'use client';

import { useState } from 'react';
import { useRouter } from 'next/navigation';
import { Lock, User, Key, ArrowRight, ShieldCheck, Loader2 } from 'lucide-react';
import Link from 'next/link';

export default function LoginPage() {
  const router = useRouter();
  const [step, setStep] = useState<'credentials' | 'otp'>('credentials');
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState('');
  
  const [formData, setFormData] = useState({
    username: '',
    password: '',
    otp: ''
  });

  const handleLogin = async (e: React.FormEvent) => {
    e.preventDefault();
    setLoading(true);
    setError('');

    try {
      const res = await fetch('/api/auth/login', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ username: formData.username, password: formData.password })
      });

      const data = await res.json();

      if (!res.ok) throw new Error(data.error || 'Error al iniciar sesión');

      if (data.requireOtp) {
        setStep('otp');
      } else {
        router.push('/');
        router.refresh();
      }
    } catch (err: any) {
      setError(err.message);
    } finally {
      setLoading(false);
    }
  };

  const handleVerifyOtp = async (e: React.FormEvent) => {
    e.preventDefault();
    setLoading(true);
    setError('');

    try {
      const res = await fetch('/api/auth/verify-otp', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ username: formData.username, otp: formData.otp })
      });

      const data = await res.json();

      if (!res.ok) throw new Error(data.error || 'Código incorrecto');

      router.push('/');
      router.refresh();
    } catch (err: any) {
      setError(err.message);
    } finally {
      setLoading(false);
    }
  };

  return (
    <div className="min-h-screen bg-slate-950 flex items-center justify-center p-4">
      <div className="w-full max-w-md bg-slate-900 border border-slate-800 rounded-2xl shadow-xl overflow-hidden">
        {/* Header */}
        <div className="bg-slate-950/50 p-6 text-center border-b border-slate-800">
          <div className="mx-auto w-12 h-12 bg-emerald-500/10 rounded-xl flex items-center justify-center mb-4">
            <Lock className="w-6 h-6 text-emerald-500" />
          </div>
          <h1 className="text-2xl font-bold text-white mb-1">Bienvenido</h1>
          <p className="text-slate-400 text-sm">Sistema de Finanzas Personales</p>
        </div>

        <div className="p-6">
          {error && (
            <div className="mb-6 p-3 bg-red-500/10 border border-red-500/20 rounded-lg text-red-400 text-sm text-center">
              {error}
            </div>
          )}

          {step === 'credentials' ? (
            <form onSubmit={handleLogin} className="space-y-4">
              <div className="space-y-2">
                <label className="text-xs font-medium text-slate-400 uppercase tracking-wider">Usuario</label>
                <div className="relative">
                  <User className="absolute left-3 top-2.5 w-5 h-5 text-slate-500" />
                  <input
                    type="text"
                    required
                    value={formData.username}
                    onChange={e => setFormData({...formData, username: e.target.value})}
                    className="w-full pl-10 pr-4 py-2.5 bg-slate-950 border border-slate-800 rounded-lg text-white focus:ring-2 focus:ring-emerald-500 focus:border-emerald-500 outline-none transition-all placeholder:text-slate-600"
                    placeholder="Ingresa tu usuario"
                  />
                </div>
              </div>

              <div className="space-y-2">
                <label className="text-xs font-medium text-slate-400 uppercase tracking-wider">Contraseña</label>
                <div className="relative">
                  <Key className="absolute left-3 top-2.5 w-5 h-5 text-slate-500" />
                  <input
                    type="password"
                    required
                    value={formData.password}
                    onChange={e => setFormData({...formData, password: e.target.value})}
                    className="w-full pl-10 pr-4 py-2.5 bg-slate-950 border border-slate-800 rounded-lg text-white focus:ring-2 focus:ring-emerald-500 focus:border-emerald-500 outline-none transition-all placeholder:text-slate-600"
                    placeholder="••••••••"
                  />
                </div>
              </div>

              <button
                type="submit"
                disabled={loading}
                className="w-full bg-emerald-600 hover:bg-emerald-500 text-white font-medium py-2.5 rounded-lg transition-colors flex items-center justify-center gap-2 disabled:opacity-50 disabled:cursor-not-allowed mt-2"
              >
                {loading ? <Loader2 className="animate-spin w-5 h-5" /> : (
                  <>
                    Ingresar <ArrowRight className="w-4 h-4" />
                  </>
                )}
              </button>
            </form>
          ) : (
            <form onSubmit={handleVerifyOtp} className="space-y-4 animate-in slide-in-from-right-8 fade-in duration-300">
              <div className="text-center mb-6">
                <div className="inline-flex items-center justify-center w-16 h-16 bg-blue-500/10 rounded-full mb-4">
                  <ShieldCheck className="w-8 h-8 text-blue-500" />
                </div>
                <h3 className="text-lg font-medium text-white">Verificación de Identidad</h3>
                <p className="text-slate-400 text-sm mt-1">
                  Hemos enviado un código a tu Telegram.
                  <br />Ingrésalo para continuar.
                </p>
              </div>

              <div className="space-y-2">
                <input
                  type="text"
                  required
                  autoFocus
                  maxLength={6}
                  value={formData.otp}
                  onChange={e => setFormData({...formData, otp: e.target.value.replace(/\D/g, '')})}
                  className="w-full text-center text-2xl tracking-[0.5em] font-mono py-3 bg-slate-950 border border-slate-800 rounded-lg text-white focus:ring-2 focus:ring-blue-500 focus:border-blue-500 outline-none transition-all"
                  placeholder="000000"
                />
              </div>

              <button
                type="submit"
                disabled={loading || formData.otp.length !== 6}
                className="w-full bg-blue-600 hover:bg-blue-500 text-white font-medium py-2.5 rounded-lg transition-colors flex items-center justify-center gap-2 disabled:opacity-50 disabled:cursor-not-allowed"
              >
                {loading ? <Loader2 className="animate-spin w-5 h-5" /> : 'Verificar Código'}
              </button>
              
              <button
                type="button"
                onClick={() => setStep('credentials')}
                className="w-full text-slate-500 text-sm hover:text-slate-300 transition-colors"
              >
                Volver atrás
              </button>
            </form>
          )}
        </div>

        <div className="bg-slate-950/50 p-4 text-center border-t border-slate-800">
          <p className="text-slate-500 text-sm">
            ¿No tienes cuenta?{' '}
            <Link href="/register" className="text-emerald-500 hover:text-emerald-400 font-medium hover:underline">
              Regístrate aquí
            </Link>
          </p>
        </div>
      </div>
    </div>
  );
}