mirror of https://github.com/moparisthebest/mail
124 lines
3.2 KiB
JavaScript
124 lines
3.2 KiB
JavaScript
/**
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* Handles generic caching of JSON objects in a lawnchair adapter
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*/
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define(['lawnchair', 'lawnchairSQL', 'lawnchairIDB'], function(Lawnchair) {
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'use strict';
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var self = {},
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db;
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self.init = function(dbName) {
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if (!dbName) {
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throw new Error('Lawnchair DB name must be specified!');
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}
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db = new Lawnchair({
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name: dbName
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}, function(lc) {
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if (!lc) {
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throw new Error('Lawnchair init failed!');
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}
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});
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};
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/**
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* Create or update an object
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*/
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self.persist = function(key, object, callback) {
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db.save({
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key: key,
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object: object
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}, callback);
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};
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/**
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* Persist a bunch of items at once
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*/
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self.batch = function(list, callback) {
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db.batch(list, callback);
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};
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/**
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* Read a single item by its key
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*/
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self.read = function(key, callback) {
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db.get(key, function(o) {
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if (o) {
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callback(o.object);
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} else {
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callback();
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}
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});
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};
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/**
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* List all the items of a certain type
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* @param type [String] The type of item e.g. 'email'
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* @param offset [Number] The offset of items to fetch (0 is the last stored item)
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* @param num [Number] The number of items to fetch (null means fetch all)
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*/
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self.list = function(type, offset, num, callback) {
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var i, from, to,
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matchingKeys = [],
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intervalKeys = [],
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list = [];
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// get all keys
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db.keys(function(keys) {
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// check if key begins with type
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keys.forEach(function(key) {
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if (key.indexOf(type) === 0) {
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matchingKeys.push(key);
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}
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});
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// sort keys
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matchingKeys.sort();
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// set window of items to fetch
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// if num is null, list all items
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from = (num) ? matchingKeys.length - offset - num : 0;
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to = matchingKeys.length - 1 - offset;
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// filter items within requested interval
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for (i = 0; i < matchingKeys.length; i++) {
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if (i >= from && i <= to) {
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intervalKeys.push(matchingKeys[i]);
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}
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}
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// return if there are no matching keys
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if (intervalKeys.length === 0) {
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callback(list);
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return;
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}
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// fetch all items from data-store with matching key
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db.get(intervalKeys, function(intervalList) {
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intervalList.forEach(function(item) {
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list.push(item.object);
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});
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// return only the interval between offset and num
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callback(list);
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});
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});
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};
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/**
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* Removes an object liter from local storage by its key (delete)
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*/
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self.remove = function(key, callback) {
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db.remove(key, callback);
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};
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/**
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* Clears the whole local storage cache
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*/
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self.clear = function(callback) {
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db.nuke(callback);
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};
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return self;
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}); |