web-annotation-discovery-webextension/src/background

import { isAnnotationMimeType } from '../discovery';
import notify from '../util/notify';
import { AnnotationSource } from '../storage/AnnotationSource';

// When the user navigates to an annotation (collection) directly, suggest
// whether they want to import the annotation(s).

function onHeadersReceived({
  responseHeaders,
  url,
}: {
  responseHeaders?: browser.webRequest.HttpHeaders;
  url: string;
}) {
  const isAnnotation = responseHeaders?.some(
    (header) =>
      header.name.toLowerCase() === 'content-type' &&
      header.value &&
      isAnnotationMimeType(header.value),
  );

  if (isAnnotation) {
    notify({
      title: 'Import Web Annotation(s)',
      iconUrl: '/assets/icon/icon.svg',
      message:
        'You opened a Web Annotation (Collection). Click here to import it to your annotation library.',
      onClicked() {
        // Note we do not have the response yet at this point. For simplicity, just
        // add it as an (inactive) source, then it will be fetched again.
        AnnotationSource.addSource(
          {
            type: 'container',
            url,
            title: 'Manually imported annotation',
          },
          false,
        );
      },
    });
  }
}

browser.webRequest.onHeadersReceived.addListener(
  onHeadersReceived,
  {
    urls: ['<all_urls>'],
    types: ['main_frame'],
  },
  ['responseHeaders'],
);

// As files loaded through file://… URLs do not have headers, we run a separate check for these.
async function onVisitFileUrl({ url, tabId }: { url: string; tabId: number }) {
  // TODO (likely to be quite a hassle, if possible at all..)
}

browser.webNavigation.onCommitted.addListener(onVisitFileUrl, {
  url: [{ schemes: ['file'] }],
});