PLEASE HELP ME SEPERATE THE BS TO THE TRUTH. Trend line EA possible or not??

I am wanting to write my own EA/robot i am mainly wanting to use a trend line where price crosses the trend line and then a order is placed.

Say were in a up trend and the price crosses for a retracement or complete reversal i want the trade to then be placed a short position and then taking profits once price crosses the trend line.

When the trade is close i want another trade to take place in the opposite direction following the trend till it crosses again which would end that trade and a new trade begin following that trend line.

I have no way of doing this i have only ever made one useless EA before where it would place a trade at the cross of a MA but it never included a stop loss or take profit.

any help would be greatly appreciated.

If this is not possible can someone or a few people please tell me.

I was told that support and resistance cant be used in a EA but i have found ones that are already made by others so anyone out there thats honest with what can be done please contact me ill try not be to annoying in the process.