How can I interact with metamask extension via embedded javascript?

Question

Let's say I am building browser based trading bot, which I want to be able to:

1. Be inserted to the page via extension or raw javascript code;
2. It will click here and there until MetaMask extension appears (to approve transaction);
3. It should be able to click on approve/submit button within MetaMask;

OR simply

It should do whatever necessary internally via exposed/SDK APIs, so that when it is embedded to the page it makes everything what user can do, but via SDK/API. Most important: login, sign, send operations.

Please give at least some directions of how to achieve that. Thanks!