'use client';

import { useState } from 'react';
import { useForm } from 'react-hook-form';
import { zodResolver } from '@hookform/resolvers/zod';
import { z } from 'zod';
import { useAuth } from '@/lib/contexts/AuthContext';
import { mfaService } from '@/lib/services/auth';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';
import { Label } from '@/components/ui/label';
import { Alert, AlertDescription } from '@/components/ui/alert';
import { AlertCircle, Loader2 } from 'lucide-react';

const loginSchema = z.object({
  email: z.string().email('Invalid email address'),
  password: z.string().min(1, 'Password is required'),
});

type LoginFormData = z.infer<typeof loginSchema>;

interface LoginFormProps {
  onSuccess?: () => void;
  onSwitchToRegister?: () => void;
  onSwitchToReset?: () => void;
}

export function LoginForm({ onSuccess, onSwitchToRegister, onSwitchToReset }: LoginFormProps) {
  const { login } = useAuth();
  const [error, setError] = useState<string>('');
  const [isLoading, setIsLoading] = useState(false);
  const [showMFAChallenge, setShowMFAChallenge] = useState(false);
  const [mfaCode, setMfaCode] = useState('');

  const {
    register,
    handleSubmit,
    formState: { errors },
  } = useForm<LoginFormData>({
    resolver: zodResolver(loginSchema),
  });

  const onSubmit = async (data: LoginFormData) => {
    setError('');
    setIsLoading(true);

    try {
      await login(data);
      onSuccess?.();
    } catch (err: any) {
      const errorMessage = err.response?.data?.detail || err.message || 'Login failed';
      
      // Check if MFA is required
      if (errorMessage.toLowerCase().includes('mfa') || errorMessage.toLowerCase().includes('two-factor')) {
        setShowMFAChallenge(true);
      } else {
        setError(errorMessage);
      }
    } finally {
      setIsLoading(false);
    }
  };

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

    try {
      await mfaService.challengeMFA({ code: mfaCode });
      // Tokens are stored automatically by the service
      onSuccess?.();
    } catch (err: any) {
      setError(err.response?.data?.detail || 'Invalid MFA code');
    } finally {
      setIsLoading(false);
    }
  };

  if (showMFAChallenge) {
    return (
      <form onSubmit={handleMFASubmit} className="space-y-4">
        <div className="text-center mb-4">
          <h3 className="text-lg font-semibold">Two-Factor Authentication</h3>
          <p className="text-sm text-muted-foreground mt-1">
            Enter the 6-digit code from your authenticator app
          </p>
        </div>

        {error && (
          <Alert variant="destructive">
            <AlertCircle className="h-4 w-4" />
            <AlertDescription>{error}</AlertDescription>
          </Alert>
        )}

        <div className="space-y-2">
          <Label htmlFor="mfa-code">Verification Code</Label>
          <Input
            id="mfa-code"
            type="text"
            inputMode="numeric"
            pattern="[0-9]*"
            maxLength={6}
            placeholder="000000"
            value={mfaCode}
            onChange={(e) => setMfaCode(e.target.value.replace(/\D/g, ''))}
            disabled={isLoading}
            autoFocus
          />
        </div>

        <div className="flex gap-2">
          <Button
            type="button"
            variant="outline"
            onClick={() => {
              setShowMFAChallenge(false);
              setMfaCode('');
              setError('');
            }}
            disabled={isLoading}
            className="flex-1"
          >
            Back
          </Button>
          <Button type="submit" disabled={isLoading || mfaCode.length !== 6} className="flex-1">
            {isLoading && <Loader2 className="mr-2 h-4 w-4 animate-spin" />}
            Verify
          </Button>
        </div>
      </form>
    );
  }

  return (
    <form onSubmit={handleSubmit(onSubmit)} className="space-y-4">
      {error && (
        <Alert variant="destructive">
          <AlertCircle className="h-4 w-4" />
          <AlertDescription>{error}</AlertDescription>
        </Alert>
      )}

      <div className="space-y-2">
        <Label htmlFor="email">Email</Label>
        <Input
          id="email"
          type="email"
          placeholder="you@example.com"
          {...register('email')}
          disabled={isLoading}
        />
        {errors.email && (
          <p className="text-sm text-destructive">{errors.email.message}</p>
        )}
      </div>

      <div className="space-y-2">
        <Label htmlFor="password">Password</Label>
        <Input
          id="password"
          type="password"
          placeholder="••••••••"
          {...register('password')}
          disabled={isLoading}
        />
        {errors.password && (
          <p className="text-sm text-destructive">{errors.password.message}</p>
        )}
      </div>

      <Button type="submit" className="w-full" disabled={isLoading}>
        {isLoading && <Loader2 className="mr-2 h-4 w-4 animate-spin" />}
        Sign In
      </Button>

      <div className="flex flex-col gap-2 text-sm text-center">
        {onSwitchToReset && (
          <button
            type="button"
            onClick={onSwitchToReset}
            className="text-primary hover:underline"
            disabled={isLoading}
          >
            Forgot password?
          </button>
        )}
        {onSwitchToRegister && (
          <button
            type="button"
            onClick={onSwitchToRegister}
            className="text-muted-foreground hover:text-foreground"
            disabled={isLoading}
          >
            Don't have an account? <span className="text-primary">Sign up</span>
          </button>
        )}
      </div>
    </form>
  );
}