/** SASL PLAIN (IRCv3). No import. */

function bareIrcB64Encode(bytes) {
  var table = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
  var s = ''
  var i = 0
  while (i < bytes.length) {
    var a = bytes[i++]
    var b = i < bytes.length ? bytes[i++] : NaN
    var c = i < bytes.length ? bytes[i++] : NaN
    var triple =
      ((a & 255) << 16) |
      ((Number.isFinite(b) ? b & 255 : 0) << 8) |
      (Number.isFinite(c) ? c & 255 : 0)
    s += table.charAt((triple >> 18) & 63)
    s += table.charAt((triple >> 12) & 63)
    s += Number.isFinite(b) ? table.charAt((triple >> 6) & 63) : '='
    s += Number.isFinite(c) ? table.charAt(triple & 63) : '='
  }
  return s
}

function bareIrcUtf8Bytes(str) {
  var s = String(str == null ? '' : str)
  if (typeof TextEncoder !== 'undefined')
    return Array.from(new TextEncoder().encode(s))
  var out = []
  for (var i = 0; i < s.length; i++) out.push(s.charCodeAt(i) & 255)
  return out
}

/**
 * AUTHENTICATE PLAIN payload (account \0 account \0 password), chunked ≤400.
 * @returns {string[]}
 */
function bareIrcSaslPlainChunks(user, pass) {
  var u = String(user || '')
  var p = String(pass || '')
  var raw = bareIrcUtf8Bytes('\0' + u + '\0' + p)
  var b64 = bareIrcB64Encode(raw)
  var chunks = []
  var i = 0
  if (!b64) return ['+']
  while (i < b64.length) {
    chunks.push(b64.slice(i, i + 400))
    i += 400
  }
  return chunks
}