import { useMemo } from 'react';
import { Link } from 'react-router-dom';
import { useActivation } from '../hooks/useActivation';
import { useTrades } from '../hooks/useTrades';
import { useWatchlist } from '../hooks/useWatchlist';
import { usePerformance } from '../hooks/usePerformance';
import { useMarketRegime } from '../hooks/useMarketRegime';
import { regimeColor, regimeDot, regimeHeadline } from '../lib/regime';
import { Callout } from '../components/ui/Callout';
import { Section } from '../components/ui/Section';
import { OpenTradesPanel } from '../components/dashboard/OpenTradesPanel';
import { SkeletonCard, SkeletonTable } from '../components/ui/Skeleton';
import { formatPrice } from '../lib/format';
import { recommendationActionLabel } from '../lib/recommendation';
import { qualifiesSetup, activationSummary, primaryTargetProbability, expectedValueR } from '../lib/qualification';
import type { TradeSetup } from '../lib/types';

function fmtR(value: number | null): string {
  if (value === null) return '—';
  return `${value > 0 ? '+' : ''}${value.toFixed(2)}R`;
}

function rColor(value: number | null): string {
  if (value === null) return 'text-gray-400';
  if (value > 0) return 'text-emerald-400';
  if (value < 0) return 'text-red-400';
  return 'text-gray-300';
}

function Metric({ label, value, sub, valueClass = 'text-gray-100' }: {
  label: string;
  value: string;
  sub?: string;
  valueClass?: string;
}) {
  return (
    <div className="glass glass-hover p-5">
      <p className="section-index">{label}</p>
      <p className={`num mt-2 text-3xl font-semibold ${valueClass}`}>{value}</p>
      {sub && <p className="mt-1 text-xs text-gray-500">{sub}</p>}
    </div>
  );
}

function DirectionTag({ direction }: { direction: string }) {
  const isLong = direction === 'long';
  return (
    <span className={`num inline-block rounded px-1.5 py-0.5 text-[10px] font-semibold uppercase tracking-wider ${
      isLong ? 'bg-emerald-500/15 text-emerald-400' : 'bg-red-500/15 text-red-400'
    }`}>
      {direction}
    </span>
  );
}

export default function DashboardPage() {
  const trades = useTrades();
  const watchlist = useWatchlist();
  const activation = useActivation();
  const performance = usePerformance();
  const regime = useMarketRegime();

  const qualifiedSetups = useMemo(
    () =>
      activation.data
        ? (trades.data ?? []).filter((t) => qualifiesSetup(t, activation.data!))
        : [],
    [trades.data, activation.data],
  );

  // Show qualified setups first; fall back to the full list when none qualify.
  // Rank by expected value (R) so the best opportunity sits at the top.
  const showingQualified = qualifiedSetups.length > 0;
  const topSetups: TradeSetup[] = useMemo(() => {
    const pool = showingQualified ? qualifiedSetups : trades.data ?? [];
    return [...pool]
      .sort((a, b) => (expectedValueR(b) ?? -Infinity) - (expectedValueR(a) ?? -Infinity))
      .slice(0, 5);
  }, [showingQualified, qualifiedSetups, trades.data]);

  const topWatchlist = useMemo(
    () =>
      [...(watchlist.data ?? [])]
        .sort((a, b) => (b.composite_score ?? -1) - (a.composite_score ?? -1))
        .slice(0, 10),
    [watchlist.data],
  );

  const today = new Date().toLocaleDateString('en-US', {
    weekday: 'long', month: 'long', day: 'numeric',
  });

  const stats = performance.data?.overall;

  return (
    <div className="space-y-8 animate-slide-up">
      {/* Hero */}
      <div>
        <p className="num text-xs uppercase tracking-[0.22em] text-gray-500">{today}</p>
        <h1 className="font-display mt-1 text-4xl font-bold tracking-tight text-gray-100">
          Market overview
        </h1>
      </div>

      {/* Market regime banner */}
      {regime.data && (
        <div className="glass-sm flex items-center gap-2.5 px-4 py-2.5">
          <span className={`inline-block h-2 w-2 rounded-full ${regimeDot(regime.data.label)}`} />
          <span className="text-sm text-gray-400">Market regime:</span>
          <span className={`text-sm font-semibold ${regimeColor(regime.data.label)}`}>
            {regimeHeadline(regime.data)}
          </span>
          {regime.data.label === 'bearish' && (
            <span className="text-xs text-gray-500">— be cautious on new longs</span>
          )}
          {regime.data.label === 'bullish' && (
            <span className="text-xs text-gray-500">— shorts are counter-trend</span>
          )}
        </div>
      )}

      {/* Metric strip */}
      {(trades.isLoading || performance.isLoading) ? (
        <div className="grid gap-4 sm:grid-cols-2 lg:grid-cols-4">
          <SkeletonCard /><SkeletonCard /><SkeletonCard /><SkeletonCard />
        </div>
      ) : (
        <div className="grid gap-4 sm:grid-cols-2 lg:grid-cols-4">
          <Metric
            label="Live Setups"
            value={String(trades.data?.length ?? 0)}
            sub="latest per ticker & direction"
          />
          <Metric
            label="Qualified"
            value={String(qualifiedSetups.length)}
            sub={activation.data ? activationSummary(activation.data) : 'clears the activation gate'}
            valueClass={qualifiedSetups.length > 0 ? 'text-blue-300' : 'text-gray-100'}
          />
          <Metric
            label="Hit Rate"
            value={stats?.hit_rate != null ? `${stats.hit_rate.toFixed(1)}%` : '—'}
            sub={stats ? `${stats.wins}W / ${stats.losses}L evaluated` : 'no outcomes yet'}
          />
          <Metric
            label="Expectancy"
            value={fmtR(stats?.avg_r ?? null)}
            valueClass={rColor(stats?.avg_r ?? null)}
            sub="average R per trade"
          />
        </div>
      )}

      {/* Open paper trades */}
      <OpenTradesPanel />

      <div className="grid gap-8 xl:grid-cols-5">
        {/* Top setups */}
        <div className="xl:col-span-3">
          <Section
            title="Top Setups"
            hint={showingQualified ? 'ranked by expected value' : 'none qualified — showing all'}
          >
            {trades.isLoading && <SkeletonTable rows={5} cols={5} />}
            {trades.isError && <Callout variant="error">Failed to load setups</Callout>}
            {trades.data && topSetups.length === 0 && (
              <Callout variant="empty">No active setups. Run the scanner from the Signals page.</Callout>
            )}
            {topSetups.length > 0 && (
              <div className="glass overflow-x-auto">
                <table className="w-full text-sm">
                  <thead>
                    <tr className="border-b border-white/[0.06] text-left text-xs uppercase tracking-wider text-gray-500">
                      <th className="px-4 py-3">Ticker</th>
                      <th className="px-4 py-3">Dir</th>
                      <th className="px-4 py-3 text-right">Entry</th>
                      <th className="px-4 py-3 text-right">R:R</th>
                      <th className="px-4 py-3 text-right">Target&nbsp;Prob</th>
                      <th className="px-4 py-3 text-right">Exp.&nbsp;Value</th>
                      <th className="hidden px-4 py-3 md:table-cell">Action</th>
                    </tr>
                  </thead>
                  <tbody>
                    {topSetups.map((setup, i) => {
                      const ev = expectedValueR(setup);
                      const isTopPick = i === 0;
                      return (
                        <tr
                          key={setup.id}
                          className={`border-b border-white/[0.04] transition-colors duration-150 hover:bg-white/[0.03] ${
                            isTopPick ? 'bg-blue-500/[0.06]' : ''
                          }`}
                        >
                          <td className="px-4 py-3">
                            <div className="flex items-center gap-2">
                              <Link to={`/ticker/${setup.symbol}`} className="font-medium text-blue-300 hover:text-blue-200 transition-colors">
                                {setup.symbol}
                              </Link>
                              {isTopPick && (
                                <span className="rounded bg-blue-500/20 px-1.5 py-0.5 text-[9px] font-semibold uppercase tracking-wider text-blue-300">
                                  Top pick
                                </span>
                              )}
                            </div>
                          </td>
                          <td className="px-4 py-3"><DirectionTag direction={setup.direction} /></td>
                          <td className="num px-4 py-3 text-right text-gray-200">{formatPrice(setup.entry_price)}</td>
                          <td className="num px-4 py-3 text-right text-gray-200">{setup.rr_ratio.toFixed(1)}:1</td>
                          <td className="num px-4 py-3 text-right text-gray-200">
                            {(() => {
                              const p = primaryTargetProbability(setup);
                              return p != null ? `${Math.round(p)}%` : '—';
                            })()}
                          </td>
                          <td className={`num px-4 py-3 text-right font-semibold ${rColor(ev)}`}>
                            {fmtR(ev)}
                          </td>
                          <td className="hidden px-4 py-3 text-xs text-gray-400 md:table-cell">
                            {recommendationActionLabel(setup.recommended_action)}
                          </td>
                        </tr>
                      );
                    })}
                  </tbody>
                </table>
                <div className="flex items-center justify-between border-t border-white/[0.04] px-4 py-2.5">
                  <span className="text-[11px] text-gray-500">
                    Exp. Value = probability-weighted payoff per unit of risk
                  </span>
                  <Link to="/signals" className="text-xs font-medium text-blue-300 hover:text-blue-200 transition-colors">
                    All setups →
                  </Link>
                </div>
              </div>
            )}
          </Section>
        </div>

        {/* My watchlist */}
        <div className="xl:col-span-2">
          <Section title="My Watchlist" hint="today's move">
            {watchlist.isLoading && <SkeletonTable rows={6} cols={3} />}
            {watchlist.isError && <Callout variant="error">Failed to load watchlist</Callout>}
            {watchlist.data && topWatchlist.length === 0 && (
              <Callout variant="empty">
                Your watchlist is empty — open any ticker and tap “☆ Add to watchlist”.
              </Callout>
            )}
            {topWatchlist.length > 0 && (
              <div className="glass overflow-hidden">
                <ul className="divide-y divide-white/[0.04]">
                  {topWatchlist.map((entry) => (
                    <li key={entry.symbol}>
                      <Link
                        to={`/ticker/${entry.symbol}`}
                        className="flex items-center justify-between px-4 py-3 transition-colors duration-150 hover:bg-white/[0.03]"
                      >
                        <span className="flex items-baseline gap-2">
                          <span className="font-medium text-gray-200">{entry.symbol}</span>
                          {entry.composite_score != null && (
                            <span className="num text-[10px] text-gray-500">score {entry.composite_score.toFixed(0)}</span>
                          )}
                        </span>
                        <span className="flex items-baseline gap-3">
                          <span className="num text-sm text-gray-200">
                            {entry.last_close != null ? formatPrice(entry.last_close) : '—'}
                          </span>
                          <span className={`num w-16 text-right text-sm font-semibold ${rColor(entry.change_pct)}`}>
                            {entry.change_pct != null
                              ? `${entry.change_pct >= 0 ? '+' : ''}${entry.change_pct.toFixed(2)}%`
                              : '—'}
                          </span>
                        </span>
                      </Link>
                    </li>
                  ))}
                </ul>
                <div className="border-t border-white/[0.04] px-4 py-2.5">
                  <Link to="/market" className="text-xs font-medium text-blue-300 hover:text-blue-200 transition-colors">
                    Full watchlist →
                  </Link>
                </div>
              </div>
            )}
          </Section>
        </div>
      </div>
    </div>
  );
}