class RBS::Parser

def self.buffer(source)
  case source
  when String
    Buffer.new(content: source, name: "a.rbs")
  when Buffer
    source
  end
end

def self.lex(source)
  buf = buffer(source)
  list = _lex(buf, buf.last_position)
  value = list.map do |type, location|
    Token.new(type: type, location: location)
  end
  LexResult.new(buffer: buf, value: value)
end

def self.magic_comment(buf)
  start_pos = 0
  while true
    case
    when match = /\A#\s*(?<keyword>resolve-type-names)\s*(?<colon>:)\s+(?<value>true|false)$/.match(buf.content, start_pos)
      value = match[:value] or raise
      kw_offset = match.offset(:keyword) #: [Integer, Integer]
      colon_offset = match.offset(:colon) #: [Integer, Integer]
      value_offset = match.offset(:value) #: [Integer, Integer]
      location = Location.new(buf, kw_offset[0], value_offset[1])
      location.add_required_child(:keyword, kw_offset[0]...kw_offset[1])
      location.add_required_child(:colon, colon_offset[0]...colon_offset[1])
      location.add_required_child(:value, value_offset[0]...value_offset[1])
      return AST::Directives::ResolveTypeNames.new(value: value == "true", location: location)
    else
      return
    end
  end
end

def self.parse_method_type(source, range: 0..., variables: [], require_eof: false)
  buf = buffer(source)
  _parse_method_type(buf, range.begin || 0, range.end || buf.last_position, variables, require_eof)
end

def self.parse_signature(source)
  buf = buffer(source)
  resolved = magic_comment(buf)
  start_pos =
    if resolved
      (resolved.location || raise).end_pos
    else
      0
    end
  dirs, decls = _parse_signature(buf, start_pos, buf.last_position)
  if resolved
    dirs = dirs.dup if dirs.frozen?
    dirs.unshift(resolved)
  end
  [buf, dirs, decls]
end

def self.parse_type(source, range: 0..., variables: [], require_eof: false)
  buf = buffer(source)
  _parse_type(buf, range.begin || 0, range.end || buf.last_position, variables, require_eof)
end