refactor: entity informing elegance

server/game.js

@@ -14,8 +14,6 @@ import {Controllable} from './traits/controllable';
 registerTrait(Controllable);
 import {Informed} from './traits/informed';
 registerTrait(Informed);
-// Define range for entity updates.
-const INFORM_SIZE = [200, 200];
 // Create game.
 export default function(avocadoServer) {
   avocadoServer.on('connect', createConnectionListener(avocadoServer));
@@ -40,12 +38,8 @@ function createConnectionListener(avocadoServer) {
     socket.entity = entity;
     // Send current state.
     const currentState = stateSynchronizer.state().toJS();
-    const nearbyEntities = entity.nearbyEntities(INFORM_SIZE);
-    const reduced = entity.reduceStateDiff(nearbyEntities, currentState);
-    // Remove dead update.
-    if (0 !== Object.keys(reduced).length) {
-      entity.inform(reduced);
-    }
+    const reduced = entity.reduceStateDiff(currentState);
+    entity.inform(reduced);
     // Listen for events.
     socket.on('message', createMessageListener(avocadoServer, socket));
     socket.on('disconnect', createDisconnectionListener(avocadoServer, socket));
@@ -66,7 +60,7 @@ function createMessageListener(avocadoServer, socket) {
 function createDisconnectionListener(avocadoServer, socket) {
   const {entity} = socket;
   return () => {
-    const nearbyEntities = entity.nearbyEntities(INFORM_SIZE);
+    const nearbyEntities = entity.entitiesToInform();
     entityList.removeEntity(entity);
     nearbyEntities.forEach((nearbyEntity) => {
       nearbyEntity.inform({
@@ -135,12 +129,8 @@ function createMainLoop(avocadoServer) {
       if (!('inform' in entity)) {
         continue;
       }
-      const nearbyEntities = entity.nearbyEntities(INFORM_SIZE);
-      const reduced = entity.reduceStateDiff(nearbyEntities, diff);
-      // Remove dead update.
-      if (0 !== Object.keys(reduced).length) {
-        entity.inform(reduced);
-      }
+      const reduced = entity.reduceStateDiff(diff);
+      entity.inform(reduced);
     }
   }
 }

server/traits/informed.js

@@ -1,8 +1,19 @@
 import * as I from 'immutable';
 
-import {Trait} from '@avocado/entity';
+import {compose} from '@avocado/core';
+import {simpleState, Trait} from '@avocado/entity';
 
-export class Informed extends Trait {
+const decorate = compose(
+  simpleState('informSize'),
+);
+
+class InformedBase extends Trait {
+
+  static defaultState() {
+    return {
+      informSize: [300, 300],
+    };
+  }
 
   initialize() {
     this._socket = this.params.get('socket');
@@ -10,53 +21,67 @@ export class Informed extends Trait {
     this.lastNearby = I.Set();
   }
 
+  reduceStateDiffForEntityList(diff) {
+    // Reduce the entity list.
+    const nearbyEntities = this.entity.entitiesToInform();
+    const reducedEntityList = {};
+    let nearby = I.Set();
+    for (const entity of nearbyEntities) {
+      nearby = nearby.add(entity);
+      const uuid = entity.instanceUuid;
+      if (this.lastNearby.has(entity)) {
+        // Keep diff.
+        if (diff.entityList[uuid]) {
+          reducedEntityList[uuid] = diff.entityList[uuid];
+        }
+      }
+      else {
+        // Added.
+        reducedEntityList[uuid] = entity.state().toJS();
+      }
+    }
+    for (const entity of this.lastNearby.values()) {
+      const uuid = entity.instanceUuid;
+      if (!nearby.has(entity)) {
+        // Removed.
+        reducedEntityList[uuid] = false;
+      }
+    }
+    // Track who's nearby.
+    this.lastNearby = nearby;
+    // Merge the reduction.
+    diff = {
+      ...diff,
+      entityList: reducedEntityList,
+    };
+    // Remove dead update.
+    if (0 === Object.keys(diff.entityList).length) {
+      delete diff.entityList;
+    }
+    return diff;
+  }
+
   methods() {
     return {
 
+      entitiesToInform: () => {
+        const informSize = this.entity.informSize.toJS();
+        return this.entity.nearbyEntities(informSize);
+      },
+
       inform: (diff) => {
+        // Remove dead updates.
+        if (0 === Object.keys(diff).length) {
+          return;
+        }
         this._socket.send({
           type: 'state-update',
           payload: diff,
         });
       },
 
-      reduceStateDiff: (nearbyEntities, diff) => {
-        // Reduce the entity list.
-        const reducedEntityListDiff = {};
-        let nearby = I.Set();
-        for (const entity of nearbyEntities) {
-          nearby = nearby.add(entity);
-          const uuid = entity.instanceUuid;
-          if (this.lastNearby.has(entity)) {
-            // Keep diff.
-            if (diff.entityList[uuid]) {
-              reducedEntityListDiff[uuid] = diff.entityList[uuid];
-            }
-          }
-          else {
-            // Added.
-            reducedEntityListDiff[uuid] = entity.state().toJS();
-          }
-        }
-        for (const entity of this.lastNearby.values()) {
-          const uuid = entity.instanceUuid;
-          if (!nearby.has(entity)) {
-            // Removed.
-            reducedEntityListDiff[uuid] = false;
-          }
-        }
-        // Track who's nearby.
-        this.lastNearby = nearby;
-        // Merge the reduction.
-        diff = {
-          ...diff,
-          entityList: reducedEntityListDiff,
-        };
-        // Remove dead update.
-        if (0 === Object.keys(diff.entityList).length) {
-          delete diff.entityList;
-        }
-        return diff;
+      reduceStateDiff: (diff) => {
+        return this.reduceStateDiffForEntityList(diff);
       },
 
     };
@@ -64,3 +89,4 @@ export class Informed extends Trait {
 
 }
 
+export class Informed extends decorate(InformedBase) {}