Local HTTP server for other players

[benknoble]

We can add an option to start a local HTTP server that players can use to enter their names, HP, and even adjust initiative. The implementation would likely consist of a servlet with forms which trigger updates to game-state observables (completing #12 might help organize this). The manager would need updates to the GUI to show the current actual state, in case of conflict (say, typing a name after someone has entered it through the server—how do we know which name is actually used?).

Starting the server should always be optional; that is, playing with a single "controller" as things stand currently should always be possible. If the server is started, there should be an informational display at the bottom of the manager (possibly with a more detailed display of logs on request). The info should at least consist of some indicator that the server is running and how it can be accessed (e.g., http://IP/frosthaven-manager.rkt).

It might be possible to display more game state (such as the main screen, or loot, etc.) in the served pages, but handling updates will be tricky.

---

The following is a "hello world" servlet:

(require web-server/servlet web-server/servlet-env)
(define (start req)
  (response/xexpr
   `(html (head (title "Hello world"))
          (body (p "Hey out there")))))
(serve/servlet start #:listen-ip #f #:port 80)

If you curl http://$(getip)/servlets/standalone.rkt after running this code, you'll see the response. (Note that getip is defined as ipconfig getifaddr en0 on my machine.)

cf. https://defn.io/2020/02/12/racket-web-server-guide/ because of weirdness with serve/servlet and servlet paths: by default, all the demo servlets are available, too.

[benknoble]

@winny- points out on Discord that the nat-traversal library implements a best-interface-ip-address function, among others.

[benknoble]

Relevant docs:

• https://docs.racket-lang.org/web-server-internal/index.html (Internal Web Server; Dispatches)
• https://defn.io/2020/02/12/racket-web-server-guide/ (Guide)
• https://docs.racket-lang.org/web-server/index.html (Web Server use; abstractions for all the things)

[benknoble]

Next up: player summons. The design for these will probably inform how monsters work, too, since they have some similar concerns around being able to change how many there are.

Also: Change initiative slider to some other kind of input for ease of use (or make it width: 80% or something).

[benknoble]

My design notes for summons:

• Modifications to existing summons go through existing idioms: web mods post actions; app mods are observed and SSE'd. Outstanding question: What observable? (I think the observable has to be the whole `(player ,c) observable -> SSE path.)
• Removing a summon deletes its HTML node (by ID, as is typical; ID in this case corresponds to list index, IIRC).
• Adding a summon from the app needs to add an entire HTML node… so the tentative design is to have the relevant SSE contain the entire HTML so that it can be inserted by the client-side JS listener. The HTML would be generated from a function summon-xexpr, which is shared with the main page generation function, composed with xexpr->string or similar.
• Creating a summon from the web client is a bit more involved. The tentative plan is to use embed/url to send the client to a form (formlet?) to give information to create the summon, and then send them back (after posting an action) to the main page.

[benknoble]

Since that worked, let's try monsters?