Repair Advice Needed

I own the top floor unit of a brownstone building and rain has been coming through the roof and leaking from the ceiling into my apartment, slowly and only whenever there is a rain storm, but there is some damages to my aparment because this problem has existed for roughly two years. Can anyone recommend someone who can both repair the water damage to the ceiling and wall and at the same time look inside the wall and ceiling to assess whether there has been any harm from the leak to the structural integrity of the wood beams in the ceiling/roof? This latter part is an important part of the job since the roof supports a deck so I want to make sure there isn’t any damage to the structure that could risk causing the roof to collapse.