From d69fb8b6527401d5de13f90454edc6262c42ef80 Mon Sep 17 00:00:00 2001
From: Samuel Degueldre <sad@odoo.com>
Date: Sun, 14 Mar 2021 18:32:21 +0100
Subject: [PATCH] [REF] minor style changes and refactoring

---
 .eslintrc.js | 11 ++++-------
 src/index.js | 24 ++++++++++++++++--------
 2 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/.eslintrc.js b/.eslintrc.js
index 7fb8905..3b01ca5 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -54,7 +54,7 @@ module.exports = {
     ],
     'consistent-return': 'error',
     'consistent-this': 'error',
-    'curly': 'off',
+    'curly': 'error',
     'default-case': 'error',
     'default-case-last': 'error',
     'default-param-last': 'error',
@@ -68,10 +68,7 @@ module.exports = {
     'func-call-spacing': 'error',
     'func-name-matching': 'error',
     'func-names': 'error',
-    'func-style': [
-      'error',
-      'declaration',
-    ],
+    'func-style': 'off',
     'function-paren-newline': 'error',
     'generator-star-spacing': 'error',
     'global-require': 'error',
@@ -82,6 +79,7 @@ module.exports = {
     'id-denylist': 'error',
     'id-length': 'off',
     'id-match': 'error',
+    'ignorePatterns': ['.eslintrc.js'],
     'implicit-arrow-linebreak': [
       'error',
       'beside',
@@ -113,7 +111,6 @@ module.exports = {
     'max-params': 'error',
     'max-statements': 'off',
     'max-statements-per-line': 'error',
-    'multiline-comment-style': 'error',
     'new-cap': 'error',
     'new-parens': 'error',
     'newline-after-var': 'off',
@@ -239,7 +236,7 @@ module.exports = {
     'padded-blocks': 'off',
     'padding-line-between-statements': 'error',
     'prefer-arrow-callback': 'error',
-    'prefer-const': 'off',
+    'prefer-const': 'warn',
     'prefer-destructuring': 'error',
     'prefer-exponentiation-operator': 'off',
     'prefer-named-capture-group': 'error',
diff --git a/src/index.js b/src/index.js
index ca1632b..afc88bf 100644
--- a/src/index.js
+++ b/src/index.js
@@ -13,6 +13,7 @@ gradient.addColorStop(1, '#008ce2');
 ctx.fillStyle = gradient;
 
 // TODO: this seems shitty. Should probably get sample rate from file...
+// This doesn't seem possible without parsing the files by hand unfortunately
 const samplingRate = 44100;
 let leftSamples, rightSamples;
 let cache = {};
@@ -28,8 +29,9 @@ function loadAudio(fileOrBlob) {
     const audioBuffer = await audioCtx.decodeAudioData(reader.result);
     leftSamples = audioBuffer.getChannelData(0);
     rightSamples = audioBuffer.getChannelData(1);
-    if (!playing)
+    if (!playing) {
       playAnim();
+    }
     console.log('Samples acquired');
   }
 }
@@ -56,8 +58,9 @@ window.addEventListener('resize', () => {
   gradient.addColorStop(1, '#008ce2');
   ctx.fillStyle = gradient;
 
-  if (!playing)
+  if (!playing) {
     playAnim();
+  }
 });
 
 const halfWinsize = 4096;
@@ -66,10 +69,14 @@ function getFrame(time) {
   const centerSample = roundTo(time * samplingRate, samplingRate / 30);
   // TODO: make cache actually useful
   if (!cache[centerSample]) {
-    let left = leftSamples.slice(Math.max(0, centerSample - halfWinsize), Math.max(2 * halfWinsize, centerSample + halfWinsize));
-    let right = rightSamples.slice(Math.max(0, centerSample - halfWinsize), Math.max(2 * halfWinsize, centerSample + halfWinsize));
-    left = left.map((v, i) => v * (Math.cos(i / left.length * 2 * Math.PI + Math.PI) + 1));
-    right = right.map((v, i) => v * (Math.cos(i / right.length * 2 * Math.PI + Math.PI) + 1));
+    const sliceStart = Math.max(0, centerSample - halfWinsize);
+    const sliceEnd = Math.max(2 * halfWinsize, centerSample + halfWinsize);
+    let left = leftSamples.slice(sliceStart, sliceEnd);
+    let right = rightSamples.slice(sliceStart, sliceEnd);
+    const scaleFactor = i => Math.cos(i / left.length * 2 * Math.PI + Math.PI) + 1;
+    left = left.map((v, i) => v * scaleFactor(i));
+    right = right.map((v, i) => v * scaleFactor(i));
+    // TODO: return something when close to boundaries
     if (left.length != 2 * halfWinsize) {
       cache[centerSample] = [
         [],
@@ -106,8 +113,9 @@ function playAnim() {
   }));
 
   channels.forEach(channel => {
-    if (channel.length == 0)
+    if (channel.length == 0) {
       return;
+    }
     ctx.beginPath();
     ctx.moveTo(0, cv.height / 2);
     ctx.lineTo(0, channel[0].y);
@@ -128,7 +136,7 @@ function playAnim() {
     ctx.fill();
   })
 
-  let now = Date.now();
+  const now = Date.now();
   if (lastFrameTime) {
     frameTimes.push(now - lastFrameTime);
   }