src/app/login/page.tsx

"use client";

import React, { useState, useEffect } from "react";
import { auth } from "@/lib/firebase";
import { signInWithEmailAndPassword, onAuthStateChanged } from "firebase/auth";
import { useRouter } from "next/navigation";

export default function LoginPage() {
  const [email, setEmail] = useState("");
  const [password, setPassword] = useState("");
  const [error, setError] = useState("");
  const [loading, setLoading] = useState(false);
  const router = useRouter();

  useEffect(() => {
    const unsub = onAuthStateChanged(auth, (user) => {
      if (user) router.push("/");
    });
    return () => unsub();
  }, [router]);

  const handleLogin = async (e: React.FormEvent) => {
    e.preventDefault();
    setLoading(true);
    setError("");
    try {
      await signInWithEmailAndPassword(auth, email, password);
      router.push("/");
    } catch (err: any) {
      setError(err.message || "Error al iniciar sesión");
    } finally {
      setLoading(false);
    }
  };

  return (
    <div className="min-h-screen bg-[#0f172a] flex items-center justify-center p-6 relative overflow-hidden">
      {/* Background Decor */}
      <div className="absolute top-0 left-0 w-full h-full">
        <div className="absolute top-[-10%] left-[-10%] w-[40%] h-[40%] bg-blue-600/20 blur-[120px] rounded-full"></div>
        <div className="absolute bottom-[-10%] right-[-10%] w-[40%] h-[40%] bg-purple-600/20 blur-[120px] rounded-full"></div>
      </div>

      <div className="w-full max-w-md relative z-10 transition-all duration-700 animate-in fade-in slide-in-from-bottom-8">
        <div className="bg-white/5 border border-white/10 p-10 rounded-[40px] backdrop-blur-3xl shadow-2xl">
          <div className="text-center mb-10">
            <h1 className="text-4xl font-black bg-gradient-to-r from-blue-400 to-indigo-500 bg-clip-text text-transparent mb-2">
              ERP System
            </h1>
            <p className="text-gray-400 text-sm font-medium">Panel de control empresarial premium</p>
          </div>

          <form onSubmit={handleLogin} className="space-y-6">
            <div>
              <input
                type="email"
                placeholder="Email corporativo"
                required
                value={email}
                onChange={(e) => setEmail(e.target.value)}
                className="w-full bg-white/5 border border-white/10 rounded-2xl px-6 py-4 outline-none focus:border-blue-500/50 focus:bg-white/10 transition-all placeholder:text-gray-600"
              />
            </div>
            <div>
              <input
                type="password"
                placeholder="Contraseña"
                required
                value={password}
                onChange={(e) => setPassword(e.target.value)}
                className="w-full bg-white/5 border border-white/10 rounded-2xl px-6 py-4 outline-none focus:border-blue-500/50 focus:bg-white/10 transition-all placeholder:text-gray-600"
              />
            </div>

            {error && (
              <div className="bg-red-500/10 border border-red-500/20 text-red-400 text-xs p-4 rounded-xl animate-shake">
                {error}
              </div>
            )}

            <button
              type="submit"
              disabled={loading}
              className="w-full bg-gradient-to-r from-blue-600 to-indigo-600 hover:from-blue-500 hover:to-indigo-500 text-white font-bold py-4 rounded-2xl shadow-lg shadow-blue-900/20 hover:shadow-blue-900/40 transition-all transform active:scale-95 disabled:opacity-50"
            >
              {loading ? (
                <span className="flex items-center justify-center gap-2">
                  <svg className="animate-spin h-5 w-5 text-white" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24">
                    <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4"></circle>
                    <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z"></path>
                  </svg>
                  Autenticando...
                </span>
              ) : (
                "Entrar"
              )}
            </button>
          </form>

          <p className="mt-8 text-center text-xs text-gray-500 font-medium">
            Acceso restringido para administradores autorizados
          </p>
        </div>
      </div>
    </div>
  );
}