You should be able to get a chainwheel replacement without a big problem and the pic shows a pretty straightforward replacement - assuming you can get by the rust! Just measure from the center of the crank spindle to the center of a chainwheel bolt and multiply by 2 for the bolt circle diameter, then start searching. You might want to disassemble the chainwheel first to make sure you can get it apart and to see clearly what the requirements would be for a replacement (thickness, recess for the bolt, etc).

Forgot to mention. Is a chainring bent that badly straightenable? Yes. Are you likely to be able to get it back in to good condition and have it remain that way? Maybe.