import { useState } from 'react';
import {
  Card,
  CardContent,
  CardDescription,
  CardHeader,
  CardTitle,
} from '@/components/ui/card';
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 { Loader2, Shield, AlertCircle } from 'lucide-react';
import { twoFactorService } from '@/services/2fa-service';
import { useToast } from '@/hooks/useToast';
import { parseApiError } from '@/utils/apiErrorHandler';

interface TwoFactorVerifyProps {
  onSuccess: (code: string) => void;
  onCancel: () => void;
}

export function TwoFactorVerify({ onSuccess, onCancel }: TwoFactorVerifyProps) {
  const [code, setCode] = useState('');
  const [backupCode, setBackupCode] = useState('');
  const [useBackupCode, setUseBackupCode] = useState(false);
  const [isVerifying, setIsVerifying] = useState(false);
  const [error, setError] = useState('');
  const { toast } = useToast();

  const handleVerify = async () => {
    if (!code && !backupCode) {
      setError('Please enter a verification code');
      return;
    }

    try {
      setIsVerifying(true);
      setError('');

      const verificationCode = useBackupCode ? backupCode : code;
      // TODO: Fix 2FA login verification
      // Issue: twoFactorService.verify(secret, code) is for 2FA setup, not login verification.
      // During login, we don't have the secret. The 2FA code should be verified as part of
      // the login flow (either via a separate endpoint like /auth/login/2fa or by including
      // the code in the login request when requires_2fa is true).
      // Current workaround: Pass code to parent via onSuccess() - parent should handle verification.
      // Action required: Check backend API contract for 2FA login verification endpoint.
      try {
        // FIXME: This is incorrect - verify() is for setup, not login
        // Remove this call once proper login 2FA verification is implemented
        await twoFactorService.verify('', verificationCode);
        onSuccess(verificationCode);
      } catch (verifyError: unknown) {
        // If verification fails, show error message
        const apiError = parseApiError(verifyError);
        const errorMessage = apiError.message;
        setError(errorMessage);
        toast({
          message: errorMessage,
          type: 'error',
        });
        throw verifyError; // Re-throw to be caught by outer catch if needed
      }
    } catch (error: unknown) {
      const apiError = parseApiError(error);
      setError(apiError.message);
      toast({
        message: apiError.message,
        type: 'error',
      });
    } finally {
      setIsVerifying(false);
    }
  };

  return (
    <Card className="w-full max-w-md">
      <CardHeader>
        <CardTitle className="flex items-center gap-2">
          <Shield className="h-5 w-5 text-kodo-steel" />
          Two-Factor Authentication
        </CardTitle>
        <CardDescription>
          Enter the code from your authenticator app
        </CardDescription>
      </CardHeader>
      <CardContent className="space-y-4">
        <Alert>
          <AlertCircle className="h-4 w-4" />
          <AlertDescription>
            Enter the 6-digit code from your authenticator app to continue
            signing in.
          </AlertDescription>
        </Alert>

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

        {!useBackupCode ? (
          <>
            <div className="space-y-2">
              <Label htmlFor="2fa-code">Verification Code</Label>
              <Input
                id="2fa-code"
                type="text"
                placeholder="000000"
                value={code}
                onChange={(e) => {
                  setCode(e.target.value.replace(/\D/g, '').slice(0, 6));
                  setError('');
                }}
                maxLength={6}
                className="text-center text-2xl tracking-widest"
                autoFocus
              />
            </div>
            <p className="text-sm text-kodo-content-dim">
              Lost access?{' '}
              <button
                onClick={() => setUseBackupCode(true)}
                className="text-kodo-cyan hover:underline"
              >
                Use a backup code
              </button>
            </p>
          </>
        ) : (
          <>
            <div className="space-y-2">
              <Label htmlFor="backup-code">Backup Code</Label>
              <Input
                id="backup-code"
                type="text"
                placeholder="Enter backup code"
                value={backupCode}
                onChange={(e) => {
                  setBackupCode(e.target.value);
                  setError('');
                }}
              />
            </div>
            <p className="text-sm text-kodo-content-dim">
              <button
                onClick={() => setUseBackupCode(false)}
                className="text-kodo-cyan hover:underline"
              >
                Use authenticator code instead
              </button>
            </p>
          </>
        )}

        <div className="flex gap-2">
          <Button onClick={onCancel} variant="outline" className="flex-1">
            Cancel
          </Button>
          <Button
            onClick={handleVerify}
            disabled={isVerifying || (!code && !backupCode)}
            className="flex-1"
          >
            {isVerifying ? (
              <>
                <Loader2 className="mr-2 h-4 w-4 animate-spin" />
                Verifying...
              </>
            ) : (
              'Verify'
            )}
          </Button>
        </div>
      </CardContent>
    </Card>
  );
}