class RuboCop::Cop::Style::TrivialAccessors

def accessor(kind, method_name)
  "attr_#{kind} :#{method_name.to_s.chomp('=')}"
end

def allow_dsl_writers?
  cop_config['AllowDSLWriters']
end

def allow_predicates?
  cop_config['AllowPredicates']
end

def allowed_method?(method_name, body)
  whitelist.include?(method_name) ||
    exact_name_match? && !names_match?(method_name, body)
end

def allowed_reader?(method_name)
  allow_predicates? && predicate?(method_name)
end

def allowed_writer?(method_name)
  allow_dsl_writers? && dsl_writer?(method_name)
end

def autocorrect(node)
  if node.type == :def
    autocorrect_instance(node)
  elsif node.type == :defs && node.children.first.type == :self
    autocorrect_class(node)
  end
end

def autocorrect_class(node)
  _, method_name, args, body = *node
  unless names_match?(method_name, body) &&
         (kind = trivial_accessor_kind(method_name, args, body))
    return
  end
  lambda do |corrector|
    indent = ' ' * node.loc.column
    corrector.replace(
      node.loc.expression,
      ['class << self',
       "#{indent}  #{accessor(kind, method_name)}",
       "#{indent}end"].join("\n")
    )
  end
end

def autocorrect_instance(node)
  method_name, args, body = *node
  unless names_match?(method_name, body) &&
         !predicate?(method_name) &&
         (kind = trivial_accessor_kind(method_name, args, body))
    return
  end
  lambda do |corrector|
    corrector.replace(node.loc.expression, accessor(kind, method_name))
  end
end

def dsl_writer?(method_name)
  !method_name.to_s.end_with?('=')
end

def exact_name_match?
  cop_config['ExactNameMatch']
end

def ignore_class_methods?
  cop_config['IgnoreClassMethods']
end

def in_module?(node)
  pnode = node.parent
  pnode = pnode.parent if pnode && pnode.type == :begin
  !pnode.nil? && pnode.type == :module
end

def looks_like_trivial_reader?(args, body)
  args.children.size == 0 && body && body.type == :ivar
end

def looks_like_trivial_writer?(args, body)
  args.children.size == 1 &&
    ![:restarg, :blockarg].include?(args.children[0].type) &&
    body && body.type == :ivasgn &&
    body.children[1] && body.children[1].type == :lvar
end

def names_match?(method_name, body)
  ivar_name, = *body
  method_name.to_s.sub(/[=?]$/, '') == ivar_name[1..-1]
end

def on_def(node)
  return if in_module?(node)
  method_name, args, body = *node
  on_method_def(node, method_name, args, body)
end

def on_defs(node)
  return if in_module?(node)
  return if ignore_class_methods?
  _scope, method_name, args, body = *node
  on_method_def(node, method_name, args, body)
end

def on_method_def(node, method_name, args, body)
  kind = if trivial_reader?(method_name, args, body)
           'reader'
         elsif trivial_writer?(method_name, args, body)
           'writer'
         end
  return unless kind
  add_offense(node, :keyword, format(MSG, kind, kind))
end

def predicate?(method_name)
  method_name[-1] == '?'
end

def trivial_accessor_kind(method_name, args, body)
  if trivial_writer?(method_name, args, body) &&
     !dsl_writer?(method_name)
    'writer'
  elsif trivial_reader?(method_name, args, body)
    'reader'
  end
end

def trivial_reader?(method_name, args, body)
  looks_like_trivial_reader?(args, body) &&
    !allowed_method?(method_name, body) &&
    !allowed_reader?(method_name)
end

def trivial_writer?(method_name, args, body)
  looks_like_trivial_writer?(args, body) &&
    !allowed_method?(method_name, body) &&
    !allowed_writer?(method_name)
end

def whitelist
  whitelist = cop_config['Whitelist']
  Array(whitelist).map(&:to_sym) + [:initialize]
end