module Opal::Nodes::Helpers

def current_indent
  compiler.parser_indent
end

def empty_line
  push fragment("\n", loc: false)
end

def indent(&block)
  compiler.indent(&block)
end

def js_truthy(sexp)
  if optimize = js_truthy_optimize(sexp)
    return optimize
  end
  helper :truthy
  [fragment('$truthy('), expr(sexp), fragment(')')]
end

def js_truthy_optimize(sexp)
  case sexp.type
  when :send
    receiver, mid, *args = *sexp
    receiver_handler_class = receiver && compiler.handlers[receiver.type]
    # Only operator calls on the truthy_optimize? node classes should be optimized.
    # Monkey patch method calls might return 'self'/aka a bridged instance and need
    # the nil check - see discussion at https://github.com/opal/opal/pull/1097
    allow_optimization_on_type = Compiler::COMPARE.include?(mid.to_s) &&
                                 receiver_handler_class &&
                                 receiver_handler_class.truthy_optimize?
    if allow_optimization_on_type ||
       mid == :block_given?
      expr(sexp)
    elsif args.count == 1
      case mid
      when :==
        helper :eqeq
        compiler.record_method_call mid
        [fragment('$eqeq('), expr(receiver), fragment(', '), expr(args.first), fragment(')')]
      when :===
        helper :eqeqeq
        compiler.record_method_call mid
        [fragment('$eqeqeq('), expr(receiver), fragment(', '), expr(args.first), fragment(')')]
      when :!=
        helper :neqeq
        compiler.record_method_call mid
        [fragment('$neqeq('), expr(receiver), fragment(', '), expr(args.first), fragment(')')]
      end
    elsif args.count == 0
      case mid
      when :!
        helper :not
        compiler.record_method_call mid
        [fragment('$not('), expr(receiver), fragment(')')]
      end
    end
  when :begin
    if sexp.children.count == 1
      js_truthy_optimize(sexp.children.first)
    end
  when :if
    _test, true_body, false_body = *sexp
    if true_body == s(:true)
      # Ensure we recurse the js_truthy call on the `false_body` of the if `expr`.
      # This transforms an expression like:
      #
      # $truthy($truthy(a) || b)
      #
      # Into:
      #
      # $truthy(a) || $truthy(b)
      sexp.meta[:do_js_truthy_on_false_body] = true
      expr(sexp)
    elsif false_body == s(:false)
      sexp.meta[:do_js_truthy_on_true_body] = true
      expr(sexp)
    end
  end
end

def line(*strs)
  push fragment("\n#{current_indent}", loc: false)
  push(*strs)
end

def mid_to_jsid(mid)
  if %r{\=|\+|\-|\*|\/|\!|\?|<|\>|\&|\||\^|\%|\~|\[|`} =~ mid.to_s
    "['$#{mid}']"
  else
    '.$' + mid
  end
end

def property(name)
  valid_name?(name) ? ".#{name}" : "[#{name.inspect}]"
end

def valid_name?(name)
  Opal::Rewriters::JsReservedWords.valid_name?(name)
end