From d730aab674dfa5190e2419fc28d3c2de827c0c3e Mon Sep 17 00:00:00 2001
From: Ritchie Martori <skawful@gmail.com>
Date: Mon, 24 Jun 2013 16:38:50 -0700
Subject: [PATCH] Move geo filter creation into reusable module.

---
 lib/adapters/memory.js |  22 +-------
 lib/geo.js             | 124 +++++++++++++++++++++++++++++++++++++----
 lib/model-builder.js   |   2 +
 3 files changed, 117 insertions(+), 31 deletions(-)

diff --git a/lib/adapters/memory.js b/lib/adapters/memory.js
index 17b614bd..39295986 100644
--- a/lib/adapters/memory.js
+++ b/lib/adapters/memory.js
@@ -133,7 +133,7 @@ Memory.prototype.all = function all(model, filter, callback) {
             nodes = nodes.sort(sorting.bind(orders));
         }
         
-        var nearFilter = nearFilter(filter.where);
+        var nearFilter = geo.nearFilter(filter.where);
         
         // geo sorting
         if(nearFilter) {
@@ -170,26 +170,6 @@ Memory.prototype.all = function all(model, filter, callback) {
         }
         return 0;
     }
-    
-    function nearFilter(where) {
-      var result = false;
-      
-      if(where && typeof where === 'object') {
-        Object.keys(where).forEach(function (key) {
-          var ex = where[key];
-          
-          if(ex && ex.near) {
-            result = {
-              near: ex.near,
-              maxDistance: ex.maxDistance,
-              key: key
-            };
-          }
-        });
-      }
-      
-      return result;
-    }
 };
 
 function applyFilter(filter) {
diff --git a/lib/geo.js b/lib/geo.js
index 69f781ce..9b42a895 100644
--- a/lib/geo.js
+++ b/lib/geo.js
@@ -1,3 +1,37 @@
+/**
+ * Dependencies.
+ */
+
+var assert = require('assert');
+
+/*!
+ * Get a near filter from a given where object. For adapter use only.
+ */
+
+exports.nearFilter = function nearFilter(where) {
+  var result = false;
+  
+  if(where && typeof where === 'object') {
+    Object.keys(where).forEach(function (key) {
+      var ex = where[key];
+      
+      if(ex && ex.near) {
+        result = {
+          near: ex.near,
+          maxDistance: ex.maxDistance,
+          key: key
+        };
+      }
+    });
+  }
+  
+  return result;
+}
+
+/*!
+ * Filter a set of objects using the given `nearFilter`.
+ */
+
 exports.filter = function (arr, filter) {
   var origin = filter.near;
   var max = filter.maxDistance > 0 ? filter.maxDistance : false;
@@ -15,12 +49,13 @@ exports.filter = function (arr, filter) {
     if(typeof loc.lat !== 'number') return;
     if(typeof loc.lng !== 'number') return;
     
-    var d = distanceBetween(origin, loc);
+    var d = GeoPoint.distanceBetween(origin, loc);
     
     if(max && d > max) {
       // dont add
     } else {
       distances[obj.id] = d;
+      loc.distance = d;
       result.push(obj);
     }
   });
@@ -34,20 +69,89 @@ exports.filter = function (arr, filter) {
       var db = distances[objB.id];
       
       if(db === da) return 0;
-      return da > db ? -1 : 1;
+      return da > db ? 1 : -1;
     } else {
       return 0;
     }
   });
 }
 
-var distanceBetween = exports.distanceBetween = function distanceBetween(a, b) {
-  var xs = 0;
-  var ys = 0;
-  xs = a.lat - b.lat;
-  xs = xs * xs;
-  ys = a.lng - b.lng;
-  ys = ys * ys;
+/**
+ * Export the `GeoPoint` class.
+ */
+
+exports.GeoPoint = GeoPoint;
+
+function GeoPoint(data) {
+  if(!(this instanceof GeoPoint)) {
+    return new GeoPoint(data);
+  }
   
-  return Math.sqrt( xs + ys );
+  assert(typeof data === 'object', 'must provide a lat and lng object when creating a GeoPoint');
+  assert(typeof data.lat === 'number', 'lat must be a number when creating a GeoPoint');
+  assert(typeof data.lng === 'number', 'lng must be a number when creating a GeoPoint');
+  assert(data.lng <= 180, 'lng must be <= 180');
+  assert(data.lng >= -180, 'lng must be >= -180');
+  assert(data.lat <= 90, 'lat must be <= 90');
+  assert(data.lat >= -90, 'lat must be >= -90');
+  
+  this.lat = data.lat;
+  this.lng = data.lng;
+}
+
+/**
+ * Determine the spherical distance between two geo points.
+ */
+
+GeoPoint.distanceBetween = function distanceBetween(a, b, options) {
+  var x1 = a.lat;
+  var y1 = a.lng;
+  
+  var x2 = b.lat;
+  var y2 = b.lng;
+  
+  return geoDistance(x1, y1, x2, y2, options);
+}
+
+/**
+ * Determine the spherical distance to the given point.
+ */
+
+GeoPoint.prototype.distanceTo = function (point, options) {
+  return GeoPoint.distanceBetween(this, point, options);
+}
+
+// ratio of a circle's circumference to its diameter
+var PI = 3.1415926535897932384626433832795;
+
+// factor to convert decimal degrees to radians
+var DEG2RAD =  0.01745329252;
+
+// factor to convert decimal degrees to radians
+var RAD2DEG = 57.29577951308;
+
+// radius of the earth
+var EARTH_RADIUS = {
+  kilometers: 6370.99056,
+  meters: 6370990.56,
+  miles: 3958.75,
+  feet: 20902200,
+  radians: 1,
+  degrees: RAD2DEG
+};
+
+function geoDistance(x1, y1, x2, y2, options) {
+  // Convert to radians
+  x1 = x1 * DEG2RAD;
+  y1 = y1 * DEG2RAD;
+  x2 = x2 * DEG2RAD;
+  y2 = y2 * DEG2RAD;
+
+  a = Math.pow(Math.sin(( y2-y1 ) / 2.0 ), 2);
+  b = Math.pow(Math.sin(( x2-x1 ) / 2.0 ), 2);
+  c = Math.sqrt( a + Math.cos( y2 ) * Math.cos( y1 ) * b );
+
+  var type = (options && options.type) || 'miles';
+
+  return 2 * Math.asin( c ) * EARTH_RADIUS[type];
 }
\ No newline at end of file
diff --git a/lib/model-builder.js b/lib/model-builder.js
index 51b8e534..2e9bdf9f 100644
--- a/lib/model-builder.js
+++ b/lib/model-builder.js
@@ -7,6 +7,7 @@ var ModelBaseClass = require('./model.js');
 var List = require('./list.js');
 var EventEmitter = require('events').EventEmitter;
 var util = require('util');
+var GeoPoint = require('./geo').GeoPoint;
 
 /**
  * Export public API
@@ -46,6 +47,7 @@ ModelBuilder.registerType(Boolean);
 ModelBuilder.registerType(Date);
 ModelBuilder.registerType(Buffer, ['Binary']);
 ModelBuilder.registerType(Array);
+ModelBuilder.registerType(GeoPoint);
 
 
 /**