import type { PondView } from '@dorfteich/shared';
import { useQuery, useQueryClient } from '@tanstack/react-query';
import { useRef, useState } from 'react';
import { useTranslation } from 'react-i18next';
import { Link, useNavigate } from 'react-router-dom';

import { useAuth } from '../auth/auth-context';
import { FormError } from '../components/forms';
import { apiGet, apiPost } from '../lib/api';
import { useDismissable } from '../lib/use-dismissable';
import { useCurrentPondRoute } from './use-pond-route';

/**
 * Top-bar dropdown to switch between the signed-in user's ponds (issue #26)
 * — and to create a new shared pond right from the menu. Creation is
 * quota-gated server-side (`additional shared ponds per user`); a rejected
 * attempt surfaces the translated error instead of hiding the option.
 */
export function PondSwitcher(): React.JSX.Element | null {
  const { t } = useTranslation();
  const { user } = useAuth();
  const { pondSlug } = useCurrentPondRoute();
  const navigate = useNavigate();
  const queryClient = useQueryClient();
  const [open, setOpen] = useState(false);
  const [creating, setCreating] = useState(false);
  const [name, setName] = useState('');
  const [description, setDescription] = useState('');
  const [error, setError] = useState<unknown>(null);
  const [busy, setBusy] = useState(false);
  const menuRef = useRef<HTMLDivElement>(null);

  const close = (): void => {
    setOpen(false);
    setCreating(false);
    setError(null);
  };
  useDismissable(menuRef, open, close);

  const ponds = useQuery({
    queryKey: ['ponds'],
    queryFn: () => apiGet<PondView[]>('/ponds'),
    enabled: Boolean(user),
  });

  if (!ponds.data || ponds.data.length === 0) return null;
  const current = ponds.data.find((pond) => pond.slug === pondSlug);

  const create = async (event: React.FormEvent): Promise<void> => {
    event.preventDefault();
    setError(null);
    setBusy(true);
    try {
      const pond = await apiPost<PondView>('/ponds', {
        name: name.trim(),
        description: description.trim(),
      });
      await queryClient.invalidateQueries({ queryKey: ['ponds'] });
      close();
      setName('');
      setDescription('');
      navigate(`/p/${pond.slug}`);
    } catch (err) {
      setError(err);
    } finally {
      setBusy(false);
    }
  };

  return (
    <div className="user-menu" ref={menuRef}>
      <button
        type="button"
        className="user-menu__trigger pond-switcher__trigger"
        aria-haspopup="menu"
        aria-expanded={open}
        aria-label={t('layout.pondSwitcher.label')}
        onClick={() => (open ? close() : setOpen(true))}
      >
        {current?.name ?? t('layout.pondSwitcher.trigger')}
      </button>
      {open && !creating && (
        <div className="user-menu__list" role="menu">
          {ponds.data.map((pond) => (
            <Link key={pond.id} role="menuitem" to={`/p/${pond.slug}`} onClick={close}>
              {pond.name}
            </Link>
          ))}
          <button
            type="button"
            role="menuitem"
            className="pond-switcher__create"
            onClick={() => setCreating(true)}
          >
            {t('pond.create.menuItem')}
          </button>
        </div>
      )}
      {open && creating && (
        <form className="user-menu__list pond-switcher__form" onSubmit={(e) => void create(e)}>
          <h3>{t('pond.create.title')}</h3>
          <FormError error={error} />
          <label>
            {t('pond.create.nameLabel')}
            <input
              type="text"
              value={name}
              required
              maxLength={80}
              autoFocus
              onChange={(e) => setName(e.target.value)}
            />
          </label>
          <label>
            {t('pond.create.descriptionLabel')}
            <input
              type="text"
              value={description}
              maxLength={500}
              onChange={(e) => setDescription(e.target.value)}
            />
          </label>
          <p className="pond-switcher__hint">{t('pond.create.quotaHint')}</p>
          <div className="pond-switcher__actions">
            <button type="submit" className="button" disabled={busy || name.trim() === ''}>
              {t('pond.create.submit')}
            </button>
            <button
              type="button"
              className="button button--outline"
              onClick={() => {
                setCreating(false);
                setError(null);
              }}
            >
              {t('pond.create.cancel')}
            </button>
          </div>
        </form>
      )}
    </div>
  );
}