import ascending from "./ascending";

export default function(values, compare) {
  if (!(n = values.length)) return;
  var n,
      i = 0,
      j = 0,
      xi,
      xj = values[j];

  if (compare == null) compare = ascending;

  while (++i < n) {
    if (compare(xi = values[i], xj) < 0 || compare(xj, xj) !== 0) {
      xj = xi, j = i;
    }
  }

  if (compare(xj, xj) === 0) return j;
}