Bath Tap regulator

Idea: I want to build an add-on device to existing bath taps. I want the device to automatically fill a bath to your desired temperature – save you water level and temperature preferences and stop the water when it is full automatically. I want it to be able to measure the temperature of the water flowing into the bath. Adjust the taps so that you can reach your desired temperature. I need it to be able to measure the volume and calculate when to stop the water flow. Run a bath at optimal temperature - Digital thermometers for measuring the actual bath temperature. Measuring water level - Could be done by a metallic line running down from the tap when submerged for more than 20 seconds it will initiate an automatic water shut off. Maybe: An LCD/LED display to select the preferences for temp and water level within the family household. Final I would like to hear your ideas on how I can incorporate these ideas into one streamline design system. I want this device to be an attachment to an existing bath and also I want to build a product which can replace the original tap. Please let me know timelines, cost and feasibility. Best, Daniel