APP needs to change font style & type on pressing of the button,

Project Description: I want you to create an app that changes style and the font type for the whole Android device in order to reach all applications including all chat applications. You will do an app that can installed smoothly in the whole Android Universe. the app needs to change the font on pressing of a button, The fonts should be changed for the whole system rather than one app and this without rooting, without launcher, without rebooting the system. its local interpretation and code will work locally OR via web services you decide as the architect That application will be targeting all applications inside your Android phone including text messaging applications such as WECHAT, SNAPCHAT, LINECHAT, FACEBOOK, etc... YOU WILL AVOID TO WORK WITH EXISTING API SUCH AS FACEBOOK API BUT RATHER YOU WILL TRY TO BYPASS ANY TEXT MESSAGING API's BUT INSTEAD DOING THE JOB WITHOUT THE API. INSIDE MY APP USER WILL BE ABLE TO ENTER INTO ANOTHER TEXT MESSAGING SERVICES APPLICATION AND ALSO INSIDE YOUR BROWSER OF YOUR SMARTPHONE. I want an Android system application connected to my NGNIX Webservers that will apply my font style into the message typing. Android has only one font style character configured inside your telephone device let's call it Font Style A. My application would provide a different font style character than the one (Font A) that is already installed in your Android device lets' call it this time Font STYLE B. Like Font A, Font B will be available in all the alphabets. In a blink of an eye, User will differentiate between the 2 fonts. This APP stays in the background and will override one or multiple other text messaging applications. You need to implement web NGNIX servers for supplying data to the app. coder need to know ruby on rails. Because for the internal android security max manufacturers don't allow users to customize the system apps. You need to find an innovative solution that will bypass this hurdle by creating the solution for realizing this challenge. supports 30+ languages: English, Chinese 2, Russian, Japanese, Korea, French, Spanish, German, Italian, Czech, Hungarian, Ukrainian, Tamil, Catalan, Turkish, Lithuanian, Portuguese... Skills required: Android, Graphic Design, Mobile Phone, PHP, Ruby on Rails