From 3045733c63fa124c30f281c58970bf46d807aa7e Mon Sep 17 00:00:00 2001
From: Jordan Eldredge <jordan@jordaneldredge.com>
Date: Mon, 23 Oct 2017 17:59:39 -0700
Subject: [PATCH] Memoize track ordering

---
 js/components/PlaylistWindow/index.js |  6 +++---
 js/selectors.js                       | 10 ++++++++++
 package.json                          |  5 +++--
 yarn.lock                             |  4 ++++
 4 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/js/components/PlaylistWindow/index.js b/js/components/PlaylistWindow/index.js
index 013c6c85..e8e6256b 100644
--- a/js/components/PlaylistWindow/index.js
+++ b/js/components/PlaylistWindow/index.js
@@ -18,6 +18,7 @@ import {
   SET_FOCUSED_WINDOW,
   SET_PLAYLIST_SCROLL_POSITION
 } from "../../actionTypes";
+import { getOrderedTracks } from "../../selectors";
 import { play, pause, stop, openFileDialog } from "../../actionCreators";
 
 import "../../../css/playlist-window.css";
@@ -148,15 +149,14 @@ const mapDispatchToProps = (dispatch, ownProps) => ({
 const mapStateToProps = state => {
   const {
     windows: { focused },
-    display: { skinPlaylistStyle, playlistScrollPosition, playlistSize },
-    playlist: { trackOrder }
+    display: { skinPlaylistStyle, playlistScrollPosition, playlistSize }
   } = state;
   return {
     focused,
     skinPlaylistStyle,
     playlistScrollPosition,
     playlistSize,
-    trackOrder: trackOrder.filter(id => state.tracks[id])
+    trackOrder: getOrderedTracks(state)
   };
 };
 
diff --git a/js/selectors.js b/js/selectors.js
index c9fa7a86..204bc729 100644
--- a/js/selectors.js
+++ b/js/selectors.js
@@ -1,5 +1,6 @@
 import { denormalize } from "./utils";
 import { BANDS } from "./constants";
+import { createSelector } from "reselect";
 
 export const getEqfData = state => {
   // state.equalizer.sliders
@@ -17,3 +18,12 @@ export const getEqfData = state => {
   };
   return eqfData;
 };
+
+const getTracks = state => state.tracks;
+const getTrackOrder = state => state.playlist.trackOrder;
+
+export const getOrderedTracks = createSelector(
+  getTracks,
+  getTrackOrder,
+  (tracks, trackOrder) => trackOrder.filter(id => tracks[id])
+);
diff --git a/package.json b/package.json
index 3ae11609..3d29c567 100644
--- a/package.json
+++ b/package.json
@@ -15,9 +15,9 @@
     "tdd": "jest --watch",
     "deploy": "ssh jordaneldredge.com HASH=$HASH sh < scripts/deploy.sh",
     "revert": "ssh jordaneldredge.com sh < scripts/revert.sh",
-    "format":
+    "format": 
       "prettier --write js/**/*.js css/**/*.css webpack.config.js webpack.production.config.js",
-    "build-skin":
+    "build-skin": 
       "rm skins/base-2.91.wsz && cd skins/base-2.91 && zip -x .* -x 'Skining Updates.txt' -r ../base-2.91.wsz .",
     "skin-info": "unzip -vl skins/base-2.91.wsz"
   },
@@ -73,6 +73,7 @@
     "redux": "^3.5.2",
     "redux-devtools-extension": "^2.13.2",
     "redux-thunk": "^2.1.0",
+    "reselect": "^3.0.1",
     "webpack": "^3.6.0",
     "winamp-eqf": "^1.0.0"
   },
diff --git a/yarn.lock b/yarn.lock
index dca64bf0..6318ab6b 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -5125,6 +5125,10 @@ requires-port@1.0.x, requires-port@1.x.x:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/requires-port/-/requires-port-1.0.0.tgz#925d2601d39ac485e091cf0da5c6e694dc3dcaff"
 
+reselect@^3.0.1:
+  version "3.0.1"
+  resolved "https://registry.yarnpkg.com/reselect/-/reselect-3.0.1.tgz#efdaa98ea7451324d092b2b2163a6a1d7a9a2147"
+
 resolve-from@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/resolve-from/-/resolve-from-1.0.1.tgz#26cbfe935d1aeeeabb29bc3fe5aeb01e93d44226"