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/repository"
	"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"`
	AsOf          string      `json:"as_of"` // YYYY-MM-DD
	Shichen       int         `json:"shichen"`
	ShichenName   string      `json:"shichen_name"`
	ValidUntil    string      `json:"valid_until"` // RFC3339 next 时辰 start
	NeedBirth     bool        `json:"need_birth"`
}

type tipsMemEntry struct {
	tips DailyTips
}

var (
	tipsMem     sync.Map // cacheKey → tipsMemEntry
	tipsInflight sync.Map // cacheKey → *sync.Mutex generating
)

func tipsCacheKey(userID uuid.UUID, start time.Time) string {
	return userID.String() + ":" + start.UTC().Format(time.RFC3339)
}

// DailyTips returns tips for the current 时辰; prefers cache, never blocks on LLM.
func (s *Service) DailyTips(ctx context.Context, userID uuid.UUID) (*DailyTips, error) {
	now := time.Now()
	loc, err := time.LoadLocation("Asia/Shanghai")
	if err != nil {
		loc = time.FixedZone("CST", 8*3600)
	}
	now = now.In(loc)
	win := CurrentShichen(now)
	asOf := now.Format("2006-01-02")

	self, ok := s.findSelf(ctx, userID)
	if !ok || userID == uuid.Nil {
		fb := decorateTips(fallbackTips(now, "", nil), win, asOf, true)
		return fb, nil
	}

	birth := self.BirthDate.Format("2006-01-02")
	key := tipsCacheKey(userID, win.Start)

	if v, hit := tipsMem.Load(key); hit {
		out := v.(tipsMemEntry).tips
		return decorateTips(&out, win, asOf, false), nil
	}
	if s.Tips != nil {
		if raw, source, err := s.Tips.GetTips(ctx, userID, win.Start); err == nil {
			var t DailyTips
			if json.Unmarshal(raw, &t) == nil {
				t.Source = source
				tipsMem.Store(key, tipsMemEntry{tips: t})
				return decorateTips(&t, win, asOf, false), nil
			}
		} else if err != repository.ErrNoTips {
			log.Printf("home daily-tips db: %v", err)
		}
	}

	// Instant path: deterministic fallback, warm LLM in background.
	fb := fallbackTips(now, birth, self.BirthTime)
	out := decorateTips(fb, win, asOf, false)
	tipsMem.Store(key, tipsMemEntry{tips: *out})
	s.persistTips(userID, win, out)
	s.warmLLMAsync(userID, birth, self.BirthTime, win, asOf, key)
	return out, nil
}

func decorateTips(t *DailyTips, win ShichenWindow, asOf string, needBirth bool) *DailyTips {
	cp := *t
	cp.AsOf = asOf
	cp.Shichen = win.Index
	cp.ShichenName = win.Name + "时"
	cp.ValidUntil = win.End.Format(time.RFC3339)
	cp.NeedBirth = needBirth
	return &cp
}

func (s *Service) persistTips(userID uuid.UUID, win ShichenWindow, tips *DailyTips) {
	if s.Tips == nil || tips == nil {
		return
	}
	raw, err := json.Marshal(tips)
	if err != nil {
		return
	}
	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
	defer cancel()
	if err := s.Tips.UpsertTips(ctx, userID, win.Start, win.Index, raw, tips.Source); err != nil {
		log.Printf("home daily-tips upsert: %v", err)
	}
}

func (s *Service) warmLLMAsync(userID uuid.UUID, birth string, birthTime *string, win ShichenWindow, asOf, key string) {
	if s.LLM == nil || !s.LLM.Enabled() {
		return
	}
	if _, loaded := tipsInflight.LoadOrStore(key, true); loaded {
		return
	}
	go func() {
		defer tipsInflight.Delete(key)
		ctx, cancel := context.WithTimeout(context.Background(), 25*time.Second)
		defer cancel()
		now := win.Start.Add(30 * time.Minute) // representative instant inside 时辰
		if now.After(win.End) {
			now = win.Start
		}
		yc := yijing.Seed(birth, birthTime, now)
		tips, err := s.generateLLMTips(ctx, yc, now, win)
		if err != nil {
			log.Printf("home daily-tips llm warm: %v", err)
			return
		}
		tips.Source = "llm"
		tips.ClothingIndex = clothingIndexFromSeed(yc, now, win.Index)
		tips.GuaName = yc.GuaName
		tips.DayPart = yc.DayPart
		out := decorateTips(tips, win, asOf, false)
		tipsMem.Store(key, tipsMemEntry{tips: *out})
		s.persistTips(userID, win, out)
	}()
}

func clothingIndexFromSeed(yc yijing.Context, now time.Time, shichen int) int {
	n := yc.GuaIndex*11 + yc.Line*5 + now.YearDay()*3 + shichen*17
	return 55 + n%41
}

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, now time.Time, win ShichenWindow) (*DailyTips, error) {
	weekday := []string{"日", "一", "二", "三", "四", "五", "六"}[now.Weekday()]
	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辰的易经卦象种子，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
- 文案必须贴合「此刻时辰」与日期，体现与上一时辰不同的节律侧重
- 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 := fmt.Sprintf(
		"%s\n今天是 %s（星期%s），当前%s时。请生成贴合本时辰的穿衣指数、颜色搭配与养生推荐，勿与通用套话雷同。",
		yc.PromptLine(), now.Format("2006-01-02"), weekday, win.Name,
	)
	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)
	}
	win := CurrentShichen(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"}},
		{{Name: "天青", Hex: "#9BB8D4"}, {Name: "陶土", Hex: "#C4A484"}},
		{{Name: "豆沙", Hex: "#C9A0A0"}, {Name: "雾绿", Hex: "#B5C9B8"}},
		{{Name: "奶油", Hex: "#F3EADF"}, {Name: "烟灰", Hex: "#B8B4B0"}},
		{{Name: "浅咖", Hex: "#C8B09A"}, {Name: "靛蓝", Hex: "#6B8CAE"}},
		{{Name: "杏白", Hex: "#F6EBDD"}, {Name: "藕荷", Hex: "#D4B8C4"}},
		{{Name: "竹青", Hex: "#A8BFA8"}, {Name: "沙色", Hex: "#E0D0B8"}},
		{{Name: "月白", Hex: "#EEF2F5"}, {Name: "焦糖", Hex: "#C4A070"}},
	}
	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。",
		"今日宜层搭：薄内搭+透气外衫，方便随时增减。",
		"选垂感面料更显松弛，走路也会轻一点。",
		"少用厚重配饰，让肩颈更轻松。",
		"浅色上衣更提气色，下装选舒适脚感即可。",
		"风大时加一件防风薄外套，比厚羽绒服更灵活。",
		"本时辰适合干净线条，少印花更省心。",
		"运动鞋或软底鞋更友好，站久也不累。",
	}
	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。", "此刻偏清透，层次更轻。",
		"暖调一点点，气色更稳。", "冷暖各一，对比柔和。", "低饱和更耐看。",
		"偏自然色，贴近户外光线。", "雾感配色，不刺眼。", "柔对比，适合慢节奏。",
	}
	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。",
		"此刻做三次深呼吸，拉长呼气更易放松。",
		"站起来伸个懒腰，活动一下髋与肩。",
		"晚饭少一点刺激，给肠胃留空档。",
		"睡前把明天三件小事写下来，心会静些。",
		"听一首慢歌，跟着节奏把呼吸放慢。",
		"把窗帘开一条缝，让自然光进一点。",
		"洗手洗脸用温水，给皮肤一点温柔。",
	}
	n := len(palettes)
	i := (yc.GuaIndex*13 + yc.Line*7 + now.YearDay()*3 + win.Index*19) % n
	if i < 0 {
		i = -i
	}
	return &DailyTips{
		ClothingIndex: clothingIndexFromSeed(yc, now, win.Index),
		Clothing:      clothing[i],
		ColorNote:     notes[i],
		Palette:       palettes[i],
		Wellness:      well[i],
		Source:        "fallback",
		GuaName:       yc.GuaName,
		DayPart:       yc.DayPart,
		AsOf:          now.Format("2006-01-02"),
	}
}