export function localDayKey(d = new Date()) {
	return `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, '0')}-${String(d.getDate()).padStart(2, '0')}`
}

export function localShichenIndex(d = new Date()) {
	return ((d.getHours() + 1) % 24) >> 1
}

function nextShichenEnd(d = new Date()) {
	const shi = localShichenIndex(d)
	const startHour = (shi * 2 + 23) % 24
	const start = new Date(d)
	start.setHours(startHour, 0, 0, 0)
	if (start.getTime() > d.getTime()) start.setDate(start.getDate() - 1)
	return new Date(start.getTime() + 2 * 3600 * 1000)
}

export function localFallbackTips() {
	const n = new Date()
	const day = Math.floor(Date.UTC(n.getFullYear(), n.getMonth(), n.getDate()) / 86400000)
	const shi = localShichenIndex(n)
	const seed = day * 13 + shi * 19
	const palettes = [
		[{ 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: '天青', hex: '#9BB8D4' }, { name: '陶土', hex: '#C4A484' }],
	]
	const clothing = [
		'轻薄透气更舒服，外套可备一件薄衫应付温差。',
		'今日宜层搭：薄内搭+透气外衫，方便随时增减。',
		'选柔软面料贴身，活动一整天也不易紧绷。',
		'宽松剪裁更自在，适合慢节奏出门与散步。',
	]
	const notes = ['清爽干净，不抢戏。', '今日偏清透，层次更轻。', '温柔耐看，适合日常。', '柔和提气色，不显沉。']
	const well = [
		'午后泡一杯温茶，给身心一点缓冲。',
		'今日做三次深呼吸，拉长呼气更易放松。',
		'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。',
	]
	const i = seed % palettes.length
	return {
		clothingIndex: 55 + (seed % 41),
		clothing: clothing[i],
		colorNote: notes[i],
		palette: palettes[i],
		wellness: well[i],
		source: 'fallback',
		needBirth: true,
		asOf: localDayKey(n),
		shichen: shi,
		validUntil: nextShichenEnd(n).toISOString(),
	}
}

export function tipsFromApi(t) {
	return {
		clothingIndex: t.clothing_index,
		clothing: t.clothing,
		colorNote: t.color_note,
		palette: (t.palette || []).map((p) => ({ name: p.name, hex: p.hex })),
		wellness: t.wellness,
		needBirth: !!t.need_birth,
		guaName: t.gua_name,
		source: t.source,
		asOf: t.as_of || localDayKey(),
		shichen: t.shichen,
		shichenName: t.shichen_name,
		validUntil: t.valid_until,
	}
}

export function ringOffset(index) {
	const c = 2 * Math.PI * 30
	const pct = Math.min(100, Math.max(0, Number(index) || 0)) / 100
	return c * (1 - pct)
}