Refactor lqi scan (zigbeer#23)

* Use a composite key for lqiScan link deduplication

Composite key of concatenated parent and device ieee address means deduplication happens for the links rather than for the devices.

* Tidy lqiScan and include debug.

* Add network map link before recursing into child router

lib/shepherd.js

@@ -453,7 +453,7 @@ ZShepherd.prototype.lqi = function (ieeeAddr, callback) {
     }).then(function (rsp) {   // { srcaddr, status, neighbortableentries, startindex, neighborlqilistcount, neighborlqilist }
         if (rsp.status === 0)  // success
             return _.map(rsp.neighborlqilist, function (neighbor) {
-                return { ieeeAddr: neighbor.extAddr, nwkAddr: neighbor.nwkAddr, lqi: neighbor.lqi };
+                return { ieeeAddr: neighbor.extAddr, nwkAddr: neighbor.nwkAddr, lqi: neighbor.lqi, depth: neighbor.depth };
             });
     }).nodeify(callback);
 };
@@ -479,24 +479,32 @@ ZShepherd.prototype.remove = function (ieeeAddr, cfg, callback) {
 ZShepherd.prototype.lqiScan = function (ieeeAddr) {
     var info = this.info();
     var self = this;
-    const noDuplicate = {};
+    const visited = new Set();
+    const linkMap = {};
 
     const processResponse = function(parent){
         return function(data){
             var chain = Q();
             data.forEach(function (devinfo) {
-                const ieeeAddr = devinfo.ieeeAddr;
-                if (ieeeAddr == "0x0000000000000000") return;
-                let dev = self._findDevByAddr(ieeeAddr);
+                const childIeeeAddr = devinfo.ieeeAddr;
+                if (childIeeeAddr == "0x0000000000000000") return;
+                let childDev = self._findDevByAddr(childIeeeAddr);
                 devinfo.parent = parent;
-                devinfo.status = dev ? dev.status : "offline";
-                const dedupKey = parent + '|' + ieeeAddr;
-                if (dev && dev.type == "Router" && !noDuplicate[dedupKey]) {
+                devinfo.status = childDev ? childDev.status : "offline";
+                const linkKey = parent + '|' + childIeeeAddr
+                if (!linkMap[linkKey]) {
+                    linkMap[linkKey] = devinfo;
+                } else {
+                    debug.shepherd('Ignoring duplicate key %s.', linkKey);
+                }
+                if (childDev && childDev.type == "Router" && !visited.has(childIeeeAddr)) {
+                    visited.add(childIeeeAddr);
                     chain = chain.then(function () {
-                        return self.lqi(ieeeAddr).then(processResponse(ieeeAddr));
+                        return self.lqi(childIeeeAddr).then(processResponse(childIeeeAddr));
                     });
+                } else {
+                    debug.shepherd('LQI scan skipping %s from parent %s', childIeeeAddr, parent);
                 }
-                noDuplicate[dedupKey] = devinfo;
             });
             return chain;
         }
@@ -510,10 +518,10 @@ ZShepherd.prototype.lqiScan = function (ieeeAddr) {
         .timeout(5000)
         .then(processResponse(ieeeAddr))
         .then(function(){
-            return Object.values(noDuplicate);
+            return Object.values(linkMap);
         })
         .catch(function(){
-            return Object.values(noDuplicate);
+            return Object.values(linkMap);
         });
 };