import { useEffect, useState } from 'react';
import { Link, f7 } from 'framework7-react';
import { apiClient, errorMessage, HealthDay } from '../services/api';
import Screen from '../components/Screen';
import Ring from '../components/charts/Ring';
import MetricCard from '../components/charts/MetricCard';
import MetricStrip from '../components/charts/MetricStrip';
import Skeleton from '../components/Skeleton';
import { useCountUp } from '../lib/motion';
import { RANGES } from '../lib/ranges';
import { METRICS, metricHref } from '../lib/metrics';
import { daysAgo, iso, shiftDay, today as todayIso } from '../lib/day';
import './Today.css';

/* A year is loaded up front so stepping back a day costs no request. */
const HISTORY_DAYS = 365;

interface RingSpec {
  label: string;
  value: number | null;
  /** Reaching this counts as a full ring. */
  target: number | null;
  unit: string;
  decimals?: number;
  goalText: string;
}

/**
 * Three rings: steps, sleep and HRV.
 *
 * Each is normalised against the point where it enters its own reference band,
 * so a full ring means the same thing for all three even though the units do
 * not compare. Rings sit side by side rather than concentric — Apple's nested
 * form works because its three rings share one idea (move/exercise/stand);
 * these three are unrelated measures and read more clearly apart.
 */
function RingRow({ today, history }: { today: HealthDay; history: HealthDay[] }) {
  const stepGoal = today.stepGoal ?? RANGES.steps.goodFrom;

  const specs: RingSpec[] = [
    {
      label: '步数',
      value: today.steps,
      target: stepGoal,
      unit: '步',
      goalText: `目标 ${stepGoal.toLocaleString()}`,
    },
    {
      label: '睡眠',
      value: today.sleepDuration,
      target: RANGES.sleepDuration.goodFrom,
      unit: '小时',
      decimals: 1,
      goalText: `目标 ${RANGES.sleepDuration.goodFrom} 小时`,
    },
    {
      label: 'HRV',
      value: today.heartRateVariability,
      target: RANGES.heartRateVariability.goodFrom,
      unit: 'ms',
      goalText: `参考 ≥${RANGES.heartRateVariability.goodFrom} ms`,
    },
  ];

  const week = history.slice(-7).map((d) => d.steps).filter((v): v is number => v != null);
  const weekAvg = week.length
    ? Math.round(week.reduce((a, b) => a + b, 0) / week.length)
    : null;

  const done = specs.filter((s) => s.value != null && s.target && s.value >= s.target).length;

  return (
    <section className="hero">
      <div className="ring-row">
        {specs.map((s) => (
          <RingCell key={s.label} spec={s} />
        ))}
      </div>

      <div className="hero-summary">
        <span className="hero-headline">
          {done === 3 ? '三项全部达标' : done === 0 ? '今日尚无达标项' : `${done} / 3 项达标`}
        </span>
        {weekAvg != null && (
          <span className="hero-aside">步数近 7 日均 {weekAvg.toLocaleString()}</span>
        )}
      </div>
    </section>
  );
}

function RingCell({ spec }: { spec: RingSpec }) {
  const animated = useCountUp(spec.value);
  const progress =
    spec.value != null && spec.target ? spec.value / spec.target : null;

  const shown =
    spec.value == null
      ? '—'
      : (animated ?? spec.value).toLocaleString(undefined, {
          minimumFractionDigits: 0,
          maximumFractionDigits: spec.decimals ?? 0,
        });

  return (
    <div className="ring-cell">
      <Ring
        progress={progress}
        size={96}
        thickness={8}
        label={`${spec.label} ${progress != null ? Math.round(progress * 100) : 0}%`}
      >
        <span className="ring-value">{shown}</span>
        <span className="ring-unit">{spec.unit}</span>
      </Ring>
      <div className="ring-label">{spec.label}</div>
      <div className="ring-goal">{spec.goalText}</div>
    </div>
  );
}

/* Which cards each section shows, by registry id. */
const SECTIONS: Array<{ title: string; items: string[] }> = [
  { title: '活动', items: ['steps', 'intensityMinutes', 'floorsAscended', 'distance'] },
  { title: '心率与压力', items: ['heartRate', 'heartRateVariability', 'stress', 'trainingReadiness'] },
  { title: '睡眠', items: ['sleepDuration', 'sleepQuality'] },
];

function TodayPage() {
  const [days, setDays] = useState<HealthDay[]>([]);
  const [selected, setSelected] = useState<string | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState('');

  useEffect(() => {
    const load = async () => {
      try {
        // A year in one read: browsing back a day should not cost a request,
        // and the cards' sparklines need the surrounding days anyway.
        setDays(await apiClient.getHealthSummary(
          daysAgo(HISTORY_DAYS - 1), todayIso()
        ));
      } catch (err: any) {
        setError(errorMessage(err, '加载数据失败'));
      } finally {
        setLoading(false);
      }
    };
    load();
  }, []);

  const newest = days.length ? days[days.length - 1].date : null;
  const date = selected ?? newest;
  const index = date ? days.findIndex((d) => d.date === date) : -1;
  const today = index >= 0 ? days[index] : undefined;

  // The window feeding the sparklines ends at the day being viewed, so the
  // trend on a card always leads up to the number above it.
  const history = index >= 0 ? days.slice(Math.max(0, index - 13), index + 1) : [];

  const oldest = days.length ? days[0].date : null;
  const canPrev = !!(date && oldest && date > oldest);
  const canNext = !!(date && newest && date < newest);

  const go = (delta: number) => {
    if (!date) return;
    const target = shiftDay(date, delta);
    // Days with no record at all are skipped over rather than shown blank.
    const nearest = delta < 0
      ? [...days].reverse().find((d) => d.date <= target)
      : days.find((d) => d.date >= target);
    if (nearest) setSelected(nearest.date);
  };

  const openCalendar = () => {
    if (!date) return;
    const calendar = f7.calendar.create({
      value: [new Date(`${date}T12:00:00`)],
      minDate: oldest ? new Date(`${oldest}T12:00:00`) : undefined,
      maxDate: newest ? new Date(`${newest}T12:00:00`) : undefined,
      closeOnSelect: true,
      on: {
        change(_c: any, value: unknown) {
          const values = value as Date[];
          if (!values?.length) return;
          const picked = iso(values[0]);
          const match = days.find((d) => d.date === picked);
          setSelected(match ? match.date : picked);
        },
        closed(c: any) { c.destroy(); },
      },
    });
    calendar.open();
  };

  const isToday = date === todayIso();
  const weekday = date
    ? ['周日', '周一', '周二', '周三', '周四', '周五', '周六'][
        new Date(`${date}T12:00:00`).getDay()
      ]
    : '';

  const open = (id: string) => f7.views.current.router.navigate(metricHref(id));

  return (
    <Screen title={!date || isToday ? '今日' : '每日数据'} subtitle={date ?? undefined}>
      {loading && (
        <>
          <div className="hero-skeleton" aria-hidden="true" />
          <Skeleton count={4} />
        </>
      )}

      {!loading && error && <div className="screen-error">{error}</div>}

      {!loading && !error && !days.length && (
        <div className="screen-empty">
          <p>还没有任何健康数据。</p>
          <Link href="/sync/" className="button button-fill button-round">
            去同步 Garmin 数据
          </Link>
        </div>
      )}

      {!loading && !error && !!days.length && date && (
        <>
          <div className="date-nav">
            <button
              className="date-arrow"
              onClick={() => go(-1)}
              disabled={!canPrev}
              aria-label="前一天"
            >
              ‹
            </button>

            <button className="date-current" onClick={openCalendar}>
              <span className="date-main">
                {isToday ? '今天' : date.slice(5).replace('-', ' / ')}
              </span>
              <span className="date-sub">
                {weekday}
                <span className="date-cal" aria-hidden="true">▾</span>
              </span>
            </button>

            <button
              className="date-arrow"
              onClick={() => go(1)}
              disabled={!canNext}
              aria-label="后一天"
            >
              ›
            </button>
          </div>

          {!today ? (
            <p className="screen-note">这一天没有记录。</p>
          ) : (
            <>
              <RingRow today={today} history={history} />

              {SECTIONS.map((section) => (
                <section className="sec" key={section.title}>
                  <h3 className="sec-title">{section.title}</h3>
                  <div className="mcard-grid">
                    {section.items.map((id) => {
                      const def = METRICS[id];
                      if (!def) return null;
                      return (
                        <MetricCard
                          key={id}
                          metric={def.range}
                          label={def.label}
                          value={def.pick(today)}
                          unit={def.unit}
                          decimals={def.decimals}
                          trend={history.map(def.pick)}
                          detail={
                            id === 'distance' && today.caloriesBurned != null
                              ? `消耗 ${Math.round(today.caloriesBurned).toLocaleString()} kcal`
                              : undefined
                          }
                          onClick={() => open(id)}
                        />
                      );
                    })}
                  </div>
                </section>
              ))}

              <section className="sec">
                <MetricStrip title="身体指标" items={[
                  { metric: 'heartRateVariability', icon: '💓', label: 'HRV', value: today.heartRateVariability, unit: 'ms' },
                  { metric: 'heartRate', icon: '❤️', label: '静息心率', value: today.heartRate, unit: 'bpm' },
                  { metric: 'respirationAvg', icon: '🫁', label: '呼吸', value: today.respirationAvg, unit: '次/分', decimals: 1 },
                  { metric: 'spo2Avg', icon: '🩸', label: '血氧', value: today.spo2Avg, unit: '%' },
                  { metric: 'bodyBatteryHigh', icon: '🔋', label: '身体电量', value: today.bodyBatteryHigh, unit: '峰值' },
                ]} />
              </section>
            </>
          )}
        </>
      )}
    </Screen>
  );
}

export default TodayPage;