module Booking

import iTasks
import Data.List

:: List a :== [a]

view label value :== viewInformation label [] value
edit label value :== updateInformation label [] value
fill label       :== enterInformation label []

share label value :== sharedStore label value
watch label store :== viewSharedInformation label [] store

ok :== const True

// (>>+) :: Task a -> List ( a -> Bool, a -> Task b ) -> Task b
(>>+) infixl 1
(>>+) task options :== task >>* map trans options
where
    trans ( p, t ) = OnValue (ifValue p t)

// (>>-) :: Task a -> (a -> Task b) -> Task b
(>>-) infixl 1
(>>-) task cont = task >>+ [ ( ok, cont ) ]

// (>>|) :: Task a -> Task b -> Task b
(>>|) infixl 1
(>>|) task next = task >>- \_ -> next

// (>>?) :: Task a -> List ( String, a -> Bool, a -> Task b ) -> Task b
(>>?) infixl 1
(>>?) task options :== task >>* map trans options
where
    trans ( a, p, t ) = OnAction (Action a) (ifValue p t)


// Data ////////////////////////////////////////////////////////////////////////

:: Seat = Seat Row Pos
:: Row :== Int
:: Pos :== Char

:: Person =
    { first_name :: String
    , last_name :: String
    , age :: Int
    }

:: Booking =
    { passengers :: List Person
    , flight_no :: String
    , seats :: List Seat
    }


// Stores //////////////////////////////////////////////////////////////////////

free_seat_store :: Shared (List Seat)
free_seat_store = share "Free seats" [ Seat r p \\ r <- [1..6], p <- ['A'..'D'] ]


// Checks //////////////////////////////////////////////////////////////////////

// Tasks ///////////////////////////////////////////////////////////////////////

removeElems :: (List a) (List a) -> List a | iTask a
removeElems xs ys =
    []
    // [ y \\ y <- ys, x <- xs | y =!= x ]
    // filter (\x -> not (elem x ys)) ys

choose_seats :: Int -> Task (List Seat)
choose_seats n =
    enterMultipleChoiceWithShared "Pick a seat" [] free_seat_store >>?
        [ ( "Continue"
          , \seats -> True//length seats == n
          , \seats -> upd (removeElems seats) free_seat_store >>| return seats
          )
        ]

main :: Task (List Seat)
main =
    (forever (watch "Free seats" free_seat_store >>* [OnAction (Action "Refresh") (always (treturn ()))]))
        ||-
    (choose_seats 2 >>- view "Chosen seats")


// Boilerplate /////////////////////////////////////////////////////////////////

derive class iTask Seat, Person, Booking

Start :: *World -> *World
Start world = startEngine main world