'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

const VERSION = "2.3.0";

/**
 * Some “list” response that can be paginated have a different response structure
 *
 * They have a `total_count` key in the response (search also has `incomplete_results`,
 * /installation/repositories also has `repository_selection`), as well as a key with
 * the list of the items which name varies from endpoint to endpoint.
 *
 * Octokit normalizes these responses so that paginated results are always returned following
 * the same structure. One challenge is that if the list response has only one page, no Link
 * header is provided, so this header alone is not sufficient to check wether a response is
 * paginated or not.
 *
 * We check if a "total_count" key is present in the response data, but also make sure that
 * a "url" property is not, as the "Get the combined status for a specific ref" endpoint would
 * otherwise match: https://developer.github.com/v3/repos/statuses/#get-the-combined-status-for-a-specific-ref
 */
function normalizePaginatedListResponse(response) {
  const responseNeedsNormalization = "total_count" in response.data && !("url" in response.data);
  if (!responseNeedsNormalization) return response; // keep the additional properties intact as there is currently no other way
  // to retrieve the same information.

  const incompleteResults = response.data.incomplete_results;
  const repositorySelection = response.data.repository_selection;
  const totalCount = response.data.total_count;
  delete response.data.incomplete_results;
  delete response.data.repository_selection;
  delete response.data.total_count;
  const namespaceKey = Object.keys(response.data)[0];
  const data = response.data[namespaceKey];
  response.data = data;

  if (typeof incompleteResults !== "undefined") {
    response.data.incomplete_results = incompleteResults;
  }

  if (typeof repositorySelection !== "undefined") {
    response.data.repository_selection = repositorySelection;
  }

  response.data.total_count = totalCount;
  return response;
}

function iterator(octokit, route, parameters) {
  const options = typeof route === "function" ? route.endpoint(parameters) : octokit.request.endpoint(route, parameters);
  const requestMethod = typeof route === "function" ? route : octokit.request;
  const method = options.method;
  const headers = options.headers;
  let url = options.url;
  return {
    [Symbol.asyncIterator]: () => ({
      next() {
        if (!url) {
          return Promise.resolve({
            done: true
          });
        }

        return requestMethod({
          method,
          url,
          headers
        }).then(normalizePaginatedListResponse).then(response => {
          // `response.headers.link` format:
          // '<https://api.github.com/users/aseemk/followers?page=2>; rel="next", <https://api.github.com/users/aseemk/followers?page=2>; rel="last"'
          // sets `url` to undefined if "next" URL is not present or `link` header is not set
          url = ((response.headers.link || "").match(/<([^>]+)>;\s*rel="next"/) || [])[1];
          return {
            value: response
          };
        });
      }

    })
  };
}

function paginate(octokit, route, parameters, mapFn) {
  if (typeof parameters === "function") {
    mapFn = parameters;
    parameters = undefined;
  }

  return gather(octokit, [], iterator(octokit, route, parameters)[Symbol.asyncIterator](), mapFn);
}

function gather(octokit, results, iterator, mapFn) {
  return iterator.next().then(result => {
    if (result.done) {
      return results;
    }

    let earlyExit = false;

    function done() {
      earlyExit = true;
    }

    results = results.concat(mapFn ? mapFn(result.value, done) : result.value.data);

    if (earlyExit) {
      return results;
    }

    return gather(octokit, results, iterator, mapFn);
  });
}

/**
 * @param octokit Octokit instance
 * @param options Options passed to Octokit constructor
 */

function paginateRest(octokit) {
  return {
    paginate: Object.assign(paginate.bind(null, octokit), {
      iterator: iterator.bind(null, octokit)
    })
  };
}
paginateRest.VERSION = VERSION;

exports.paginateRest = paginateRest;
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