Writing of an Expert Advisor based on moving average crossover

Hello, I want to create a trading robot which will buy and sell based on moving average crossover. Profit levels will be decided by multiples of atr.  Average out of the trade once it start going in our favour. Few simple entry rules which shall be discussed more in detail nothing too complex. No stop loss. Close position if reverse signal generated and open a fresh trade in the direction. Only one trade at a time. I should be able to choose moving average period for fast and slow, atr period, atr multiples for different average out, lots etc.