require 'dl'

module DL
  module ValueUtil
    def unsigned_value(val, ty)
      case ty.abs
      when TYPE_CHAR
        [val].pack("c").unpack("C")[0]
      when TYPE_SHORT
        [val].pack("s!").unpack("S!")[0]
      when TYPE_INT
        [val].pack("i!").unpack("I!")[0]
      when TYPE_LONG
        [val].pack("l!").unpack("L!")[0]
      when TYPE_LONG_LONG
        [val].pack("q").unpack("Q")[0]
      else
        val
      end
    end

    def signed_value(val, ty)
      case ty.abs
      when TYPE_CHAR
        [val].pack("C").unpack("c")[0]
      when TYPE_SHORT
        [val].pack("S!").unpack("s!")[0]
      when TYPE_INT
        [val].pack("I!").unpack("i!")[0]
      when TYPE_LONG
        [val].pack("L!").unpack("l!")[0]
      when TYPE_LONG_LONG
        [val].pack("Q").unpack("q")[0]
      else
        val
      end
    end

    def wrap_args(args, tys, funcs, &block)
      result = []
      tys ||= []
      args.each_with_index{|arg, idx|
        result.push(wrap_arg(arg, tys[idx], funcs, &block))
      }
      result
    end

    def wrap_arg(arg, ty, funcs = [], &block)
        require 'dl/func'

        funcs ||= []
        case arg
        when nil
          return 0
        when CPtr
          return arg.to_i
        when IO
          case ty
          when TYPE_VOIDP
            return CPtr[arg].to_i
          else
            return arg.to_i
          end
        when Function
          if( block )
            arg.bind_at_call(&block)
            funcs.push(arg)
          elsif !arg.bound?
            raise(RuntimeError, "block must be given.")
          end
          return arg.to_i
        when String
          if( ty.is_a?(Array) )
            return arg.unpack('C*')
          else
            case SIZEOF_VOIDP
            when SIZEOF_LONG
              return [arg].pack("p").unpack("l!")[0]
            when SIZEOF_LONG_LONG
              return [arg].pack("p").unpack("q")[0]
            else
              raise(RuntimeError, "sizeof(void*)?")
            end
          end
        when Float, Integer
          return arg
        when Array
          if( ty.is_a?(Array) ) # used only by struct
            case ty[0]
            when TYPE_VOIDP
              return arg.collect{|v| Integer(v)}
            when TYPE_CHAR
              if( arg.is_a?(String) )
                return val.unpack('C*')
              end
            end
            return arg
          else
            return arg
          end
        else
          if( arg.respond_to?(:to_ptr) )
            return arg.to_ptr.to_i
          else
            begin
              return Integer(arg)
            rescue
              raise(ArgumentError, "unknown argument type: #{arg.class}")
            end
          end
        end
    end
  end
end