Add timer and prevent screen lock in simple Android app feature

I need an Android app. I already have a design for it, I just need it to be built. I have an android app that play sounds and i need someone to fix the loop feature. Currently the loop feature allows user to replay sounds continuously. However I need to add the following to the loop feature: 1. Add timer options, 5 mins, 15 mins, 30 mins, 1 hour, 2 hours, 3 hours, 4 hours, and continuous. 2. Stop sound, close app, and put phone to sleep after timer expires. 3. Prevent phone from going to sleep or screen from locking while loop timer is active, because it will stop sound from playing.