from high to low. I need total size of the candle

I want to develop an EA based on Biggest candle of the day. I want this EA to run after Asian session ends it should look for the biggest candle and set the threshold according to that. Lets say the biggest candle is 20 pips in Asian session based on the timeframe i choose, then if current candle goes above 20 pips it should place the trade before the candle closes. If candle is bullish then open sell and if bearish then buy. after that it should reset the threshold level of 20 pips and check again for the biggest candle for the day no matter if its bullish or bearish