class YARD::Tags::DefaultFactory

def extract_name_from_text(text)
  text.strip.split(/\s+/, 2)
end

def extract_title_and_desc_from_text(text)
  raise TagFormatError if text.nil? || text.empty?
  title = nil
  desc = nil
  if text =~ /\A[ \t]\n/
    desc = text
  else
    text = text.split(/\r?\n/)
    title = text.shift.squeeze(' ').strip
    desc = text.join("\n")
  end
  [title, desc]
end

def extract_types_and_name_from_text(text, opening_types = TYPELIST_OPENING_CHARS, closing_types = TYPELIST_CLOSING_CHARS)
  before, list, text = *extract_types_and_name_from_text_unstripped(text, opening_types, closing_types)
  if list.nil?
    [nil, nil, text.strip]
  else
    [before ? before.strip : nil, list.map(&:strip), text.strip]
  end
end

def extract_types_and_name_from_text_unstripped(text, opening_types = TYPELIST_OPENING_CHARS, closing_types = TYPELIST_CLOSING_CHARS)
  e = 0
  before = String.new("")
  list = [String.new("")]
  level = 0
  seen_space = false
  i = 0
  last_seen = ''
  text ||= ''
  while i < text.length
    c = text[i, 1]
    if (c == '"' || c == "'") && text[i..-1] =~ /#{c}.+?#{c}/
      list.last << $&
      i += $&.length
      next
    end
    if level > 0 && c == '#' && text[i + 1..-1] =~ CodeObjects::METHODNAMEMATCH
      list.last << c + $&
      i += $&.length + 1
      next
    elsif opening_types.include?(c)
      list.last << c if level > 0
      level += 1
    elsif closing_types.include?(c)
      level -= 1 unless last_seen == '=' && c == '>'
      break e = i if level == 0
      list.last << c
    elsif c == ',' && level == 1
      list.push String.new("")
    elsif c =~ /\S/ && level == 0
      break e = i if seen_space && list == ['']
      before << c
    elsif c =~ /[ \t]/ && level == 0 && !before.empty?
      seen_space = true
    elsif level >= 1
      list.last << c
    elsif level == 0 && c == "\n"
      break e = i
    end
    last_seen = c
    i += 1
  end
  before = before.empty? ? nil : before
  if list.size == 1 && list.first == ''
    [nil, nil, text]
  else
    [before, list, text[(e + 1)..-1]]
  end
end

def parse_tag(tag_name, text)
  Tag.new(tag_name, text.strip)
end

def parse_tag_with_name(tag_name, text)
  name, text = *extract_name_from_text(text)
  Tag.new(tag_name, text, nil, name)
end

def parse_tag_with_options(tag_name, text)
  name, text = *extract_name_from_text(text)
  OptionTag.new(tag_name, name, parse_tag_with_types_name_and_default(tag_name, text))
end

def parse_tag_with_title_and_text(tag_name, text)
  title, desc = *extract_title_and_desc_from_text(text)
  Tag.new(tag_name, desc, nil, title)
end

def parse_tag_with_types(tag_name, text)
  name, types, text = *extract_types_and_name_from_text(text)
  raise TagFormatError, "cannot specify a name before type list for '@#{tag_name}'" if name
  Tag.new(tag_name, text, types)
end

def parse_tag_with_types_and_name(tag_name, text)
  name, types, text = *extract_types_and_name_from_text(text)
  name, text = *extract_name_from_text(text) unless name
  Tag.new(tag_name, text, types, name)
end

def parse_tag_with_types_and_title(tag_name, text)
  name, types, text = *extract_types_and_name_from_text_unstripped(text)
  if name
    title = name
    desc = text
  else
    title, desc = *extract_title_and_desc_from_text(text)
  end
  Tag.new(tag_name, desc, types, title)
rescue TagFormatError
  Tag.new(tag_name, '', types, nil)
end

def parse_tag_with_types_name_and_default(tag_name, text)
  # Can't allow () in a default tag, otherwise the grammar is too ambiguous when types is omitted.
  open = TYPELIST_OPENING_CHARS.delete('(')
  close = TYPELIST_CLOSING_CHARS.delete(')')
  name, types, text = *extract_types_and_name_from_text(text, open, close)
  name, text = *extract_name_from_text(text) unless name
  if text && text.start_with?('(')
    _, default, text = *extract_types_and_name_from_text(text, '(', ')')
    DefaultTag.new(tag_name, text, types, name, default)
  else
    DefaultTag.new(tag_name, text, types, name, nil)
  end
end