blueimp/jQuery-File-Upload — reverse-engineered prompt

Build me a reusable file upload widget for a website.

I want users to be able to pick several files at once or drag and drop them onto the page. Show each file in a list with its upload progress, plus an overall progress bar. Let people cancel uploads, and support large files by uploading in chunks and resuming if something gets interrupted.

For images, audio, and video, show a preview before upload when the browser supports it. Images should be able to resize in the browser before sending. It should still work as a normal file upload form if fancy browser features are not available.

Please make it easy to plug into a regular backend that accepts standard form file uploads, with a simple PHP example included. Also include safe defaults and notes for secure upload handling. Use jQuery, since this needs to fit into an older site, and keep the UI simple and customizable.