'use client';
import { useState, useEffect } from 'react';

const GREEN = '#16A34A';
const RED = '#DC2626';
const BLUE = '#2563EB';

export default function PaperDashboard() {
  const [data, setData] = useState(null);
  const [trades, setTrades] = useState({});
  const [loading, setLoading] = useState(true);
  const [activeStrat, setActiveStrat] = useState(null);
  const [resetting, setResetting] = useState(false);

  useEffect(() => {
    const fetchState = async () => {
      try {
        const res = await fetch('/api/state');
        const json = await res.json();
        setData(json);
        if (!activeStrat && json.strategies?.length) {
          setActiveStrat(json.strategies[0].name);
        }
        setLoading(false);
      } catch (e) {
        console.error('State fetch error:', e);
      }
    };

    fetchState();
    const interval = setInterval(fetchState, 2000);
    return () => clearInterval(interval);
  }, [activeStrat]);

  useEffect(() => {
    if (!activeStrat) return;

    const fetchTrades = async () => {
      try {
        const res = await fetch(`/api/trades?strategy=${encodeURIComponent(activeStrat)}`);
        const json = await res.json();
        setTrades(prev => ({ ...prev, [activeStrat]: json.trades || [] }));
      } catch (e) {
        console.error('Trades fetch error:', e);
      }
    };

    fetchTrades();
    const interval = setInterval(fetchTrades, 10000);
    return () => clearInterval(interval);
  }, [activeStrat]);

  const handleReset = async () => {
    if (!confirm('Reset ALL paper trading data? This clears all history, stats, and open positions for every strategy.')) return;
    setResetting(true);
    try {
      await fetch('/api/reset', { method: 'POST' });
      setTrades({});
    } catch (e) {
      console.error('Reset error:', e);
    }
    setTimeout(() => setResetting(false), 2000);
  };

  if (loading) {
    return (
      <div className="min-h-screen bg-gray-50 flex items-center justify-center">
        <div className="text-green-600 text-lg animate-pulse">Loading Paper Trading...</div>
      </div>
    );
  }

  const market = data?.market;
  const strategies = data?.strategies || [];
  const paperByStrategy = data?.paperByStrategy || {};
  const activeStratData = strategies.find(s => s.name === activeStrat);
  const activeStats = paperByStrategy[activeStrat];
  const activeTrades = trades[activeStrat] || [];

  return (
    <div className="min-h-screen bg-gray-50 text-gray-900 font-sans pb-20">
      <header className="sticky top-0 z-50 bg-white/95 backdrop-blur border-b border-gray-200 px-4 py-3 shadow-sm">
        <div className="flex items-center justify-between max-w-lg mx-auto">
          <div className="flex items-center gap-2">
            <h1 className="text-lg font-bold" style={{ color: GREEN }}>Kalbot</h1>
            <span className="text-xs bg-amber-100 text-amber-700 px-2 py-0.5 rounded-full font-medium">PAPER</span>
          </div>
          <div className="flex items-center gap-3">
            <button
              onClick={handleReset}
              disabled={resetting}
              className="text-[10px] px-2 py-1 rounded bg-red-50 text-red-600 border border-red-200 hover:bg-red-100 transition-colors disabled:opacity-50 font-medium"
            >
              {resetting ? 'Resetting...' : '🗑 Reset All'}
            </button>
            <div className="flex items-center gap-1.5">
              <span className={`w-2 h-2 rounded-full ${data?.lastUpdate ? 'bg-green-500 animate-pulse' : 'bg-red-500'}`} />
              <span className="text-xs text-gray-500">
                {data?.lastUpdate ? 'Live' : 'Offline'}
              </span>
            </div>
          </div>
        </div>
      </header>

      <main className="max-w-lg mx-auto px-4 pt-4 space-y-4">
        <MarketCardCompact market={market} />

        <div className="flex gap-1 bg-gray-100 rounded-lg p-1 overflow-x-auto">
          {strategies.map(s => (
            <button
              key={s.name}
              onClick={() => setActiveStrat(s.name)}
              className={`flex-shrink-0 py-2 px-3 rounded-md text-xs font-medium transition-all whitespace-nowrap ${
                activeStrat === s.name
                  ? 'bg-white text-gray-900 shadow-sm'
                  : 'text-gray-500 hover:text-gray-700'
              }`}
            >
              <span className={`inline-block w-1.5 h-1.5 rounded-full mr-1.5 ${
                s.enabled && !s.paused ? 'bg-green-500' : 'bg-red-500'
              }`} />
              {s.name}
            </button>
          ))}
        </div>

        {activeStrat && activeStratData && (
          <StrategyDetailView
            strategy={activeStratData}
            stats={activeStats}
            trades={activeTrades}
          />
        )}

        <AllStrategiesOverview paperByStrategy={paperByStrategy} strategies={strategies} />
      </main>

      <div className="fixed bottom-0 left-0 right-0 bg-white/95 backdrop-blur border-t border-gray-200 py-2 px-4">
        <div className="max-w-lg mx-auto flex justify-between text-xs text-gray-400">
          <span>Worker: {formatUptime(data?.workerUptime)}</span>
          <span>{data?.lastUpdate ? new Date(data.lastUpdate).toLocaleTimeString() : 'never'}</span>
        </div>
      </div>
    </div>
  );
}

function MarketCardCompact({ market }) {
  if (!market) {
    return (
      <div className="bg-white rounded-xl p-4 border border-gray-200 shadow-sm">
        <p className="text-gray-400 text-center text-sm">No active market — waiting...</p>
      </div>
    );
  }

  const timeLeft = market.closeTime ? getTimeLeft(market.closeTime) : null;

  return (
    <div className="bg-white rounded-xl p-4 border border-gray-200 shadow-sm">
      <div className="flex items-center justify-between mb-3">
        <div>
          <h2 className="font-bold text-sm text-gray-900">BTC Up or Down</h2>
          <p className="text-[10px] text-gray-400">15 min</p>
        </div>
        <div className="flex items-center gap-2">
          {timeLeft && (
            <span className="text-[10px] bg-gray-100 px-2 py-0.5 rounded-full text-gray-600">⏱ {timeLeft}</span>
          )}
          <span className="text-lg">₿</span>
        </div>
      </div>
      <div className="flex items-center gap-3">
        <div className="flex-1">
          <div className="flex justify-between text-xs mb-1">
            <span className="text-gray-600">Up</span>
            <span style={{ color: GREEN }} className="font-medium">{market.yesPct}%</span>
          </div>
          <div className="w-full bg-gray-100 rounded-full h-1.5">
            <div className="h-1.5 rounded-full transition-all duration-500" style={{ width: `${market.yesPct}%`, backgroundColor: GREEN }} />
          </div>
        </div>
        <div className="flex-1">
          <div className="flex justify-between text-xs mb-1">
            <span className="text-gray-600">Down</span>
            <span style={{ color: BLUE }} className="font-medium">{market.noPct}%</span>
          </div>
          <div className="w-full bg-gray-100 rounded-full h-1.5">
            <div className="h-1.5 rounded-full transition-all duration-500" style={{ width: `${market.noPct}%`, backgroundColor: BLUE }} />
          </div>
        </div>
      </div>
      <div className="flex justify-between text-[10px] text-gray-400 mt-2">
        <span>${(market.volume || 0).toLocaleString()} vol</span>
        <span className="font-mono">{market.ticker}</span>
      </div>
    </div>
  );
}

function StrategyDetailView({ strategy, stats, trades }) {
  const s = stats || { balance: 1000, totalPnL: 0, wins: 0, losses: 0, winRate: 0, totalTrades: 0, openPositions: [] };
  const pnlColor = s.totalPnL >= 0 ? GREEN : RED;

  return (
    <div className="space-y-3">
      <div className="bg-white rounded-xl p-4 border border-gray-200 shadow-sm">
        <div className="flex items-center justify-between mb-3">
          <div className="flex items-center gap-2">
            <span className={`w-2 h-2 rounded-full ${strategy.enabled && !strategy.paused ? 'bg-green-500' : 'bg-red-500'}`} />
            <h3 className="font-bold text-sm capitalize text-gray-900">{strategy.name}</h3>
          </div>
          <span className="text-[10px] px-2 py-0.5 rounded-full bg-amber-100 text-amber-700 font-medium">{strategy.mode}</span>
        </div>

        <div className="grid grid-cols-4 gap-2 mb-3">
          <StatBox label="Balance" value={`$${s.balance}`} />
          <StatBox label="PnL" value={`${s.totalPnL >= 0 ? '+' : ''}$${s.totalPnL}`} color={pnlColor} />
          <StatBox label="Win Rate" value={`${s.winRate}%`} color={s.winRate >= 50 ? GREEN : RED} />
          <StatBox label="Trades" value={s.totalTrades} />
        </div>

        <div className="space-y-1 text-xs text-gray-500 border-t border-gray-100 pt-3">
          {strategy.config && Object.entries(strategy.config).map(([k, v]) => (
            <div key={k} className="flex justify-between">
              <span>{k}</span>
              <span className="text-gray-700">{typeof v === 'number' ? v : String(v)}</span>
            </div>
          ))}
          {strategy.consecutiveLosses !== undefined && (
            <div className="flex justify-between mt-1 pt-1 border-t border-gray-100">
              <span>Consecutive Losses</span>
              <span className={strategy.consecutiveLosses > 0 ? 'text-red-600' : 'text-gray-700'}>
                {strategy.consecutiveLosses}
              </span>
            </div>
          )}
          {strategy.currentBetSize !== undefined && (
            <div className="flex justify-between">
              <span>Next Bet</span>
              <span className="text-gray-700">${strategy.currentBetSize}</span>
            </div>
          )}
          {strategy.round !== undefined && (
            <div className="flex justify-between">
              <span>Cycle Round</span>
              <span className="text-gray-700">{strategy.round}/{strategy.maxRounds}</span>
            </div>
          )}
          {strategy.cycleWins !== undefined && (
            <div className="flex justify-between">
              <span>Cycles Won/Lost</span>
              <span className="text-gray-700">{strategy.cycleWins}W / {strategy.cycleLosses}L</span>
            </div>
          )}
          {strategy.cycleWinRate !== undefined && (
            <div className="flex justify-between">
              <span>Cycle Win Rate</span>
              <span className={strategy.cycleWinRate >= 50 ? 'text-green-600' : 'text-red-600'}>
                {strategy.cycleWinRate}%
              </span>
            </div>
          )}
          {strategy.paused && (
            <div className="text-red-600 font-medium mt-1">⚠️ PAUSED — max losses reached</div>
          )}
        </div>
      </div>

      {s.openPositions.length > 0 && (
        <div>
          <h4 className="text-[10px] text-gray-400 uppercase tracking-wider mb-2 font-bold">Open Positions ({s.openPositions.length})</h4>
          {s.openPositions.map((t, i) => <TradeRow key={i} trade={t} isOpen />)}
        </div>
      )}

      <div>
        <h4 className="text-[10px] text-gray-400 uppercase tracking-wider mb-2 font-bold">
          Trade History ({trades.length})
        </h4>
        {trades.length === 0 ? (
          <p className="text-gray-400 text-xs text-center py-4">No settled trades yet.</p>
        ) : (
          trades.map((t, i) => <TradeRow key={i} trade={t} />)
        )}
      </div>
    </div>
  );
}

function AllStrategiesOverview({ paperByStrategy, strategies }) {
  const entries = strategies.map(s => ({
    name: s.name,
    stats: paperByStrategy[s.name] || { balance: 1000, totalPnL: 0, winRate: 0, totalTrades: 0 },
    enabled: s.enabled,
    paused: s.paused
  }));

  if (!entries.length) return null;

  entries.sort((a, b) => b.stats.totalPnL - a.stats.totalPnL);

  return (
    <div className="bg-white rounded-xl border border-gray-200 overflow-hidden shadow-sm">
      <div className="px-4 py-3 border-b border-gray-100">
        <h3 className="text-xs text-gray-500 uppercase tracking-wider font-bold">📊 Strategy Leaderboard</h3>
      </div>
      {entries.map((e, i) => {
        const pnlColor = e.stats.totalPnL >= 0 ? GREEN : RED;
        return (
          <div key={e.name} className={`flex items-center justify-between px-4 py-3 ${i < entries.length - 1 ? 'border-b border-gray-100' : ''}`}>
            <div className="flex items-center gap-2">
              <span className="text-xs text-gray-400 w-4">{i + 1}.</span>
              <span className={`w-1.5 h-1.5 rounded-full ${e.enabled && !e.paused ? 'bg-green-500' : 'bg-red-500'}`} />
              <span className="text-sm font-medium capitalize text-gray-800">{e.name}</span>
            </div>
            <div className="flex items-center gap-4 text-xs">
              <span className="text-gray-400">{e.stats.totalTrades} trades</span>
              <span className="text-gray-400">{e.stats.winRate}% wr</span>
              <span className="font-bold" style={{ color: pnlColor }}>
                {e.stats.totalPnL >= 0 ? '+' : ''}${e.stats.totalPnL}
              </span>
            </div>
          </div>
        );
      })}
    </div>
  );
}

function StatBox({ label, value, color }) {
  return (
    <div className="bg-gray-50 rounded-lg p-2 border border-gray-100 text-center">
      <p className="text-[9px] text-gray-400 uppercase tracking-wider">{label}</p>
      <p className="text-xs font-bold mt-0.5" style={color ? { color } : { color: '#111827' }}>{value}</p>
    </div>
  );
}

function TradeRow({ trade, isOpen }) {
  // Fix: Check side vs result for actual win condition, not strictly PNL > 0
  const won = trade.result && trade.side.toLowerCase() === trade.result.toLowerCase();
  const isNeutral = trade.result === 'cancelled' || trade.result === 'expired';
  
  const pnlColor = trade.pnl == null ? 'text-gray-400' : trade.pnl > 0 ? 'text-green-600' : trade.pnl < 0 ? 'text-red-600' : 'text-gray-600';

  return (
    <div className="bg-white rounded-lg p-3 border border-gray-200 mb-2 shadow-sm">
      <div className="flex items-center justify-between">
        <div className="flex items-center gap-2">
          {isOpen ? (
            <span className="w-2 h-2 rounded-full bg-amber-400 animate-pulse" />
          ) : (
            <span>{isNeutral ? '➖' : won ? '✅' : '❌'}</span>
          )}
          <span className="text-sm font-medium capitalize text-gray-900">{trade.side}</span>
          <span className="text-xs text-gray-400">@ {trade.price}¢</span>
          <span className="text-[10px] text-gray-400">${trade.size}</span>
        </div>
        <span className={`text-sm font-bold ${pnlColor}`}>
          {trade.pnl != null ? `${trade.pnl >= 0 ? '+' : ''}$${trade.pnl}` : 'open'}
        </span>
      </div>
      <div className="flex justify-between mt-1">
        <span className="text-[10px] text-gray-400">{trade.reason}</span>
      </div>
      <div className="flex justify-between items-center mt-0.5">
        {trade.result && !isOpen && (
          <span className="text-[10px] text-gray-400">Result: {trade.result}</span>
        )}
        {!trade.result && <span />}
        <span className="text-[10px] text-gray-400">
          {trade.entryTime ? new Date(trade.entryTime).toLocaleTimeString() : ''}
        </span>
      </div>
    </div>
  );
}

function getTimeLeft(closeTime) {
  const diff = new Date(closeTime).getTime() - Date.now();
  if (diff <= 0) return 'Closing...';
  const mins = Math.floor(diff / 60000);
  const secs = Math.floor((diff % 60000) / 1000);
  return `${mins}:${secs.toString().padStart(2, '0')}`;
}

function formatUptime(seconds) {
  if (!seconds) return '0s';
  const h = Math.floor(seconds / 3600);
  const m = Math.floor((seconds % 3600) / 60);
  const s = Math.floor(seconds % 60);
  if (h > 0) return `${h}h ${m}m`;
  if (m > 0) return `${m}m ${s}s`;
  return `${s}s`;
}