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316 lines
8.5 KiB
316 lines
8.5 KiB
'use strict';
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var utils = require('./utils');
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var calculate = module.exports = {};
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/**
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* Group array into object where keys are groups and values are arrays.
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* Groups determined by provided `fn`.
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*
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* ```js
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* var groups = calculate.group(downloads, function(download) {
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* // day is formatted as '2010-12-25'
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* // add this download to the '2010-12' group
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* return download.day.substr(0, 7);
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* });
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* ```
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* @param {Array} `arr` Array of download objects
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* @param {Function} `fn` Function to determine group the download belongs in.
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* @return {String} Key to use for the group
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* @api public
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*/
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calculate.group = function(arr, fn) {
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var groups = {};
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var len = arr.length, i = 0;
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while (len--) {
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var download = arr[i++];
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var groupArr = utils.arrayify(fn(download));
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groupArr.reduce(function(acc, group) {
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if (typeof group === 'string') {
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group = { name: group };
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}
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acc[group.name] = acc[group.name] || group;
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acc[group.name].downloads = acc[group.name].downloads || [];
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acc[group.name].downloads.push(download);
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return acc;
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}, groups);
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}
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return groups;
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};
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/**
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* Calculate the total for each group (key) in the object.
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*
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* @name group.total
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* @param {Object} `groups` Object created by a `group` function.
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* @return {Object} Object with calculated totals
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* @api public
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*/
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calculate.group.total = function(groups) {
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var res = {};
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var keys = Object.keys(groups);
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var len = keys.length, i = 0;
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while (len--) {
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var key = keys[i++];
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var group = groups[key];
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if (Array.isArray(group)) {
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res[key] = calculate.total(group);
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} else {
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res[key] = calculate.total(group.downloads);
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}
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}
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return res;
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};
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/**
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* Calculate the total downloads for an array of download objects.
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*
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* @param {Array} `arr` Array of download objects (must have a `.downloads` property)
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* @return {Number} Total of all downloads in the array.
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* @api public
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*/
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calculate.total = function(arr) {
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arr = utils.arrayify(arr);
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var len = arr.length, i = 0;
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var total = 0;
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while (len--) total += arr[i++].downloads || 0;
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return total;
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};
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/**
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* Calculate the average for each group (key) in the object.
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*
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* @name group.avg
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* @param {Object} `groups` Object created by a `group` function.
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* @return {Object} Object with calculated average
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* @api public
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*/
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calculate.group.avg = function(groups, days) {
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var res = {};
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var keys = Object.keys(groups);
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var len = keys.length, i = 0;
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while (len--) {
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var key = keys[i++];
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res[key] = calculate.avg(groups[key], days);
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}
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return res;
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};
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/**
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* Calculate the average downloads for an array of download objects.
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*
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* @param {Array} `arr` Array of download objects (must have a `.downloads` property)
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* @return {Number} Average of all downloads in the array.
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* @api public
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*/
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calculate.avg = function(arr, days) {
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arr = utils.arrayify(arr);
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var len = arr.length, i = 0;
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var total = 0;
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while (len--) {
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total += arr[i++].downloads || 0;
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}
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if (typeof days === 'undefined' || days === 0) {
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days = arr.length;
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}
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return total / days;
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};
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/**
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* Create an array of downloads before specified day.
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*
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* @name group.before
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* @param {String} `day` Day specifying last day to use in group.
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* @param {Array} `arr` Array of downloads to check.
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* @return {Array} Array of downloads happened before or on specified day.
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* @api public
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*/
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calculate.group.before = function(day, arr) {
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var end = utils.format(normalizeDate(utils.moment(day)));
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var group = [];
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var len = arr.length, i = 0;
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while (len--) {
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var download = arr[i++];
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if (download.day <= end) {
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group.push(download);
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}
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}
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return group;
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};
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/**
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* Calculate the total downloads happening before the specified day.
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*
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* @param {String} `day` Day specifying last day to use in group.
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* @param {Array} `arr` Array of downloads to check.
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* @return {Number} Total downloads happening before or on specified day.
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* @api public
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*/
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calculate.before = function(day, arr) {
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var group = calculate.group.before(day, arr);
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return calculate.total(group);
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};
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/**
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* Create an array of downloads for the last `X` days.
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*
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* @name group.last
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* @param {Number} `days` Number of days to go back.
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* @param {Array} `arr` Array of downloads to check.
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* @param {String} `init` Optional day to use as the last day to include. (Days from `init || today` - `days` to `init || today`)
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* @return {Array} Array of downloads for last `X` days.
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* @api public
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*/
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calculate.group.last = function(days, arr, init) {
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var today = init ? utils.moment.utc(init) : utils.moment.utc();
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var start = utils.moment.utc(today);
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start.subtract(days, 'days')
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today = utils.format(today);
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start = utils.format(start);
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var group = [];
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var len = arr.length, i = 0;
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while (len--) {
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var download = arr[i++];
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if (download.day > start && download.day <= today) {
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group.push(download);
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}
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}
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return group;
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};
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/**
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* Calculate total downloads for the last `X` days.
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*
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* @name last
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* @param {Number} `days` Number of days to go back.
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* @param {Array} `arr` Array of downloads to check.
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* @param {String} `init` Optional day to use as the last day to include. (Days from `init || today` - `days` to `init || today`)
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* @return {Array} Array of downloads for last `X` days.
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* @api public
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*/
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calculate.last = function(days, arr, init) {
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var group = calculate.group.last(days, arr, init);
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return calculate.total(group);
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};
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/**
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* Create an array of downloads for the previous `X` days.
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*
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* @name group.prev
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* @param {Number} `days` Number of days to go back.
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* @param {Array} `arr` Array of downloads to check.
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* @param {String} `init` Optional day to use as the prev day to include. (Days from `init || today` - `days` - `days` to `init || today` - `days`)
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* @return {Array} Array of downloads for prev `X` days.
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* @api public
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*/
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calculate.group.prev = function(days, arr, init) {
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var today = init ? utils.moment(init) : utils.moment();
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var end = utils.moment(today);
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end.subtract(days, 'days');
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return calculate.group.last(days, arr, end);
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};
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/**
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* Calculate total downloads for the previous `X` days.
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*
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* @name prev
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* @param {Number} `days` Number of days to go back.
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* @param {Array} `arr` Array of downloads to check.
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* @param {String} `init` Optional day to use as the prev day to include. (Days from `init || today` - `days` - `days` to `init || today` - `days`)
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* @return {Array} Array of downloads for prev `X` days.
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* @api public
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*/
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calculate.prev = function(days, arr, init) {
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var group = calculate.group.prev(days, arr, init);
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return calculate.total(group);
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};
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/**
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* Create an object of download groups by month.
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*
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* @param {Array} `arr` Array of downloads to group and total.
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* @return {Object} Groups with arrays of download objects
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* @api public
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*/
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calculate.group.monthly = function(arr) {
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return calculate.group(arr, function(download) {
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return download.day.substr(0, 7);
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});
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};
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function normalizeDate(date) {
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date.utc().hour(0);
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date.utc().minute(0);
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date.utc().second(0);
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return date;
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}
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calculate.group.window = function(days, arr, init) {
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var today = init ? utils.moment(init) : normalizeDate(utils.moment());
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arr = calculate.group.before(today, arr);
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return calculate.group(arr, function(download) {
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var day = utils.moment.utc(download.day);
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var diff = day.diff(today, 'days');
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var period = Math.floor((diff * -1) / days);
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var start = utils.moment(today);
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start.subtract((period + 1) * days, 'days');
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return {
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name: period,
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period: utils.format(start)
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};
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});
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};
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/**
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* Calculate total downloads grouped by month.
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*
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* @param {Array} `arr` Array of downloads to group and total.
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* @return {Object} Groups with total downloads calculated
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* @api public
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*/
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calculate.monthly = function(arr) {
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var months = calculate.group.monthly(arr);
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return calculate.group.total(months);
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};
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/**
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* Create an object of download groups by month.
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*
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* @param {Array} `arr` Array of downloads to group and total.
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* @return {Object} Groups with arrays of download objects
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* @api public
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*/
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calculate.group.yearly = function(arr) {
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return calculate.group(arr, function(download) {
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return download.day.substr(0, 4);
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});
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};
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/**
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* Calculate total downloads grouped by year.
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*
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* @param {Array} `arr` Array of downloads to group and total.
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* @return {Object} Groups with total downloads calculated
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* @api public
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*/
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calculate.yearly = function(arr) {
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var years = calculate.group.yearly(arr);
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return calculate.group.total(years);
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};
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