243 lines
9.5 KiB
JavaScript
243 lines
9.5 KiB
JavaScript
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// Class MBLinks : query MusicBrainz for urls and display links for matching urls
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// The main method is searchAndDisplayMbLink()
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// Example:
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// $(document).ready(function () {
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//
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// var mblinks = new MBLinks('EXAMPLE_MBLINKS_CACHE', 7*24*60); // force refresh of cached links once a week
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//
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// var artist_link = 'http://' + window.location.href.match( /^https?:\/\/(.*)\/album\/.+$/i)[1];
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// mblinks.searchAndDisplayMbLink(artist_link, 'artist', function (link) { $('div#there').before(link); } );
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//
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// var album_link = 'http://' + window.location.href.match( /^https?:\/\/(.*\/album\/.+)$/i)[1];
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// mblinks.searchAndDisplayMbLink(album_link, 'release', function (link) { $('div#there').after(link); } );
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// }
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// user_cache_key = textual key used to store cached data in local storage
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// version = optionnal version, to force creation of a cache (ie. when format of keys changes)
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// expiration = time in minutes before an entry is refreshed, value <= 0 disables cache reads, if undefined or false, use defaults
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var MBLinks = function (user_cache_key, version, expiration) {
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this.supports_local_storage = (function () {
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try {
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return !!localStorage.getItem;
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} catch (e) {
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return false;
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}
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})();
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this.ajax_requests = {
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// properties: "key": {handler: function, next: property, context: {}}
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first: '',
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last: '',
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empty: function () {
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return this.first == '';
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},
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push: function (key, handler, context) {
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if (key in this) {
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this[key].handler = handler;
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this[key].context = context;
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} else {
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this[key] = { handler: handler, next: '', context: context };
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if (this.first == '') {
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this.first = this.last = key;
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} else {
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this[this.last].next = key;
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this.last = key;
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}
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}
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},
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shift: function () {
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if (this.empty()) {
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return;
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}
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let key = this.first;
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let handler = this[key].handler;
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let context = this[key].context;
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this.first = this[key].next;
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delete this[key]; // delete this property
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return $.proxy(handler, context);
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},
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};
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this.cache = {};
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this.expirationMinutes = typeof expiration != 'undefined' && expiration !== false ? parseInt(expiration, 10) : 90 * 24 * 60; // default to 90 days
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let cache_version = 2;
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this.user_cache_key = user_cache_key;
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this.cache_key = `${this.user_cache_key}-v${cache_version}${typeof version != 'undefined' ? `.${version}` : ''}`;
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this.mb_server = '//musicbrainz.org';
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// overrides link title and img src url (per type), see createMusicBrainzLink()
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this.type_link_info = {
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release_group: {
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title: 'See this release group on MusicBrainz',
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},
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place: {
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img_src: `<img src="${this.mb_server}/static/images/entity/place.svg" height=16 width=16 />`,
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},
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};
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this.initAjaxEngine = function () {
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let ajax_requests = this.ajax_requests;
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setInterval(function () {
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if (!ajax_requests.empty()) {
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let request = ajax_requests.shift();
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if (typeof request === 'function') {
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request();
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}
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}
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}, 1000);
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};
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this.initCache = function () {
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if (!this.supports_local_storage) return;
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// Check if we already added links for this content
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this.cache = JSON.parse(localStorage.getItem(this.cache_key) || '{}');
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// remove old entries
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this.clearCacheExpired();
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// remove old cache versions
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this.removeOldCacheVersions();
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};
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this.saveCache = function () {
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if (!this.supports_local_storage) return;
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try {
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localStorage.setItem(this.cache_key, JSON.stringify(this.cache));
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} catch (e) {
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alert(e);
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}
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};
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this.removeOldCacheVersions = function () {
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let to_remove = [];
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for (var i = 0, len = localStorage.length; i < len; ++i) {
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let key = localStorage.key(i);
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if (key.indexOf(this.user_cache_key) === 0) {
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if (key != this.cache_key) {
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// we don't want to remove current cache
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to_remove.push(key);
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}
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}
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}
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// remove old cache keys
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for (var i = 0; i < to_remove.length; i++) {
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localStorage.removeItem(to_remove[i]);
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}
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};
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this.clearCacheExpired = function () {
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//var old_cache_entries = Object.keys(this.cache).length;
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//console.log("clearCacheExpired " + old_cache_entries);
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let now = new Date().getTime();
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let new_cache = {};
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let that = this;
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$.each(this.cache, function (key, value) {
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if (that.is_cached(key)) {
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new_cache[key] = that.cache[key];
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}
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});
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//var new_cache_entries = Object.keys(new_cache).length;
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//console.log("Cleared cache entries: " + old_cache_entries + ' -> ' + new_cache_entries);
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this.cache = new_cache;
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};
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this.is_cached = function (key) {
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return (
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this.cache[key] &&
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this.expirationMinutes > 0 &&
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new Date().getTime() < this.cache[key].timestamp + this.expirationMinutes * 60 * 1000
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);
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};
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// Search for ressource 'url' in local cache, and return the matching MBID if there's only matching MB entity.
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// If the url is not known by the cache, no attempt will be made to request the MusicBrainz webservice, in order to keep this method synchronous.
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this.resolveMBID = function (key) {
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if (this.is_cached(key) && this.cache[key].urls.length == 1) {
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return this.cache[key].urls[0].slice(-36);
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}
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};
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this.createMusicBrainzLink = function (mb_url, _type) {
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let title = `See this ${_type} on MusicBrainz`;
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let img_url = `${this.mb_server}/static/images/entity/${_type}.svg`;
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let img_src = `<img src="${img_url}" height=16 width=16 />`;
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// handle overrides
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let ti = this.type_link_info[_type];
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if (ti) {
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if (ti.title) title = ti.title;
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if (ti.img_url) img_url = ti.img_url;
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if (ti.img_src) img_src = ti.img_src;
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}
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return `<a href="${mb_url}" title="${title}">${img_src}</a> `;
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};
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// Search for ressource 'url' on MB, for relation of type 'mb_type' (artist, release, label, release-group, ...)
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// and call 'insert_func' function with matching MB links (a tag built in createMusicBrainzLink) for each
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// entry found
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this.searchAndDisplayMbLink = function (url, mb_type, insert_func, key) {
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let mblinks = this;
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let _type = mb_type.replace('-', '_'); // underscored type
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if (!key) key = url;
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if (this.is_cached(key)) {
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$.each(mblinks.cache[key].urls, function (idx, mb_url) {
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insert_func(mblinks.createMusicBrainzLink(mb_url, _type));
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});
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} else {
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// webservice query url
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let query = `${mblinks.mb_server}/ws/2/url?resource=${encodeURIComponent(url)}&inc=${mb_type}-rels`;
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// Merge with previous context if there's already a pending ajax request
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let handlers = [];
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if (query in mblinks.ajax_requests) {
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handlers = mblinks.ajax_requests[query].context.handlers;
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}
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handlers.push(insert_func);
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mblinks.ajax_requests.push(
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// key
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query,
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// handler
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function () {
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let ctx = this; // context from $.proxy()
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let mbl = ctx.mblinks;
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$.getJSON(ctx.query, function (data) {
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if ('relations' in data) {
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mbl.cache[ctx.key] = {
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timestamp: new Date().getTime(),
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urls: [],
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};
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$.each(data['relations'], function (idx, relation) {
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if (ctx._type in relation) {
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let mb_url = `${mbl.mb_server}/${ctx.mb_type}/${relation[ctx._type]['id']}`;
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if ($.inArray(mb_url, mbl.cache[ctx.key].urls) == -1) {
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// prevent dupes
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mbl.cache[ctx.key].urls.push(mb_url);
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$.each(ctx.handlers, function (i, handler) {
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handler(mbl.createMusicBrainzLink(mb_url, ctx._type));
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});
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}
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}
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});
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mbl.saveCache();
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}
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});
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},
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// context
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{
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key: key, // cache key
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handlers: handlers, // list of handlers
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mb_type: mb_type, // musicbrainz type ie. release-group
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_type: _type, // musicbrainz type '-' replaced, ie. release_group
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query: query, // json request url
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mblinks: mblinks, // MBLinks object
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}
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);
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}
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};
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this.initCache();
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this.initAjaxEngine();
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return this;
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};
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