Average Cost Line Indicator

Hello, 

This is my first job post here so forgive me if I am not exactly sure of all the protocal. 

I need a average cost indicator for my charts.

The program needs to calculate the average cost of my positions and then place a line on the chart to indicate this.

Simple example (the program would need to obviously go out 5 decimal points as well as figure out position sizes that include micro,mini and full lots.)

This is full lots just for example.

Trade 1 Sell 1 EUR/USD @ 1.24000

Trade 2 Sell 1 EUR/USD @ 1.23000

Trade 3 Sell 1 EUR?USD @ 1.23500 

Trade 4 Sell 1 EUR/USD @ 1.24500

Total Position Sell 4 EUR  Average cost of position = 1.24500 + 1.24000 + 1.23500 + 1.23000 / 4 = 1.2375

The indicator would now put a line on the chart at 1.2375

Obviously each time a position is added to or subtracted from the calculation would change and the bar would adjust.

I have included a script that i found that was supposed to do what I am looking for but it does not seem to be able to add in mucro/mini lots because i just tried to use it and the calculation is wrong. It may however provide someone with a base they can use to speed up the process.

I look forward to hearing from someone that can help get this done for me.