package portrait

import (
	"time"

	"github.com/yuxingu/digital-psychology/apps/api/internal/companion"
)

var (
	tg  = []string{"甲", "乙", "丙", "丁", "戊", "己", "庚", "辛", "壬", "癸"}
	dz  = []string{"子", "丑", "寅", "卯", "辰", "巳", "午", "未", "申", "酉", "戌", "亥"}
	tge = map[string]string{"甲": "木", "乙": "木", "丙": "火", "丁": "火", "戊": "土", "己": "土", "庚": "金", "辛": "金", "壬": "水", "癸": "水"}
	dze = map[string]string{"子": "水", "丑": "土", "寅": "木", "卯": "木", "辰": "土", "巳": "火", "午": "火", "未": "土", "申": "金", "酉": "金", "戌": "土", "亥": "水"}
	eo  = []string{"木", "火", "土", "金", "水"}
	ec  = map[string]string{"木": "#5CB85C", "火": "#E54D42", "土": "#E8985A", "金": "#C8923A", "水": "#4A90E2"}
)

var yiJi = map[string]struct{ Yi, Ji string }{
	"木": {"早睡养肝血 · 舒展拉伸 · 绿色蔬菜", "久坐 · 生闷气 · 熬夜"},
	"火": {"午休15分钟 · 菊花/莲子 · 平心静气", "暴晒 · 辛辣油腻 · 过度兴奋"},
	"土": {"规律三餐 · 健脾山药 · 饭后散步", "思虑过度 · 生冷 · 暴饮暴食"},
	"金": {"滋润养肺 · 白色食物 · 深呼吸", "干燥受凉 · 悲忧 · 剧烈耗气"},
	"水": {"早卧晚起 · 温补黑色食物 · 护腰腹", "受寒 · 过劳 · 惊恐紧张"},
}

// seasonEl maps month index (0=Jan) → 时令五行 (decode.js SEASON_EL).
var seasonEl = []string{"水", "水", "木", "木", "木", "火", "火", "火", "土", "金", "金", "水"}

type pillar struct{ tg, dz string }

type bazi struct {
	year, month, day, hour pillar
}

// getBazi mirrors js/common.js getBazi (hour default 12 = 午时).
// Day-pillar index uses civil days since 1900-01-01 minus 1, matching legacy
// browser Date local-midnight flooring under historical CN TZ/DST (decode.js).
func getBazi(y, m, d, h int) bazi {
	gzY := pillar{tg: tg[(y-4+10000)%10], dz: dz[(y-4+12000)%12]}
	birth := time.Date(y, time.Month(m), d, 0, 0, 0, 0, time.UTC)
	dayOfYear := birth.YearDay()
	lcDay := 35
	mi := int(float64((dayOfYear-lcDay+365)%365) / 30.44)
	if mi < 0 {
		mi += 12
	}
	if mi >= 12 {
		mi = 11
	}
	mTg := tg[(((y-4+10000)%10)*2+mi)%10]
	mDz := dz[(mi+2)%12]

	base := time.Date(1900, 1, 1, 0, 0, 0, 0, time.UTC)
	dd := int(birth.Sub(base).Hours()/24) - 1
	dTg := tg[((dd%10)+10)%10]
	dDz := dz[((dd%12)+12)%12]
	hDz := dz[((h+1)/2)%12]
	hTg := tg[(indexOf(tg, dTg)*2+indexOf(dz, hDz))%10]
	return bazi{
		year:  gzY,
		month: pillar{tg: mTg, dz: mDz},
		day:   pillar{tg: dTg, dz: dDz},
		hour:  pillar{tg: hTg, dz: hDz},
	}
}

func calc5E(bz bazi) map[string]int {
	c := map[string]int{"木": 0, "火": 0, "土": 0, "金": 0, "水": 0}
	for _, p := range []pillar{bz.year, bz.month, bz.day, bz.hour} {
		c[tge[p.tg]]++
		c[dze[p.dz]]++
	}
	t := 0
	for _, e := range eo {
		t += c[e]
	}
	r := map[string]int{}
	for _, e := range eo {
		if t == 0 {
			r[e] = 0
		} else {
			r[e] = int(float64(c[e])/float64(t)*100 + 0.5) // Math.round
		}
	}
	return r
}

func strongestEl(p map[string]int) string {
	best := eo[0]
	for _, e := range eo[1:] {
		if p[e] > p[best] {
			best = e
		}
	}
	return best
}

func weakestEl(p map[string]int) string {
	worst := eo[0]
	for _, e := range eo[1:] {
		if p[e] < p[worst] {
			worst = e
		}
	}
	return worst
}

func wuxingBars(p map[string]int) []map[string]any {
	bars := make([]map[string]any, 0, 5)
	for _, e := range eo {
		bars = append(bars, map[string]any{
			"el": e, "pct": p[e], "color": ec[e],
		})
	}
	return bars
}

// WuxingBlock builds the shared 五行 summary block (bars + tendency labels).
func WuxingBlock(birth time.Time) map[string]any {
	y, m, d := birth.Date()
	bz := getBazi(y, int(m), d, 12)
	pct := calc5E(bz)
	strong := strongestEl(pct)
	weak := weakestEl(pct)
	cst := constitutionByElement[strong]
	emo := emotionByElement[strong]
	return map[string]any{
		"bars":      wuxingBars(pct),
		"primary":   cst.Primary,
		"strong":    cst.Strong,
		"weak":      cst.Weak,
		"strong_el": strong,
		"weak_el":   weak,
		"emotion":   emo.Strength,
		"care_dir":  "养" + cst.Strong + " · 需呵护" + cst.Weak,
	}
}

func todayTip(now time.Time) map[string]any {
	st := companion.TodaySolar(now)
	el := seasonEl[int(now.Month())-1]
	yj := yiJi[el]
	return map[string]any{
		"solar_term": st.Name,
		"season_el":  el,
		"yi":         yj.Yi,
		"ji":         yj.Ji,
		"tip":        st.Tip,
	}
}

func indexOf(arr []string, s string) int {
	for i, v := range arr {
		if v == s {
			return i
		}
	}
	return 0
}