Hack to reopen last book

I would find a way to reopen the last opened book at startup, if I shut down when the book was opened.
What I want to do is to write the document path to some file before the device is shut down if the document is open, and re-open the document when the OS is ready. The problems are:

1. how can I insert an action before the shutting down?
2. where can I find the last opened document? I'm quite sure this information is stored somewhere (the db?)
3. how can I open a document?