class RuboCop::Cop::Style::SelfAssignment

x += 1
# good
x = x + 1
# bad
@example
This cop enforces the use the shorthand for self-assignment.

def check(node, var_type) 

def check(node, var_type)
  var_name, rhs = *node
  return unless rhs
  if rhs.type == :send
    check_send_node(node, rhs, var_name, var_type)
  elsif [:and, :or].include?(rhs.type)
    check_boolean_node(node, rhs, var_name, var_type)
  end
end

def check_boolean_node(node, rhs, var_name, var_type) 

def check_boolean_node(node, rhs, var_name, var_type)
  first_operand, _second_operand = *rhs
  target_node = s(var_type, var_name)
  return unless first_operand == target_node
  operator = rhs.loc.operator.source
  add_offense(node, :expression, format(MSG, operator))
end

def check_send_node(node, rhs, var_name, var_type) 

def check_send_node(node, rhs, var_name, var_type)
  receiver, method_name, *_args = *rhs
  return unless OPS.include?(method_name)
  target_node = s(var_type, var_name)
  return unless receiver == target_node
  add_offense(node, :expression, format(MSG, method_name))
end

def on_cvasgn(node) 

def on_cvasgn(node)
  check(node, :cvar)
end

def on_ivasgn(node) 

def on_ivasgn(node)
  check(node, :ivar)
end

def on_lvasgn(node) 

def on_lvasgn(node)
  check(node, :lvar)
end