99 lines
2.4 KiB
JavaScript
99 lines
2.4 KiB
JavaScript
const EventEmitter = require('events').EventEmitter,
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common = require('../../lib/common');
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/**
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* Resource cache.
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*/
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class Resource extends EventEmitter {
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constructor(type, obj) {
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super();
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this.data = {};
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this.config = {
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type: type,
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reserved: false
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};
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Object.assign(this.data, obj);
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}
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/**
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* @description Get the type of the resource e.g. posts, users ...
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* @returns {String} type
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*/
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getType() {
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return this.config.type;
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}
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/**
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* @description Reserve a resource.
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*
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* This happens if a url generator's conditions matches a resource.
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* We have to reserve resources, because otherwise resources can appear in multiple url structures.
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*/
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reserve() {
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if (!this.config.reserved) {
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this.config.reserved = true;
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} else {
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common.logging.error(new common.errors.InternalServerError({
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message: 'Resource is already taken. This should not happen.',
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code: 'URLSERVICE_RESERVE_RESOURCE'
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}));
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}
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}
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/**
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* @description Release a resource.
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*
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* This happens if conditions of a url generator no longer matches a resource.
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* e.g. change a post to a page.
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*/
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release() {
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this.config.reserved = false;
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}
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/**
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* @description Check whether a resource is reserved.
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* @returns {boolean}
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*/
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isReserved() {
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return this.config.reserved === true;
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}
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/**
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* @description Update the resource cache.
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*
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* Emit update to subscribers - observer pattern.
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* e.g. url generator will listen on it's own resource's.
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*
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* @param {Object} obj - raw resource data
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*/
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update(obj) {
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Object.assign(this.data, obj);
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if (!this.isReserved()) {
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return;
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}
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this.emit('updated', this);
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}
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/**
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* @description Remove a resource.
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*
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* The fn is only useful to emit the action/event right now.
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*
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* CASE: url generator needs to know if one of it's resources/url should be removed.
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*/
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remove() {
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// CASE: do not emit, if it is not reserved, because nobody will listen on events.
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if (!this.isReserved()) {
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return;
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}
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this.emit('removed', this);
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}
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}
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module.exports = Resource;
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