Guess user timezone

moment-timezone-utils.js

@@ -117,6 +117,18 @@
 		return abbrs.join(' ') + '|' + offsets.join(' ') + '|' + indices.join('');
 	}
 
+	function packPopulation (number) {
+		if (!number) {
+			return '';
+		}
+		if (number < 1000) {
+			return '|' + number;
+		}
+		var exponent = String(number | 0).length - 2;
+		var precision = Math.round(number / Math.pow(10, exponent));
+		return '|' + precision + 'e' + exponent;
+	}
+
 	function validatePackData (source) {
 		if (!source.name)    { throw new Error("Missing name"); }
 		if (!source.abbrs)   { throw new Error("Missing abbrs"); }
@@ -132,7 +144,11 @@
 
 	function pack (source) {
 		validatePackData(source);
-		return source.name + '|' + packAbbrsAndOffsets(source) + '|' + packUntils(source.untils);
+		return [
+			source.name,
+			packAbbrsAndOffsets(source),
+			packUntils(source.untils) + packPopulation(source.population)
+		].join('|');
 	}
 
 	/************************************
@@ -157,24 +173,35 @@
 	}
 
 	function findAndCreateLinks (input, output, links) {
-		var i, j, a, b, isUnique;
+		var i, j, a, b, group, foundGroup, groups = [];
 
 		for (i = 0; i < input.length; i++) {
-			isUnique = true;
+			foundGroup = false;
 			a = input[i];
 
-			for (j = 0; j < output.length; j++) {
-				b = output[j];
-
+			for (j = 0; j < groups.length; j++) {
+				group = groups[j];
+				b = group[0];
 				if (zonesAreEqual(a, b)) {
-					links.push(b.name + '|' + a.name);
-					isUnique = false;
-					continue;
+					if (a.population > b.population) {
+						group.unshift(a);
+					} else {
+						group.push(a);
+					}
+					foundGroup = true;
 				}
 			}
 
-			if (isUnique) {
-				output.push(a);
+			if (!foundGroup) {
+				groups.push([a]);
+			}
+		}
+
+		for (i = 0; i < groups.length; i++) {
+			group = groups[i];
+			output.push(group[0]);
+			for (j = 1; j < group.length; j++) {
+				links.push(group[0].name + '|' + group[j].name);
 			}
 		}
 	}
@@ -240,10 +267,11 @@
 		untils[untils.length - 1] = null;
 
 		return {
-			name    : source.name,
-			abbrs   : slice.apply(source.abbrs, indices),
-			untils  : untils,
-			offsets : slice.apply(source.offsets, indices)
+			name       : source.name,
+			abbrs      : slice.apply(source.abbrs, indices),
+			untils     : untils,
+			offsets    : slice.apply(source.offsets, indices),
+			population : source.population
 		};
 	}
 

moment-timezone.js

@@ -28,6 +28,8 @@
 		zones = {},
 		links = {},
 		names = {},
+		guesses = {},
+		cachedGuess,
 
 		momentVersion = moment.version.split('.'),
 		major = +momentVersion[0],
@@ -120,10 +122,11 @@
 		intToUntil(untils, indices.length);
 
 		return {
-			name    : data[0],
-			abbrs   : mapIndices(data[1].split(' '), indices),
-			offsets : mapIndices(offsets, indices),
-			untils  : untils
+			name       : data[0],
+			abbrs      : mapIndices(data[1].split(' '), indices),
+			offsets    : mapIndices(offsets, indices),
+			untils     : untils,
+			population : data[5] | 0
 		};
 	}
 
@@ -139,10 +142,11 @@
 
 	Zone.prototype = {
 		_set : function (unpacked) {
-			this.name    = unpacked.name;
-			this.abbrs   = unpacked.abbrs;
-			this.untils  = unpacked.untils;
-			this.offsets = unpacked.offsets;
+			this.name       = unpacked.name;
+			this.abbrs      = unpacked.abbrs;
+			this.untils     = unpacked.untils;
+			this.offsets    = unpacked.offsets;
+			this.population = unpacked.population;
 		},
 
 		_index : function (timestamp) {
@@ -192,6 +196,154 @@
 		}
 	};
 
+	/************************************
+		Current Timezone
+	************************************/
+
+	function OffsetAt(at) {
+		var timeString = at.toTimeString();
+		var abbr = timeString.match(/\(.+\)/);
+		if (abbr && abbr[0]) {
+			// 17:56:31 GMT-0600 (CST)
+			// 17:56:31 GMT-0600 (Central Standard Time)
+			abbr = abbr[0].match(/[A-Z]/g).join('');
+		} else {
+			// 17:56:31 CST
+			abbr = timeString.match(/[A-Z]{3,5}/g)[0];
+		}
+
+		if (abbr === 'GMT') {
+			abbr = undefined;
+		}
+
+		this.at = +at;
+		this.abbr = abbr;
+		this.offset = at.getTimezoneOffset();
+	}
+
+	function ZoneScore(zone) {
+		this.zone = zone;
+		this.offsetScore = 0;
+		this.abbrScore = 0;
+	}
+
+	ZoneScore.prototype.scoreOffsetAt = function (offsetAt) {
+		this.offsetScore += Math.abs(this.zone.offset(offsetAt.at) - offsetAt.offset);
+		if (this.zone.abbr(offsetAt.at).match(/[A-Z]/g).join('') !== offsetAt.abbr) {
+			this.abbrScore++;
+		}
+	};
+
+	function findChange(low, high) {
+		var mid, diff;
+
+		while ((diff = ((high.at - low.at) / 12e4 | 0) * 6e4)) {
+			mid = new OffsetAt(new Date(low.at + diff));
+			if (mid.offset === low.offset) {
+				low = mid;
+			} else {
+				high = mid;
+			}
+		}
+
+		return low;
+	}
+
+	function userOffsets() {
+		var startYear = new Date().getFullYear() - 2,
+			last = new OffsetAt(new Date(startYear, 0, 1)),
+			offsets = [last],
+			change, next, i;
+
+		for (i = 1; i < 48; i++) {
+			next = new OffsetAt(new Date(startYear, i, 1));
+			if (next.offset !== last.offset) {
+				change = findChange(last, next);
+				offsets.push(change);
+				offsets.push(new OffsetAt(new Date(change.at + 6e4)));
+			}
+			last = next;
+		}
+
+		for (i = 0; i < 4; i++) {
+			offsets.push(new OffsetAt(new Date(startYear + i, 0, 1)));
+			offsets.push(new OffsetAt(new Date(startYear + i, 6, 1)));
+		}
+
+		return offsets;
+	}
+
+	function sortZoneScores (a, b) {
+		if (a.offsetScore !== b.offsetScore) {
+			return a.offsetScore - b.offsetScore;
+		}
+		if (a.abbrScore !== b.abbrScore) {
+			return a.abbrScore - b.abbrScore;
+		}
+		return b.zone.population - a.zone.population;
+	}
+
+	function addToGuesses (name, offsets) {
+		var i, offset;
+		arrayToInt(offsets);
+		for (i = 0; i < offsets.length; i++) {
+			offset = offsets[i];
+			guesses[offset] = guesses[offset] || {};
+			guesses[offset][name] = true;
+		}
+	}
+
+	function guessesForUserOffsets (offsets) {
+		var offsetsLength = offsets.length,
+			filteredGuesses = {},
+			out = [],
+			i, j, guessesOffset;
+
+		for (i = 0; i < offsetsLength; i++) {
+			guessesOffset = guesses[offsets[i].offset] || {};
+			for (j in guessesOffset) {
+				if (guessesOffset.hasOwnProperty(j)) {
+					filteredGuesses[j] = true;
+				}
+			}
+		}
+
+		for (i in filteredGuesses) {
+			if (filteredGuesses.hasOwnProperty(i)) {
+				out.push(names[i]);
+			}
+		}
+
+		return out;
+	}
+
+	function rebuildGuess () {
+		var offsets = userOffsets(),
+			offsetsLength = offsets.length,
+			guesses = guessesForUserOffsets(offsets),
+			zoneScores = [],
+			zoneScore, i, j;
+
+		for (i = 0; i < guesses.length; i++) {
+			zoneScore = new ZoneScore(getZone(guesses[i]), offsetsLength);
+			for (j = 0; j < offsetsLength; j++) {
+				zoneScore.scoreOffsetAt(offsets[j]);
+			}
+			zoneScores.push(zoneScore);
+		}
+
+		zoneScores.sort(sortZoneScores);
+
+		return zoneScores.length > 0 ? zoneScores[0].zone.name : undefined;
+	}
+
+	function guess (ignoreCache) {
+		if (!cachedGuess || ignoreCache) {
+			cachedGuess = rebuildGuess();
+		}
+		return cachedGuess;
+	}
+
 	/************************************
 		Global Methods
 	************************************/
@@ -201,17 +353,21 @@
 	}
 
 	function addZone (packed) {
-		var i, name, normalized;
+		var i, name, split, normalized;
 
 		if (typeof packed === "string") {
 			packed = [packed];
 		}
 
 		for (i = 0; i < packed.length; i++) {
-			name = packed[i].split('|')[0];
+			split = packed[i].split('|');
+			name = split[0];
 			normalized = normalizeName(name);
 			zones[normalized] = packed[i];
 			names[normalized] = name;
+			if (split[5]) {
+				addToGuesses(normalized, split[2].split(' '));
+			}
 		}
 	}
 
@@ -220,7 +376,7 @@
 
 		var zone = zones[name];
 		var link;
-		
+
 		if (zone instanceof Zone) {
 			return zone;
 		}
@@ -328,6 +484,7 @@
 	tz.load         = loadData;
 	tz.zone         = getZone;
 	tz.zoneExists   = zoneExists; // deprecated in 0.1.0
+	tz.guess        = guess;
 	tz.names        = getNames;
 	tz.Zone         = Zone;
 	tz.unpack       = unpack;

tasks/data-collect.js

@@ -1,7 +1,8 @@
 "use strict";
 
 var path = require('path'),
-	moment = require('moment');
+	moment = require('moment'),
+	populations = require('./population.json');
 
 module.exports = function (grunt) {
 	grunt.registerTask('data-collect', '4. Collect all data from zdump(8) into a single json file.', function (version) {
@@ -12,6 +13,7 @@ module.exports = function (grunt) {
 
 		files.forEach(function (file) {
 			var lines   = grunt.file.read(path.join('temp/zdump/' + version, file)).split('\n'),
+				name    = file.replace(/\.zdump$/, ''),
 				abbrs   = [],
 				untils  = [],
 				offsets = [];
@@ -30,10 +32,11 @@ module.exports = function (grunt) {
 			});
 
 			data.push({
-				name    : file.replace(/\.zdump$/, ''),
-				abbrs   : abbrs,
-				untils  : untils,
-				offsets : offsets
+				name       : name,
+				abbrs      : abbrs,
+				untils     : untils,
+				offsets    : offsets,
+				population : populations[name] | 0
 			});
 		});
 

tasks/data-dedupe.js

@@ -17,10 +17,11 @@ function dedupe(zone) {
 	}
 
 	return {
-		name    : zone.name,
-		abbrs   : abbrs,
-		untils  : untils,
-		offsets : offsets
+		name       : zone.name,
+		abbrs      : abbrs,
+		untils     : untils,
+		offsets    : offsets,
+		population : zone.population
 	};
 }
 
@@ -53,4 +54,4 @@ module.exports = function (grunt) {
 
 		grunt.log.ok('Deduped data for ' + version);
 	});
-};
+};