Wordpress plugin Ajax-Enabled Enhanced Layered Navigation

I'm looking for an experienced Wordpress developer that will create a wp plugin called Ajax-Enabled Enhanced Layered Navigation. Similar to the Prestashop Layered navigation module, I want something like that inside Wordpress. To be more specific it will be for 'Easy Digital Downloads' (an ecommerce plugin which is similar to woocommerce). The idea is that I can create search filter templates that are only visible inside selected wordpress (post type archives) pages. These search filter templates will have the following fields: Dropdowns, checkboxes, radio buttons, multi-select, (price, number) range, number, and date (for starters). Inside these fields, the following data should be displayed: Taxomomies, custom fields, posts, pages, posttypes, authors (seperate wp database table), wp users (for starters). We'll working on this task together. You'll be hired to focus mainly on the functions, while I'll continue to focus further on the design. Please note, I'm a web developer myself, so I'll be checking your code thoroughly. You're expected to take great care to use the latest coding standards; hooks/filters (in all functions), data validation, nonces, etc. I prefer to use jSON as well. The plugin that you'll be working on, is already in its initial stages; meaning that so far the post type is registered and so does the required metaboxes. Plugin is created with [login to view URL] (boilerplate). I also created a widget with html code for the front-end display of the fields that you can use for your work; Certain scripts for multi-select, price range, and date fields are already enqueued inside the plugin as well. Please note that this widget will also be used to display the fields inside the edd posttype archive page (similar to the layered nav module of prestashop). Attached some screenshots to give you a visual example of how the plugin should look like. Attached two other screenshots of what has been done already. Further details will follow after you're hired. To all applicants, show a sample (or a snippet) of a function that you would create if you're coding this plugin. Make sure to not make any mistakes inside your example function.