// Startseite „/“: kompakter Hero mit großer Karte und direkt darunter die Community-Galerie (Anker #community).
// Suche (`?q=`) und Tag (`?tag=`) kommen aus der Adresse; Label-Admins sehen zusätzlich die Filter Alle/Gemeldet/Ausgeblendet.
import '../community/community.css';
import { currentUser, isAdmin, onAuthChange, type User } from '../account/auth';
import { mountGalleryGrid, type GalleryGrid } from '../community/gallery-grid';
import { listGallery, loadGalleryImage, type GalleryCard, type GalleryFilter, type GalleryOptions } from '../community/gallery';
import { el } from '../editor/dom';
import { navigate, scrollToHash } from './router';

type Page = { cards: GalleryCard[]; nextCursor: string | null };

/** Alles, was die Seite von außen braucht (für Tests austauschbar). */
export interface HomeDeps {
  listGallery(opts: GalleryOptions): Promise<Page>;
  loadImage(card: GalleryCard, size: 'full' | 'preview'): Promise<Blob>;
  currentUser(): User | null;
  onAuthChange(fn: (user: User | null) => void): () => void;
  navigate(path: string): void;
  scrollToHash(hash: string): void;
}

export const defaultDeps: HomeDeps = {
  listGallery,
  loadImage: loadGalleryImage,
  currentUser,
  onAuthChange,
  navigate,
  scrollToHash,
};

const EXAMPLE_IMAGE = '/hero-beispiel.png';
const EXAMPLE_ALT = 'Beispielmotiv: violetter Verlauf mit Wellen und dem AirCard-IOS-Symbol';
const CARD_W = 1536;
const CARD_H = 969;

const LOADING = 'Karten werden geladen …';
const LOAD_ERROR = 'Die Community-Karten konnten gerade nicht geladen werden.';
const MORE_ERROR = 'Weitere Karten konnten nicht geladen werden. Bitte nochmal versuchen.';
const EMPTY = 'Noch keine Community-Karten – sei die erste!';
const EMPTY_VIEW = 'Keine Karten in dieser Ansicht.';

const FILTERS: ReadonlyArray<readonly [GalleryFilter, string]> = [
  ['all', 'Alle'],
  ['reported', 'Gemeldet'],
  ['hidden', 'Ausgeblendet'],
];

/** `/` plus Suche und/oder Tag, mit Anker auf die Galerie. */
function communityPath(next: { q?: string; tag?: string }): string {
  const parts: string[] = [];
  if (next.q) parts.push(`q=${encodeURIComponent(next.q)}`);
  if (next.tag) parts.push(`tag=${encodeURIComponent(next.tag)}`);
  return `/${parts.length > 0 ? `?${parts.join('&')}` : ''}#community`;
}

export function mountHomePage(root: HTMLElement, deps: HomeDeps = defaultDeps): () => void {
  const params = new URLSearchParams(location.search);
  const query = (params.get('q') ?? '').trim();
  const tag = (params.get('tag') ?? '').trim();

  let disposed = false;
  let filter: GalleryFilter = 'all';
  let loadToken = 0;
  let cursor: string | null = null;
  let loadingMore = false;
  let moreError = '';
  let grid: GalleryGrid | null = null;
  let heroUrl: string | null = null;

  const options = (): GalleryOptions => ({ q: query || undefined, tag: tag || undefined, filter });

  // Das Suchfeld der Kopfzeile gehört zu main.ts; hier bekommt es den Suchbegriff der Adresse (per .value, nie als HTML).
  const headerInput = document.querySelector<HTMLInputElement>('.header-search-input');
  if (headerInput) headerInput.value = query;

  // ---- Hero ----

  const heroCard = el('div', { class: 'hero-card is-loading' });
  const hero = el(
    'section',
    { class: 'home-hero', 'aria-label': 'Willkommen' },
    el(
      'div',
      { class: 'home-hero-copy' },
      el('p', { class: 'home-hero-eyebrow' }, 'Ein bisschen Kunst für dein Wallet'),
      el('h1', { class: 'home-hero-title' }, 'Kartendesigns für Apple Wallet'),
      el('p', { class: 'home-hero-lead' }, 'Entdecke Motive der Community, gestalte dein eigenes und lade es als PNG herunter.'),
      el(
        'div',
        { class: 'home-hero-actions' },
        el('a', { class: 'home-btn home-btn-primary', href: '#community', 'data-link': true }, 'Karten entdecken ↓'),
        el('a', { class: 'home-btn', href: '/gestalten', 'data-link': true }, 'Gestalten'),
      ),
    ),
    el('div', { class: 'home-hero-visual' }, heroCard),
  );

  function setHeroImage(src: string, alt: string, card: GalleryCard | null): void {
    const img = el('img', { src, alt, width: CARD_W, height: CARD_H });
    heroCard.classList.remove('is-loading');
    heroCard.replaceChildren(
      card ? el('a', { class: 'hero-card-link', href: `/community/${encodeURIComponent(card.id)}`, 'data-link': true }, img) : img,
    );
  }

  const showExample = () => setHeroImage(EXAMPLE_IMAGE, EXAMPLE_ALT, null);

  /** Die große Karte: Vollbild der neuesten sichtbaren Karte; ohne Karte oder bei Fehlern das Beispielmotiv. */
  function showHero(newest: Promise<GalleryCard | null>): void {
    newest.then(
      async (card) => {
        if (disposed) return;
        if (!card) return showExample();
        try {
          const blob = await deps.loadImage(card, 'full');
          if (disposed) return;
          heroUrl = URL.createObjectURL(blob);
          setHeroImage(heroUrl, `Community-Karte „${card.title}“`, card);
        } catch {
          if (!disposed) showExample();
        }
      },
      () => {
        if (!disposed) showExample();
      },
    );
  }

  // ---- Galerie-Abschnitt ----

  const filterSlot = el('div', { class: 'community-filter-slot' });
  const activeSlot = el('div', { class: 'community-active-slot' });
  const statusSlot = el('div', { class: 'community-status-slot' });
  const gridHost = el('div', { class: 'community-grid-host' });
  const moreSlot = el('div', { class: 'community-more' });

  const section = el(
    'section',
    { id: 'community', class: 'home-community', 'aria-labelledby': 'community-title' },
    el(
      'div',
      { class: 'community-head' },
      el(
        'div',
        { class: 'community-head-text' },
        el('h2', { id: 'community-title', class: 'community-title' }, 'Community-Karten'),
        el('p', { class: 'community-sub' }, 'Entdecke Motive der Community – und veröffentliche deine eigenen.'),
      ),
      el('a', { class: 'home-btn home-btn-primary community-publish', href: '/gestalten', 'data-link': true }, 'Gestalten & veröffentlichen'),
    ),
    el('div', { class: 'community-toolbar' }, activeSlot, filterSlot),
    statusSlot,
    gridHost,
    moreSlot,
  );

  root.replaceChildren(hero, section);

  // Aktiver Suchbegriff / Tag mit „ד (zurück zur Galerie ohne diesen Begriff)
  function chip(label: string, value: string, clearLabel: string, target: string): HTMLElement {
    const clear = el('button', { type: 'button', class: 'community-chip-clear', 'aria-label': clearLabel }, '×');
    clear.addEventListener('click', () => deps.navigate(target));
    return el(
      'span',
      { class: 'community-chip' },
      el('span', { class: 'community-chip-label' }, `${label}:`),
      el('strong', { class: 'community-chip-value' }, value),
      clear,
    );
  }

  if (query || tag) {
    const active = el('div', { class: 'community-active' });
    if (query) active.append(chip('Suche', query, 'Suche zurücksetzen', communityPath({ tag })));
    if (tag) active.append(chip('Tag', tag, 'Tag-Filter zurücksetzen', communityPath({ q: query })));
    activeSlot.append(active);
  }

  // Admin-Filter
  const filterButtons = new Map<GalleryFilter, HTMLButtonElement>();
  function syncFilterButtons(): void {
    for (const [value, button] of filterButtons) button.setAttribute('aria-pressed', String(value === filter));
  }

  function renderFilter(user: User | null): void {
    filterButtons.clear();
    if (!isAdmin(user)) {
      filterSlot.replaceChildren();
      return;
    }
    const group = el('div', { class: 'community-filter', role: 'group', 'aria-label': 'Ansicht' });
    for (const [value, label] of FILTERS) {
      const button = el('button', { type: 'button', class: 'community-filter-btn' }, label);
      button.addEventListener('click', () => setFilter(value));
      filterButtons.set(value, button);
      group.append(button);
    }
    filterSlot.replaceChildren(group);
    syncFilterButtons();
  }

  function setFilter(next: GalleryFilter): void {
    if (next === filter) return;
    filter = next;
    syncFilterButtons();
    loadFirst(deps.listGallery(options()));
  }

  // ---- Laden ----

  function showStatus(text: string, role: 'status' | 'alert', retry = false): void {
    const message = el('p', { class: `community-status${role === 'alert' ? ' is-error' : ''}`, role }, text);
    const nodes: Node[] = [message];
    if (retry) {
      const button = el('button', { type: 'button', class: 'home-btn home-btn-primary' }, 'Nochmal versuchen');
      button.addEventListener('click', () => loadFirst(deps.listGallery(options())));
      nodes.push(button);
    }
    statusSlot.replaceChildren(...nodes);
  }

  function showEmpty(): void {
    const nodes: Node[] = [];
    if (filter !== 'all') {
      nodes.push(el('p', {}, EMPTY_VIEW));
    } else if (query || tag) {
      nodes.push(el('p', {}, `Nichts gefunden für „${[query, tag].filter(Boolean).join(' · ')}“`));
    } else {
      nodes.push(
        el('p', {}, EMPTY),
        el('a', { class: 'home-btn home-btn-primary', href: '/gestalten', 'data-link': true }, 'Gestalten'),
      );
    }
    statusSlot.replaceChildren(el('div', { class: 'community-empty' }, ...nodes));
  }

  function renderMore(): void {
    if (!cursor) {
      moreSlot.replaceChildren();
      return;
    }
    const button = el('button', { type: 'button', class: 'home-btn community-more-btn' }, 'Mehr laden');
    if (loadingMore) {
      button.disabled = true;
      button.setAttribute('aria-busy', 'true');
    }
    button.addEventListener('click', () => void loadMore());
    moreSlot.replaceChildren(
      ...(moreError ? [el('p', { class: 'community-more-msg is-error', role: 'alert' }, moreError)] : []),
      button,
    );
  }

  /** Beginnt die Liste neu (andere Ansicht, Wiederholen); `pending` ist die schon laufende Abfrage der ersten Seite. */
  function loadFirst(pending: Promise<Page>): void {
    const token = ++loadToken;
    grid?.dispose();
    grid = mountGalleryGrid(gridHost, {
      load: (card) => deps.loadImage(card, 'preview'),
      onTag: (name) => deps.navigate(communityPath({ tag: name })),
      showStatus: filter !== 'all', // Moderations-Marken nur in den Admin-Ansichten
    });
    cursor = null;
    loadingMore = false;
    moreError = '';
    moreSlot.replaceChildren();
    showStatus(LOADING, 'status');
    pending.then(
      (res) => {
        if (disposed || token !== loadToken) return;
        statusSlot.replaceChildren();
        if (res.cards.length === 0) showEmpty();
        else grid?.append(res.cards);
        cursor = res.nextCursor;
        renderMore();
      },
      () => {
        if (disposed || token !== loadToken) return;
        showStatus(LOAD_ERROR, 'alert', true);
      },
    );
  }

  async function loadMore(): Promise<void> {
    if (!cursor || loadingMore) return;
    const token = loadToken;
    loadingMore = true;
    moreError = '';
    renderMore();
    try {
      const res = await deps.listGallery({ ...options(), cursor });
      if (disposed || token !== loadToken) return;
      loadingMore = false;
      grid?.append(res.cards);
      cursor = res.nextCursor;
    } catch {
      if (disposed || token !== loadToken) return;
      loadingMore = false;
      moreError = MORE_ERROR;
    }
    renderMore();
  }

  // ---- Start ----

  renderFilter(deps.currentUser());
  const stopAuth = deps.onAuthChange((user) => {
    if (disposed) return;
    renderFilter(user);
    // Wer keine Admin-Rechte (mehr) hat, kann keine Admin-Ansicht offen haben.
    if (!isAdmin(user) && filter !== 'all') {
      filter = 'all';
      loadFirst(deps.listGallery(options()));
    }
  });

  const first = deps.listGallery(options());
  loadFirst(first);
  // Die Hero-Karte zeigt immer die neueste sichtbare Karte, auch bei Suche/Tag: dann braucht sie eine eigene Abfrage.
  const unfiltered = !query && !tag;
  showHero((unfiltered ? first : deps.listGallery({})).then((res) => res.cards[0] ?? null));

  // Der Anker (z. B. /#community) existiert erst jetzt; nach dem ersten Laden noch einmal, weil die Seite dann länger ist.
  if (location.hash) {
    deps.scrollToHash(location.hash);
    const hash = location.hash;
    const again = () => {
      if (!disposed) deps.scrollToHash(hash);
    };
    first.then(again, again);
  }

  return () => {
    disposed = true;
    stopAuth();
    grid?.dispose();
    grid = null;
    if (heroUrl) URL.revokeObjectURL(heroUrl);
    heroUrl = null;
  };
}