class RuboCop::Cop::Performance::RedundantMerge

def autocorrect(node)
  redundant_merge(node) do |receiver, pairs|
    lambda do |corrector|
      new_source = to_assignments(receiver, pairs).join("\n")
      parent = node.parent
      if parent && pairs.size > 1
        if modifier_flow_control(parent)
          new_source = rewrite_with_modifier(node, parent, new_source)
          node = parent
        else
          padding = "\n#{leading_spaces(node)}"
          new_source.gsub!(/\n/, padding)
        end
      end
      corrector.replace(node.source_range, new_source)
    end
  end
end

def each_redundant_merge(node)
  redundant_merge(node) do |receiver, pairs|
    next if node.value_used? &&
            !value_used_inside_each_with_object?(node, receiver)
    next if pairs.size > 1 && !receiver.pure?
    next if pairs.size > max_key_value_pairs
    yield receiver, pairs
  end
end

def indent_width
  @config.for_cop('IndentationWidth')['Width'] || 2
end

def leading_spaces(node)
  node.source_range.source_line[/\A\s*/]
end

def max_key_value_pairs
  cop_config['MaxKeyValuePairs'].to_i
end

def on_send(node)
  each_redundant_merge(node) do |receiver, pairs|
    assignments = to_assignments(receiver, pairs).join('; ')
    message = format(MSG, assignments, node.source)
    add_offense(node, :expression, message)
  end
end

def rewrite_with_modifier(node, parent, new_source)
  cond, = *parent
  padding = "\n#{(' ' * indent_width) + leading_spaces(node)}"
  new_source.gsub!(/\n/, padding)
  parent.loc.keyword.source << ' ' << cond.source << padding <<
    new_source << "\n" << leading_spaces(node) << 'end'
end

def to_assignments(receiver, pairs)
  pairs.map do |pair|
    key, value = *pair
    key_src = if key.sym_type? && !key.source.start_with?(':')
                ":#{key.source}"
              else
                key.source
              end
    format(AREF_ASGN, receiver.source, key_src, value.source)
  end
end

def value_used_inside_each_with_object?(node, receiver)
  while receiver.respond_to?(:send_type?) && receiver.send_type?
    receiver, = *receiver
  end
  unless receiver.respond_to?(:lvar_type?) && receiver.lvar_type?
    return false
  end
  parent = node.parent
  grandparent = parent.parent if parent.begin_type?
  second_arg = each_with_object_node(grandparent || parent)
  return false if second_arg.nil?
  receiver.loc.name.source == second_arg.loc.name.source
end