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

import { apiDelete, apiGet, apiPost } from '../lib/api';
import { usePondLabels } from './use-pond-labels';

/**
 * Page label picker (issue #44): a searchable, hierarchy-aware multi-select of
 * the pond's labels. Toggling a label assigns/unassigns it immediately and
 * refreshes both the page's labels and the sidebar (chips + filter). Shown only
 * to users who may edit the page; the api enforces the permission.
 */
export function LabelPicker({
  pageId,
  pondId,
  pondSlug,
  onClose,
}: {
  pageId: string;
  pondId: string;
  pondSlug: string;
  onClose: () => void;
}): React.JSX.Element {
  const { t } = useTranslation('labels');
  const queryClient = useQueryClient();
  const { flat, isLoading } = usePondLabels(pondId);
  const [search, setSearch] = useState('');
  const [busy, setBusy] = useState<string | null>(null);

  const assigned = useQuery({
    queryKey: ['page-labels', pageId],
    queryFn: () => apiGet<LabelView[]>(`/pages/${pageId}/labels`),
  });
  const assignedIds = new Set((assigned.data ?? []).map((l) => l.id));

  async function toggle(label: LabelView, checked: boolean): Promise<void> {
    setBusy(label.id);
    try {
      if (checked) {
        await apiPost(`/pages/${pageId}/labels`, { labelId: label.id });
      } else {
        await apiDelete(`/pages/${pageId}/labels/${label.id}`);
      }
      // Refresh the page's own labels and the sidebar list (chips + filter).
      await queryClient.invalidateQueries({ queryKey: ['page-labels', pageId] });
      await queryClient.invalidateQueries({ queryKey: ['pages', pondId] });
    } finally {
      setBusy(null);
    }
  }

  const term = search.trim().toLowerCase();
  const shown = term ? flat.filter((l) => l.name.toLowerCase().includes(term)) : flat;

  return (
    <aside className="label-picker" aria-label={t('picker.title')}>
      <header className="label-picker__header">
        <h2>{t('picker.title')}</h2>
        <button type="button" className="button" onClick={onClose}>
          {t('picker.close')}
        </button>
      </header>

      {isLoading ? null : flat.length === 0 ? (
        <p className="label-picker__empty">
          {t('picker.empty')} <Link to={`/p/${pondSlug}/settings`}>{t('picker.manageHint')}</Link>
        </p>
      ) : (
        <>
          <input
            type="search"
            className="label-picker__search"
            value={search}
            placeholder={t('picker.searchPlaceholder')}
            aria-label={t('picker.searchPlaceholder')}
            onChange={(event) => setSearch(event.target.value)}
          />
          {shown.length === 0 ? (
            <p className="label-picker__empty">{t('picker.noMatches')}</p>
          ) : (
            <ul className="label-picker__list">
              {shown.map((label) => {
                const indent = term ? 0 : labelDepth(flat, label.id) - 1;
                const checked = assignedIds.has(label.id);
                return (
                  <li key={label.id} style={{ paddingInlineStart: `${indent * 1.25}rem` }}>
                    <label className="label-picker__option">
                      <input
                        type="checkbox"
                        checked={checked}
                        disabled={busy === label.id}
                        onChange={(event) => void toggle(label, event.target.checked)}
                      />
                      <span
                        className="label-chip__swatch"
                        style={{ backgroundColor: label.color }}
                        aria-hidden
                      />
                      <span>{label.name}</span>
                    </label>
                  </li>
                );
              })}
            </ul>
          )}
        </>
      )}
    </aside>
  );
}