Config issue for rewrite / redirect

I just want to setup a simple redirect or rewrite between subdomain and domain but I am quite new to this so I can't figure it out. I have 3 things in my mind (not sure if all 3 is possible at same time)

1-) Redirect or rewrite http://api.domain.com/api?t=... request as http://domain.com/api?t=...
2-) Shouldn't change URL at addressbar
3-) Would be great if it gives 200 status instead of 301 or 302.

I tried rewrite but because they are not on same domain, nginx changes the URL.

Any help is appreciated!