Using the new response_format=service_item on Transpose API Endpoint while preserving old behavior

src/app/components/chord-view/chord-view.component.ts

@@ -16,14 +16,53 @@ export class ChordViewComponent extends StageViewComponent {
   songTransposeMap = new Map();
   // current songs transpose level
   transposeLevel = 0;
+  currentSlide = 0;
+  useNewTransposeEndpoint = this.openlpService.assertApiVersionMinimum(2, 2);
 
+  updateCurrentSlides(serviceItemId: string, currentSlide: number): void {
+    this.currentSlide = currentSlide;
+    this.useNewTransposeEndpoint = this.openlpService.assertApiVersionMinimum(2, 2);
+    this.serviceItemSubscription$?.unsubscribe();
+    const newServiceItemTransposeLevel = this.songTransposeMap.get(serviceItemId);
 
-  setNewSlides(slides: Slide[]): void {
+    if (this.useNewTransposeEndpoint && newServiceItemTransposeLevel && (newServiceItemTransposeLevel !== 0)) {
-    super.setNewSlides(slides);
+      this.serviceItemSubscription$ = this.openlpService
+          .transposeSong(newServiceItemTransposeLevel, 'service_item')
+          .subscribe(serviceItem => {
+            this.serviceItem = serviceItem;
+            if (serviceItem instanceof Array) {
+              this.setNewSlides(serviceItem, currentSlide);
+            }
+            else {
+              this.setNewSlides(serviceItem.slides, currentSlide);
+              this.setNotes(serviceItem.notes);
+            }
+          });
+    } else {
+      if (this.useNewTransposeEndpoint) {
+        this.songTransposeMap.set(serviceItemId, 0);
+        this.transposeLevel = 0;
+      }
+      super.updateCurrentSlides(serviceItemId, currentSlide);
+    }
+  }
+
+  setNewSlides(slides: Slide[], currentSlide: number): void {
+    super.setNewSlides(slides, currentSlide);
+    if (this.openlpService.assertApiVersionExact(2, 2)) {
+      // API Version 2.2 released on OpenLP 3.0.2 contains a bug on which 'selected' is not set correctly
+      // on Transponse Service Item response.
+      if (slides[currentSlide]) {
+        slides[currentSlide].selected = true;
+      }
+    }
     // if this song is already known
     if (this.songTransposeMap.has(this.serviceItem.id)) {
-      if (this.songTransposeMap.get(this.serviceItem.id) !== 0) {
+      const transposeLevel = this.songTransposeMap.get(this.serviceItem.id);
+      if (transposeLevel) {
+        if (!this.useNewTransposeEndpoint) {
           this.transposeChords();
+        }
       } else {
         this.transposeLevel = this.songTransposeMap.get(this.serviceItem.id);
       }
@@ -57,7 +96,15 @@ export class ChordViewComponent extends StageViewComponent {
   transposeChords(): void {
     const tmpTranspose = this.songTransposeMap.get(this.serviceItem.id);
     this.transposeLevel = tmpTranspose;
-    this.openlpService.transposeSong(tmpTranspose).subscribe(transposedLyrics => {
+    if (this.useNewTransposeEndpoint) {
+      this.updateCurrentSlides(this.serviceItem.id, this.currentSlide);
+    } else {
+      this.transposeChordsLegacy(tmpTranspose);
+    }
+  }
+
+  transposeChordsLegacy(transposeLevel): void {
+    this.openlpService.transposeSong(transposeLevel).subscribe(transposedLyrics => {
       // Replace the chords in the currentSlides with the returned transposed chords
       if (transposedLyrics instanceof Array) {
         for (let i = 0; i < transposedLyrics.length; ++i) {

src/app/components/stage-view/stage-view.component.ts

@@ -1,4 +1,5 @@
 import { Component, OnInit, ViewEncapsulation } from '@angular/core';
+import { Subscription } from 'rxjs';
 import { OpenLPService } from '../../openlp.service';
 import { ServiceItem, Slide } from '../../responses';
 
@@ -21,24 +22,26 @@ export class StageViewComponent implements OnInit {
   tags: Tag[] = [];
   time = new Date();
   showNotes = true;
+  serviceItemSubscription$: Subscription = null;
 
   constructor(public openlpService: OpenLPService) {
     setInterval(() => this.time = new Date(), 1000);
   }
 
   ngOnInit() {
-    this.updateCurrentSlides();
+    this.updateCurrentSlides(null, null);
-    this.openlpService.stateChanged$.subscribe(item => this.updateCurrentSlides());
+    this.openlpService.stateChanged$.subscribe(item => this.updateCurrentSlides(item.item, item.slide));
   }
 
-  updateCurrentSlides(): void {
+  updateCurrentSlides(serviceItemId: string, currentSlide: number): void {
-    this.openlpService.getServiceItem().subscribe(serviceItem => {
+    this.serviceItemSubscription$?.unsubscribe();
+    this.serviceItemSubscription$ = this.openlpService.getServiceItem().subscribe(serviceItem => {
       this.serviceItem = serviceItem;
       if (serviceItem instanceof Array) {
-        this.setNewSlides(serviceItem);
+        this.setNewSlides(serviceItem, currentSlide);
       }
       else {
-        this.setNewSlides(serviceItem.slides);
+        this.setNewSlides(serviceItem.slides, currentSlide);
         this.setNotes(serviceItem.notes);
       }
     });
@@ -48,7 +51,7 @@ export class StageViewComponent implements OnInit {
     return this.currentSlides.slice(this.activeSlide + 1);
   }
 
-  setNewSlides(slides: Slide[]): void {
+  setNewSlides(slides: Slide[], currentSlide: number): void {
     if (slides.length === 0) {
       return;
     }

src/app/openlp.service.ts

@@ -1,7 +1,7 @@
 import { Injectable, EventEmitter } from '@angular/core';
 import { HttpClient, HttpHeaders } from '@angular/common/http';
 import { Observable, Subscription } from 'rxjs';
-import { finalize, shareReplay } from 'rxjs/operators';
+import { finalize, shareReplay, tap } from 'rxjs/operators';
 
 import {
   PluginDescription,
@@ -44,6 +44,8 @@ export enum WebSocketStatus {
 @Injectable()
 export class OpenLPService {
   private apiURL: string;
+  public apiVersion: number | null;
+  public apiRevision: number | null;
   private host: string;
   public stateChanged$: EventEmitter<State>;
   public webSocketStateChanged$: EventEmitter<WebSocketStatus>;
@@ -69,6 +71,14 @@ export class OpenLPService {
     this.createWebSocket();
   }
 
+  assertApiVersionExact(version: number, revision: number) {
+    return version === this.apiVersion && revision === this.apiRevision;
+  }
+
+  assertApiVersionMinimum(version: number, revision: number) {
+    return version >= this.apiVersion && revision >= this.apiRevision;
+  }
+
   setAuthToken(token: string): void {
     httpOptions.headers = httpOptions.headers.set('Authorization', token);
   }
@@ -78,7 +88,13 @@ export class OpenLPService {
   }
 
   retrieveSystemInformation(): Observable<SystemInformation> {
-    return this.doGet<SystemInformation>(`${this.apiURL}/core/system`);
+    return this.doGet<SystemInformation>(`${this.apiURL}/core/system`)
+      .pipe(tap(systemInfo => {
+        if (systemInfo.api_version) {
+          this.apiVersion = systemInfo.api_version;
+          this.apiRevision = systemInfo.api_revision;
+        }
+      }));
   }
 
   getMainImage(): Observable<MainView> {
@@ -185,8 +201,8 @@ export class OpenLPService {
     return this.doPost(`${this.apiURL}/plugins/${plugin}/add`, {id});
   }
 
-  transposeSong(transpose_value): Observable<any> {
+  transposeSong(transpose_value, return_format = 'default'): Observable<any> {
-    return this.doGet(`${this.apiURL}/plugins/songs/transpose-live-item/${transpose_value}`);
+    return this.doGet(`${this.apiURL}/plugins/songs/transpose-live-item/${transpose_value}?response_format=${return_format}`);
   }
 
   login(credentials: Credentials): Observable<AuthToken> {

src/app/responses.ts

@@ -12,6 +12,7 @@ export class State {
   blank: boolean;
   twelve: boolean;
   theme: boolean;
+  item: string;
 
   live = () => !(this.blank || this.display || this.theme);
 
@@ -68,6 +69,8 @@ export interface MainView {
 export interface SystemInformation {
   websocket_port: number;
   login_required: boolean;
+  api_version?: number;
+  api_revision?: number;
 }
 
 export interface Credentials {