/** IRC message codec + casemap (modern.ircdocs.horse). No import. */

var BARE_IRC_MAX_LINE = 512
var BARE_IRC_MAX_TAGS = 8191

function bareIrcStripCrlf(s) {
  var t = String(s == null ? '' : s)
  if (t.charAt(t.length - 1) === '\n') t = t.slice(0, -1)
  if (t.charAt(t.length - 1) === '\r') t = t.slice(0, -1)
  return t
}

function bareIrcUnescapeTagValue(v) {
  var s = String(v == null ? '' : v)
  var out = ''
  for (var i = 0; i < s.length; i++) {
    var c = s.charAt(i)
    if (c !== '\\') {
      out += c
      continue
    }
    var n = s.charAt(i + 1)
    if (n === ':') {
      out += ';'
      i++
    } else if (n === 's') {
      out += ' '
      i++
    } else if (n === '\\') {
      out += '\\'
      i++
    } else if (n === 'r') {
      out += '\r'
      i++
    } else if (n === 'n') {
      out += '\n'
      i++
    } else if (n) {
      out += n
      i++
    }
  }
  return out
}

function bareIrcEscapeTagValue(v) {
  var s = String(v == null ? '' : v)
  var out = ''
  for (var i = 0; i < s.length; i++) {
    var c = s.charAt(i)
    if (c === ';') out += '\\:'
    else if (c === ' ') out += '\\s'
    else if (c === '\\') out += '\\\\'
    else if (c === '\r') out += '\\r'
    else if (c === '\n') out += '\\n'
    else out += c
  }
  return out
}

/**
 * @param {string} line
 * @returns {{ tags: Record<string, string>, source: string, nick: string, user: string, host: string, command: string, params: string[] } | null}
 */
function bareIrcParseMessage(line) {
  var raw = bareIrcStripCrlf(line)
  if (!raw) return null
  var tags = {}
  var i = 0
  if (raw.charAt(0) === '@') {
    var sp = raw.indexOf(' ')
    if (sp < 0) return null
    var tagStr = raw.slice(1, sp)
    i = sp + 1
    while (i < raw.length && raw.charAt(i) === ' ') i++
    var parts = tagStr.split(';')
    for (var t = 0; t < parts.length; t++) {
      var item = parts[t]
      if (!item) continue
      var eq = item.indexOf('=')
      if (eq < 0) tags[item] = ''
      else tags[item.slice(0, eq)] = bareIrcUnescapeTagValue(item.slice(eq + 1))
    }
    raw = raw.slice(i)
    i = 0
  }
  var source = ''
  var nick = ''
  var user = ''
  var host = ''
  if (raw.charAt(0) === ':') {
    var sp2 = raw.indexOf(' ')
    if (sp2 < 0) return null
    source = raw.slice(1, sp2)
    raw = raw.slice(sp2 + 1)
    while (raw.charAt(0) === ' ') raw = raw.slice(1)
    var bang = source.indexOf('!')
    var at = source.indexOf('@')
    if (bang >= 0) {
      nick = source.slice(0, bang)
      if (at > bang) {
        user = source.slice(bang + 1, at)
        host = source.slice(at + 1)
      } else user = source.slice(bang + 1)
    } else if (at >= 0) {
      nick = source.slice(0, at)
      host = source.slice(at + 1)
    } else nick = source
  }
  while (raw.charAt(0) === ' ') raw = raw.slice(1)
  var cmdEnd = raw.indexOf(' ')
  var command
  var rest
  if (cmdEnd < 0) {
    command = raw
    rest = ''
  } else {
    command = raw.slice(0, cmdEnd)
    rest = raw.slice(cmdEnd + 1)
  }
  if (!command) return null
  var params = []
  while (rest.length) {
    while (rest.charAt(0) === ' ') rest = rest.slice(1)
    if (!rest) break
    if (rest.charAt(0) === ':') {
      params.push(rest.slice(1))
      break
    }
    var nsp = rest.indexOf(' ')
    if (nsp < 0) {
      params.push(rest)
      break
    }
    params.push(rest.slice(0, nsp))
    rest = rest.slice(nsp + 1)
  }
  return {
    tags: tags,
    source: source,
    nick: nick,
    user: user,
    host: host,
    command: command,
    params: params
  }
}

/**
 * @param {{ tags?: Record<string, string>, source?: string, command: string, params?: string[] }} msg
 */
function bareIrcSerializeMessage(msg) {
  var m = msg || {}
  var out = ''
  var tags = m.tags
  if (tags && typeof tags === 'object') {
    var keys = []
    var k
    for (k in tags) {
      if (Object.prototype.hasOwnProperty.call(tags, k)) keys.push(k)
    }
    if (keys.length) {
      out += '@'
      for (var i = 0; i < keys.length; i++) {
        if (i) out += ';'
        var val = tags[keys[i]]
        if (val == null || val === '') out += keys[i]
        else out += keys[i] + '=' + bareIrcEscapeTagValue(val)
      }
      out += ' '
    }
  }
  if (m.source) out += ':' + m.source + ' '
  out += String(m.command || '')
  var params = Array.isArray(m.params) ? m.params : []
  for (var p = 0; p < params.length; p++) {
    var part = String(params[p] == null ? '' : params[p])
    var last = p === params.length - 1
    if (last) {
      out += ' :' + part
    } else {
      out += ' ' + part
    }
  }
  return out + '\r\n'
}

/**
 * Byte/string accumulator. Returns complete lines without the delimiter.
 */
function bareIrcCreateLineBuffer() {
  var acc = ''
  return {
    push: function (chunk) {
      if (chunk == null) return []
      var s
      if (typeof chunk === 'string') s = chunk
      else if (typeof TextDecoder !== 'undefined') {
        s = new TextDecoder('utf-8', { fatal: false }).decode(
          chunk instanceof Uint8Array ? chunk : new Uint8Array(chunk)
        )
      } else {
        var u = chunk instanceof Uint8Array ? chunk : []
        s = ''
        for (var i = 0; i < u.length; i++) s += String.fromCharCode(u[i])
      }
      acc += s.replace(/\r\n/g, '\n').replace(/\r/g, '\n')
      var out = []
      for (;;) {
        var n = acc.indexOf('\n')
        if (n < 0) break
        var line = acc.slice(0, n)
        acc = acc.slice(n + 1)
        if (line) out.push(line)
      }
      return out
    },
    pending: function () {
      return acc
    }
  }
}

function bareIrcRfc1459LowerChar(c) {
  var code = c.charCodeAt(0)
  if (code >= 65 && code <= 90) return String.fromCharCode(code + 32)
  if (c === '[') return '{'
  if (c === ']') return '}'
  if (c === '\\') return '|'
  if (c === '~') return '^'
  return c
}

function bareIrcCasemap(s, mapping) {
  var t = String(s == null ? '' : s)
  var kind = String(mapping || 'rfc1459').toLowerCase()
  if (kind === 'ascii') return t.toLowerCase()
  var out = ''
  for (var i = 0; i < t.length; i++) out += bareIrcRfc1459LowerChar(t.charAt(i))
  return out
}

function bareIrcEqual(a, b, mapping) {
  return bareIrcCasemap(a, mapping) === bareIrcCasemap(b, mapping)
}

function bareIrcIsChannel(name, chantypes) {
  var n = String(name || '')
  if (!n) return false
  var types = chantypes || '#'
  return types.indexOf(n.charAt(0)) >= 0
}