import { createPlugin, windowTransport, type PageSummary } from '@dorfteich/plugin-sdk';

import de from '../i18n/de.json';
import en from '../i18n/en.json';

/**
 * Page-index reference plugin (issue #77, plugin-architecture.md §Reference
 * plugins): lists the pond's pages the viewer may read (`readPond` — the
 * server filters per page, so permissions are inherently respected), with
 * label chips to filter by. Clicking a page navigates via `ui.openPage`.
 *
 * Strings are bundled (the sandbox CSP blocks runtime fetches); the files in
 * `i18n/` are the single source and are inlined at build time.
 */
const STRINGS: Record<string, Record<string, string>> = { de, en };

function labelFor(locale: string, key: string): string {
  const base = locale.split('-')[0] ?? locale;
  return STRINGS[base]?.[key] ?? STRINGS.en?.[key] ?? key;
}

const { host } = createPlugin({
  transport: windowTransport({
    // Window.postMessage's overloads don't structurally match the transport's
    // minimal shape; this adapter pins the sandbox-safe wildcard origin.
    target: { postMessage: (message) => window.parent.postMessage(message, '*') },
    source: window,
  }),
  onRender: (context) => void render(context.locale),
});

/** The active label filter; `null` shows every readable page. */
let activeLabel: string | null = null;

async function render(locale: string): Promise<void> {
  let pages: PageSummary[];
  try {
    pages = await host.readPond.listPages();
  } catch {
    document.body.textContent = labelFor(locale, 'error');
    return;
  }

  document.body.textContent = '';
  document.body.className = 'dt-page-index';

  const labels = [...new Set(pages.flatMap((page) => page.labels))].sort();
  if (labels.length > 0) {
    document.body.appendChild(buildFilterBar(labels, locale));
  }

  const shown = activeLabel ? pages.filter((page) => page.labels.includes(activeLabel!)) : pages;
  if (shown.length === 0) {
    const empty = document.createElement('p');
    empty.textContent = labelFor(locale, 'empty');
    document.body.appendChild(empty);
  } else {
    const list = document.createElement('ul');
    for (const page of shown) {
      const item = document.createElement('li');
      const link = document.createElement('a');
      link.href = '#';
      link.textContent = page.title;
      link.dataset.pageId = page.id;
      link.addEventListener('click', (event) => {
        event.preventDefault();
        void host.ui.openPage(page.id);
      });
      item.appendChild(link);
      if (page.labels.length > 0) {
        const chips = document.createElement('span');
        chips.textContent = ` (${page.labels.join(', ')})`;
        item.appendChild(chips);
      }
      list.appendChild(item);
    }
    document.body.appendChild(list);
  }

  void host.ui.resize(document.body.scrollHeight + 16);
}

function buildFilterBar(labels: string[], locale: string): HTMLElement {
  const bar = document.createElement('p');
  bar.className = 'dt-page-index__filters';
  const options: Array<{ value: string | null; text: string }> = [
    { value: null, text: labelFor(locale, 'all') },
    ...labels.map((label) => ({ value: label, text: label })),
  ];
  for (const option of options) {
    const button = document.createElement('button');
    button.type = 'button';
    button.textContent = option.text;
    button.dataset.filter = option.value ?? '';
    button.style.fontWeight = option.value === activeLabel ? 'bold' : 'normal';
    button.addEventListener('click', () => {
      activeLabel = option.value;
      void render(locale);
    });
    bar.appendChild(button);
    bar.appendChild(document.createTextNode(' '));
  }
  return bar;
}