1 files changed, 102 insertions, 0 deletions
diff --git a/src/client/Model/Income.elm b/src/client/Model/Income.elm
new file mode 100644
index 0000000..34578c6
--- /dev/null
+++ b/src/client/Model/Income.elm
@@ -0,0 +1,102 @@
+module Model.Income exposing
+  ( Incomes
+  , Income
+  , IncomeId
+  , incomesDecoder
+  , incomeIdDecoder
+  , incomeDefinedForAll
+  , userCumulativeIncomeSince
+  , cumulativeIncomesSince
+  )
+
+import Json.Decode as Decode exposing (Decoder)
+import Utils.Json as Json
+import Time exposing (Time, hour)
+import List exposing (..)
+import Dict exposing (Dict)
+
+import Model.Date exposing (timeDecoder)
+import Model.User exposing (UserId, userIdDecoder)
+
+import Utils.Maybe as Maybe
+
+type alias Incomes = Dict IncomeId Income
+
+type alias IncomeId = Int
+
+type alias Income =
+  { userId : UserId
+  , time : Float
+  , amount : Int
+  }
+
+incomesDecoder : Decoder Incomes
+incomesDecoder =
+  Json.dictDecoder (Decode.field "id" incomeIdDecoder) <|
+    Decode.map3 Income
+      (Decode.field "userId" userIdDecoder)
+      (Decode.field "date" timeDecoder)
+      (Decode.field "amount" Decode.int)
+
+incomeIdDecoder : Decoder IncomeId
+incomeIdDecoder = Decode.int
+
+incomeDefinedForAll : List UserId -> Incomes -> Maybe Time
+incomeDefinedForAll userIds incomes =
+  let userIncomes = List.map (\userId -> List.filter ((==) userId << .userId) << Dict.values <| incomes) userIds
+      firstIncomes = map (head << sortBy .time) userIncomes
+  in  if all Maybe.isJust firstIncomes
+        then head << reverse << List.sort << map .time << Maybe.cat <| firstIncomes
+        else Nothing
+
+userCumulativeIncomeSince : Time -> Time -> Incomes -> UserId -> Int
+userCumulativeIncomeSince currentTime since incomes userId =
+  incomes
+    |> Dict.values
+    |> List.filter (\income -> income.userId == userId)
+    |> cumulativeIncomesSince currentTime since
+
+cumulativeIncomesSince : Time -> Time -> (List Income) -> Int
+cumulativeIncomesSince currentTime since incomes =
+  cumulativeIncome currentTime (getOrderedIncomesSince since incomes)
+
+getOrderedIncomesSince : Time -> List Income -> List Income
+getOrderedIncomesSince time incomes =
+  let mbStarterIncome = getIncomeAt time incomes
+      orderedIncomesSince = filter (\income -> income.time >= time) incomes
+  in  (Maybe.toList mbStarterIncome) ++ orderedIncomesSince
+
+getIncomeAt : Time -> List Income -> Maybe Income
+getIncomeAt time incomes =
+  case incomes of
+    [x] ->
+      if x.time < time
+        then Just { userId = x.userId, time = time, amount = x.amount }
+        else Nothing
+    x1 :: x2 :: xs ->
+      if x1.time < time && x2.time >= time
+        then Just { userId = x1.userId, time = time, amount = x1.amount }
+        else getIncomeAt time (x2 :: xs)
+    [] ->
+      Nothing
+
+cumulativeIncome : Time -> List Income -> Int
+cumulativeIncome currentTime incomes =
+  getIncomesWithDuration currentTime (List.sortBy .time incomes)
+    |> map durationIncome
+    |> sum
+
+getIncomesWithDuration : Time -> List Income -> List (Float, Int)
+getIncomesWithDuration currentTime incomes =
+  case incomes of
+    [] ->
+      []
+    [income] ->
+      [(currentTime - income.time, income.amount)]
+    (income1 :: income2 :: xs) ->
+      (income2.time - income1.time, income1.amount) :: (getIncomesWithDuration currentTime (income2 :: xs))
+
+durationIncome : (Float, Int) -> Int
+durationIncome (duration, income) =
+  duration * toFloat income / (hour * 24 * 365 / 12)
+    |> truncate