'use client';

import React, { useState, useEffect } from 'react';
import { Calculator, TrendingUp, ShieldCheck, Sparkles } from 'lucide-react';

export default function BudgetSimulator() {
  const [spend, setSpend] = useState<number>(1000);
  const [channel, setChannel] = useState<string>('meta');
  const [simulation, setSimulation] = useState<any>(null);
  const [loading, setLoading] = useState<boolean>(false);

  useEffect(() => {
    const timer = setTimeout(() => {
      fetchSimulation(spend, channel);
    }, 200);
    return () => clearTimeout(timer);
  }, [spend, channel]);

  async function fetchSimulation(amount: number, ch: string) {
    setLoading(true);
    try {
      const res = await fetch('/api/simulate', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ spend: amount, channel: ch })
      });
      if (res.ok) {
        const data = await res.json();
        setSimulation(data);
      }
    } catch (e) {
      console.error('Error simulating budget:', e);
    } finally {
      setLoading(false);
    }
  }

  const p10 = simulation?.conservative_p10 || {};
  const p50 = simulation?.expected_p50 || {};
  const p90 = simulation?.optimistic_p90 || {};
  const baseline = simulation?.baseline || {};

  return (
    <div className="bg-[#111827] border border-gray-800 rounded-xl p-6 space-y-6">
      <div className="flex flex-col md:flex-row md:items-center justify-between gap-4 border-b border-gray-800 pb-4">
        <div>
          <div className="flex items-center gap-2">
            <Calculator className="w-5 h-5 text-brand-500" />
            <h3 className="text-lg font-bold text-white">Simulador Determinista "¿Qué pasa si...?"</h3>
          </div>
          <p className="text-xs text-gray-400 mt-1">
            Proyección matemática basada en el histórico de CPL, tasa de cierre y ticket medio en Supabase.
          </p>
        </div>
        <div className="flex items-center gap-2">
          {['meta', 'google', 'tiktok', 'blended'].map((ch) => (
            <button
              key={ch}
              onClick={() => setChannel(ch)}
              className={`px-3 py-1 rounded-lg text-xs font-semibold uppercase transition-all ${
                channel === ch
                  ? 'bg-brand-600 text-white shadow-lg shadow-brand-500/20'
                  : 'bg-gray-800 text-gray-400 hover:text-white'
              }`}
            >
              {ch}
            </button>
          ))}
        </div>
      </div>

      {/* Control del presupuesto */}
      <div className="space-y-2">
        <div className="flex justify-between items-center">
          <label className="text-xs font-medium text-gray-300">
            Inversión Adicional Proyectada
          </label>
          <span className="text-lg font-extrabold text-brand-400">
            {spend.toLocaleString('es-ES')} €
          </span>
        </div>
        <input
          type="range"
          min="200"
          max="10000"
          step="100"
          value={spend}
          onChange={(e) => setSpend(Number(e.target.value))}
          className="w-full accent-brand-500 bg-gray-800 rounded-lg cursor-pointer h-2"
        />
        <div className="flex justify-between text-[10px] text-gray-400">
          <span>200 €</span>
          <span>2.500 €</span>
          <span>5.000 €</span>
          <span>10.000 €</span>
        </div>
      </div>

      {/* Baseline Info */}
      <div className="flex flex-wrap items-center gap-3 bg-gray-900/60 p-3 rounded-lg border border-gray-800/80 text-xs text-gray-300">
        <span className="text-gray-400">Parámetros Base Reales:</span>
        <span className="bg-gray-800 px-2 py-0.5 rounded text-gray-200">
          CPL Histórico: <strong>{Number(baseline.historical_cpl || 0).toFixed(2)} €</strong>
        </span>
        <span className="bg-gray-800 px-2 py-0.5 rounded text-gray-200">
          Tasa Cierre: <strong>{baseline.conversion_rate_pct || 0}%</strong>
        </span>
        <span className="bg-gray-800 px-2 py-0.5 rounded text-gray-200">
          Ticket Medio: <strong>{Number(baseline.avg_ticket || 0).toLocaleString('es-ES')} €</strong>
        </span>
      </div>

      {/* Las 3 Bandas de Confianza */}
      <div className="grid grid-cols-1 md:grid-cols-3 gap-4 pt-2">
        {/* Conservador p10 */}
        <div className="bg-[#0B0F19] border border-gray-800/80 rounded-xl p-4 flex flex-col justify-between">
          <div>
            <div className="flex items-center justify-between mb-2">
              <span className="text-xs font-semibold text-gray-400">Conservador (p10)</span>
              <ShieldCheck className="w-4 h-4 text-amber-400" />
            </div>
            <p className="text-2xl font-extrabold text-white">
              +{Number(p10.revenue || 0).toLocaleString('es-ES', { minimumFractionDigits: 2 })} €
            </p>
            <p className="text-xs text-emerald-400 font-semibold mt-1">
              ROAS {p10.roas || 0}x
            </p>
          </div>
          <div className="mt-4 pt-3 border-t border-gray-800/60 text-xs text-gray-400 space-y-1">
            <div className="flex justify-between">
              <span>Leads estimados:</span>
              <strong className="text-gray-200">{p10.leads || 0}</strong>
            </div>
            <div className="flex justify-between">
              <span>Ventas cerradas:</span>
              <strong className="text-gray-200">{p10.deals || 0}</strong>
            </div>
          </div>
        </div>

        {/* Esperado p50 (Destacado) */}
        <div className="bg-gradient-to-b from-brand-950/40 to-[#0B0F19] border-2 border-brand-500/60 rounded-xl p-4 flex flex-col justify-between relative shadow-lg shadow-brand-900/20">
          <div className="absolute -top-2.5 right-3 bg-brand-600 text-white text-[9px] uppercase tracking-wider font-bold px-2 py-0.5 rounded-full">
            Más Probable
          </div>
          <div>
            <div className="flex items-center justify-between mb-2">
              <span className="text-xs font-semibold text-brand-300">Esperado (p50)</span>
              <Sparkles className="w-4 h-4 text-brand-400" />
            </div>
            <p className="text-2xl font-extrabold text-white">
              +{Number(p50.revenue || 0).toLocaleString('es-ES', { minimumFractionDigits: 2 })} €
            </p>
            <p className="text-xs text-brand-400 font-semibold mt-1">
              ROAS {p50.roas || 0}x
            </p>
          </div>
          <div className="mt-4 pt-3 border-t border-brand-800/40 text-xs text-gray-300 space-y-1">
            <div className="flex justify-between">
              <span>Leads estimados:</span>
              <strong className="text-white">{p50.leads || 0}</strong>
            </div>
            <div className="flex justify-between">
              <span>Ventas cerradas:</span>
              <strong className="text-white">{p50.deals || 0}</strong>
            </div>
          </div>
        </div>

        {/* Optimista p90 */}
        <div className="bg-[#0B0F19] border border-gray-800/80 rounded-xl p-4 flex flex-col justify-between">
          <div>
            <div className="flex items-center justify-between mb-2">
              <span className="text-xs font-semibold text-gray-400">Optimista (p90)</span>
              <TrendingUp className="w-4 h-4 text-emerald-400" />
            </div>
            <p className="text-2xl font-extrabold text-white">
              +{Number(p90.revenue || 0).toLocaleString('es-ES', { minimumFractionDigits: 2 })} €
            </p>
            <p className="text-xs text-emerald-400 font-semibold mt-1">
              ROAS {p90.roas || 0}x
            </p>
          </div>
          <div className="mt-4 pt-3 border-t border-gray-800/60 text-xs text-gray-400 space-y-1">
            <div className="flex justify-between">
              <span>Leads estimados:</span>
              <strong className="text-gray-200">{p90.leads || 0}</strong>
            </div>
            <div className="flex justify-between">
              <span>Ventas cerradas:</span>
              <strong className="text-gray-200">{p90.deals || 0}</strong>
            </div>
          </div>
        </div>
      </div>
    </div>
  );
}