import { useState, useEffect } from 'react'
import {
  BarChart,
  Bar,
  XAxis,
  YAxis,
  Tooltip,
  ResponsiveContainer,
  CartesianGrid,
  PieChart,
  Pie,
} from 'recharts'
import { api } from '../utils/api'
import KpiTilesOverview from './KpiTilesOverview'

const PERIODS = [
  { v: 7, label: '7 Tage' },
  { v: 28, label: '28 Tage' },
  { v: 90, label: '90 Tage' },
  { v: 9999, label: 'Gesamt' },
]

/**
 * Layer 2b: Kennzahlen und Charts nur aus GET /api/charts/fitness-dashboard-viz (activity_metrics).
 */
export default function FitnessDashboardOverview() {
  const [period, setPeriod] = useState(28)
  const [viz, setViz] = useState(null)
  const [loading, setLoading] = useState(true)
  const [err, setErr] = useState(null)

  useEffect(() => {
    let cancelled = false
    setLoading(true)
    setErr(null)
    api
      .getFitnessDashboardViz(period)
      .then((v) => {
        if (!cancelled) setViz(v)
      })
      .catch((e) => {
        if (!cancelled) setErr(e.message || 'Laden fehlgeschlagen')
      })
      .finally(() => {
        if (!cancelled) setLoading(false)
      })
    return () => {
      cancelled = true
    }
  }, [period])

  if (loading) {
    return (
      <div className="card section-gap">
        <div className="card-title">Fitness-Übersicht</div>
        <div className="spinner" style={{ margin: 24 }} />
      </div>
    )
  }

  if (err) {
    return (
      <div className="card section-gap">
        <div className="card-title">Fitness-Übersicht</div>
        <div style={{ color: 'var(--danger)' }}>{err}</div>
      </div>
    )
  }

  if (!viz?.has_activity_entries) {
    return (
      <div className="card section-gap">
        <div className="card-title">Fitness-Übersicht</div>
        <p style={{ fontSize: 12, color: 'var(--text3)', lineHeight: 1.45 }}>
          Noch keine Aktivitätsdaten. Sobald du Trainings erfasst oder importierst, erscheinen Kennzahlen und
          Diagramme hier.
        </p>
      </div>
    )
  }

  const vol = viz.charts?.training_volume
  const typ = viz.charts?.training_type_distribution
  const volRows = (vol?.data?.labels || []).map((name, i) => ({
    name,
    min: vol?.data?.datasets?.[0]?.data?.[i] ?? 0,
  }))
  const pieLabels = typ?.data?.labels || []
  const pieVals = typ?.data?.datasets?.[0]?.data || []
  const pieColors = typ?.data?.datasets?.[0]?.backgroundColor || []
  const pieData = pieLabels.map((name, i) => ({
    name,
    value: pieVals[i],
    fill: pieColors[i] || '#888780',
  }))

  const kpiTiles = (viz.kpi_tiles || []).map((t) => ({
    ...t,
    sublabel:
      typeof t.sublabel === 'string' && t.sublabel.length > 42 ? `${t.sublabel.slice(0, 40)}…` : t.sublabel,
  }))

  const eff = viz.effective_window_days
  const wUsed = viz.training_volume_weeks_used
  const dTyp = viz.training_type_dist_days_used

  return (
    <div className="card section-gap">
      <div className="card-title" style={{ display: 'flex', flexWrap: 'wrap', alignItems: 'center', gap: 12 }}>
        <span>Fitness-Übersicht</span>
        <label style={{ fontSize: 12, fontWeight: 500, color: 'var(--text3)', display: 'flex', alignItems: 'center', gap: 8 }}>
          Zeitraum
          <select
            className="form-input"
            style={{ maxWidth: 140, padding: '6px 10px', fontSize: 13 }}
            value={period}
            onChange={(e) => setPeriod(Number(e.target.value))}
          >
            {PERIODS.map((p) => (
              <option key={p.v} value={p.v}>
                {p.label}
              </option>
            ))}
          </select>
        </label>
      </div>

      <p style={{ fontSize: 11, color: 'var(--text3)', lineHeight: 1.45, marginBottom: 10 }}>
        Kennzahlen und Charts nutzen dieselbe Berechnung wie die KI-Platzhalter (Aktivitäts-Data-Layer). Zusammenfassung
        ca. <strong>{eff}</strong> Tage · Volumen-Chart <strong>{wUsed}</strong> Wochen · Typ-Verteilung{' '}
        <strong>{dTyp}</strong> Tage
        {viz.last_updated ? (
          <>
            {' '}
            · letzte Aktivität <strong>{viz.last_updated}</strong>
          </>
        ) : null}
        .
      </p>

      <KpiTilesOverview tiles={kpiTiles} heading="Kennzahlen" />

      <div
        style={{
          display: 'grid',
          gridTemplateColumns: 'repeat(auto-fit, minmax(280px, 1fr))',
          gap: 16,
          marginTop: 8,
        }}
      >
        <div>
          <div style={{ fontSize: 12, fontWeight: 600, color: 'var(--text3)', marginBottom: 6 }}>
            Trainingsvolumen (Minuten / Woche)
          </div>
          {volRows.length >= 1 ? (
            <ResponsiveContainer width="100%" height={200}>
              <BarChart data={volRows} margin={{ top: 4, right: 8, bottom: 0, left: -12 }}>
                <CartesianGrid stroke="var(--border)" strokeDasharray="3 3" />
                <XAxis dataKey="name" tick={{ fontSize: 9, fill: 'var(--text3)' }} tickLine={false} interval={0} angle={-35} textAnchor="end" height={48} />
                <YAxis tick={{ fontSize: 9, fill: 'var(--text3)' }} tickLine={false} />
                <Tooltip
                  contentStyle={{
                    background: 'var(--surface)',
                    border: '1px solid var(--border)',
                    borderRadius: 8,
                    fontSize: 11,
                  }}
                  formatter={(v) => [`${Math.round(v)} min`, 'Volumen']}
                />
                <Bar dataKey="min" fill="#1D9E75" radius={[3, 3, 0, 0]} name="Minuten" />
              </BarChart>
            </ResponsiveContainer>
          ) : (
            <div style={{ fontSize: 12, color: 'var(--text3)' }}>Keine Wochendaten im gewählten Fenster.</div>
          )}
        </div>

        <div>
          <div style={{ fontSize: 12, fontWeight: 600, color: 'var(--text3)', marginBottom: 6 }}>
            Training nach Kategorie
          </div>
          {pieData.length >= 1 ? (
            <ResponsiveContainer width="100%" height={200}>
              <PieChart>
                <Pie
                  data={pieData}
                  dataKey="value"
                  nameKey="name"
                  cx="50%"
                  cy="50%"
                  outerRadius={72}
                  label={({ name, percent }) => `${name} ${(percent * 100).toFixed(0)}%`}
                />
                <Tooltip
                  contentStyle={{
                    background: 'var(--surface)',
                    border: '1px solid var(--border)',
                    borderRadius: 8,
                    fontSize: 11,
                  }}
                />
              </PieChart>
            </ResponsiveContainer>
          ) : (
            <div style={{ fontSize: 12, color: 'var(--text3)' }}>Keine kategorisierten Sessions im Fenster.</div>
          )}
        </div>
      </div>
    </div>
  )
}