/**
 * VITEC — collapse/expand toggle for container content elements in the
 * TYPO3 v14 Page module.
 *
 * Adds a chevron button into the `.btn-toolbar` of every VITEC container
 * (vitec_container, vitec_cols_*, vitec_cards_carousel — anything that
 * renders a nested b13 grid). Clicking it hides/shows the container body
 * (the nested child columns). State is persisted per element uid in
 * localStorage, so it survives reloads.
 *
 * Pure DOM enhancement — no core or b13 template overrides.
 */
class VitecContainerCollapse {
  constructor() {
    this.storagePrefix = 'vitec-ce-collapsed-';
    this.ready();
  }

  ready() {
    if (document.readyState === 'loading') {
      document.addEventListener('DOMContentLoaded', () => this.boot());
    } else {
      this.boot();
    }
  }

  boot() {
    this.processAll();
    // Page module can re-render columns via AJAX; watch for new elements.
    const root = document.querySelector('.t3js-page-columns-wrapper, .module, body');
    if (root) {
      const observer = new MutationObserver(() => {
        window.clearTimeout(this._debounce);
        this._debounce = window.setTimeout(() => this.processAll(), 150);
      });
      observer.observe(root, { childList: true, subtree: true });
    }
  }

  processAll() {
    document.querySelectorAll('.t3-page-ce[data-uid]').forEach((ce) => this.enhance(ce));
  }

  isCollapsed(uid) {
    try {
      return window.localStorage.getItem(this.storagePrefix + uid) === '1';
    } catch (e) {
      return false;
    }
  }

  setCollapsed(uid, collapsed) {
    try {
      if (collapsed) {
        window.localStorage.setItem(this.storagePrefix + uid, '1');
      } else {
        window.localStorage.removeItem(this.storagePrefix + uid);
      }
    } catch (e) {
      /* storage unavailable — ignore */
    }
  }

  enhance(ce) {
    if (ce.dataset.vitecCollapseReady === '1') {
      return;
    }

    // The direct body of THIS element (not a nested child's body).
    const element = ce.querySelector(':scope > .t3-page-ce-element');
    if (!element) {
      return;
    }
    const body = element.querySelector(':scope > .t3-page-ce-body');
    if (!body) {
      return;
    }

    // A container is recognised by a nested b13 grid inside its body.
    const hasNestedGrid = body.querySelector('.t3-grid-container') !== null;
    if (!hasNestedGrid) {
      return;
    }

    // Best-effort VITEC filter via the header icon identifier
    // (b13 sets the icon identifier to the CType, e.g. "vitec_container").
    const iconEl = ce.querySelector(
      '.t3-page-ce-header-left typo3-backend-icon[identifier], .t3-page-ce-header-left [data-identifier]'
    );
    if (iconEl) {
      const identifier =
        iconEl.getAttribute('identifier') || iconEl.getAttribute('data-identifier') || '';
      if (identifier && identifier.indexOf('vitec') === -1) {
        return; // a non-VITEC container — leave it alone
      }
    }

    const toolbar = element.querySelector(
      ':scope > .t3-page-ce-header .btn-toolbar .btn-group'
    );
    if (!toolbar) {
      return;
    }

    ce.dataset.vitecCollapseReady = '1';
    const uid = ce.dataset.uid;

    const button = document.createElement('button');
    button.type = 'button';
    button.className = 'btn btn-sm btn-default btn-borderless vitec-collapse-toggle';
    button.title = 'Collapse / expand container';
    button.setAttribute('aria-label', 'Collapse or expand container');
    button.innerHTML =
      '<typo3-backend-icon identifier="actions-chevron-up" size="small"></typo3-backend-icon>';

    toolbar.insertBefore(button, toolbar.firstChild);

    if (this.isCollapsed(uid)) {
      ce.classList.add('vitec-ce-collapsed');
    }
    this.syncPreviewHeader(ce);

    button.addEventListener('click', (event) => {
      event.preventDefault();
      event.stopPropagation();
      const collapsed = ce.classList.toggle('vitec-ce-collapsed');
      this.setCollapsed(uid, collapsed);
      this.syncPreviewHeader(ce);
    });
  }

  /**
   * Keep the element's own `.element-preview-header` visible while collapsed:
   * it is moved into the CE header row (after `.t3-page-ce-header-right`) and
   * moved back to its original spot (placeholder marker) on expand.
   */
  syncPreviewHeader(ce) {
    const element = ce.querySelector(':scope > .t3-page-ce-element');
    if (!element) {
      return;
    }
    const header = element.querySelector(':scope > .t3-page-ce-header');
    const body = element.querySelector(':scope > .t3-page-ce-body');
    if (!header || !body) {
      return;
    }

    const collapsed = ce.classList.contains('vitec-ce-collapsed');

    if (collapsed) {
      // Find THIS element's preview header (not one of a nested child CE).
      let preview = null;
      for (const candidate of body.querySelectorAll('.element-preview-header')) {
        if (candidate.closest('.t3-page-ce') === ce) {
          preview = candidate;
          break;
        }
      }
      if (!preview || header.contains(preview)) {
        return;
      }
      const placeholder = document.createElement('span');
      placeholder.className = 'vitec-preview-header-placeholder';
      placeholder.hidden = true;
      preview.before(placeholder);
      preview.classList.add('vitec-preview-header--in-header');
      const headerRight = header.querySelector('.t3-page-ce-header-right');
      if (headerRight) {
        headerRight.insertAdjacentElement('afterend', preview);
      } else {
        header.appendChild(preview);
      }
    } else {
      const preview = header.querySelector('.element-preview-header.vitec-preview-header--in-header');
      const placeholder = body.querySelector('.vitec-preview-header-placeholder');
      if (preview && placeholder) {
        preview.classList.remove('vitec-preview-header--in-header');
        placeholder.replaceWith(preview);
      } else if (preview) {
        preview.classList.remove('vitec-preview-header--in-header');
        body.prepend(preview);
      }
    }
  }
}

export default new VitecContainerCollapse();