JW Player RTD Module : fallback to lone player on page (prebid#11186)

* fallsback

* improves error messaging

* updates div id name

* adds tests

modules/jwplayerRtdProvider.js

@@ -12,7 +12,7 @@
 import {submodule} from '../src/hook.js';
 import {config} from '../src/config.js';
 import {ajaxBuilder} from '../src/ajax.js';
-import {deepAccess, logError} from '../src/utils.js';
+import { deepAccess, logError, logWarn } from '../src/utils.js'
 import {find} from '../src/polyfill.js';
 import {getGlobal} from '../src/prebidGlobal.js';
 
@@ -429,17 +429,37 @@ export function addTargetingToBid(bid, targeting) {
   bid.rtd = Object.assign({}, rtd, jwRtd);
 }
 
-function getPlayer(playerDivId) {
+export function getPlayer(playerDivId) {
   const jwplayer = window.jwplayer;
   if (!jwplayer) {
     logError(SUBMODULE_NAME + '.js was not found on page');
     return;
   }
 
-  const player = jwplayer(playerDivId);
-  if (!player || !player.getPlaylist) {
-    logError('player ID did not match any players');
+  let player = jwplayer(playerDivId);
+  if (player && player.getPlaylist) {
+    return player;
+  }
+
+  const playerOnPageCount = document.getElementsByClassName('jwplayer').length;
+  if (playerOnPageCount === 0) {
+    logError('No JWPlayer instances have been detected on the page');
     return;
   }
-  return player;
+
+  let errorMessage = `player Div ID ${playerDivId} did not match any players.`;
+
+  // If there are multiple instances on the page, we cannot guess which one should be targeted.
+  if (playerOnPageCount > 1) {
+    logError(errorMessage);
+    return;
+  }
+
+  player = jwplayer();
+  if (player && player.getPlaylist) {
+    logWarn(`${errorMessage} Targeting player Div ID ${player.id} instead`);
+    return player;
+  }
+
+  logError(errorMessage);
 }

test/spec/modules/jwplayerRtdProvider_spec.js

@@ -12,6 +12,7 @@ import {
   getVatFromCache,
   getVatFromPlayer,
   setOverrides,
+  getPlayer,
   jwplayerSubmodule
 } from 'modules/jwplayerRtdProvider.js';
 import {server} from 'test/mocks/xhr.js';
@@ -1603,6 +1604,66 @@ describe('jwplayerRtdProvider', function() {
     });
   });
 
+  describe('Player detection', function () {
+    const playerInstanceMock = {
+      getPlaylist: () => [],
+      getPlaylistItem: () => ({})
+    };
+
+    beforeEach(function () {
+      window.jwplayer = sinon.stub();
+    });
+
+    afterEach(function () {
+      delete window.jwplayer;
+    });
+
+    it('should fail if jwplayer global does not exist', function () {
+      delete window.jwplayer;
+      expect(getPlayer('divId')).to.be.undefined;
+    });
+
+    it('should return the player instance for the specified div id', function () {
+      window.jwplayer.returns(playerInstanceMock);
+      const player = getPlayer('divId');
+      expect(player).to.deep.equal(playerInstanceMock);
+    });
+
+    it('should request a player when the div id does not match a player on the page and only 1 player is in the DOM', function () {
+      const playerDomElement = document.createElement('div');
+      playerDomElement.className = 'jwplayer';
+      document.body.appendChild(playerDomElement);
+
+      window.jwplayer.withArgs('invalidDivId').returns(undefined);
+      window.jwplayer.returns(playerInstanceMock);
+
+      const playerInstance = getPlayer('invalidDivId');
+
+      expect(playerInstance).to.deep.equal(playerInstanceMock);
+
+      document.body.removeChild(playerDomElement);
+    });
+
+    it('should fail when the div id does not match a player on the page, and multiple players are instantiated', function () {
+      const firstPlayerDomElement = document.createElement('div');
+      const secondPlayerDomElement = document.createElement('div');
+      firstPlayerDomElement.className = 'jwplayer';
+      secondPlayerDomElement.className = 'jwplayer';
+      document.body.appendChild(firstPlayerDomElement);
+      document.body.appendChild(secondPlayerDomElement);
+
+      window.jwplayer.withArgs('invalidDivId').returns(undefined);
+      window.jwplayer.returns(playerInstanceMock);
+
+      const playerInstance = getPlayer('invalidDivId');
+
+      expect(playerInstance).to.be.undefined;
+
+      document.body.removeChild(firstPlayerDomElement);
+      document.body.removeChild(secondPlayerDomElement);
+    });
+  });
+
   describe('jwplayerSubmodule', function () {
     it('successfully instantiates', function () {
       expect(jwplayerSubmodule.init()).to.equal(true);