Frustrated, i imagine

Sometimes I think that it would be best if I can type anywhere or as fast as my brain is thinking. I am imagining a computer brain that can read the brain signal and type whatever is in the mind into a word processor. This is very useful when making a thesis, a book, a journal or any writing that requires a lot of thinking. The computer program should be able to differentiate the signals that require the dictation and signals that are just thought that should not be recorded. Then there should be a mean to tell the program, ok so start writing from this thought to that thought and stop whenever necessary. Indeed it would be a very complicated program to make and I don’t know if it would be realized anytime soon and be sold in the market.