bluetooth: refactor code

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/a630b2a4cf864baa9c21a4713b7bf803/
tower: https://tower.im/projects/15081ba156b14fa4bd6d9e82f91edff3/todos/2a264f0e1b4c4872a8f8452455734fb3/
Change-Id: Ibd31eb5a498a6274e136d73c635c97cf5ae9a4ab