'use client';
import { useState, useEffect, useMemo } from 'react';
import { api } from '@/lib/trpc';

interface HistoryEntry {
  settlementDate: string;
  sharesShort: number | null;
  avgDailyVolume: number | null;
  daysToCover: number;
}

interface ShortInterestData {
  symbol: string;
  sharesShort: number | null;
  sharesShortPriorMonth: number | null;
  sharesPercentSharesOut: number | null;
  shortRatio: number | null;
  shortPercentOfFloat: number | null;
  dateShortInterest: string | null;
  floatShares: number | null;
  sharesOutstanding: number | null;
  daysToCover: number | null;
  settlementDate: string | null;
  history: HistoryEntry[] | null;
  sources: { yfinance: { available: boolean; stale: boolean }; nasdaq: { available: boolean; stale: boolean } };
  stale: boolean;
}

function formatNumber(n: number | null): string {
  if (n === null || n === undefined) return '—';
  if (n >= 1e9) return `${(n / 1e9).toFixed(2)}B`;
  if (n >= 1e6) return `${(n / 1e6).toFixed(1)}M`;
  if (n >= 1e3) return `${(n / 1e3).toFixed(1)}K`;
  return String(n);
}

function formatPct(n: number | null): string {
  if (n === null || n === undefined) return '—';
  return `${(n * 100).toFixed(2)}%`;
}

export function ShortInterestPanel({ symbol }: { symbol: string | null }) {
  const [data, setData] = useState<ShortInterestData | null>(null);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [retryKey, setRetryKey] = useState(0);

  useEffect(() => {
    if (!symbol) return;
    setLoading(true);
    setError(null);
    let cancelled = false;
    api.institutional.shortInterest(symbol).then((res) => {
      if (cancelled) return;
      setData(res);
    }).catch((e: Error) => {
      if (cancelled) return;
      setError(e.message);
    }).finally(() => {
      if (!cancelled) setLoading(false);
    });
    return () => { cancelled = true; };
  }, [symbol, retryKey]);

  if (!symbol) return null;
  if (loading) return <div className="text-xs text-fg-muted py-2">Loading short interest...</div>;
  if (error) return (
    <div className="text-xs text-danger py-2 flex items-center gap-2">
      <span>Short interest: {error}</span>
      <button className="text-up hover:underline" onClick={() => setRetryKey((k) => k + 1)}>Retry</button>
    </div>
  );
  if (!data) return <div className="text-xs text-fg-muted py-2">No short interest data available for {symbol}.</div>;

  const dateLabel = data.settlementDate
    ? `Settlement: ${data.settlementDate}`
    : data.dateShortInterest
      ? `Yahoo: ${data.dateShortInterest}`
      : null;

  const sourceTags = [] as string[];
  if (data.sources.nasdaq.available) sourceTags.push('NASDAQ');
  if (data.sources.yfinance.available) sourceTags.push('Yahoo');
  const sourceLabel = sourceTags.length ? sourceTags.join(' + ') : '—';

  const historySlice = data.history ? data.history.slice(0, 6) : [];

  return (
    <div className="rounded-lg bg-surface-sunken border border-line p-4 space-y-3">
      <h4 className="text-sm font-semibold text-fg">Short Interest</h4>
      {dateLabel && (
        <p className="text-[10px] text-fg-muted">{dateLabel}{data.stale ? ' — stale' : ''} ({sourceLabel})</p>
      )}
      {data.sharesShort !== null && (
        <dl className="grid grid-cols-2 gap-x-6 gap-y-1 text-sm">
          <div className="flex justify-between"><dt className="text-fg-muted">Shares Short</dt><dd className="text-fg font-mono">{formatNumber(data.sharesShort)}</dd></div>
          <div className="flex justify-between"><dt className="text-fg-muted">% of Float</dt><dd className="text-fg font-mono">{formatPct(data.sharesPercentSharesOut)}</dd></div>
          <div className="flex justify-between"><dt className="text-fg-muted">Short Ratio</dt><dd className="text-fg font-mono">{data.shortRatio !== null ? `${data.shortRatio.toFixed(1)}d` : '—'}</dd></div>
          {data.daysToCover !== null && (
            <div className="flex justify-between"><dt className="text-fg-muted">Days to Cover</dt><dd className="text-fg font-mono">{data.daysToCover.toFixed(2)}d</dd></div>
          )}
          {data.sharesShortPriorMonth !== null && data.floatShares ? (
            <div className="flex justify-between"><dt className="text-fg-muted">% Float (prior)</dt><dd className="text-fg font-mono">{formatPct(data.sharesShortPriorMonth / data.floatShares)}</dd></div>
          ) : null}
          {data.floatShares !== null && (
            <div className="flex justify-between"><dt className="text-fg-muted">Float Shares</dt><dd className="text-fg font-mono">{formatNumber(data.floatShares)}</dd></div>
          )}
          {data.sharesOutstanding !== null && (
            <div className="flex justify-between"><dt className="text-fg-muted">Shares Out</dt><dd className="text-fg font-mono">{formatNumber(data.sharesOutstanding)}</dd></div>
          )}
        </dl>
      )}
      {historySlice.length > 0 && (
        <div className="mt-2">
          <p className="text-[10px] text-fg-muted mb-1">6-month history (NASDAQ source)</p>
          <div className="overflow-x-auto">
            <table className="w-full text-[10px] text-fg-muted">
              <thead><tr><th className="text-left py-0.5">Date</th><th className="text-right py-0.5">Short</th><th className="text-right py-0.5">Days</th></tr></thead>
              <tbody>
                {historySlice.map((h, i) => (
                  <tr key={i} className="border-b border-line/40">
                    <td className="py-0.5">{h.settlementDate}</td>
                    <td className="text-right font-mono">{formatNumber(h.sharesShort)}</td>
                    <td className="text-right font-mono">{h.daysToCover.toFixed(2)}</td>
                  </tr>
                ))}
              </tbody>
            </table>
          </div>
        </div>
      )}
      <p className="text-[10px] text-fg-muted mt-1">
        Reconciled from NASDAQ (days-to-cover, history) + Yahoo Finance (all tickers). Educational display only.
      </p>
    </div>
  );
}