WYSIWYM Editor

[rafalp]

While originally I was mulling over replacing Misago's custom editor (that has snippets of code going back all the way to my 2006 forum software "Callisto" that my cousin has writen for me) with either Medium Editor or Draft.js, ultimately I've decided to go with ProseMirror that seems to fit the bill most:

• WYSIWYM editor that operates on node graphs instead of DOM
• been around for a while and is battletested as well as has examples and community around it
• supports tree node graph which should make it easier to implement quotes and spoilers than on, say, draft.js
• plays nice with React.js components

This task will be paradigm switch for Misago:

• messages sources will be stored as JSON structures
• they will still be preparsed to html for initial render speed
• they will need new checksuming tactic to protect from malicious post json injection
• database migrations for posts will get complex to understand as they'll get changed to use JSON in new initial migration, and only offer html to JSON migration for those who started out on older versions.

Fallback editor

Old textarea-based editor will still remain, and users will be able to toggle between either, with difference that textarea editor will be parsed to markdown in client and will also emit JSON structure on change. That way we'll be able to rely on much more solid node libraries for message preparation, and replace somewhat hacky parsing setup with something simpler and using less dependencies.

Lastly, fallback editor will be always enabled for Android users (and possibly iOS too) due to mobile browsers being plagued by some behavior differences breaking current WYSIWYM editors.

[rafalp]

Facebook now develops Lexical.js as replacement for Draft.js, and that seems much better choice due to its development with one eye to React.js and rich examples library.

[rafalp]

We obviously can't have markup parser in the client if we want to support posting without JavaScript. If we went this route we would have to update our parser to emit same JSON structure as ProseMirror. But this task has low priority for me.