import { ACTIVITY_WEEKS, WEEK_MS } from '#/lib/activity.js';
import { cn } from '#/lib/utils.js';

/**
 * How often this ref was committed to, week by week, as a row of ticks read
 * like a gauge. The dates come from the walk the page already made for its
 * latest commit, so this costs no read of its own.
 *
 * A week with no commits keeps a floor tick, so the row reads as a scale
 * rather than as gaps. Heights are against the busiest week in view, which
 * makes the shape of the work legible whatever the repository's volume.
 */
export function ActivityTicks({ dates, className }) {
  const now = Date.now();
  /** @type {{start: number, count: number}[]} oldest first */
  const weeks = Array.from({ length: ACTIVITY_WEEKS }, (_, index) => ({
    start: now - (ACTIVITY_WEEKS - index) * WEEK_MS,
    count: 0,
  }));
  for (const at of dates) {
    const week = Math.floor((now - at) / WEEK_MS);
    if (week >= 0 && week < ACTIVITY_WEEKS) {
      weeks[ACTIVITY_WEEKS - 1 - week].count += 1;
    }
  }

  const busiest = Math.max(...weeks.map((week) => week.count));
  if (busiest === 0) return null;
  const total = weeks.reduce((sum, week) => sum + week.count, 0);
  const words = `${total} ${total === 1 ? 'commit' : 'commits'} in the last ${ACTIVITY_WEEKS} weeks`;

  return (
    // The ticks spread across the whole row, as the language gauge's do, so
    // the two read against one scale rather than as a long bar beside a
    // short one. Each tick takes an equal share of whatever room the row
    // has, so the gauge draws the same shape in a sidebar and in a card.
    <div
      className={cn('flex h-3 w-full items-end gap-[2px]', className)}
      role="img"
      aria-label={words}
      title={words}
    >
      {weeks.map((week) => (
        <span
          key={week.start}
          className={cn(
            'min-w-0 flex-1',
            week.count > 0 ? 'bg-key' : 'h-[2px] bg-border',
          )}
          style={
            week.count > 0
              ? { height: `${Math.max(20, (week.count / busiest) * 100)}%` }
              : undefined
          }
        />
      ))}
    </div>
  );
}