Open bands

// Bands a set percentage above and below the day's open (00:00 UTC), for how far the day has
// stretched. Bands far from price are drawn where they fall, but unless "Fit bands in view" is
// on they do not stretch the price scale (autoscale: false), so the candles keep the view.
indicator('Open bands', { overlay: true });

const near = input.float('Near band (%)', 2, { min: 0.1, max: 50, step: 0.1 });
const far = input.float('Far band (%)', 5, { min: 0.1, max: 50, step: 0.1 });
const fit = input.bool('Fit bands in view', false);

const chart = bars();
const day = state.bar<number>(na);
const open = state.bar<number>(na);

const tone = color.study(12);
const farAbove = plot.line('Far above', { color: color.withAlpha(tone, 0.55), style: 'dashed', autoscale: fit });
const nearAbove = plot.line('Near above', { color: tone, autoscale: fit });
const dayOpen = plot.line('Open', { color: color.withAlpha(color.neutral, 0.6), style: 'dotted', autoscale: fit });
const nearBelow = plot.line('Near below', { color: tone, autoscale: fit });
const farBelow = plot.line('Far below', { color: color.withAlpha(tone, 0.55), style: 'dashed', autoscale: fit });

chart.onBar(() => {
  const start = clock.startOf(chart.time, 'day');
  if (start !== day.value) {
    day.value = start;
    open.value = chart.open;
  }
  const base = open.value;
  farAbove.set(base * (1 + far / 100));
  nearAbove.set(base * (1 + near / 100));
  dayOpen.set(base);
  nearBelow.set(base * (1 - near / 100));
  farBelow.set(base * (1 - far / 100));
});