import React, { useEffect, useMemo, useState } from 'react';
import { useForm } from '@inertiajs/react';
import { useTranslation } from 'react-i18next';
import { LoaderCircle } from 'lucide-react';
import { Button } from '@/components/ui/button';
import { Checkbox } from '@/components/ui/checkbox';
import { Input } from '@/components/ui/input';
import { Label } from '@/components/ui/label';
import InputError from '@/components/input-error';
import TextLink from '@/components/text-link';
import { Alert, AlertDescription } from '@/components/ui/alert';

interface LoginFormProps {
  onSuccess?: (payload: any) => void;
  canResetPassword?: boolean;
}

const getCsrfToken = () =>
  (document.querySelector('meta[name="csrf-token"]') as HTMLMetaElement | null)?.content ?? '';

const parseJson = async (response: Response) => {
  if (response.headers.get('Content-Type')?.includes('application/json')) {
    const json = await response.json().catch(() => null);
    if (json) return json;
  }

  const text = await response.text();
  throw new Error(text || 'Invalid server response (unexpected end of data or non-JSON).');
};

export default function LoginForm({ onSuccess, canResetPassword = true }: LoginFormProps) {
  const { t } = useTranslation('auth');
  const csrfToken = useMemo(getCsrfToken, []);

  const { data, setData, errors, setError, clearErrors, reset } = useForm({
    login: '',
    password: '',
    remember: false,
  });

  const [hasTriedSubmit, setHasTriedSubmit] = useState(false);
  const [submitting, setSubmitting] = useState(false);
  const [formError, setFormError] = useState<string | null>(null);

  const handleSubmit = async (event: React.FormEvent<HTMLFormElement>) => {
    event.preventDefault();
    setHasTriedSubmit(true);
    setSubmitting(true);
    setFormError(null);
    clearErrors();

    try {
      const response = await fetch('/purchase/auth/login', {
        method: 'POST',
        credentials: 'same-origin',
        headers: {
          'Content-Type': 'application/json',
          Accept: 'application/json',
          'X-CSRF-TOKEN': csrfToken,
          'X-Requested-With': 'XMLHttpRequest',
        },
        body: JSON.stringify({
          login: data.login,
          password: data.password,
          remember: data.remember,
        }),
      });

      if (response.ok) {
        const payload = await parseJson(response);
        reset({ login: payload?.user?.email ?? data.login, password: '', remember: false });
        setHasTriedSubmit(false);
        if (onSuccess) {
          onSuccess(payload);
        }
        return;
      }

      if (response.status === 422) {
        const body = await parseJson(response);
        const validationErrors = body.errors ?? {};
        let fallbackMessage: string | null = body.message ?? null;

        Object.entries(validationErrors as Record<string, string | string[]>).forEach(([key, value]) => {
          const message = Array.isArray(value) ? value[0] : value;
          if (typeof message === 'string') {
            setError(key as keyof typeof data, message);
            if (!fallbackMessage) {
              fallbackMessage = message;
            }
          }
        });

        if (fallbackMessage) {
          setFormError(fallbackMessage);
        }
        return;
      }

      setFormError(t('login.generic_error', { defaultValue: 'Login failed. Please try again.' }));
    } catch (error) {
      setFormError(t('login.generic_error', { defaultValue: 'Login failed. Please try again.' }));
    } finally {
      setSubmitting(false);
    }
  };

  useEffect(() => {
    if (!hasTriedSubmit) {
      return;
    }

    const errorKeys = Object.keys(errors);
    if (errorKeys.length === 0) {
      return;
    }

    const field = document.querySelector<HTMLInputElement>(`[name="${errorKeys[0]}"]`);

    if (field) {
      field.scrollIntoView({ behavior: 'smooth', block: 'center' });
      field.focus();
    }
  }, [errors, hasTriedSubmit]);

  return (
    <form className="flex flex-col gap-6" onSubmit={handleSubmit} noValidate>
      <div className="grid gap-6">
        <div className="grid gap-2">
          <Label htmlFor="login">{t('login.email')}</Label>
          <Input
            id="login"
            type="text"
            name="login"
            autoComplete="username"
            required
            autoFocus
            placeholder={t('login.email_placeholder')}
            value={data.login}
            onChange={(event) => {
              setData('login', event.target.value);
              if (errors.login) {
                clearErrors('login');
              }
            }}
          />
          <InputError message={errors.login} />
        </div>

        <div className="grid gap-2">
          <div className="flex items-center">
            <Label htmlFor="password">{t('login.password')}</Label>
            {canResetPassword && (
              <TextLink href="/forgot-password" className="ml-auto text-sm">
                {t('login.forgot')}
              </TextLink>
            )}
          </div>
          <Input
            id="password"
            type="password"
            name="password"
            autoComplete="current-password"
            required
            placeholder={t('login.password_placeholder')}
            value={data.password}
            onChange={(event) => {
              setData('password', event.target.value);
              if (errors.password) {
                clearErrors('password');
              }
            }}
          />
          <InputError message={errors.password} />
        </div>

        <div className="flex items-center space-x-3">
          <Checkbox
            id="remember"
            name="remember"
            checked={data.remember}
            onCheckedChange={(checked) => setData('remember', Boolean(checked))}
          />
          <Label htmlFor="remember">{t('login.remember')}</Label>
        </div>

        <Button type="submit" className="w-full" disabled={submitting}>
          {submitting && <LoaderCircle className="h-4 w-4 animate-spin mr-2" />}
          {t('login.submit')}
        </Button>
      </div>

      {(formError || Object.keys(errors).length > 0) && (
        <Alert variant="destructive">
          <AlertDescription>
            {formError || Object.values(errors).join(' ')}
          </AlertDescription>
        </Alert>
      )}
    </form>
  );
}