","hex":"#RRGGBB"},{"name":"色名","hex":"#RRGGBB"}],"wellness":"一句养生建议"}
- clothing_index 为 55–95 整数；palette 恰好 2 项；文案各不超过 40 字`

	user := yc.PromptLine() + "\n请生成今日穿衣指数、颜色搭配与养生推荐。"
	raw, err := s.LLM.Chat(ctx, []deepseek.Message{
		{Role: "system", Content: sys},
		{Role: "user", Content: user},
	})
	if err != nil {
		return nil, err
	}
	return parseTipsJSON(raw)
}

func parseTipsJSON(raw string) (*DailyTips, error) {
	raw = strings.TrimSpace(raw)
	if i := strings.Index(raw, "{"); i >= 0 {
		raw = raw[i:]
	}
	if j := strings.LastIndex(raw, "}"); j >= 0 {
		raw = raw[:j+1]
	}
	var t DailyTips
	if err := json.Unmarshal([]byte(raw), &t); err != nil {
		return nil, err
	}
	if t.ClothingIndex < 40 || t.ClothingIndex > 100 {
		t.ClothingIndex = 72
	}
	t.Clothing = clampRunes(t.Clothing, 48)
	t.ColorNote = clampRunes(t.ColorNote, 40)
	t.Wellness = clampRunes(t.Wellness, 48)
	if len(t.Palette) != 2 {
		return nil, fmt.Errorf("palette len")
	}
	for i := range t.Palette {
		t.Palette[i].Name = clampRunes(t.Palette[i].Name, 8)
		if !looksHex(t.Palette[i].Hex) {
			t.Palette[i].Hex = "#E8DCC8"
		}
	}
	return &t, nil
}

func clampRunes(s string, max int) string {
	s = strings.TrimSpace(s)
	if utf8.RuneCountInString(s) <= max {
		return s
	}
	r := []rune(s)
	return string(r[:max])
}

func looksHex(h string) bool {
	if len(h) != 7 || h[0] != '#' {
		return false
	}
	for i := 1; i < 7; i++ {
		c := h[i]
		if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
			return false
		}
	}
	return true
}

func fallbackTips(now time.Time, birth string, birthTime *string) *DailyTips {
	yc := yijing.Seed(birth, birthTime, now)
	if birth == "" {
		yc = yijing.Seed(now.Format("2006-01-02"), nil, now)
	}
	palettes := [][]ColorChip{
		{{Name: "米白", Hex: "#F5F0E8"}, {Name: "雾霾蓝", Hex: "#A8C4D8"}},
		{{Name: "燕麦色", Hex: "#E8DCC8"}, {Name: "浅杏", Hex: "#F0C9A8"}},
		{{Name: "浅灰", Hex: "#D8D6D4"}, {Name: "雾粉", Hex: "#E8B8C4"}},
		{{Name: "象牙白", Hex: "#F7F4EC"}, {Name: "鼠尾草", Hex: "#A8C4B0"}},
		{{Name: "浅卡其", Hex: "#DCC8A8"}, {Name: "浅蓝", Hex: "#B0D0E8"}},
	}
	clothing := []string{
		"轻薄透气更舒服，外套可备一件薄衫应付温差。",
		"选柔软面料贴身，活动一整天也不易紧绷。",
		"上下同色系更省心，再加一件小配饰点睛即可。",
		"宽松剪裁更自在，适合慢节奏出门与散步。",
		"内里干净简约，外搭一件有质感的外套就够。",
	}
	notes := []string{"清爽干净，不抢戏。", "温柔耐看，适合日常。", "柔和提气色，不显沉。", "安静又有呼吸感。", "干净利落，好搭配。"}
	well := []string{
		"午后泡一杯温茶，给身心一点缓冲。",
		"今晚早点放下屏幕，让眼睛歇一会儿。",
		"走路时把肩膀放松，呼吸会顺很多。",
		"饭后慢走十分钟，比猛坐着更舒服。",
		"喝水提醒自己小口多次，别等口渴再灌。",
	}
	i := (yc.GuaIndex + yc.Line + now.Hour()) % 5
	return &DailyTips{
		ClothingIndex: 62 + (yc.GuaIndex % 31),
		Clothing:      clothing[i],
		ColorNote:     notes[i],
		Palette:       palettes[i],
		Wellness:      well[i],
		Source:        "fallback",
		GuaName:       yc.GuaName,
		DayPart:       yc.DayPart,
	}
}