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module Payer
( getExceedingPayers
) where
import Data.Map (Map)
import qualified Data.Map as M
import Common.Model (ExceedingPayer (..), User (..), UserId)
data Payer = Payer
{ _payer_userId :: UserId
, _payer_preIncomePayments :: Int
, _payer_postIncomePayments :: Int
, _payer_income :: Int
}
data PostPaymentPayer = PostPaymentPayer
{ _postPaymentPayer_userId :: UserId
, _postPaymentPayer_preIncomePayments :: Int
, _postPaymentPayer_cumulativeIncome :: Int
, _postPaymentPayer_ratio :: Float
}
getExceedingPayers :: [User] -> Map UserId Int -> Map UserId Int -> Map UserId Int -> [ExceedingPayer]
getExceedingPayers users cumulativeIncome preIncomeRepartition postIncomeRepartition =
let userIds = map _user_id users
payers = getPayers userIds cumulativeIncome preIncomeRepartition postIncomeRepartition
postPaymentPayers = map getPostPaymentPayer payers
mbMaxRatio = safeMaximum . map _postPaymentPayer_ratio $ postPaymentPayers
in case mbMaxRatio of
Just maxRatio ->
exceedingPayersFromAmounts
. map (\p -> (_postPaymentPayer_userId p, getFinalDiff maxRatio p))
$ postPaymentPayers
Nothing ->
exceedingPayersFromAmounts
. map (\p -> (_payer_userId p, _payer_preIncomePayments p))
$ payers
getPayers :: [UserId] -> Map UserId Int -> Map UserId Int -> Map UserId Int -> [Payer]
getPayers userIds cumulativeIncome preIncomeRepartition postIncomeRepartition =
flip map userIds (\userId -> Payer
{ _payer_userId = userId
, _payer_preIncomePayments = M.findWithDefault 0 userId preIncomeRepartition
, _payer_postIncomePayments = M.findWithDefault 0 userId postIncomeRepartition
, _payer_income = M.findWithDefault 0 userId cumulativeIncome
}
)
exceedingPayersFromAmounts :: [(UserId, Int)] -> [ExceedingPayer]
exceedingPayersFromAmounts userAmounts =
case mbMinAmount of
Nothing ->
[]
Just minAmount ->
filter (\payer -> _exceedingPayer_amount payer > 0)
. map (\userAmount ->
ExceedingPayer
{ _exceedingPayer_userId = fst userAmount
, _exceedingPayer_amount = snd userAmount - minAmount
}
)
$ userAmounts
where mbMinAmount = safeMinimum . map snd $ userAmounts
getPostPaymentPayer :: Payer -> PostPaymentPayer
getPostPaymentPayer payer =
PostPaymentPayer
{ _postPaymentPayer_userId = _payer_userId payer
, _postPaymentPayer_preIncomePayments = _payer_preIncomePayments payer
, _postPaymentPayer_cumulativeIncome = _payer_income payer
, _postPaymentPayer_ratio = (fromIntegral . _payer_postIncomePayments $ payer) / (fromIntegral $ _payer_income payer)
}
getFinalDiff :: Float -> PostPaymentPayer -> Int
getFinalDiff maxRatio payer =
let postIncomeDiff =
truncate $ -1.0 * (maxRatio - _postPaymentPayer_ratio payer) * (fromIntegral . _postPaymentPayer_cumulativeIncome $ payer)
in postIncomeDiff + _postPaymentPayer_preIncomePayments payer
safeMinimum :: (Ord a) => [a] -> Maybe a
safeMinimum [] = Nothing
safeMinimum xs = Just . minimum $ xs
safeMaximum :: (Ord a) => [a] -> Maybe a
safeMaximum [] = Nothing
safeMaximum xs = Just . maximum $ xs
|
