# vim:sw=2:sts=2:
- [ ] Output formats:
  - [x] text long
  - [x] text short
  - [ ] HTML
  - [ ] JSON
- [ ] Convert to Typed Racket
  - requires: build executable (otherwise too slow)
- [x] Build executable
  Implies fix of "collection not found" when executing the built executable
    outside the source directory:

    collection-path: collection not found
      collection: "tt"
      in collection directories:
      context...:
       /usr/share/racket/collects/racket/private/collect.rkt:11:53: fail
       /usr/share/racket/collects/setup/getinfo.rkt:17:0: get-info
       /usr/share/racket/collects/racket/contract/private/arrow-val-first.rkt:555:3
       /usr/share/racket/collects/racket/cmdline.rkt:191:51
       '|#%mzc:p

- [ ] Support redirects
  - should permanent redirects update the feed somehow?
- [ ] Support time ranges (i.e. reading the timeline between given time points)
- [x] Implement rfc3339->epoch
- [x] Remove dependency on rfc3339-old
- [x] remove dependency on http-client
- [ ] optional text wrap
- [ ] write
- [x] caching (use cache by default, unless explicitly asked for update)
  - [x] value --> cache
  - [x] value <-- cache
    requires: d command
- [ ] timeline limits
- [ ] feed set operations (perhaps better done externally?)
- [ ] timeline as a result of a query (feed set op + filter expressions)
- [ ] named timelines
- [ ] config files
- [ ] parse "following" from feed
  - following = <nick> <uri>
- [ ] parse mentions:
  - @<source.nick source.url> | @<source.url>
- [ ] highlight mentions
- [ ] filter on mentions
- [ ] highlight hashtags
- [ ] filter on hashtags
- [ ] hashtags as channels? initial hashtag special?
- [ ] query language
- [ ] console logger colors by level ('error)
- [ ] file logger ('debug)
- [-] commands:
  - [x] r | read
    - see timeline ops above
  - [ ] w | write
    - arg or stdin
    - nick expand to URI
  - [ ] q | query
    - see timeline ops above
    - see hashtag and channels above
  - [x] d | download
  - [x] u | upload
    - calls user-configured command to upload user's own feed file to their server
  Looks like a better CLI parser than "racket/cmdline": https://docs.racket-lang.org/natural-cli/
  But it is no longer necessary now that I've figured out how to chain (command-line ..) calls.
- [ ] Suport immutable timelines
    - store individual messages
      - where?
        - something like DBM or SQLite - faster
        - filesystem - transparent, easily published - probably best
  - [ ] block(chain/tree) of twtxts
    - distributed twtxt.db
    - each twtxt.txt is a ledger
    - peers can verify states of ledgers
    - peers can publish known nick->url mappings
    - peers can vote on nick->url mappings
    - we could break time periods into blocks
    - how to handle the facts that many(most?) twtxt are unseen by peers
    - longest X wins?
- [ ] Peer discovery
  requires:
    - parse mentions
    - parse following
  rough sketch from late 2019:

        let read file =
            ...
        let write file peers =
            ...
        let fetch peer =
            (* Fetch could mean either or both of:
             * - fetch peer's we-are-twtxt.txt
             * - fetch peer's twtxt.txt and extract mentioned peer URIs
             * *)
            ...
        let test peers =
            ...
        let rec discover peers_old =
            let peers_all =
                Set.fold peers_old ~init:peers_old ~f:(fun peers p ->
                    match fetch p with
                    | Error _ ->
                        (* TODO: Should p be moved to down set here? *)
                        log_warning ...;
                        peers
                    | Ok peers_fetched ->
                        Set.union peers peers_fetched
                )
            in
            if Set.empty (Set.diff peers_old peers_all) then
                peers_all
            else
                discover peers_all
        let rec loop interval peers_old =
            let peers_all = discover peers_old in
            let (peers_up, peers_down) = test peers_all in
            write "peers-all.txt"  peers_all;
            write "peers-up.txt"   peers_up;
            write "peers-down.txt" peers_down;
            sleep interval;
            loop interval peers_all
        let () =
            loop (Sys.argv.(1)) (read "peers-all.txt")