mac - add strategy for adding / removing attribute ID's

lib/mac/bindings.js

@@ -150,7 +150,57 @@ blenoBindings.on('kCBMsgId17', function(args) {
 });
 
 blenoBindings.addService = function AddGATTService(service) {
-  var attributeId = this._attributes.length ? this._attributes.length - 1 : 1;
+  var attributeId;
+  var attributeCount = 1 + service.characteristics.length;
+  var attributes = this._attributes;
+
+  /**
+   * The goal is to find an attribute range that can host the full service, which in most cases will be the next available push
+   * position. In the edge case, where our attribute consumes more Id's than the standard permits (0xFFFF), we must find
+   * a place within our attributes array that has been vacated or throw an error.
+   */
+  if(!attributes.length){
+    atrributeId = 1;
+} else if((attributes.length - 1 + attributeCount) >= 0xFFFF){
+    // perform search to find somewhere within our attributes array that contains a hole that can host the attributeCount
+    var consecutiveCount = 0;
+    var groupedOpenings = {};
+    for(var i = 0, ii = attributes.length; i++){
+        var attribute = attributes[i];
+        if(!attribute.kCBMsgArgAttributeID){
+            consecutiveCount++;
+        } else if(attribute.kCBMsgArgAttributeID && consecutiveCount){
+
+            // If we have found this amount of openings before, don't mark in our group so we use the first available.
+            if(!groupedOpenings[consecutiveCount].start){
+                var start = i - 1 - consecutiveCount;
+                var end = i + consecutiveCount - 1;
+                groupedOpenings[consecutiveCount] = { start: start, end: end};
+
+                if(consecutiveCount === attributeCount){
+                    break;
+                }
+            }
+            consecutiveCount = 0;
+        }
+    }
+
+    if(groupedOpenings[attributeCount].start){
+        attributeId = groupedOpenings[attributeCount].start;
+    } else {
+        for(var openingCount in groupedOpenings){
+            if(parseInt(openingCount, 10) > attributeCount){
+                attributeId = groupedOpenings[openingCount].start;
+                break;
+            }
+        }
+    }
+
+    if(!attributeId){
+        throw new Error('Not enough space to add service.');
+    }
+  }
+
   var arg = {
     kCBMsgArgAttributeID: attributeId,
     kCBMsgArgAttributeIDs: [],
@@ -225,6 +275,7 @@ blenoBindings.addService = function AddGATTService(service) {
       kCBMsgArgUUID: new Buffer(characteristic.uuid, 'hex')
     };
     this._attributes[attributeId] = characteristic;
+    characteristic.attributeId = attributeId;
 
     for (var k = 0; k < characteristic.descriptors.length; k++) {
       var descriptor = characteristic.descriptors[k];
@@ -241,17 +292,24 @@ blenoBindings.addService = function AddGATTService(service) {
 };
 
 blenoBindings.removeService = function RemoveGATTService(service){
-    var attributeId = this._attributes[service.attributeId];
+    var attributes = this._attributes;
+    var attributeId = service.attributeId;
+    var attribute = attributes[attributeId];
+    for(var i = 0, ii = attribute.characteristics.length; i < ii; i++){
+        var characteristic = attribute.characteristics[i];
+        attributes[characteristic.attributeId] = {};
+    }
+    attributes[attributeId] = {};
     var messageBody = {
         kCBMsgArgAttributeID: attributeId
     };
-    this._attributes[service.attributeId] = {};
     this.sendCBMsg(11, attributeId);
-}
+};
 
 blenoBindings.removeAllServices = function RemoveAllGATTServices(){
+    this._attributes = [];
     this.sendCBMsg(12, null);
-}
+};
 
 blenoBindings.setServices = function SetGATTServices(services) {
   this.sendCBMsg(12, null);