class RuboCop::Cop::Style::FileName

def expect_matching_definition?
  cop_config['ExpectMatchingDefinition']
end

def filename_good?(basename)
  basename = basename.sub(/\.[^\.]+$/, '')
  basename =~ (regex || SNAKE_CASE)
end

def find_class_or_module(node, namespace)
  return nil if node.nil?
  name = namespace.pop
  on_node([:class, :module, :casgn], node) do |child|
    next unless (const = child.defined_module)
    const_namespace, const_name = *const
    next unless name == const_name
    return node if namespace.empty?
    return node if match_namespace(child, const_namespace, namespace)
  end
  nil
end

def investigate(processed_source)
  file_path = processed_source.buffer.name
  return if config.file_to_include?(file_path)
  basename = File.basename(file_path)
  if filename_good?(basename)
    return unless expect_matching_definition?
    return if find_class_or_module(processed_source.ast,
                                   to_namespace(file_path))
    range = source_range(processed_source.buffer, 1, 0)
    msg   = format(MSG_NO_DEFINITION,
                   basename,
                   to_namespace(file_path).join('::'))
  else
    first_line = processed_source.lines.first
    return if cop_config['IgnoreExecutableScripts'] &&
              shebang?(first_line)
    range = source_range(processed_source.buffer, 1, 0)
    msg = regex ? format(MSG_REGEX, basename, regex) : MSG_SNAKE_CASE
  end
  add_offense(nil, range, msg)
end

def match_namespace(node, namespace, expected)
  expected = expected.dup
  match_partial = lambda do |ns|
    next if ns.nil?
    while ns
      return expected.empty? || expected == [:Object] if ns.cbase_type?
      ns, name = *ns
      name == expected.last ? expected.pop : (return false)
    end
  end
  match_partial.call(namespace)
  node.each_ancestor(:class, :module, :sclass, :casgn) do |ancestor|
    return false if ancestor.sclass_type?
    match_partial.call(ancestor.defined_module)
  end
  expected.empty? || expected == [:Object]
end

def regex
  cop_config['Regex']
end

def shebang?(line)
  line && line.start_with?('#!')
end

def to_module_name(basename)
  words = basename.sub(/\..*/, '').split('_')
  words.map(&:capitalize).join.to_sym
end

def to_namespace(path)
  components = Pathname(path).each_filename.to_a
  # To convert a pathname to a Ruby namespace, we need a starting point
  # But RC can be run from any working directory, and can check any path
  # We can't assume that the working directory, or any other, is the
  # "starting point" to build a namespace
  start = %w(lib spec test src)
  if components.find { |c| start.include?(c) }
    components = components.drop_while { |c| !start.include?(c) }
    components.drop(1).map { |fn| to_module_name(fn) }
  else
    [to_module_name(components.last)]
  end
end