WhatsForLunch.fs

module MonkeyBot.Plugins.WhatsForLunch

open System
open DDay.iCal
open MonkeyBot

let ZeroCaterId = "..."

type LunchResponse =
    | Lunch of string
    | NoLunch
    | Error of exn

let getTodaysLunch () =
    try
        let calendar =
            sprintf "http://www.zerocater.com/calendar?id=%s" ZeroCaterId
            |> fun url -> iCalendar.LoadFromUri (Uri url)
            |> Seq.head
        let today = calendar.GetOccurrences DateTime.Today
        if Seq.isEmpty today then NoLunch else
            let event = today.[0].Source :?> RecurringComponent
            Lunch event.Description
    with e -> Error e

[<RespondTo("what(.*) lunch")>]
let ``what's for lunch?`` (bot: IBot) =
    match getTodaysLunch () with
    | Lunch description -> bot.Send description
    | NoLunch -> bot.Send "You're on your own for lunch today."
    | Error e ->
        sprintf "I can't figure out what's for lunch (%s)" e.Message
        |> bot.Send