Accept & save posted form data in mysql using curl in Wordpress

Here's what I need:

1. I need to create a url in Wordpress that accepts the posted data from third party using curl.
2. A remote party will submit their form data using rest api and curl to this url

4. We'll insert the data into our table and return the last inserted id to remote url as reference

Here's what I want:
1. We will create a table with say 10 fields
2. Create a url that accepts the posted data from third party using curl
3. A remote party will submit their form data using rest api and curl to our api url
4. Posted data will be in JSON format so we have to decode the data
5. We'll insert the data into our mysql table and return the last inserted id to remote url as reference

I don't need any security etc as I can implement the API keys etc myself.