chat-engine
Version:
217 lines (168 loc) • 7.04 kB
JavaScript
const Emitter = require('../modules/emitter');
const eachSeries = require('async/eachSeries');
const eventFilter = require('../plugins/filter/event');
const senderFilter = require('../plugins/filter/sender');
/**
Returned by {@link Chat#search}. This is our Search class which allows one to search the backlog of messages.
Powered by [PubNub History](https://www.pubnub.com/docs/web-javascript/storage-and-history).
@class Search
@extends Emitter
@extends RootEmitter
@param {ChatEngine} chatEngine This instance of the {@link ChatEngine} object.
@param {Chat} chat The {@link Chat} object to search.
@param {Object} config The configuration object. See {@link Chat#search} for a list of parameters.
*/
class Search extends Emitter {
constructor(chatEngine, chat, config = {}) {
super(chatEngine);
this.chatEngine = chatEngine;
this.name = 'Search';
/**
The {@link Chat} used for searching.
@type Chat
*/
this.chat = chat;
/**
An object containing configuration parameters supplied by {@link Chat#search}. See {@link Chat#search} for possible parameters.
@type {Object}
*/
this.config = config;
this.config.event = config.event;
this.config.limit = config.limit || 20;
this.config.channel = this.chat.channel;
this.config.includeTimetoken = true;
this.config.stringifiedTimeToken = true;
this.config.count = this.config.count || 100;
this.config.pages = this.config.pages || 10;
/** @private */
this.maxPage = this.config.pages;
/** @private */
this.numPage = 0;
/** @private */
this.referenceDate = this.config.end || 0;
/**
* Flag which represent whether there is potentially more data available in {@link Chat} history. This flag can
* be used for conditional call of {@link Chat#search}.
* @type {boolean}
*/
this.hasMore = true;
/** @private */
this.messagesBetweenTimetokens = this.config.start > '0' && this.config.end > '0';
/** @private */
this.needleCount = 0;
/**
* Call PubNub history in a loop.
* @private
*/
this.page = (pageDone) => {
let searchConfiguration = Object.assign({}, this.config, { start: this.referenceDate });
delete searchConfiguration.reverse;
delete searchConfiguration.end;
/**
* Requesting another page from PubNub History.
* @event Search#$"."page"."request
*/
this._emit('$.search.page.request');
this.chatEngine.pubnub.history(searchConfiguration, (status, response) => {
/**
* PubNub History returned a response.
* @event Search#$"."page"."response
*/
this._emit('$.search.page.response');
if (status.error) {
/**
* There was a problem fetching the history of this chat
* @event Chat#$"."error"."history
*/
this.chatEngine.throwError(this, 'trigger', 'search', new Error('There was a problem searching history. Make sure your request parameters are valid and history is enabled for this PubNub key.'), status);
} else {
const startDate = response.startTimeToken;
this.referenceDate = response.startTimeToken;
this.hasMore = response.messages.length === this.config.count && startDate !== '0';
response.messages.sort((left, right) => (left.timetoken < right.timetoken ? -1 : 1));
if (this.config.start && startDate < this.config.start) {
this.hasMore = false;
response.messages = response.messages.filter(event => event.timetoken >= this.config.start);
}
pageDone(response);
}
});
};
/**
* @private
*/
this.triggerHistory = (message, cb) => {
if (this.needleCount < this.config.limit || this.messagesBetweenTimetokens) {
message.entry.timetoken = message.timetoken;
this.trigger(message.entry.event, message.entry, (reject) => {
if (!reject) {
this.needleCount += 1;
}
cb();
});
} else {
cb();
}
};
/**
* Continue searching the next batch of pages.
* @see $.search.pause
*/
this.next = () => {
if (this.hasMore) {
this.maxPage = this.maxPage + this.config.pages;
this.find();
} else {
/**
* Search has returned all results or reached the end of history.
* @event Search#$."search"."finish"
*/
this._emit('$.search.finish');
}
};
/**
* @private
*/
this.find = () => {
this.page((response) => {
response.messages.reverse();
this.numPage += 1;
eachSeries(response.messages, this.triggerHistory, () => {
if (this.hasMore && this.numPage === this.maxPage) {
/**
* PubNub History has reached the maximum allocated pages and requires user input to continue.
* @see Search#next
* @event Search#$"."search"."pause"
*/
this._emit('$.search.pause');
} else if (this.hasMore && (this.needleCount < this.config.limit || this.messagesBetweenTimetokens)) {
this.find();
} else {
if (this.needleCount >= this.config.limit && !this.messagesBetweenTimetokens) {
this.hasMore = false;
}
/**
* Search has returned all results or reached the end of history.
* @event Search#$"."search"."finish
*/
this._emit('$.search.finish');
}
});
});
return this;
};
if (this.config.event) {
this.plugins.unshift(eventFilter(this.config.event));
}
if (this.config.sender) {
this.plugins.unshift(senderFilter(this.config.sender));
}
/**
* Search has started.
* @event Search#$"."search"."start
*/
this._emit('$.search.start');
this.find();
}
}
module.exports = Search;