8 files changed, 207 insertions, 0 deletions
diff --git a/src/chord.ts b/src/chord.ts
new file mode 100644
index 0000000..b2645e2
--- /dev/null
+++ b/src/chord.ts
@@ -0,0 +1,14 @@
+export type Options = {
+  major: boolean,
+  minor: boolean
+}
+
+export function generate({ major, minor }: Options): string {
+  let choices: string[] = []
+  if (major) choices = choices.concat(all)
+  if (minor) choices = choices.concat(all.map(chord => `${chord}m`))
+
+  return choices[Math.floor(Math.random() * choices.length)]
+}
+
+const all: string[] = [ 'C', 'D♭', 'D', 'E♭', 'E', 'F', 'G♭', 'G', 'A♭', 'A', 'B♭', 'B' ]
diff --git a/src/lib/dom.ts b/src/lib/dom.ts
new file mode 100644
index 0000000..0b6a0ab
--- /dev/null
+++ b/src/lib/dom.ts
@@ -0,0 +1,15 @@
+export function show(elements: Element[]): void {
+  document.body.innerHTML = ''
+  elements.forEach(element => document.body.appendChild(element))
+}
+
+/* Trigger animation in any case.
+ *
+ * Trigger reflow between removing and adding the classname.
+ * See https://css-tricks.com/restart-css-animation/
+ */
+export function triggerAnimation(element: HTMLElement, animation: string) {
+  element.classList.remove(animation)
+  void element.offsetWidth
+  element.classList.add(animation)
+}
diff --git a/src/lib/h.ts b/src/lib/h.ts
new file mode 100644
index 0000000..8b1abf3
--- /dev/null
+++ b/src/lib/h.ts
@@ -0,0 +1,34 @@
+type Child = Element | Text | string | number
+
+export default function h(
+  tagName: string,
+  attrs: object,
+  ...children: Child[]
+): Element {
+  const isSvg = tagName === 'svg' || tagName === 'path'
+
+  let elem = isSvg
+    ? document.createElementNS('http://www.w3.org/2000/svg', tagName)
+    : document.createElement(tagName)
+
+  if (isSvg) {
+    Object.entries(attrs).forEach(([key, value]) => {
+      elem.setAttribute(key, value)
+    })
+  } else {
+    elem = Object.assign(elem, attrs)
+  }
+
+  for (const child of children) {
+    if (typeof child === 'number')
+      elem.append(child.toString())
+    else
+      elem.append(child)
+  }
+
+  return elem
+}
+
+export function classNames(obj: {[key: string]: boolean }): string {
+  return Object.keys(obj).filter(k => obj[k]).join(' ')
+}
diff --git a/src/main.ts b/src/main.ts
new file mode 100644
index 0000000..aecb754
--- /dev/null
+++ b/src/main.ts
@@ -0,0 +1,4 @@
+import * as form from 'view/form'
+import * as dom from 'lib/dom'
+
+dom.show(form.view())
diff --git a/src/view/form.ts b/src/view/form.ts
new file mode 100644
index 0000000..a74a7de
--- /dev/null
+++ b/src/view/form.ts
@@ -0,0 +1,55 @@
+import h, { classNames } from 'lib/h'
+import * as dom from 'lib/dom'
+import * as play from 'view/play'
+import * as layout from 'view/layout'
+import * as chord from 'chord'
+import * as options from 'view/options'
+
+// View
+
+export function view(): Element[] {
+  let opts = options.load()
+
+  return layout.view(
+    h('form',
+      { 
+        className: 'g-Form', 
+        onsubmit 
+      },
+      labelInput({ type: 'checkbox', name: 'major', label: 'Major', checked: opts.major }),
+      labelInput({ type: 'checkbox', name: 'minor', label: 'Minor', checked: opts.minor }),
+      labelInput({ type: 'number', name: 'bpm', label: 'BPM', value: opts.bpm.toString() }),
+      labelInput({ type: 'number', name: 'beatsPerChord', label: 'Beats per Chord', value: opts.beatsPerChord.toString() }),
+      h('input', { type: 'submit', value: 'Play' })
+    )
+  )
+}
+
+function onsubmit(event: Event): void {
+  event.preventDefault()
+  let input = (name: String) => document.querySelector(`input[name="${name}"]`) as HTMLInputElement
+  let opts = {
+    major: input('major').checked,
+    minor: input('minor').checked,
+    bpm: parseInt(input('bpm').value),
+    beatsPerChord: parseInt(input('beatsPerChord').value)
+  }
+  options.save(opts)
+  dom.show(play.view(opts))
+}
+
+type LabelInputParams = {
+  type: string,
+  name: string,
+  label: string,
+  checked?: boolean,
+  value?: string
+}
+
+function labelInput({ type, name, label, checked, value }: LabelInputParams) {
+  return h('label',
+    {},
+    h('input', { type, name, checked, value }),
+    label
+  )
+}
diff --git a/src/view/layout.ts b/src/view/layout.ts
new file mode 100644
index 0000000..ac62290
--- /dev/null
+++ b/src/view/layout.ts
@@ -0,0 +1,13 @@
+import h from 'lib/h'
+import * as dom from 'lib/dom'
+import * as form from 'view/form'
+
+export function view(main: Element): Element[] {
+  return [
+    h('header', 
+      { onclick: () => dom.show(form.view()) }, 
+      'Chords'
+    ),
+    main
+  ]
+}
diff --git a/src/view/options.ts b/src/view/options.ts
new file mode 100644
index 0000000..4c71be2
--- /dev/null
+++ b/src/view/options.ts
@@ -0,0 +1,24 @@
+export type Options = {
+  major: boolean,
+  minor: boolean,
+  bpm: number,
+  beatsPerChord: number
+}
+
+let defaultOptions: Options = {
+  major: true,
+  minor: false,
+  bpm: 90,
+  beatsPerChord: 4
+}
+
+let key: string = 'options'
+
+export function load(): Options {
+  let str = localStorage[key]
+  return str && JSON.parse(str) || defaultOptions
+}
+
+export function save(options: Options): void {
+  localStorage[key] = JSON.stringify(options)
+}
diff --git a/src/view/play.ts b/src/view/play.ts
new file mode 100644
index 0000000..26558cd
--- /dev/null
+++ b/src/view/play.ts
@@ -0,0 +1,48 @@
+import h, { classNames } from 'lib/h'
+import * as dom from 'lib/dom'
+import { Options } from 'view/options'
+import * as chord from 'chord'
+import * as layout from 'view/layout'
+
+export function view(options: Options): Element[] {
+  let chords = h('div', 
+    { className: 'g-Play' }, 
+    chordNode(),
+    chordNode(),
+    chordNode(options),
+    chordNode(options)
+  )
+
+  let chordBeat = 1
+
+  dom.triggerAnimation(chords as HTMLElement, 'g-Play--Shift')
+  dom.triggerAnimation(chords.children[2] as HTMLElement, 'g-Chord--Beat')
+  setInterval(() => {
+    if (chordBeat == options.beatsPerChord) {
+      shiftChords(chords, options)
+      chords.children[0].classList.remove('g-Chord--Beat')
+      dom.triggerAnimation(chords as HTMLElement, 'g-Play--Shift')
+      dom.triggerAnimation(chords.children[2] as HTMLElement, 'g-Chord--Beat')
+      chordBeat = 1
+    } else {
+      dom.triggerAnimation(chords.children[2] as HTMLElement, 'g-Chord--Beat')
+      chordBeat += 1
+    }
+  }, 60 / options.bpm * 1000)
+
+  return layout.view(chords)
+}
+
+/* Shift chords and generate a new random one.
+ */
+function shiftChords(chords: Element, options: Options) {
+  chords.removeChild(chords.children[0])
+  chords.appendChild(chordNode(options))
+}
+
+function chordNode(options?: Options): Element {
+  return h('div', 
+    { className: 'g-Chord' }, 
+    options ? chord.generate(options) : ''
+  )
+}