blob: 6550eaa0395aaf113135360066aa3cf5f37e0544 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
|
module Model.Payers
( Payers
, ExceedingPayer
, payersDecoder
, updatePayers
, getOrderedExceedingPayers
) where
import Json.Decode as Json exposing (..)
import Dict exposing (..)
import List
import Maybe
type alias Payers = Dict String Int
payersDecoder : Decoder Payers
payersDecoder = Json.map Dict.fromList (list payerDecoder)
payerDecoder : Decoder (String, Int)
payerDecoder =
object2 (,)
("userName" := string)
("totalPayment" := int)
updatePayers : Payers -> String -> Int -> Payers
updatePayers payers userName amountDiff =
Dict.update
userName
(\mbAmount ->
case mbAmount of
Just amount -> Just (amount + amountDiff)
Nothing -> Nothing
)
payers
type alias ExceedingPayer =
{ userName : String
, amount : Int
}
getOrderedExceedingPayers : Payers -> List ExceedingPayer
getOrderedExceedingPayers payers =
let orderedPayers =
Dict.toList payers
|> List.map (\(userName, amount) -> ExceedingPayer userName amount)
|> List.sortBy .amount
maybeMinAmount =
List.head orderedPayers
|> Maybe.map .amount
in case maybeMinAmount of
Just minAmount ->
orderedPayers
|> List.map (\payer -> { payer | amount <- payer.amount - minAmount })
|> List.filter (\payer -> payer.amount /= 0)
|> List.reverse
Nothing ->
[]
|
