/** Guest TUI counter. Run as a Bare OS script: `run` / `ctx.tui` only. */

async function run(ctx) {
  if (!ctx.tui || !ctx.tui.isTTY()) {
    ctx.console.error('tui-counter: needs a TTY')
    ctx.exitCode = 1
    return
  }
  const app = {
    n: 0,
    init: function () {
      return null
    },
    update: function (msg) {
      if (ctx.tui.key.matches(msg, 'q', 'ctrl+c')) return [this, ctx.tui.quit]
      if (ctx.tui.key.matches(msg, 'up', 'k')) this.n++
      if (ctx.tui.key.matches(msg, 'down', 'j')) this.n--
      return [this, null]
    },
    view: function () {
      return ctx.tui
        .style()
        .border(ctx.tui.style.borders.rounded)
        .padding(1, 2)
        .render('count: ' + this.n + '\n\n↑/↓ or k/j change · q quit')
    }
  }
  await ctx.tui.run(app)
}