import { useEffect, useState } from 'react';
import { api, type SpaceStats, type StatsLeader } from '../../../api/client';
import { Avatar } from '../../ui/Avatar';
import { useT, type TranslationKey } from '../../../i18n';

interface StatsPanelProps {
  spaceId: string;
}

const RANGES: { days: number; key: TranslationKey }[] = [
  { days: 7, key: 'stats.range.7' },
  { days: 30, key: 'stats.range.30' },
  { days: 365, key: 'stats.range.365' },
];

function Leaderboard({
  title,
  rows,
  format,
}: {
  title: string;
  rows: StatsLeader[];
  format: (value: number) => string;
}) {
  // The bar is relative to the leader, not to the total: with five people the
  // share of a total is tiny and every bar looks the same.
  const max = rows.length > 0 ? Math.max(...rows.map((r) => r.value)) : 0;

  return (
    <div>
      <h3 className="text-[11px] uppercase tracking-wide font-semibold text-txt-tertiary mb-2">{title}</h3>
      <ul className="space-y-1.5">
        {rows.map((row) => (
          <li key={row.userId} className="flex items-center gap-3">
            <Avatar src={row.avatar} name={row.displayName ?? row.username} size={26} userId={row.userId} />
            <div className="min-w-0 flex-1">
              <div className="flex items-baseline justify-between gap-2">
                <span className="text-[13px] text-txt-secondary truncate">
                  {row.displayName ?? row.username}
                </span>
                <span className="text-[12px] text-txt-tertiary tabular-nums flex-shrink-0">
                  {format(row.value)}
                </span>
              </div>
              <div className="h-[3px] rounded-full bg-interactive-muted mt-1 overflow-hidden">
                <div
                  className="h-full bg-accent-primary rounded-full"
                  style={{ width: max > 0 ? `${(row.value / max) * 100}%` : '0%' }}
                />
              </div>
            </div>
          </li>
        ))}
      </ul>
    </div>
  );
}

export function StatsPanel({ spaceId }: StatsPanelProps) {
  const t = useT();
  const [days, setDays] = useState(30);
  const [stats, setStats] = useState<SpaceStats | null>(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    let cancelled = false;
    setLoading(true);
    api.stats.space(spaceId, days)
      .then((data) => { if (!cancelled) setStats(data); })
      .catch(() => { if (!cancelled) setStats(null); })
      .finally(() => { if (!cancelled) setLoading(false); });
    return () => { cancelled = true; };
  }, [spaceId, days]);

  const formatDuration = (ms: number) => {
    const minutes = Math.round(ms / 60000);
    const hours = Math.floor(minutes / 60);
    return hours > 0
      ? t('stats.hours', { hours, minutes: minutes % 60 })
      : t('stats.minutes', { minutes });
  };

  const isEmpty = !stats || (stats.voice.length === 0 && stats.messages.length === 0);

  return (
    <div className="max-w-2xl">
      <h2 className="text-lg font-semibold text-txt-primary mb-4">{t('stats.title')}</h2>

      <div className="flex gap-1.5 mb-5">
        {RANGES.map((range) => (
          <button
            key={range.days}
            type="button"
            onClick={() => setDays(range.days)}
            className={`px-2.5 py-1 rounded-full text-[12px] font-medium transition-colors ${
              days === range.days
                ? 'bg-accent-primary text-white'
                : 'bg-surface-elevated text-txt-secondary hover:text-txt-primary'
            }`}
          >
            {t(range.key)}
          </button>
        ))}
      </div>

      {loading ? (
        <div className="space-y-2">
          {Array.from({ length: 4 }).map((_, i) => (
            <div key={i} className="h-10 rounded-lg bg-surface-elevated animate-pulse" />
          ))}
        </div>
      ) : isEmpty ? (
        <p className="text-[13px] text-txt-tertiary">{t('stats.empty')}</p>
      ) : (
        <div className="space-y-6">
          {stats.voice.length > 0 && (
            <div>
              <Leaderboard title={t('stats.voice.title')} rows={stats.voice} format={formatDuration} />
              <p className="text-[11px] text-txt-tertiary mt-2">
                {t('stats.total.voice', { value: formatDuration(stats.totals.voiceMs) })}
              </p>
            </div>
          )}
          {stats.messages.length > 0 && (
            <div>
              <Leaderboard
                title={t('stats.messages.title')}
                rows={stats.messages}
                format={(value) => String(value)}
              />
              <p className="text-[11px] text-txt-tertiary mt-2">
                {t('stats.total.messages', { value: stats.totals.messages })}
              </p>
            </div>
          )}
        </div>
      )}

      <p className="text-[11px] text-txt-tertiary mt-6">{t('stats.note')}</p>
    </div>
  );
}