/** RPL_ISUPPORT (005) token map. */

function bareIrcParseIsupport(params) {
  var tokens = {}
  var list = Array.isArray(params) ? params : []
  var last = list.length
  if (last && String(list[last - 1]).indexOf('are supported') >= 0) last--
  var start = 0
  if (
    list.length &&
    !/=/.test(String(list[0])) &&
    !/^[A-Z]+$/.test(String(list[0]))
  ) {
    start = 1
  }
  for (var i = start; i < last; i++) {
    var raw = String(list[i] || '')
    if (!raw) continue
    var eq = raw.indexOf('=')
    if (eq < 0) tokens[raw] = true
    else tokens[raw.slice(0, eq)] = raw.slice(eq + 1)
  }
  return tokens
}

function bareIrcIsupportDefaults() {
  return {
    CASEMAPPING: 'rfc1459',
    CHANTYPES: '#&',
    PREFIX: '(ov)@+',
    NICKLEN: '16',
    CHANNELLEN: '50',
    TOPICLEN: '390',
    NETWORK: ''
  }
}

function bareIrcMergeIsupport(cur, incoming) {
  var out = cur && typeof cur === 'object' ? cur : bareIrcIsupportDefaults()
  var next = incoming && typeof incoming === 'object' ? incoming : {}
  var k
  for (k in next) {
    if (Object.prototype.hasOwnProperty.call(next, k)) out[k] = next[k]
  }
  return out
}

function bareIrcPrefixMap(isupport) {
  var raw =
    isupport && isupport.PREFIX != null ? String(isupport.PREFIX) : '(ov)@+'
  var m = /^\(([^)]+)\)(.*)$/.exec(raw)
  var modes = m ? m[1] : 'ov'
  var prefs = m ? m[2] : '@+'
  var byMode = {}
  var byPref = {}
  var i
  for (i = 0; i < modes.length && i < prefs.length; i++) {
    byMode[modes.charAt(i)] = prefs.charAt(i)
    byPref[prefs.charAt(i)] = modes.charAt(i)
  }
  return { modes: modes, prefixes: prefs, byMode: byMode, byPref: byPref }
}

function bareIrcNicklen(isupport) {
  var n = parseInt(isupport && isupport.NICKLEN, 10)
  return Number.isFinite(n) && n > 0 ? n : 16
}

function bareIrcChantypes(isupport) {
  return (isupport && isupport.CHANTYPES) || '#'
}

function bareIrcCasemapping(isupport) {
  return (isupport && isupport.CASEMAPPING) || 'rfc1459'
}