import {NotFoundError, NetworkError, BadRequestError} from "./errors";
import forEach from 'lodash/forEach';
let URI = require("urijs");
let URITemplate = require("urijs/src/URITemplate");
let axios = require("axios");
var EventSource = (typeof window === 'undefined') ? require('eventsource') : window.EventSource;
let toBluebird = require("bluebird").resolve;
/**
* Creates a new {@link CallBuilder} pointed to server defined by serverUrl.
*
* This is an **abstract** class. Do not create this object directly, use {@link Server} class.
* @param {string} serverUrl
* @class CallBuilder
*/
export class CallBuilder {
constructor(serverUrl) {
this.url = serverUrl;
this.filter = [];
this.originalSegments = this.url.segment() || [];
}
/**
* @private
*/
checkFilter() {
if (this.filter.length >= 2) {
throw new BadRequestError("Too many filters specified", this.filter);
}
if (this.filter.length === 1) {
//append filters to original segments
let newSegment = this.originalSegments.concat(this.filter[0]);
this.url.segment(newSegment);
}
}
/**
* Triggers a HTTP request using this builder's current configuration.
* Returns a Promise that resolves to the server's response.
* @returns {Promise}
*/
call() {
this.checkFilter();
return this._sendNormalRequest(this.url)
.then(r => this._parseResponse(r));
}
/**
* Creates an EventSource that listens for incoming messages from the server. To stop listening for new
* events call the function returned by this method.
* @see [Frontier Response Format](https://developer.digitalbits.io/frontier/learn/responses.html)
* @see [MDN EventSource](https://developer.mozilla.org/en-US/docs/Web/API/EventSource)
* @param {object} [options] EventSource options.
* @param {function} [options.onmessage] Callback function to handle incoming messages.
* @param {function} [options.onerror] Callback function to handle errors.
* @param {number} [options.reconnectTimeout] Custom stream connection timeout in ms, default is 15 seconds.
* @returns {function} Close function. Run to close the connection and stop listening for new events.
*/
stream(options) {
this.checkFilter();
// EventSource object
let es;
// timeout is the id of the timeout to be triggered if there were no new messages
// in the last 15 seconds. The timeout is reset when a new message arrive.
// It prevents closing EventSource object in case of 504 errors as `readyState`
// property is not reliable.
let timeout;
var createTimeout = () => {
timeout = setTimeout(() => {
es.close();
es = createEventSource();
}, options.reconnectTimeout || 15*1000);
};
var createEventSource = () => {
try {
es = new EventSource(this.url.toString());
} catch (err) {
if (options.onerror) {
options.onerror(err);
options.onerror('EventSource not supported');
}
return false;
}
createTimeout();
es.onmessage = message => {
var result = message.data ? this._parseRecord(JSON.parse(message.data)) : message;
if (result.paging_token) {
this.url.setQuery("cursor", result.paging_token);
}
clearTimeout(timeout);
createTimeout();
options.onmessage(result);
};
es.onerror = error => {
if (options.onerror) {
options.onerror(error);
}
};
return es;
};
createEventSource();
return function close() {
clearTimeout(timeout);
es.close();
};
}
/**
* @private
*/
_requestFnForLink(link) {
return opts => {
let uri;
if (link.templated) {
let template = URITemplate(link.href);
uri = URI(template.expand(opts || {}));
} else {
uri = URI(link.href);
}
return this._sendNormalRequest(uri).then(r => this._parseRecord(r));
};
}
/**
* Convert each link into a function on the response object.
* @private
*/
_parseRecord(json) {
if (!json._links) {
return json;
}
forEach(json._links, (n, key) => {
// If the key with the link name already exists, create a copy
if (typeof json[key] != 'undefined') {
json[`${key}_attr`] = json[key];
}
json[key] = this._requestFnForLink(n);
});
return json;
}
_sendNormalRequest(url) {
if (url.authority() === '') {
url = url.authority(this.url.authority());
}
if (url.protocol() === '') {
url = url.protocol(this.url.protocol());
}
// Temp fix for: https://github.com/digitalbitsorg/js-digitalbits-sdk/issues/15
url.addQuery('c', Math.random());
var promise = axios.get(url.toString())
.then(response => response.data)
.catch(this._handleNetworkError);
return toBluebird(promise);
}
/**
* @private
*/
_parseResponse(json) {
if (json._embedded && json._embedded.records) {
return this._toCollectionPage(json);
} else {
return this._parseRecord(json);
}
}
/**
* @private
*/
_toCollectionPage(json) {
for (var i = 0; i < json._embedded.records.length; i++) {
json._embedded.records[i] = this._parseRecord(json._embedded.records[i]);
}
return {
records: json._embedded.records,
next: () => {
return this._sendNormalRequest(URI(json._links.next.href))
.then(r => this._toCollectionPage(r));
},
prev: () => {
return this._sendNormalRequest(URI(json._links.prev.href))
.then(r => this._toCollectionPage(r));
}
};
}
/**
* @private
*/
_handleNetworkError(response) {
if (response instanceof Error) {
return Promise.reject(response);
} else {
switch (response.status) {
case 404:
return Promise.reject(new NotFoundError(response.data, response));
default:
return Promise.reject(new NetworkError(response.status, response));
}
}
}
/**
* Adds `cursor` parameter to the current call. Returns the CallBuilder object on which this method has been called.
* @see [Paging](https://developer.digitalbits.io/frontier/learn/paging.html)
* @param {string} cursor A cursor is a value that points to a specific location in a collection of resources.
*/
cursor(cursor) {
this.url.addQuery("cursor", cursor);
return this;
}
/**
* Adds `limit` parameter to the current call. Returns the CallBuilder object on which this method has been called.
* @see [Paging](https://developer.digitalbits.io/frontier/learn/paging.html)
* @param {number} number Number of records the server should return.
*/
limit(number) {
this.url.addQuery("limit", number);
return this;
}
/**
* Adds `order` parameter to the current call. Returns the CallBuilder object on which this method has been called.
* @param {"asc"|"desc"} direction
*/
order(direction) {
this.url.addQuery("order", direction);
return this;
}
}