Simple EA based on MACD

I do need an Ea based on an indicator a traditional Macd histogram crossing up a zero line for a buy signal and crossing down a zero line for a sell. There is a filter which is a volume with MA line should be always above 50 for entry unless otherwise no entry. Moreover, another entry should be a min and max value of ATR should be put as an option. For instance,  for US 30 ATR should be 40 -100. No trades less than 40 and greater than 100. but this is different for different instruments so it should be put as an open in the parameters section. Stop loss should be 1 ATR value always. Exit should be a change of histogram color. Lot size should be left as an option so that I can put it according to the account size.