net8.ts

const parseRequest = (s: string): Request => {
  const [firstLine, rest] = divideStringOn(s, '\r\n')
  const [method, url, protocol] = firstLine.split(' ', 3)
  const [headers, body] = divideStringOn(rest, '\r\n\r\n')
  const parsedHeaders = headers.split('\r\n').reduce((map, header) => {
    const [key, value] = divideStringOn(header, ': ')
    return map.set(key, value)
  }, new Map())
  return { protocol, method, url, headers: parsedHeaders, body }
}

const divideStringOn = (s: string, search: string) => {
  const index = s.indexOf(search)
  const first = s.slice(0, index)
  const rest = s.slice(index + search.length)
  return [first, rest]
}