8 files changed, 103 insertions, 38 deletions

diff --git a/README.md b/README.md
index d437233..b50e068 100644
--- a/README.md
+++ b/README.md
@@ -10,17 +10,17 @@ Then, open your browser at `http://localhost:8000`.
 
 # Sounds
 
-- bass: https://freesound.org/people/karolist/sounds/371192/
-- snare: https://lasonotheque.org/detail-2304-caisse-claire-1.html
 - hit-hat (closed): https://lasonotheque.org/detail-2302-charleston-fermee-7.html
+- snare: https://lasonotheque.org/detail-2304-caisse-claire-1.html
+- bass: https://freesound.org/people/karolist/sounds/371192/
 
 # Todo
 
 Multi-sound sequencer:
 
-- [ ] Provide more drum sounds
-- [ ] Add / Remove beat integrated into sequencer
+- [ ] Sub divide beats ?
 
 Working on increasing tempo:
 
+- [ ] Add / Remove beat integrated into sequencer
 - [ ] Augment the BPM by X after Y cycles
diff --git a/public/main.css b/public/main.css
index 134d92b..9540a7f 100644
--- a/public/main.css
+++ b/public/main.css
@@ -53,16 +53,22 @@ body {
   gap: var(--spacing-cat);
 }
 
-.g-Sequencer__Sounds > li {
+.g-Sequencer__Blocks {
+  display: flex;
+  align-items: center;
+  gap: var(--spacing-cat);
+}
+
+.g-Sequencer__Column > li {
   display: flex;
   align-items: center;
   height: var(--spacing-horse);
   cursor: pointer;
 }
 
-.g-Sequencer__Blocks {
+.g-Sequencer__Column {
   display: flex;
-  align-items: center;
+  flex-direction: column;
   gap: var(--spacing-cat);
 }
 
diff --git a/public/sounds/kick.opus b/public/sounds/bass.opus
index 40a8d60..40a8d60 100644
--- a/public/sounds/kick.opus
+++ b/public/sounds/bass.opus
diff --git a/public/sounds/hit-hat-closed.opus b/public/sounds/hit-hat-closed.opus
new file mode 100644
index 0000000..1513a5e
--- /dev/null
+++ b/public/sounds/hit-hat-closed.opus
diff --git a/public/sounds/snare.opus b/public/sounds/snare.opus
new file mode 100644
index 0000000..1808dd3
--- /dev/null
+++ b/public/sounds/snare.opus
diff --git a/src/sounds.ts b/src/sounds.ts
index 9ce8d2e..5e4c68a 100644
--- a/src/sounds.ts
+++ b/src/sounds.ts
@@ -1,5 +1,13 @@
-export interface Sounds {
-  kick: AudioBuffer
+export type Sounds = Record<Sound, AudioBuffer>
+
+export enum Sound {
+  Bass,
+  Snare,
+  HitHatClosed,
+}
+
+export function all(): Array<Sound> {
+  return [Sound.HitHatClosed, Sound.Snare, Sound.Bass]
 }
 
 const audioContext = new AudioContext()
@@ -9,21 +17,30 @@ export async function load(): Promise<Sounds> {
   if (lazy !== undefined) {
     return lazy
   } else {
+    let [bass, snare, hitHatClosed] = await Promise.all([
+      fetchSound('/sounds/bass.opus'),
+      fetchSound('/sounds/snare.opus'),
+      fetchSound('/sounds/hit-hat-closed.opus')
+    ])
 
-    const kick = await fetch('/sounds/kick.opus')
-      .then(res => res.arrayBuffer())
-      .then(ArrayBuffer => audioContext.decodeAudioData(ArrayBuffer))
-
-    lazy = {
-      kick
+    lazy = { 
+      [Sound.Bass]: bass,
+      [Sound.Snare]: snare,
+      [Sound.HitHatClosed]: hitHatClosed
     }
     return lazy
   }
 }
 
-export function playKick(sounds: Sounds) {
+async function fetchSound(name: string): Promise<AudioBuffer> {
+  return await fetch(name)
+    .then(res => res.arrayBuffer())
+    .then(ArrayBuffer => audioContext.decodeAudioData(ArrayBuffer))
+}
+
+export function play(sounds: Sounds, sound: Sound): void {
   const source = audioContext.createBufferSource()
-  source.buffer = sounds.kick
+  source.buffer = sounds[sound]
   source.connect(audioContext.destination)
   source.start()
 }
diff --git a/src/view/sequencer.ts b/src/view/sequencer.ts
index 3bca278..74eb0ea 100644
--- a/src/view/sequencer.ts
+++ b/src/view/sequencer.ts
@@ -1,18 +1,33 @@
 import h, { classNames } from 'lib/h'
 import * as soundsLib from 'sounds'
+import { Sound } from 'sounds'
 import * as play from 'view/sequencer/play'
 import * as addRemoveBeat from 'view/sequencer/addRemoveBeat'
 import * as block from 'view/sequencer/block'
 
 export function view() {
   let index = -1
-  let blocks = [true]
+  let blocks = [{
+    [Sound.Bass]: true,
+    [Sound.Snare]: false,
+    [Sound.HitHatClosed]: false,
+  }]
   let blocksNode = h('div', 
     { className: 'g-Sequencer__Blocks' }, 
-    block.view({ 
-      checked: true,
-      onCheck: checked => blocks[0] = checked
-    })
+    block.column([
+      { 
+        checked: false,
+        onCheck: checked => blocks[0][Sound.HitHatClosed] = checked
+      },
+      { 
+        checked: false,
+        onCheck: checked => blocks[0][Sound.Snare] = checked
+      },
+      { 
+        checked: true,
+        onCheck: checked => blocks[0][Sound.Bass] = checked
+      }
+    ])
   )
 
   let onNextStep = (sounds: soundsLib.Sounds) => {
@@ -24,9 +39,17 @@ export function view() {
     if (oldBlock !== undefined) oldBlock.classList.remove('g-Sequencer__Block--Beat')
 
     let newBlock = blocksNode.childNodes[newIndex] as HTMLElement
+
+    // Trigger reflow between removing and adding the classname.
+    // Allow to re-trigger the animation if there is only one column.
+    // See https://css-tricks.com/restart-css-animation/
+    void newBlock.offsetWidth
+
     newBlock.classList.add('g-Sequencer__Block--Beat')
 
-    if (blocks[newIndex]) soundsLib.playKick(sounds)
+    soundsLib.all().forEach(sound => {
+      if (blocks[newIndex][sound]) soundsLib.play(sounds, sound)
+    })
   }
 
   let sequencer = h('div', { className: 'g-Sequencer' },
@@ -46,25 +69,26 @@ export function view() {
         blocks.pop()
       },
       onAdd: index => {
-        blocks.push(false)
-        blocksNode.appendChild(block.view({ 
-          checked: false,
-          onCheck: checked => blocks[index] = checked
-        })) 
+        blocks.push({
+          [Sound.Bass]: false,
+          [Sound.Snare]: false,
+          [Sound.HitHatClosed]: false,
+        })
+        blocksNode.appendChild(block.column(
+          soundsLib.all().map(sound => ({
+            checked: false,
+            onCheck: checked => blocks[index][sound] = checked
+          }))
+        ))
       }
     }),
     h('div',
       { className: 'g-Sequencer__Grid' },
       h('ol',
-        { className: 'g-Sequencer__Sounds' },
-        h('li', 
-          { onclick: async () => {
-              let sounds = await soundsLib.load()
-              soundsLib.playKick(sounds)
-            }
-          },
-          'Bass'
-        )
+        { className: 'g-Sequencer__Column' },
+        soundItem('Hit-hat (closed)', Sound.HitHatClosed),
+        soundItem('Snare', Sound.Snare),
+        soundItem('Bass', Sound.Bass)
       ),
       blocksNode
     )
@@ -72,3 +96,14 @@ export function view() {
 
   return sequencer
 }
+
+function soundItem(name: string, sound: Sound): Element {
+  return h('li', 
+    { onclick: async () => {
+        let sounds = await soundsLib.load()
+        soundsLib.play(sounds, sound)
+      }
+    },
+    name
+  )
+}
diff --git a/src/view/sequencer/block.ts b/src/view/sequencer/block.ts
index 5776120..ff8d2db 100644
--- a/src/view/sequencer/block.ts
+++ b/src/view/sequencer/block.ts
@@ -5,7 +5,14 @@ interface Params {
   onCheck: (checked: boolean) => void
 }
 
-export function view({ checked, onCheck }: Params) {
+export function column(xs: Array<Params>) {
+  return h('ol',
+    { className: 'g-Sequencer__Column' },
+    ...xs.map(params => h('li', {}, block(params)))
+  )
+}
+
+function block({ checked, onCheck }: Params) {
   return h('div', 
     { className: classNames({
         'g-Sequencer__Block': true,