import { useEffect, useState } from 'react'
import { Users, PawPrint, MessageSquare, Activity, TrendingUp, CalendarDays, UserPlus, Repeat } from 'lucide-react'
import {
  ResponsiveContainer, AreaChart, Area, BarChart, Bar, LineChart, Line,
  XAxis, YAxis, CartesianGrid, Tooltip, Cell,
} from 'recharts'
import { api } from '@/lib/api'
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'

const ORANGE = '#F5A93E'
const GREEN = '#3FB984'
const BLUE = '#5B9BD5'

type Pt = { date: string; count: number }
type Ret = { day: number; rate: number; base: number }
type Analytics = {
  summary: {
    total_users: number; new_today: number; new_month: number
    dau: number; wau: number; mau: number
    total_pets: number; total_posts: number; total_records: number
  }
  new_trend: Pt[]; active_trend: Pt[]; mau_trend: Pt[]; retention: Ret[]
}

const RANGES = [
  { label: '近 7 天', days: 7 },
  { label: '近 30 天', days: 30 },
  { label: '近 90 天', days: 90 },
]

export default function Dashboard() {
  const [days, setDays] = useState(30)
  const [a, setA] = useState<Analytics | null>(null)
  const [loading, setLoading] = useState(true)

  useEffect(() => {
    setLoading(true)
    api.analytics(days).then((d) => { setA(d); setLoading(false) }).catch(() => setLoading(false))
  }, [days])

  const s = a?.summary
  const kpis = [
    { label: '真实用户', value: s?.total_users, icon: Users, tint: ORANGE },
    { label: '日活 DAU', value: s?.dau, icon: Activity, tint: GREEN },
    { label: '周活 WAU', value: s?.wau, icon: CalendarDays, tint: BLUE },
    { label: '月活 MAU', value: s?.mau, icon: TrendingUp, tint: ORANGE },
    { label: '今日新增', value: s?.new_today, icon: UserPlus, tint: GREEN },
    { label: '本月新增', value: s?.new_month, icon: UserPlus, tint: BLUE },
  ]
  const mini = [
    { label: '宠物', value: s?.total_pets, icon: PawPrint },
    { label: '帖子', value: s?.total_posts, icon: MessageSquare },
    { label: '健康记录', value: s?.total_records, icon: Activity },
  ]
  const retData = (a?.retention || []).map((r) => ({ ...r, pct: Math.round(r.rate * 1000) / 10 }))

  return (
    <div className="space-y-6">
      <div className="flex items-center justify-between">
        <h1 className="text-2xl font-bold">概览</h1>
        <div className="flex gap-1 rounded-lg border bg-card p-1">
          {RANGES.map((r) => (
            <button
              key={r.days}
              onClick={() => setDays(r.days)}
              className={`rounded-md px-3 py-1 text-sm transition ${
                days === r.days ? 'bg-primary text-primary-foreground' : 'text-muted-foreground hover:text-foreground'
              }`}
            >
              {r.label}
            </button>
          ))}
        </div>
      </div>

      {/* KPI 卡 */}
      <div className="grid grid-cols-2 gap-4 lg:grid-cols-6">
        {kpis.map((c) => (
          <Card key={c.label}>
            <CardHeader className="flex-row items-center justify-between space-y-0 pb-1">
              <CardTitle className="text-xs text-muted-foreground">{c.label}</CardTitle>
              <c.icon className="h-4 w-4" style={{ color: c.tint }} />
            </CardHeader>
            <CardContent>
              <div className="text-2xl font-bold">{c.value ?? '—'}</div>
            </CardContent>
          </Card>
        ))}
      </div>

      {/* 图表区 */}
      <div className="grid grid-cols-1 gap-4 lg:grid-cols-2">
        <ChartCard title="新增趋势" hint={`每日新增真实用户 · ${days} 天`}>
          <ResponsiveContainer width="100%" height={260}>
            <AreaChart data={a?.new_trend || []} margin={{ top: 8, right: 12, left: -18, bottom: 0 }}>
              <defs>
                <linearGradient id="gNew" x1="0" y1="0" x2="0" y2="1">
                  <stop offset="0%" stopColor={ORANGE} stopOpacity={0.35} />
                  <stop offset="100%" stopColor={ORANGE} stopOpacity={0} />
                </linearGradient>
              </defs>
              <CartesianGrid strokeDasharray="3 3" vertical={false} stroke="#eee" />
              <XAxis dataKey="date" tick={{ fontSize: 11 }} interval="preserveStartEnd" minTickGap={24} />
              <YAxis tick={{ fontSize: 11 }} allowDecimals={false} width={36} />
              <Tooltip {...tipProps} />
              <Area type="monotone" dataKey="count" name="新增" stroke={ORANGE} strokeWidth={2} fill="url(#gNew)" />
            </AreaChart>
          </ResponsiveContainer>
        </ChartCard>

        <ChartCard title="活跃趋势" hint={`每日活跃用户 DAU · ${days} 天`}>
          <ResponsiveContainer width="100%" height={260}>
            <LineChart data={a?.active_trend || []} margin={{ top: 8, right: 12, left: -18, bottom: 0 }}>
              <CartesianGrid strokeDasharray="3 3" vertical={false} stroke="#eee" />
              <XAxis dataKey="date" tick={{ fontSize: 11 }} interval="preserveStartEnd" minTickGap={24} />
              <YAxis tick={{ fontSize: 11 }} allowDecimals={false} width={36} />
              <Tooltip {...tipProps} />
              <Line type="monotone" dataKey="count" name="活跃" stroke={GREEN} strokeWidth={2.5} dot={false} />
            </LineChart>
          </ResponsiveContainer>
        </ChartCard>

        <ChartCard title="月活 MAU" hint="近 6 个月去重活跃用户">
          <ResponsiveContainer width="100%" height={260}>
            <BarChart data={a?.mau_trend || []} margin={{ top: 8, right: 12, left: -18, bottom: 0 }}>
              <CartesianGrid strokeDasharray="3 3" vertical={false} stroke="#eee" />
              <XAxis dataKey="date" tick={{ fontSize: 11 }} />
              <YAxis tick={{ fontSize: 11 }} allowDecimals={false} width={36} />
              <Tooltip {...tipProps} />
              <Bar dataKey="count" name="月活" fill={BLUE} radius={[6, 6, 0, 0]} maxBarSize={44} />
            </BarChart>
          </ResponsiveContainer>
        </ChartCard>

        <ChartCard title="留存曲线" hint="注册后第 N 天仍活跃的比例（滚动口径）">
          <ResponsiveContainer width="100%" height={260}>
            <LineChart data={retData} margin={{ top: 8, right: 12, left: -18, bottom: 0 }}>
              <CartesianGrid strokeDasharray="3 3" vertical={false} stroke="#eee" />
              <XAxis dataKey="day" tick={{ fontSize: 11 }} tickFormatter={(d) => `D${d}`} />
              <YAxis tick={{ fontSize: 11 }} width={40} unit="%" domain={[0, 100]} />
              <Tooltip
                contentStyle={tipProps.contentStyle}
                formatter={(v: any, _n: any, p: any) => [`${v}%（分母 ${p.payload.base}）`, '留存率']}
                labelFormatter={(d) => `注册后第 ${d} 天`}
              />
              <Line type="monotone" dataKey="pct" name="留存率" stroke={ORANGE} strokeWidth={2.5}>
                {retData.map((_, i) => <Cell key={i} />)}
              </Line>
            </LineChart>
          </ResponsiveContainer>
        </ChartCard>
      </div>

      {/* 底部小计数 */}
      <div className="grid grid-cols-3 gap-4">
        {mini.map((c) => (
          <Card key={c.label}>
            <CardHeader className="flex-row items-center justify-between space-y-0 pb-1">
              <CardTitle className="text-xs text-muted-foreground">{c.label}</CardTitle>
              <c.icon className="h-4 w-4 text-muted-foreground" />
            </CardHeader>
            <CardContent><div className="text-2xl font-bold">{c.value ?? '—'}</div></CardContent>
          </Card>
        ))}
      </div>

      {loading && <div className="text-center text-sm text-muted-foreground">加载中…</div>}
    </div>
  )
}

const tipProps = {
  contentStyle: { borderRadius: 10, border: '1px solid #eee', fontSize: 12 },
  cursor: { fill: 'rgba(245,169,62,.08)' },
}

function ChartCard({ title, hint, children }: { title: string; hint?: string; children: React.ReactNode }) {
  return (
    <Card>
      <CardHeader className="pb-2">
        <CardTitle className="text-base">{title}</CardTitle>
        {hint && <p className="text-xs text-muted-foreground">{hint}</p>}
      </CardHeader>
      <CardContent>{children}</CardContent>
    </Card>
  )
}