Count pages via JS on upload, and block presigned urls if exceeded

[ajkiessl]

Can we do this via JavaScript in Uppy? The library the ASU/AWS team uses to get page counts is implemented here:

https://github.com/ASUCICREPO/PDF_accessability_UI/blob/main/pdf_ui/src/components/UploadSection.jsx#L139-L143

We should be able to do something similar, and send the count back to the ruby app on page submit to store with the Job in the database.

Also, I think we can pass the file size along during signing, and block the presigned url from generating if the user exceeds their limit. I haven't dug deeply enough into our code yet to confirm this, though.

[ajkiessl]

To make this fully secure and non-exploitable, we could add a pending_pages field to GUIUser, and add the page count to that on signing. So, if someone tried opening a bunch of tabs to get around the restrictions, each time they sign it will check their page count + pending pages. This will prevent people trying to "hack" more uploads. The pending pages would then be deducted from the user's pending_pages on the successful upload. We'd need some process to clear pending pages, though, if someone were to sign and then leave the site without submitting.

Or we could add another data model to handle something like UploadReservations, rather than storing this on the user record.

We would also need strong params set up in our PdfJobsController.

[Smullz622]

Something to consider, scholarsphere is using the pdf-reader gem to pull page count from file metadata. I'm not sure if it will implement easily here, but if it does, it could simplify/avoid the vulnerability of JS implementation

[ajkiessl]

I moved the above two comments to #234 to continue that discussion there. For this issue we want:

• Store page count on upload complete with Job
• Prevent signing if the uploaded file exceeds page count limits (total + daily)