catalog.js

/*
 * List .json files found in root or first subdirectory level and
 * return them as a mirador catalog
 * This code works for webpack dev server and caddy (as file server), and is not expected
 * to function for other webservers
 */

export default {
  // url: relative or absolute path
  // depth: maximum depth for search of .json (use 0 to search only at root, 1 for first-level folders, etc)
  // subfolder: only for internal usage
  get_initial_catalog: function(url = '/data', depth=1, subfolder='') {
    if (depth < 0) {
      return;
    }
    const req_init = {headers: {'Accept': 'application/json'}};
    return fetch(`${url}/${subfolder}`, req_init)
      .then(response => {
        if (!response.ok) {
          throw new Error(`failed to list manifests from ${url}, http response code: ${reponse.status}`);
        }
        return response.json();
      })
      .then(async (response_json) => {
        // handling caddy response, which is like
        // [{name: "first.json", ...}, {name: "second.json", ...}, ...]
        if (response_json.length >= 1 && response_json[0].hasOwnProperty('name')) {
          response_json = response_json.map(e => e.name.replace(/\/$/, ''));
        }

        // assume all files which don't end in .json are folder
        let subfolders_content = await Promise.allSettled(response_json
          .filter(e => !e.endsWith('.json'))
          .map(folder => this.get_initial_catalog(url, depth - 1, folder))
        );

        // filter files from current folder
        // & append files from subfolders
        let items = response_json
          .filter(e => e.endsWith('.json'))
          .concat(subfolders_content
            // get only successfull queries & with a content
            .filter(p => p.status === "fulfilled" && p.value != null)
            .map(p => p.value)
          ).flat();

        // prepend with original url only if we are at the root folder,
        // else prepend only with current folder
        return items
          .map(e => subfolder == '' ? `${url}/${e}` : `${subfolder}/${e}`);
      });
  }
}