Update copyright using deno

update-copyright.ts

const encoder = new TextEncoder();
const decoder = new TextDecoder("utf-8");
const simplePat = /Copyright (201[0-9]) Kodebox/g;
const complexPat = /Copyright (\d+)-(\d+) Kodebox/g;

for (let i = 1; i < Deno.args.length; i++) {
  let filename = Deno.args[i];
  if (!await isFileExist(filename)) {
    continue;
  }
  let bytes = await Deno.readFile(filename);
  const allText = decoder.decode(bytes);
  let lines = allText.split("\n");
  lines = lines.map(line =>
    line.replace(simplePat, "Copyright $1-2020 Kodebox")
  );
  lines = lines.map(line =>
    line.replace(complexPat, "Copyright $1-2020 Kodebox")
  );

  await Deno.writeFile(filename, encoder.encode(lines.join("\n")));
}

async function isFileExist(fileName: string) {
  try {
    const fileInfo = await Deno.lstat(fileName);
    if (!fileInfo.isFile()) {
      return false;
    }
  } catch (err) {
    return false;
  }
  return true;
}