Flat Channel Indicator

I need to build indicator that find and analyze flat market by candles - without any indicator help

Rules:

1. Trade time : 15M

2. Time filter : European and London sessions, so the analyze should be before its opening time

3. What is the channel - it's the line of candles, when the price does not move too much, does not jump. The more candels you can put inside the channel the better. Better if it's not wider then 10-15 pips between upper and lower line of the channel
   

4. How to draw the channel? The upper and the lower lines should touch the ends of the bodies not the wicks of the candles, of course some will be the wicks, but the most should be the bodies of the candels inside the channel.