your code loops very fast maintaining the led power as the input is high, you need to modify it to say,
set a flag when the input starts high, turn on led, continue looping.
If input is still high, check time led has been on.
If on to long turn off led and wait for low input to reset.
if on too short, leave on and keep looping.
using millis and a few variables you can store timings and state flags.