import h, { classNames } from 'lib/h'
import * as time from 'lib/time'
import * as soundsLib from 'sounds'

const MIN_BPM: number = 1
const MAX_BPM: number = 1000

interface Params {
  onNextStep: (sounds: soundsLib.Sounds) => void,
  onStop: () => void
}

export function view({ onNextStep, onStop }: Params) {
  let bpm = 60
  let isPlaying = false
  let lastBeat: undefined | number = undefined

  return h('div', {},
    h('button',
      { className: 'g-PlayStop',
        onclick: async (e: Event) => {
          const target = e.target as HTMLButtonElement
          isPlaying = !isPlaying
          target.innerText = isPlaying ? '■' : '▶'

          let sounds = await soundsLib.load()
          let step = (timestamp: number) => {
            if (lastBeat === undefined || timestamp - lastBeat > 1000 * 60 / bpm) {
              lastBeat = timestamp
              onNextStep(sounds)
            }

            if (isPlaying) window.requestAnimationFrame(step)
          }

          if (isPlaying) {
            window.requestAnimationFrame(step)
          } else {
            onStop()
          }
        }
      },
      '▶'
    )
    , h('label', 
      { className: 'g-Bpm' },
      'BPM',
      h('input', 
        { className: 'g-Input', 
          type: 'number', 
          value: bpm,
          min: MIN_BPM,
          max: MAX_BPM,
          oninput: time.debounce(
            (e: Event) => {
              const target = e.target as HTMLInputElement
              const n = parseInt(target.value)
              if (n >= MIN_BPM && n <= MAX_BPM) {
                bpm = n
              }
            },
            1000
          )
        }
      )
    )
  )
}