class RuboCop::Cop::Lint::DuplicateMethods

def check_const_receiver(node, name, const_name)
  qualified = lookup_constant(node, const_name)
  return unless qualified
  found_method(node, "#{qualified}.#{name}")
end

def check_self_receiver(node, name)
  enclosing = node.parent_module_name
  return unless enclosing
  found_method(node, "#{enclosing}.#{name}")
end

def found_attr(node, args, readable: false, writable: false)
  args.each do |arg|
    name = sym_name(arg)
    next unless name
    found_instance_method(node, name) if readable
    found_instance_method(node, "#{name}=") if writable
  end
end

def found_instance_method(node, name)
  return found_sclass_method(node, name) unless (scope = node.parent_module_name)
  # Humanize the scope
  scope = scope.sub(
    /(?:(?<name>.*)::)#<Class:\k<name>>|#<Class:(?<name>.*)>(?:::)?/,
    '\k<name>.'
  )
  scope << '#' unless scope.end_with?('.')
  found_method(node, "#{scope}#{name}")
end

def found_method(node, method_name)
  key = method_key(node, method_name)
  scope = node.each_ancestor(:rescue, :ensure).first&.type
  if @definitions.key?(key)
    if scope && !@scopes[scope].include?(key)
      @definitions[key] = node
      @scopes[scope] << key
      return
    end
    message = message_for_dup(node, method_name, key)
    add_offense(location(node), message: message)
  else
    @definitions[key] = node
  end
end

def found_sclass_method(node, name)
  singleton_ancestor = node.each_ancestor.find(&:sclass_type?)
  return unless singleton_ancestor
  singleton_receiver_node = singleton_ancestor.children[0]
  return unless singleton_receiver_node.send_type?
  found_method(node, "#{singleton_receiver_node.method_name}.#{name}")
end

def initialize(config = nil, options = nil)
  super
  @definitions = {}
  @scopes = Hash.new { |hash, key| hash[key] = [] }
end

def location(node)
  if DEF_TYPES.include?(node.type)
    node.loc.keyword.join(node.loc.name)
  else
    node.source_range
  end
end

def lookup_constant(node, const_name)
  # this method is quite imperfect and can be fooled
  # to do much better, we would need to do global analysis of the whole
  # codebase
  node.each_ancestor(:class, :module, :casgn) do |ancestor|
    namespace, mod_name = *ancestor.defined_module
    loop do
      if mod_name == const_name
        return qualified_name(ancestor.parent_module_name, namespace, mod_name)
      end
      break if namespace.nil?
      namespace, mod_name = *namespace
    end
  end
end

def message_for_dup(node, method_name, key)
  format(MSG, method: method_name, defined: source_location(@definitions[key]),
              current: source_location(node))
end

def method_key(node, method_name)
  if (ancestor_def = node.each_ancestor(*DEF_TYPES).first)
    "#{ancestor_def.method_name}.#{method_name}"
  else
    method_name
  end
end

def on_alias(node)
  return unless (name = method_alias?(node))
  return if node.ancestors.any?(&:if_type?)
  return if possible_dsl?(node)
  found_instance_method(node, name)
end

def on_attr(node, attr_name, args)
  case attr_name
  when :attr
    writable = args.size == 2 && args.last.true_type?
    found_attr(node, [args.first], readable: true, writable: writable)
  when :attr_reader
    found_attr(node, args, readable: true)
  when :attr_writer
    found_attr(node, args, writable: true)
  when :attr_accessor
    found_attr(node, args, readable: true, writable: true)
  end
end

def on_def(node)
  # if a method definition is inside an if, it is very likely
  # that a different definition is used depending on platform, etc.
  return if node.each_ancestor.any?(&:if_type?)
  return if possible_dsl?(node)
  found_instance_method(node, node.method_name)
end

def on_defs(node)
  return if node.each_ancestor.any?(&:if_type?)
  return if possible_dsl?(node)
  if node.receiver.const_type?
    _, const_name = *node.receiver
    check_const_receiver(node, node.method_name, const_name)
  elsif node.receiver.self_type?
    check_self_receiver(node, node.method_name)
  end
end

def on_send(node)
  if (name = alias_method?(node))
    return if node.ancestors.any?(&:if_type?)
    return if possible_dsl?(node)
    found_instance_method(node, name)
  elsif (attr = node.attribute_accessor?)
    on_attr(node, *attr)
  end
end

def possible_dsl?(node)
  # DSL methods may evaluate a block in the context of a newly created
  # class or module
  # Assume that if a method definition is inside any block call which
  # we can't identify, it could be a DSL
  node.each_ancestor(:block).any? do |ancestor|
    ancestor.method_name != :class_eval && !ancestor.class_constructor?
  end
end

def qualified_name(enclosing, namespace, mod_name)
  if enclosing != 'Object'
    if namespace
      "#{enclosing}::#{namespace.const_name}::#{mod_name}"
    else
      "#{enclosing}::#{mod_name}"
    end
  elsif namespace
    "#{namespace.const_name}::#{mod_name}"
  else
    mod_name
  end
end

def source_location(node)
  range = node.source_range
  path = smart_path(range.source_buffer.name)
  "#{path}:#{range.line}"
end