// FM synthesis — DX7-style frequency modulation.
// Run: node examples/fm-synthesis.js 440 2 5 3s
// Run: node examples/fm-synthesis.js carrier=440 ratio=2 index=5 -d 3s
// Keys: ←/→ ±0.5 ratio · ↑/↓ ±1 index · q quit

import { AudioContext } from 'web-audio-api'
import { init } from './graphs/fm-synthesis.js'
import { args, num, sec, keys, status, clearLine, pausedTag, help } from './utils.js'

help({
  description: 'explore DX7-style frequency modulation synthesis',
  usage: ['', '[carrier] [ratio] [index] [duration]', 'carrier=440 ratio=2 index=5 dur=3s'],
  options: [
    ['carrier=<hz|note>', 'carrier frequency (default: 440)'],
    ['ratio=<number>', 'modulator/carrier frequency ratio (default: 2)'],
    ['index=<number>', 'modulation index (default: 5)'],
    ['-d, --duration <time>', 'run time with optional s/m/h suffix (default: 30s)'],
  ],
  controls: [['Space', 'pause/resume'], ['← / →', 'change ratio by 0.5'], ['↑ / ↓', 'change index by 1'], ['Q / Esc', 'quit']],
})

let { pos, $ } = args()
let nums = pos.filter(t => /^\d/.test(t) && !/[smh]$/.test(t) || /^[A-G][#b]?\d$/i.test(t))
let carrier = num(nums[0] || $('carrier', 440))
let ratio = +(nums[1] || $('ratio', 2))
let index = +(nums[2] || $('index', 5))
let dur = sec(pos.find(t => /\d[smh]$/.test(t)) || $('dur', '30'))

let ctx = new AudioContext()
await ctx.resume()

let demo = init(ctx, { carrier, ratio, index, duration: dur, gain: 0.3 })
let [mod, modGain] = demo.nodes

let apply = () => {
  let t = ctx.currentTime
  mod.frequency.setTargetAtTime(carrier * ratio, t, 0.02)
  modGain.gain.setTargetAtTime(index * carrier * ratio, t, 0.02)
}

let render = status()
let ui = setInterval(() => render(`FM · carrier ${carrier}Hz · ratio ${ratio.toFixed(1)} · index ${index.toFixed(1)} · space pause · ←→ ratio · ↑↓ index · q quit${pausedTag(ctx)}`), 80)

keys({
  left: () => { ratio = Math.max(0.1, ratio - 0.5); apply() },
  right: () => { ratio += 0.5; apply() },
  up: () => { index += 1; apply() },
  down: () => { index = Math.max(0, index - 1); apply() },
}, () => { clearInterval(ui); clearLine(); ctx.close() }, ctx)

console.log(`FM: carrier=${carrier}Hz, ratio=${ratio}, index=${index} (${dur}s)  ←→ ratio · ↑↓ index · q quit`)

setTimeout(() => { clearInterval(ui); clearLine(); ctx.close(); process.exit(0) }, dur * 1000)