hledger/hledger-lib/Hledger/Data/Amount.hs

{-# LANGUAGE CPP, StandaloneDeriving, RecordWildCards #-}
{-|
A simple 'Amount' is some quantity of money, shares, or anything else.
It has a (possibly null) 'Commodity' and a numeric quantity:

@
  $1
  £-50
  EUR 3.44
  GOOG 500
  1.5h
  90 apples
  0
@

It may also have an assigned 'Price', representing this amount's per-unit
or total cost in a different commodity. If present, this is rendered like
so:

@
  EUR 2 \@ $1.50  (unit price)
  EUR 2 \@\@ $3   (total price)
@

A 'MixedAmount' is zero or more simple amounts, so can represent multiple
commodities; this is the type most often used:

@
  0
  $50 + EUR 3
  16h + $13.55 + AAPL 500 + 6 oranges
@

When a mixed amount has been \"normalised\", it has no more than one amount
in each commodity and no zero amounts; or it has just a single zero amount
and no others.

Limited arithmetic with simple and mixed amounts is supported, best used
with similar amounts since it mostly ignores assigned prices and commodity
exchange rates.

-}

module Hledger.Data.Amount (
  -- * Amount
  amount,
  nullamt,
  missingamt,
  num,
  usd,
  eur,
  gbp,
  hrs,
  at,
  (@@),
  amountWithCommodity,
  -- ** arithmetic
  costOfAmount,
  divideAmount,
  -- ** rendering
  amountstyle,
  showAmount,
  showAmountWithZeroCommodity,
  showAmountDebug,
  showAmountWithoutPrice,
  maxprecision,
  maxprecisionwithpoint,
  setAmountPrecision,
  withPrecision,
  canonicaliseAmount,
  -- * MixedAmount
  nullmixedamt,
  missingmixedamt,
  mixed,
  amounts,
  filterMixedAmount,
  filterMixedAmountByCommodity,
  normaliseMixedAmountSquashPricesForDisplay,
  normaliseMixedAmount,
  -- ** arithmetic
  costOfMixedAmount,
  divideMixedAmount,
  isNegativeMixedAmount,
  isZeroMixedAmount,
  isReallyZeroMixedAmount,
  isReallyZeroMixedAmountCost,
  -- ** rendering
  showMixedAmount,
  showMixedAmountDebug,
  showMixedAmountWithoutPrice,
  showMixedAmountOneLineWithoutPrice,
  showMixedAmountWithZeroCommodity,
  showMixedAmountWithPrecision,
  setMixedAmountPrecision,
  canonicaliseMixedAmount,
  -- * misc.
  ltraceamount,
  tests_Hledger_Data_Amount
) where

import Data.Char (isDigit)
#ifndef DOUBLE
import Data.Decimal
#endif
import Data.Function (on)
import Data.List
import Data.Map (findWithDefault)
import Data.Maybe
import Test.HUnit
import Text.Printf
import qualified Data.Map as M

import Hledger.Data.Types
import Hledger.Data.Commodity
import Hledger.Utils


deriving instance Show HistoricalPrice

amountstyle = AmountStyle L False 0 (Just '.') Nothing

-------------------------------------------------------------------------------
-- Amount

instance Show Amount where
  show _a@Amount{..}
    --  debugLevel < 2 = showAmountWithoutPrice a
    --  debugLevel < 3 = showAmount a
    | debugLevel < 6 =
       printf "Amount {acommodity=%s, aquantity=%s, ..}" (show acommodity) (show aquantity)
    | otherwise      = --showAmountDebug a
       printf "Amount {acommodity=%s, aquantity=%s, aprice=%s, astyle=%s}" (show acommodity) (show aquantity) (showPriceDebug aprice) (show astyle)

instance Num Amount where
    abs a@Amount{aquantity=q}    = a{aquantity=abs q}
    signum a@Amount{aquantity=q} = a{aquantity=signum q}
    fromInteger i                = nullamt{aquantity=fromInteger i}
    negate a@Amount{aquantity=q} = a{aquantity=(-q)}
    (+)                          = similarAmountsOp (+)
    (-)                          = similarAmountsOp (-)
    (*)                          = similarAmountsOp (*)

-- | The empty simple amount.
amount, nullamt :: Amount
amount = Amount{acommodity="", aquantity=0, aprice=NoPrice, astyle=amountstyle}
nullamt = amount

-- | A temporary value for parsed transactions which had no amount specified.
missingamt :: Amount
missingamt = amount{acommodity="AUTO"}

-- handy amount constructors for tests
#ifdef DOUBLE
roundTo = flip const
#endif
num n = amount{acommodity="",  aquantity=n}
usd n = amount{acommodity="$", aquantity=roundTo 2 n, astyle=amountstyle{asprecision=2}}
eur n = amount{acommodity="€", aquantity=roundTo 2 n, astyle=amountstyle{asprecision=2}}
gbp n = amount{acommodity="£", aquantity=roundTo 2 n, astyle=amountstyle{asprecision=2}}
hrs n = amount{acommodity="h", aquantity=roundTo 1 n, astyle=amountstyle{asprecision=1, ascommodityside=R}}
amt `at` priceamt = amt{aprice=UnitPrice priceamt}
amt @@ priceamt = amt{aprice=TotalPrice priceamt}

-- | Apply a binary arithmetic operator to two amounts, which should
-- be in the same commodity if non-zero (warning, this is not checked).
-- A zero result keeps the commodity of the second amount.
-- The result's display style is that of the second amount, with
-- precision set to the highest of either amount.
-- Prices are ignored and discarded.
-- Remember: the caller is responsible for ensuring both amounts have the same commodity.
similarAmountsOp :: (Quantity -> Quantity -> Quantity) -> Amount -> Amount -> Amount
similarAmountsOp op Amount{acommodity=_,  aquantity=q1, astyle=AmountStyle{asprecision=p1}}
                    Amount{acommodity=c2, aquantity=q2, astyle=s2@AmountStyle{asprecision=p2}} =
   -- trace ("a1:"++showAmountDebug a1) $ trace ("a2:"++showAmountDebug a2) $ traceWith (("= :"++).showAmountDebug)
   amount{acommodity=c2, aquantity=q1 `op` q2, astyle=s2{asprecision=max p1 p2}}
  --  c1==c2 || q1==0 || q2==0 =
  --  otherwise = error "tried to do simple arithmetic with amounts in different commodities"

-- | Convert an amount to the specified commodity, ignoring and discarding
-- any assigned prices and assuming an exchange rate of 1.
amountWithCommodity :: Commodity -> Amount -> Amount
amountWithCommodity c a = a{acommodity=c, aprice=NoPrice}

-- | Convert an amount to the commodity of its assigned price, if any.  Notes:
--
-- - price amounts must be MixedAmounts with exactly one component Amount (or there will be a runtime error)
--
-- - price amounts should be positive, though this is not currently enforced
costOfAmount :: Amount -> Amount
costOfAmount a@Amount{aquantity=q, aprice=price} =
    case price of
      NoPrice -> a
      UnitPrice  p@Amount{aquantity=pq} -> p{aquantity=pq * q}
      TotalPrice p@Amount{aquantity=pq} -> p{aquantity=pq * signum q}

-- | Divide an amount's quantity by a constant.
divideAmount :: Amount -> Quantity -> Amount
divideAmount a@Amount{aquantity=q} d = a{aquantity=q/d}

-- | Is this amount negative ? The price is ignored.
isNegativeAmount :: Amount -> Bool
isNegativeAmount Amount{aquantity=q} = q < 0

digits = "123456789" :: String

-- | Does this amount appear to be zero when displayed with its given precision ?
isZeroAmount :: Amount -> Bool
isZeroAmount a --  a==missingamt = False
               | otherwise     = (null . filter (`elem` digits) . showAmountWithoutPriceOrCommodity) a

-- | Is this amount "really" zero, regardless of the display precision ?
-- Since we are using floating point, for now just test to some high precision.
isReallyZeroAmount :: Amount -> Bool
isReallyZeroAmount Amount{aquantity=q} = iszero q
  where
   iszero =
#ifdef DOUBLE
    null . filter (`elem` digits) . printf ("%."++show zeroprecision++"f") where zeroprecision = 8
#else
    (==0)
#endif

-- | Get the string representation of an amount, based on its commodity's
-- display settings except using the specified precision.
showAmountWithPrecision :: Int -> Amount -> String
showAmountWithPrecision p = showAmount . setAmountPrecision p

-- | Set an amount's display precision.
setAmountPrecision :: Int -> Amount -> Amount
setAmountPrecision p a@Amount{astyle=s} = a{astyle=s{asprecision=p}}

-- | Set an amount's display precision, flipped.
withPrecision :: Amount -> Int -> Amount
withPrecision = flip setAmountPrecision

-- | Get a string representation of an amount for debugging,
-- appropriate to the current debug level. 9 shows maximum detail.
showAmountDebug :: Amount -> String
showAmountDebug Amount{acommodity="AUTO"} = "(missing)"
showAmountDebug Amount{..} = printf "Amount {acommodity=%s, aquantity=%s, aprice=%s, astyle=%s}" (show acommodity) (show aquantity) (showPriceDebug aprice) (show astyle)

-- | Get the string representation of an amount, without any \@ price.
showAmountWithoutPrice :: Amount -> String
showAmountWithoutPrice a = showAmount a{aprice=NoPrice}

-- | Get the string representation of an amount, without any price or commodity symbol.
showAmountWithoutPriceOrCommodity :: Amount -> String
showAmountWithoutPriceOrCommodity a = showAmount a{acommodity="", aprice=NoPrice}

showPrice :: Price -> String
showPrice NoPrice         = ""
showPrice (UnitPrice pa)  = " @ "  ++ showAmount pa
showPrice (TotalPrice pa) = " @@ " ++ showAmount pa

showPriceDebug :: Price -> String
showPriceDebug NoPrice         = ""
showPriceDebug (UnitPrice pa)  = " @ "  ++ showAmountDebug pa
showPriceDebug (TotalPrice pa) = " @@ " ++ showAmountDebug pa

-- | Get the string representation of an amount, based on its
-- commodity's display settings. String representations equivalent to
-- zero are converted to just \"0\". The special "missing" amount is
-- displayed as the empty string.
showAmount :: Amount -> String
showAmount = showAmountHelper False

showAmountHelper :: Bool -> Amount -> String
showAmountHelper _ Amount{acommodity="AUTO"} = ""
showAmountHelper showzerocommodity a@(Amount{acommodity=c, aprice=p, astyle=AmountStyle{..}}) =
    case ascommodityside of
      L -> printf "%s%s%s%s" c' space quantity' price
      R -> printf "%s%s%s%s" quantity' space c' price
    where
      quantity = showamountquantity a
      displayingzero = null $ filter (`elem` digits) $ quantity
      (quantity',c') | displayingzero && not showzerocommodity = ("0","")
                     | otherwise = (quantity, quoteCommoditySymbolIfNeeded c)
      space = if (not (null c') && ascommodityspaced) then " " else "" :: String
      price = showPrice p

-- | Like showAmount, but show a zero amount's commodity if it has one.
showAmountWithZeroCommodity :: Amount -> String
showAmountWithZeroCommodity = showAmountHelper True

-- | Get the string representation of the number part of of an amount,
-- using the display settings from its commodity.
showamountquantity :: Amount -> String
showamountquantity Amount{aquantity=q, astyle=AmountStyle{asprecision=p, asdecimalpoint=mdec, asdigitgroups=mgrps}} =
    punctuatenumber (fromMaybe '.' mdec) mgrps $ qstr
    where
      -- isint n = fromIntegral (round n) == n
      qstr -- p == maxprecision && isint q = printf "%d" (round q::Integer)
#ifdef DOUBLE
        | p == maxprecisionwithpoint = printf "%f" q
        | p == maxprecision          = chopdotzero $ printf "%f" q
        | otherwise                  = printf ("%."++show p++"f") q
#else
        | p == maxprecisionwithpoint = show q
        | p == maxprecision          = chopdotzero $ show q
        | otherwise                  = show $ roundTo (fromIntegral p) q
#endif

-- | Replace a number string's decimal point with the specified character,
-- and add the specified digit group separators. The last digit group will
-- be repeated as needed.
punctuatenumber :: Char -> Maybe DigitGroupStyle -> String -> String
punctuatenumber dec mgrps s = sign ++ reverse (applyDigitGroupStyle mgrps (reverse int)) ++ frac''
    where
      (sign,num) = break isDigit s
      (int,frac) = break (=='.') num
      frac' = dropWhile (=='.') frac
      frac'' | null frac' = ""
             | otherwise  = dec:frac'

applyDigitGroupStyle :: Maybe DigitGroupStyle -> String -> String
applyDigitGroupStyle Nothing s = s
applyDigitGroupStyle (Just (DigitGroups c gs)) s = addseps (repeatLast gs) s
  where
    addseps [] s = s
    addseps (g:gs) s
      | length s <= g = s
      | otherwise     = let (part,rest) = splitAt g s
                        in part ++ [c] ++ addseps gs rest
    repeatLast [] = []
    repeatLast gs = init gs ++ repeat (last gs)

chopdotzero str = reverse $ case reverse str of
                              '0':'.':s -> s
                              s         -> s

-- | For rendering: a special precision value which means show all available digits.
maxprecision :: Int
maxprecision = 999998

-- | For rendering: a special precision value which forces display of a decimal point.
maxprecisionwithpoint :: Int
maxprecisionwithpoint = 999999

-- like journalCanonicaliseAmounts
-- | Canonicalise an amount's display style using the provided commodity style map.
canonicaliseAmount :: M.Map Commodity AmountStyle -> Amount -> Amount
canonicaliseAmount styles a@Amount{acommodity=c, astyle=s} = a{astyle=s'}
    where
      s' = findWithDefault s c styles

-------------------------------------------------------------------------------
-- MixedAmount

instance Show MixedAmount where
  show
    | debugLevel < 3 = intercalate "\\n" . lines . showMixedAmountWithoutPrice
    --  debugLevel < 6 = intercalate "\\n" . lines . showMixedAmount
    | otherwise      = showMixedAmountDebug

instance Num MixedAmount where
    fromInteger i = Mixed [fromInteger i]
    negate (Mixed as) = Mixed $ map negate as
    (+) (Mixed as) (Mixed bs) = normaliseMixedAmount $ Mixed $ as ++ bs
    (*)    = error' "error, mixed amounts do not support multiplication"
    abs    = error' "error, mixed amounts do not support abs"
    signum = error' "error, mixed amounts do not support signum"

-- | The empty mixed amount.
nullmixedamt :: MixedAmount
nullmixedamt = Mixed []

-- | A temporary value for parsed transactions which had no amount specified.
missingmixedamt :: MixedAmount
missingmixedamt = Mixed [missingamt]

-- | Convert amounts in various commodities into a normalised MixedAmount.
mixed :: [Amount] -> MixedAmount
mixed = normaliseMixedAmount . Mixed

-- | Simplify a mixed amount's component amounts:
--
-- * amounts in the same commodity are combined unless they have different prices or total prices
--
-- * multiple zero amounts are replaced by just one. If they had the same commodity, it is preserved.
--
-- * an empty amount list is replaced with a single commodityless zero
--
-- * the special "missing" mixed amount remains unchanged
--
normaliseMixedAmount :: MixedAmount -> MixedAmount
normaliseMixedAmount = normaliseHelper False

normaliseHelper :: Bool -> MixedAmount -> MixedAmount
normaliseHelper squashprices (Mixed as)
  | missingamt `elem` as = missingmixedamt -- missingamt should always be alone, but detect it even if not
  | null nonzeros        = Mixed [newzero]
  | otherwise            = Mixed nonzeros
  where
    newzero = case filter (/= "") (map acommodity zeros) of
               [c] -> nullamt{acommodity=c}
               _   -> nullamt
    (zeros, nonzeros) = partition isReallyZeroAmount $
                        map sumSimilarAmountsUsingFirstPrice $
                        groupBy groupfn $
                        sortBy sortfn $
                        as
    sortfn  | squashprices = compare `on` acommodity
            | otherwise    = compare `on` \a -> (acommodity a, aprice a)
    groupfn | squashprices = (==) `on` acommodity
            | otherwise    = \a1 a2 -> acommodity a1 == acommodity a2 && combinableprices a1 a2

    combinableprices Amount{aprice=NoPrice} Amount{aprice=NoPrice} = True
    combinableprices Amount{aprice=UnitPrice p1} Amount{aprice=UnitPrice p2} = p1 == p2
    combinableprices _ _ = False

tests_normaliseMixedAmount = [
  "normaliseMixedAmount" ~: do
   -- assertEqual "missing amount is discarded" (Mixed [nullamt]) (normaliseMixedAmount $ Mixed [usd 0, missingamt])
   assertEqual "any missing amount means a missing mixed amount" missingmixedamt (normaliseMixedAmount $ Mixed [usd 0, missingamt])
   assertEqual "unpriced same-commodity amounts are combined" (Mixed [usd 2]) (normaliseMixedAmount $ Mixed [usd 0, usd 2])
   -- amounts with same unit price are combined
   normaliseMixedAmount (Mixed [usd 1 `at` eur 1, usd 1 `at` eur 1]) `is` Mixed [usd 2 `at` eur 1]
   -- amounts with different unit prices are not combined
   normaliseMixedAmount (Mixed [usd 1 `at` eur 1, usd 1 `at` eur 2]) `is` Mixed [usd 1 `at` eur 1, usd 1 `at` eur 2]
   -- amounts with total prices are not combined
   normaliseMixedAmount (Mixed  [usd 1 @@ eur 1, usd 1 @@ eur 1]) `is` Mixed [usd 1 @@ eur 1, usd 1 @@ eur 1]
 ]

-- | Like normaliseMixedAmount, but combine each commodity's amounts
-- into just one by throwing away all prices except the first. This is
-- only used as a rendering helper, and could show a misleading price.
normaliseMixedAmountSquashPricesForDisplay :: MixedAmount -> MixedAmount
normaliseMixedAmountSquashPricesForDisplay = normaliseHelper True

tests_normaliseMixedAmountSquashPricesForDisplay = [
  "normaliseMixedAmountSquashPricesForDisplay" ~: do
    normaliseMixedAmountSquashPricesForDisplay (Mixed []) `is` Mixed [nullamt]
    assertBool "" $ isZeroMixedAmount $ normaliseMixedAmountSquashPricesForDisplay
      (Mixed [usd 10
             ,usd 10 @@ eur 7
             ,usd (-10)
             ,usd (-10) @@ eur 7
             ])
 ]

-- | Sum same-commodity amounts in a lossy way, applying the first
-- price to the result and discarding any other prices. Only used as a
-- rendering helper.
sumSimilarAmountsUsingFirstPrice :: [Amount] -> Amount
sumSimilarAmountsUsingFirstPrice [] = nullamt
sumSimilarAmountsUsingFirstPrice as = (sum as){aprice=aprice $ head as}

-- | Sum same-commodity amounts. If there were different prices, set
-- the price to a special marker indicating "various". Only used as a
-- rendering helper.
-- sumSimilarAmountsNotingPriceDifference :: [Amount] -> Amount
-- sumSimilarAmountsNotingPriceDifference [] = nullamt
-- sumSimilarAmountsNotingPriceDifference as = undefined

-- | Get a mixed amount's component amounts.
amounts :: MixedAmount -> [Amount]
amounts (Mixed as) = as

-- | Filter a mixed amount's component amounts by a predicate.
filterMixedAmount :: (Amount -> Bool) -> MixedAmount -> MixedAmount
filterMixedAmount p (Mixed as) = Mixed $ filter p as

-- | Return an unnormalised MixedAmount containing exactly one Amount
-- with the specified commodity and the quantity of that commodity
-- found in the original. NB if Amount's quantity is zero it will be
-- discarded next time the MixedAmount gets normalised.
filterMixedAmountByCommodity :: Commodity -> MixedAmount -> MixedAmount
filterMixedAmountByCommodity c (Mixed as) = Mixed as'
  where
    as' = case filter ((==c) . acommodity) as of
            []   -> [nullamt{acommodity=c}]
            as'' -> [sum as'']

-- | Convert a mixed amount's component amounts to the commodity of their
-- assigned price, if any.
costOfMixedAmount :: MixedAmount -> MixedAmount
costOfMixedAmount (Mixed as) = Mixed $ map costOfAmount as

-- | Divide a mixed amount's quantities by a constant.
divideMixedAmount :: MixedAmount -> Quantity -> MixedAmount
divideMixedAmount (Mixed as) d = Mixed $ map (flip divideAmount d) as

-- | Is this mixed amount negative, if it can be normalised to a single commodity ?
isNegativeMixedAmount :: MixedAmount -> Maybe Bool
isNegativeMixedAmount m = case as of [a] -> Just $ isNegativeAmount a
                                     _   -> Nothing
    where as = amounts $ normaliseMixedAmountSquashPricesForDisplay m

-- | Does this mixed amount appear to be zero when displayed with its given precision ?
isZeroMixedAmount :: MixedAmount -> Bool
isZeroMixedAmount = all isZeroAmount . amounts . normaliseMixedAmountSquashPricesForDisplay

-- | Is this mixed amount "really" zero ? See isReallyZeroAmount.
isReallyZeroMixedAmount :: MixedAmount -> Bool
isReallyZeroMixedAmount = all isReallyZeroAmount . amounts . normaliseMixedAmountSquashPricesForDisplay

-- | Is this mixed amount "really" zero, after converting to cost
-- commodities where possible ?
isReallyZeroMixedAmountCost :: MixedAmount -> Bool
isReallyZeroMixedAmountCost = isReallyZeroMixedAmount . costOfMixedAmount

-- -- | MixedAmount derived Eq instance in Types.hs doesn't know that we
-- -- want $0 = EUR0 = 0. Yet we don't want to drag all this code over there.
-- -- For now, use this when cross-commodity zero equality is important.
-- mixedAmountEquals :: MixedAmount -> MixedAmount -> Bool
-- mixedAmountEquals a b = amounts a' == amounts b' || (isZeroMixedAmount a' && isZeroMixedAmount b')
--     where a' = normaliseMixedAmountSquashPricesForDisplay a
--           b' = normaliseMixedAmountSquashPricesForDisplay b

-- | Get the string representation of a mixed amount, after
-- normalising it to one amount per commodity. Assumes amounts have
-- no or similar prices, otherwise this can show misleading prices.
showMixedAmount :: MixedAmount -> String
showMixedAmount = showMixedAmountHelper False

-- | Like showMixedAmount, but zero amounts are shown with their
-- commodity if they have one.
showMixedAmountWithZeroCommodity :: MixedAmount -> String
showMixedAmountWithZeroCommodity = showMixedAmountHelper True

showMixedAmountHelper :: Bool -> MixedAmount -> String
showMixedAmountHelper showzerocommodity m =
  vConcatRightAligned $ map showw $ amounts $ normaliseMixedAmountSquashPricesForDisplay m
  where
    showw | showzerocommodity = showAmountWithZeroCommodity
          | otherwise         = showAmount

-- | Compact labelled trace of a mixed amount, for debugging.
ltraceamount :: String -> MixedAmount -> MixedAmount
ltraceamount s = traceWith (((s ++ ": ") ++).showMixedAmount)

-- | Set the display precision in the amount's commodities.
setMixedAmountPrecision :: Int -> MixedAmount -> MixedAmount
setMixedAmountPrecision p (Mixed as) = Mixed $ map (setAmountPrecision p) as

-- | Get the string representation of a mixed amount, showing each of its
-- component amounts with the specified precision, ignoring their
-- commoditys' display precision settings.
showMixedAmountWithPrecision :: Int -> MixedAmount -> String
showMixedAmountWithPrecision p m =
    vConcatRightAligned $ map (showAmountWithPrecision p) $ amounts $ normaliseMixedAmountSquashPricesForDisplay m

-- | Get an unambiguous string representation of a mixed amount for debugging.
showMixedAmountDebug :: MixedAmount -> String
showMixedAmountDebug m | m == missingmixedamt = "(missing)"
                       | otherwise       = printf "Mixed [%s]" as
    where as = intercalate "\n       " $ map showAmountDebug $ amounts m

-- | Get the string representation of a mixed amount, but without
-- any \@ prices.
showMixedAmountWithoutPrice :: MixedAmount -> String
showMixedAmountWithoutPrice m = concat $ intersperse "\n" $ map showfixedwidth as
    where
      (Mixed as) = normaliseMixedAmountSquashPricesForDisplay $ stripPrices m
      stripPrices (Mixed as) = Mixed $ map stripprice as where stripprice a = a{aprice=NoPrice}
      width = maximum $ map (length . showAmount) as
      showfixedwidth = printf (printf "%%%ds" width) . showAmountWithoutPrice

-- | Get the one-line string representation of a mixed amount, but without
-- any \@ prices.
showMixedAmountOneLineWithoutPrice :: MixedAmount -> String
showMixedAmountOneLineWithoutPrice m = concat $ intersperse ", " $ map showAmountWithoutPrice as
    where
      (Mixed as) = normaliseMixedAmountSquashPricesForDisplay $ stripPrices m
      stripPrices (Mixed as) = Mixed $ map stripprice as where stripprice a = a{aprice=NoPrice}

-- | Canonicalise a mixed amount's display styles using the provided commodity style map.
canonicaliseMixedAmount :: M.Map Commodity AmountStyle -> MixedAmount -> MixedAmount
canonicaliseMixedAmount styles (Mixed as) = Mixed $ map (canonicaliseAmount styles) as

-------------------------------------------------------------------------------
-- misc

tests_Hledger_Data_Amount = TestList $
     tests_normaliseMixedAmount
  ++ tests_normaliseMixedAmountSquashPricesForDisplay
  ++ [

  -- Amount

   "costOfAmount" ~: do
    costOfAmount (eur 1) `is` eur 1
    costOfAmount (eur 2){aprice=UnitPrice $ usd 2} `is` usd 4
    costOfAmount (eur 1){aprice=TotalPrice $ usd 2} `is` usd 2
    costOfAmount (eur (-1)){aprice=TotalPrice $ usd 2} `is` usd (-2)

  ,"isZeroAmount" ~: do
    assertBool "" $ isZeroAmount $ amount
    assertBool "" $ isZeroAmount $ usd 0

  ,"negating amounts" ~: do
    let a = usd 1
    negate a `is` a{aquantity=(-1)}
    let b = (usd 1){aprice=UnitPrice $ eur 2}
    negate b `is` b{aquantity=(-1)}

  ,"adding amounts without prices" ~: do
    let a1 = usd 1.23
    let a2 = usd (-1.23)
    let a3 = usd (-1.23)
    (a1 + a2) `is` usd 0
    (a1 + a3) `is` usd 0
    (a2 + a3) `is` usd (-2.46)
    (a3 + a3) `is` usd (-2.46)
    sum [a1,a2,a3,-a3] `is` usd 0
    -- highest precision is preserved
    let ap1 = usd 1 `withPrecision` 1
        ap3 = usd 1 `withPrecision` 3
    (asprecision $ astyle $ sum [ap1,ap3]) `is` 3
    (asprecision $ astyle $ sum [ap3,ap1]) `is` 3
    -- adding different commodities assumes conversion rate 1
    assertBool "" $ isZeroAmount (a1 - eur 1.23)

  ,"showAmount" ~: do
    showAmount (usd 0 + gbp 0) `is` "0"

  -- MixedAmount

  ,"adding mixed amounts, preserving minimum precision and a single commodity on zero" ~: do
    (sum $ map (Mixed . (:[]))
             [usd 1.25
             ,usd (-1) `withPrecision` 0
             ,usd (-0.25)
             ])
      `is` Mixed [usd 0 `withPrecision` 0]

  ,"adding mixed amounts with total prices" ~: do
    (sum $ map (Mixed . (:[]))
     [usd 1 @@ eur 1
     ,usd (-2) @@ eur 1
     ])
      `is` (Mixed [usd 1 @@ eur 1
                  ,usd (-2) @@ eur 1
                  ])

  ,"showMixedAmount" ~: do
    showMixedAmount (Mixed [usd 1]) `is` "$1.00"
    showMixedAmount (Mixed [usd 1 `at` eur 2]) `is` "$1.00 @ €2.00"
    showMixedAmount (Mixed [usd 0]) `is` "0"
    showMixedAmount (Mixed []) `is` "0"
    showMixedAmount missingmixedamt `is` ""

  ,"showMixedAmountWithoutPrice" ~: do
    let a = usd 1 `at` eur 2
    showMixedAmountWithoutPrice (Mixed [a]) `is` "$1.00"
    showMixedAmountWithoutPrice (Mixed [a, (-a)]) `is` "0"

  ]