fix(core): incorrect state tracking

The current state of a device was not taken into consideration when generating the updated state after receiving an update from atvscript. This way, attributes that are not reported in that specific result of atvscript, default to null, which is unwanted since in reality they are still unchanged. E.g. when changing the volume, all attributes beside the volume are set to null, since the volume attribute is the only one reported by atvscript when changing the volume.

src/lib/device-events.ts

@@ -91,7 +91,7 @@ export default class NodePyATVDeviceEvents extends EventEmitter {
 
     private applyPushUpdate(update: NodePyATVInternalState, reqId: string): void {
         try {
-            const newState = parseState(update, reqId, this.options);
+            const newState = parseState(update, this.state, reqId, this.options);
             this.applyStateAndEmitEvents(newState);
         }
         catch(error) {

src/lib/device.ts

@@ -34,7 +34,7 @@ export default class NodePyATVDevice implements EventEmitter{
 
     constructor(options: NodePyATVDeviceOptions) {
         this.options = Object.assign({}, options);
-        this.state = parseState({}, '', {});
+        this.state = parseState({}, undefined, '', {});
         this.events = new NodePyATVDeviceEvents(this.state, this, this.options);
 
         // @todo basic validation
@@ -232,7 +232,7 @@ export default class NodePyATVDevice implements EventEmitter{
             const parameters = getParamters(this.options);
 
             const result = await request(id, NodePyATVExecutableType.atvscript, [...parameters, 'playing'], this.options);
-            const newState = parseState(result, id, this.options);
+            const newState = parseState(result, this.state, id, this.options);
 
             this.applyState(newState);
             return newState;
@@ -248,7 +248,7 @@ export default class NodePyATVDevice implements EventEmitter{
      * @category State
      */
     clearState(): void {
-        this.applyState(parseState({}, '', {}));
+        this.applyState(parseState({}, undefined, '', {}));
     }
 
     private applyState(newState: NodePyATVState): void {

src/lib/tools.ts

@@ -234,7 +234,7 @@ function parseStateStringAttr(
     d(`No ${outputAttr} value found in input (${JSON.stringify(input)})`);
 }
 
-export function parseState(input: NodePyATVInternalState, id: string, options: NodePyATVInstanceOptions): NodePyATVState {
+export function parseState(input: NodePyATVInternalState, currentState: NodePyATVState, id: string, options: NodePyATVInstanceOptions): NodePyATVState {
     const d = (msg: string) => debug(id, msg, options);
     const result: NodePyATVState = {
         dateTime: null,
@@ -253,7 +253,8 @@ export function parseState(input: NodePyATVInternalState, id: string, options: N
         appId: null,
         powerState: null,
         volume: null,
-        focusState: null
+        focusState: null,
+        ...currentState
     };
     if (!input || typeof input !== 'object') {
         return result;