Convert a Windows Desktop App to Apple MAC APP

We have a Desktop application related to Video communication. Need some one to convert it into an Apple Mac Application. The application now is a Web & Windows Desktop based system, if needed we can provide the codes of already existing app. Please let us know if you would be able to pull this off & if you have done anything similar before. Also mention the estimated time to be taken. We will send the existing Application to the shortlisted developers & codes would only be shared once awarded the project. Please feel free to ask questions & propose solutions.