Figure out how to export Forecast CSV files from the data fetched.

[yongrenjie]

cf. alan-turing-institute/Hut23#1360

[yongrenjie]

(started on fc-export branch)

[yongrenjie]

Roadmap (as of 14 March); all done!

• [x] Start and end dates must be specified on the command-line (i.e. via a string). How many formats do we propose to parse?
  • [x] Probably just YYYYMMDD and variations thereof for simplicity Any string containing 8 digits (non-digit characters are ignored). Interpreted as YYYYMMDD. 6-digit strings are also accepted and parsed as YYMMDD, although this will break in the year 2100.
• [x] What should the default values be?
  • [x] 1st of previous month to last day of next month
• [x] Note that having two optional positional parameters (start and end date) means that some combinations cannot be specified. We might want to have a sentinel value (maybe an underscore) to denote an empty start date.
• [x] Output option:
  • [x] whatwhat export [START] [END] -o [FILE] -> print to given file
  • [x] whatwhat export [START] [END] -o -> print to default file name (in working directory)
  • [x] whatwhat export [START] [END] -> print to stdout
• [x] Calculate hours per week for each week from Forecast data (which is in ... seconds per day), then add them to the CSV output
• [x] Merge assignments which have the same people and same project. I'm aware that there's code in lib/forecast.ml which does this. Here's the function to do so:

  (** essentially Data.List.groupBy from Haskell *)
  let group_by (p : 'a -> 'a -> bool) (xs : 'a list) : 'a list list =
  let acc x grps =
  match grps with
  | [] -> [ [ x ] ]
  | grp :: rest ->
      if p x (List.hd grp) then (x :: grp) :: rest else [ x ] :: grp :: rest
  in
  List.fold_right acc xs []

• [x] Make the proper subcommand instead of using a different executable
• [ ] Document usage in wiki

[yongrenjie]

Bonus (not necessarily part of this issue)

• [ ] Figure out why project code from raw Forecast data can be None
• [ ] Clean up and/or document forecastRaw.ml, which is currently a huge mess