A local agenda that uploads freetime on internet and downloads data from internet

Hello Guys, I need an expert to handle this project because it's a project that is a bit complex. I would like the freelancer to create a local agenda that looks like the google calendar, and when I say like it's almost a copy past of it, but of course with some litle differences. The way of adding an appointment and deleting it, should be exactly the same, a small calendar to navigate through different dates will be needed. 2 main filters will be created in order to allow stores to see what professional they want to book, or what service they want to book. The idea is allow a beauty salon to use that agenda even if the internet is offline, but the main feature is to upload on internet what time is free to receive new customer. If booking is not set manually (local) the system must assume that they are free and offer those time on my website (which is been build in PHP and will be ready in a few days). If someone schedules it on the website this information has to be downloaded to the local agenda so we can be sure that no one will book a service at the same time. Performance is a big issue here, because we have to upload and download it very fast in order to avoid people offering free times that are not available anymore. There are a lot of details that have to be discuss, and 2 word documents will be provided after project is awarded. Take a close look at this overview and just place your bid if you are really understanding what's the complexity of the project. Be sure you can handle it. If you need more details please send me private message to calrify it. Thanks.