import { useState, useRef, useEffect } from 'react';
import { useNavigate, Link } from '@tanstack/react-router';
import { useTrends, useDocument } from '../api/hooks';
import { TrendArrow, ConfidenceBar, LoadingSpinner, Card } from '../components/ui';
import type { TrendSummary } from '../api/hooks';

const WINDOWS = ['intraday', '1d', '7d', '30d', '90d'];

export function TrendsPage() {
  const navigate = useNavigate();
  const [ticker, setTicker] = useState('');
  const [debouncedTicker, setDebouncedTicker] = useState('');
  const [window, setWindow] = useState<string | undefined>(undefined);
  const inputRef = useRef<HTMLInputElement>(null);

  // Debounce ticker search — only query after 300ms of no typing
  useEffect(() => {
    const timer = setTimeout(() => setDebouncedTicker(ticker), 300);
    return () => clearTimeout(timer);
  }, [ticker]);

  const { data, isLoading } = useTrends({ ticker: debouncedTicker || undefined, window, limit: 100 });

  if (isLoading) return <LoadingSpinner />;

  return (
    <div>
      <div className="mb-4 flex items-center justify-between">
        <h1 className="text-xl font-semibold text-gray-100">Trends</h1>
        <div className="flex items-center gap-3">
          <input
            ref={inputRef}
            type="text"
            placeholder="Ticker…"
            value={ticker}
            onChange={(e) => setTicker(e.target.value.toUpperCase())}
            className="w-24 rounded-md border border-surface-700 bg-surface-900 px-2 py-1 text-xs text-gray-200 placeholder-gray-500 focus:border-brand-500 focus:outline-none"
            aria-label="Filter by ticker"
          />
          <div className="inline-flex rounded-md border border-surface-700" role="group" aria-label="Window selector">
            <button
              onClick={() => setWindow(undefined)}
              className={`px-2 py-1 text-xs font-medium first:rounded-l-md last:rounded-r-md ${!window ? 'bg-brand-600 text-white' : 'bg-surface-900 text-gray-400 hover:bg-surface-800'}`}
            >
              All
            </button>
            {WINDOWS.map((w) => (
              <button
                key={w}
                onClick={() => setWindow(w)}
                className={`px-2 py-1 text-xs font-medium last:rounded-r-md ${window === w ? 'bg-brand-600 text-white' : 'bg-surface-900 text-gray-400 hover:bg-surface-800'}`}
              >
                {w}
              </button>
            ))}
          </div>
        </div>
      </div>

      <div className="grid gap-3 sm:grid-cols-2 lg:grid-cols-3">
        {(data ?? []).map((trend) => (
          <TrendCard key={trend.id} trend={trend} onClick={() => navigate({ to: '/trends/$id', params: { id: trend.id } })} />
        ))}
        {data?.length === 0 && <p className="col-span-full text-center text-gray-500">No trends found</p>}
      </div>
    </div>
  );
}

function TrendCard({ trend, onClick }: { trend: TrendSummary; onClick: () => void }) {
  const [expanded, setExpanded] = useState(false);

  return (
    <Card className="cursor-pointer transition-colors hover:border-brand-500/50">
      <div onClick={onClick}>
        <div className="flex items-center justify-between">
          <div className="flex items-center gap-2">
            <span className="font-mono font-semibold text-brand-300">{trend.entity_id}</span>
            <TrendArrow direction={trend.trend_direction} />
          </div>
          <span className="rounded bg-surface-800 px-2 py-0.5 text-xs text-gray-400">{trend.window}</span>
        </div>

        <div className="mt-3 space-y-2">
          <div className="flex items-center justify-between text-xs">
            <span className="text-gray-500">Strength</span>
            <div className="h-1.5 w-24 rounded-full bg-surface-700">
              <div className="h-full rounded-full bg-brand-500" style={{ width: `${trend.trend_strength * 100}%` }} />
            </div>
          </div>
          <div className="flex items-center justify-between text-xs">
            <span className="text-gray-500">Confidence</span>
            <ConfidenceBar value={trend.confidence} />
          </div>
          <div className="flex items-center justify-between text-xs">
            <span className="text-gray-500">Contradiction</span>
            <span className={`font-mono ${trend.contradiction_score > 0.5 ? 'text-yellow-400' : 'text-gray-400'}`}>
              {(trend.contradiction_score * 100).toFixed(0)}%
            </span>
          </div>
        </div>

        {trend.dominant_catalysts && trend.dominant_catalysts.length > 0 && (
          <div className="mt-2 flex flex-wrap gap-1">
            {trend.dominant_catalysts.map((c, i) => (
              <span key={i} className="rounded bg-surface-800 px-1.5 py-0.5 text-[10px] text-gray-400">{c}</span>
            ))}
          </div>
        )}
      </div>

      {/* Expandable evidence preview */}
      {(trend.top_supporting_evidence?.length || trend.top_opposing_evidence?.length) && (
        <button
          onClick={(e) => { e.stopPropagation(); setExpanded(!expanded); }}
          className="mt-2 text-xs text-brand-400 hover:underline"
        >
          {expanded ? 'Hide' : 'Show'} evidence ({(trend.top_supporting_evidence?.length ?? 0) + (trend.top_opposing_evidence?.length ?? 0)})
        </button>
      )}
      {expanded && (
        <div className="mt-2 space-y-1 text-xs">
          {[...new Set(trend.top_supporting_evidence ?? [])].map((e, i) => (
            <EvidenceRef key={i} id={e} direction="supporting" />
          ))}
          {[...new Set(trend.top_opposing_evidence ?? [])].map((e, i) => (
            <EvidenceRef key={i} id={e} direction="opposing" />
          ))}
        </div>
      )}
    </Card>
  );
}

const UUID_RE = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;

function EvidenceRef({ id, direction }: { id: string; direction: 'supporting' | 'opposing' }) {
  const sign = direction === 'supporting' ? '+' : '−';
  const color = direction === 'supporting' ? 'text-green-400' : 'text-red-400';
  const isUuid = UUID_RE.test(id);
  const { data: doc } = useDocument(isUuid ? id : undefined);

  // Pattern IDs like "pattern:META:other:1d" are already readable
  if (id.startsWith('pattern:')) {
    const parts = id.split(':');
    const label = parts.length >= 4
      ? `${parts[1]} ${parts[2]} (${parts[3]})`
      : id.replace('pattern:', '');
    return (
      <div className={`truncate ${color}`}>
        {sign} <span className="rounded bg-surface-800 px-1 py-0.5 text-[10px]">pattern</span> {label}
      </div>
    );
  }

  // UUIDs — show document title if available, otherwise short ID
  if (isUuid) {
    const label = doc?.title ?? `doc:${id.slice(0, 8)}…`;
    return (
      <div className={`truncate ${color}`}>
        {sign}{' '}
        <Link
          to="/documents/$id"
          params={{ id }}
          className="hover:underline"
          onClick={(e) => e.stopPropagation()}
        >
          {label}
        </Link>
      </div>
    );
  }

  // Fallback — show as-is but truncated
  return <div className={`truncate ${color}`}>{sign} {id}</div>;
}