import { Options } from './stego';
import { Locator, loc2idx, loc2coord } from './locator';

export function isBlockVisibleAt(
  { data }: ImageData,
  loc: Locator,
  options: Options
) {
  const { size } = options;
  const _loc = {
    ...loc,
    c: 0, // mask is a gray image since only red red was read
  };
  const [x1, y1] = loc2coord(_loc, options);
  for (let i = 0; i < size * size; i += 1) {
    const value = data[loc2idx(_loc, options, x1, y1, i)];

    if (typeof value !== 'undefined' && value < 127) {
      return false;
    }
  }
  return true;
}

export function isPixelVisibleAt(
  { data }: ImageData,
  loc: number,
  options: Options
) {
  return typeof data[loc] === 'undefined' || data[loc] > 127;
}