browser-layer.js

'use strict';

var MapiResponse = require('../classes/mapi-response');
var MapiError = require('../classes/mapi-error');
var constants = require('../constants');
var parseHeaders = require('../helpers/parse-headers');

// Keys are request IDs, values are XHRs.
var requestsUnderway = {};

function browserAbort(request) {
  var xhr = requestsUnderway[request.id];
  if (!xhr) return;
  xhr.abort();
  delete requestsUnderway[request.id];
}

function createResponse(request, xhr) {
  return new MapiResponse(request, {
    body: xhr.response,
    headers: parseHeaders(xhr.getAllResponseHeaders()),
    statusCode: xhr.status
  });
}

function normalizeBrowserProgressEvent(event) {
  var total = event.total;
  var transferred = event.loaded;
  var percent = (100 * transferred) / total;
  return {
    total: total,
    transferred: transferred,
    percent: percent
  };
}

function sendRequestXhr(request, xhr) {
  return new Promise(function(resolve, reject) {
    xhr.onprogress = function(event) {
      request.emitter.emit(
        constants.EVENT_PROGRESS_DOWNLOAD,
        normalizeBrowserProgressEvent(event)
      );
    };

    var file = request.file;
    if (file) {
      xhr.upload.onprogress = function(event) {
        request.emitter.emit(
          constants.EVENT_PROGRESS_UPLOAD,
          normalizeBrowserProgressEvent(event)
        );
      };
    }

    xhr.onerror = function(error) {
      reject(error);
    };

    xhr.onabort = function() {
      var mapiError = new MapiError({
        request: request,
        type: constants.ERROR_REQUEST_ABORTED
      });
      reject(mapiError);
    };

    xhr.onload = function() {
      delete requestsUnderway[request.id];
      if (xhr.status < 200 || xhr.status >= 400) {
        var mapiError = new MapiError({
          request: request,
          body: xhr.response,
          statusCode: xhr.status
        });
        reject(mapiError);
        return;
      }
      resolve(xhr);
    };

    var body = request.body;

    // matching service needs to send a www-form-urlencoded request
    if (typeof body === 'string') {
      xhr.send(body);
    } else if (body) {
      xhr.send(JSON.stringify(body));
    } else if (file) {
      xhr.send(file);
    } else {
      xhr.send();
    }

    requestsUnderway[request.id] = xhr;
  }).then(function(xhr) {
    return createResponse(request, xhr);
  });
}

// The accessToken argument gives this function flexibility
// for Mapbox's internal client.
function createRequestXhr(request, accessToken) {
  var url = request.url(accessToken);
  var xhr = new window.XMLHttpRequest();
  xhr.open(request.method, url);
  Object.keys(request.headers).forEach(function(key) {
    xhr.setRequestHeader(key, request.headers[key]);
  });
  return xhr;
}

function browserSend(request) {
  return Promise.resolve().then(function() {
    var xhr = createRequestXhr(request, request.client.accessToken);
    return sendRequestXhr(request, xhr);
  });
}

module.exports = {
  browserAbort: browserAbort,
  sendRequestXhr: sendRequestXhr,
  browserSend: browserSend,
  createRequestXhr: createRequestXhr
};