Good Lord man, I thought mine was a mess!
Have a look at the link in my signature if you want to get some idea of what a "bad as it gets and still be fixable" cab looks like. Like the cren sez, I hate to discourage you but that's well beyond a practical fix.
Find a new cab, or better yet have a real good look at the rest of the truck, like the frame and make a serious decision as to exactly how much is salvageable.
