Process

"So let's play a song for the bathroom occupier!"

Components

Input: Switch // I wish I could use a sensor here, but for the time limit, I will explore after the due :(

Output: 

1. LEDs to show the time states;

2. Piezo: Music (SuperMario Theme)

3. LED as alarming light flashing with the tempo of song; 

4. LED as showing as a indicator of turning off the song

Sensor: 2 Photoresistors // If he/she turned off the notification, there's still a sensor with a indicating LED to track whether she/he's moving.

Other:  Jumper wires and 1kΩ resistors

Conceptual Workflow

Timing -> Alarming -> (If alarm turned off)Tracking