class Opal::Nodes::DefNode

def arity_check(args, opt, splat, block_name, mid)
  meth = mid.to_s.inspect
  arity = args.size - 1
  arity -= (opt.size - 1) if opt
  arity -= 1 if splat
  arity = -arity - 1 if opt or splat
  # $arity will point to our received arguments count
  aritycode = "var $arity = arguments.length;"
  if arity < 0 # splat or opt args
    aritycode + "if ($arity < #{-(arity + 1)}) { $opal.ac($arity, #{arity}, this, #{meth}); }"
  else
    aritycode + "if ($arity !== #{arity}) { $opal.ac($arity, #{arity}, this, #{meth}); }"
  end
end

def compile
  jsid = mid_to_jsid mid.to_s
  params = nil
  scope_name = nil
  # opt args if last arg is sexp
  opt = args.pop if Sexp === args.last
  argc = args.length - 1
  # block name (&block)
  if args.last.to_s.start_with? '&'
    block_name = variable(args.pop.to_s[1..-1]).to_sym
    argc -= 1
  end
  # splat args *splat
  if args.last.to_s.start_with? '*'
    uses_splat = true
    if args.last == :*
      argc -= 1
    else
      splat = args[-1].to_s[1..-1].to_sym
      args[-1] = splat
      argc -= 1
    end
  end
  if compiler.arity_check?
    arity_code = arity_check(args, opt, uses_splat, block_name, mid)
  end
  in_scope do
    scope.mid = mid
    scope.defs = true if recvr
    if block_name
      scope.uses_block!
      scope.add_arg block_name
    end
    yielder = block_name || '$yield'
    scope.block_name = yielder
    params = process(args)
    stmt_code = stmt(compiler.returns(stmts))
    add_temp 'self = this'
    line "#{variable(splat)} = $slice.call(arguments, #{argc});" if splat
    opt[1..-1].each do |o|
      next if o[2][2] == :undefined
      line "if (#{variable(o[1])} == null) {"
      line '  ', expr(o)
      line "}"
    end if opt
    # must do this after opt args incase opt arg uses yield
    scope_name = scope.identity
    if scope.uses_block?
      add_temp "$iter = #{scope_name}._p"
      add_temp "#{yielder} = $iter || nil"
      line "#{scope_name}._p = null;"
    end
    unshift "\n#{current_indent}", scope.to_vars
    line stmt_code
    unshift arity_code if arity_code
    unshift "var $zuper = $slice.call(arguments, 0);" if scope.uses_zuper
    if scope.catch_return
      unshift "try {\n"
      line "} catch ($returner) { if ($returner === $opal.returner) { return $returner.$v }"
      push " throw $returner; }"
    end
  end
  unshift ") {"
  unshift(params)
  unshift "function("
  unshift "#{scope_name} = " if scope_name
  line "}"
  if recvr
    unshift '$opal.defs(', recv(recvr), ", '$#{mid}', "
    push ')'
  elsif scope.class? and %w(Object BasicObject).include?(scope.name)
    wrap "$opal.defn(self, '$#{mid}', ", ')'
  elsif scope.class_scope?
    scope.methods << "$#{mid}"
    unshift "#{scope.proto}#{jsid} = "
  elsif scope.iter?
    wrap "$opal.defn(self, '$#{mid}', ", ')'
  elsif scope.type == :sclass
    unshift "self._proto#{jsid} = "
  elsif scope.top?
    unshift "$opal.Object._proto#{jsid} = "
  else
    unshift "def#{jsid} = "
  end
  wrap '(', ', nil)' if expr?
end