```{-# LANGUAGE StandaloneDeriving #-}
{-|
An 'Amount' is some quantity of money, shares, or anything else.

A simple amount is a 'Commodity', quantity pair:

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

An amount may also have a per-unit price, or conversion rate, in terms
of some other commodity. If present, this is displayed after \@:

@
EUR 3 \@ \$1.35
@

A 'MixedAmount' is zero or more simple amounts.  Mixed amounts are
usually normalised so that there is no more than one amount in each
commodity, and no zero amounts (or, there is just a single zero amount
and no others.):

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

We can do limited arithmetic with simple or mixed amounts: either
price-preserving arithmetic with similarly-priced amounts, or

-}

module Hledger.Data.Amount
where
import qualified Data.Map as Map
import Data.Map (findWithDefault)

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

instance Show Amount where show = showAmount
instance Show MixedAmount where show = showMixedAmount
deriving instance Show HistoricalPrice

instance Num Amount where
abs (Amount c q p) = Amount c (abs q) p
signum (Amount c q p) = Amount c (signum q) p
fromInteger i = Amount (comm "") (fromInteger i) Nothing
(+) = amountop (+)
(-) = amountop (-)
(*) = amountop (*)

instance Ord Amount where
compare (Amount ac aq ap) (Amount bc bq bp) = compare (ac,aq,ap) (bc,bq,bp)

instance Num MixedAmount where
fromInteger i = Mixed [Amount (comm "") (fromInteger i) Nothing]
negate (Mixed as) = Mixed \$ map negateAmountPreservingPrice as
(+) (Mixed as) (Mixed bs) = normaliseMixedAmount \$ Mixed \$ as ++ bs
(*)    = error' "programming error, mixed amounts do not support multiplication"
abs    = error' "programming error, mixed amounts do not support abs"
signum = error' "programming error, mixed amounts do not support signum"

instance Ord MixedAmount where
compare (Mixed as) (Mixed bs) = compare as bs

negateAmountPreservingPrice a = (-a){price=price a}

-- | Apply a binary arithmetic operator to two amounts, converting to the
-- second one's commodity (and display precision), discarding any price
-- information. (Using the second commodity is best since sum and other
amountop :: (Double -> Double -> Double) -> Amount -> Amount -> Amount
amountop op a@(Amount _ _ _) (Amount bc bq _) =
Amount bc (quantity (convertAmountTo bc a) `op` bq) Nothing

-- | Convert an amount to the specified commodity using the appropriate
-- exchange rate (which is currently always 1).
convertAmountTo :: Commodity -> Amount -> Amount
convertAmountTo c2 (Amount c1 q _) = Amount c2 (q * conversionRate c1 c2) Nothing

-- | Convert mixed amount to the specified commodity
convertMixedAmountTo :: Commodity -> MixedAmount -> Amount
convertMixedAmountTo c2 (Mixed ams) = Amount c2 total Nothing
where
total = sum . map (quantity . convertAmountTo c2) \$ ams

-- | Convert an amount to the commodity of its saved price, if any.
costOfAmount :: Amount -> Amount
costOfAmount a@(Amount _ _ Nothing) = a
costOfAmount (Amount _ q (Just price))
| isZeroMixedAmount price = nullamt
| otherwise = Amount pc (pq*q) Nothing
where (Amount pc pq _) = head \$ amounts price

-- | Get the string representation of an amount, based on its commodity's
-- display settings.
showAmount :: Amount -> String
showAmount (Amount (Commodity {symbol="AUTO"}) _ _) = "" -- can appear in an error message
showAmount a@(Amount (Commodity {symbol=sym,side=side,spaced=spaced}) _ pri) =
case side of
L -> printf "%s%s%s%s" sym' space quantity price
R -> printf "%s%s%s%s" quantity space sym' price
where
sym' = quoteCommoditySymbolIfNeeded sym
space = if (spaced && not (null sym')) then " " else ""
quantity = showAmount' a
price = case pri of (Just pamt) -> " @ " ++ showMixedAmount pamt
Nothing -> ""

-- | 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

setAmountPrecision p a@Amount{commodity=c} = a{commodity=c{precision=p}}

-- XXX refactor
-- | Get the unambiguous string representation of an amount, for debugging.
showAmountDebug :: Amount -> String
showAmountDebug (Amount c q pri) = printf "Amount {commodity = %s, quantity = %s, price = %s}"
(show c) (show q) (maybe "" showMixedAmountDebug pri)

-- | Get the string representation of an amount, without any \@ price.
showAmountWithoutPrice :: Amount -> String
showAmountWithoutPrice a = showAmount a{price=Nothing}

-- | Get the string representation of an amount, without any price or commodity symbol.
showAmountWithoutPriceOrCommodity :: Amount -> String
showAmountWithoutPriceOrCommodity a@Amount{commodity=c} = showAmount a{commodity=c{symbol=""}, price=Nothing}

-- | Get the string representation of the number part of of an amount,
-- using the display precision from its commodity.
showAmount' :: Amount -> String
showAmount' (Amount (Commodity {comma=comma,precision=p}) q _) = addthousandsseparators \$ qstr
where
addthousandsseparators = if comma then punctuatethousands else id
qstr | p == maxprecision && isint q = printf "%d" (round q::Integer)
| p == maxprecision            = printf "%f" q
| otherwise                    = printf ("%."++show p++"f") q
isint n = fromIntegral (round n) == n

maxprecision = 999999

-- | Add thousands-separating commas to a decimal number string
punctuatethousands :: String -> String
punctuatethousands s =
sign ++ addcommas int ++ frac
where
(sign,num) = break isDigit s
(int,frac) = break (=='.') num
addcommas = reverse . concat . intersperse "," . triples . reverse
triples [] = []
triples l  = take 3 l : triples (drop 3 l)

-- | Does this amount appear to be zero when displayed with its given precision ?
isZeroAmount :: Amount -> Bool
isZeroAmount = null . filter (`elem` "123456789") . showAmountWithoutPriceOrCommodity

-- | 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 = null . filter (`elem` "123456789") . printf ("%."++show zeroprecision++"f") . quantity
where zeroprecision = 8

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

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

-- | Does this mixed amount appear to be zero - empty, or
-- containing only simple amounts which appear to be zero ?
isZeroMixedAmount :: MixedAmount -> Bool
isZeroMixedAmount = all isZeroAmount . amounts . normaliseMixedAmount

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

-- | 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 \$ normaliseMixedAmount m

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

-- | MixedAmount derives Eq in Types.hs, but that doesn't know that we
-- want \$0 = EUR0 = 0. Yet we don't want to drag all this code in there.
-- When zero equality is important, use this, for now; should be used
-- everywhere.
mixedAmountEquals :: MixedAmount -> MixedAmount -> Bool
mixedAmountEquals a b = amounts a' == amounts b' || (isZeroMixedAmount a' && isZeroMixedAmount b')
where a' = normaliseMixedAmount a
b' = normaliseMixedAmount b

-- | Get the string representation of a mixed amount, showing each of
-- its component amounts. NB a mixed amount can have an empty amounts
-- list in which case it shows as \"\".
showMixedAmount :: MixedAmount -> String
showMixedAmount m = vConcatRightAligned \$ map show \$ amounts \$ normaliseMixedAmount m

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. NB a mixed amount can have an
-- empty amounts list in which case it shows as \"\".
showMixedAmountWithPrecision :: Int -> MixedAmount -> String
showMixedAmountWithPrecision p m =
vConcatRightAligned \$ map (showAmountWithPrecision p) \$ amounts \$ normaliseMixedAmount m

-- | Get an unambiguous string representation of a mixed amount for debugging.
showMixedAmountDebug :: MixedAmount -> String
showMixedAmountDebug m = printf "Mixed [%s]" as
where as = intercalate "\n       " \$ map showAmountDebug \$ amounts \$ normaliseMixedAmount 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) = normaliseMixedAmountIgnoringPrice m
width = maximum \$ map (length . show) as
showfixedwidth = printf (printf "%%%ds" width) . showAmountWithoutPrice

-- | Get the string representation of a mixed amount, and if it
-- appears to be all zero just show a bare 0, ledger-style.
showMixedAmountOrZero :: MixedAmount -> String
showMixedAmountOrZero a | a == missingamt = ""
| isZeroMixedAmount a = "0"
| otherwise = showMixedAmount a

-- | Get the string representation of a mixed amount, or a bare 0,
-- without any \@ prices.
showMixedAmountOrZeroWithoutPrice :: MixedAmount -> String
showMixedAmountOrZeroWithoutPrice a
| isZeroMixedAmount a = "0"
| otherwise = showMixedAmountWithoutPrice a

-- | Simplify a mixed amount by combining any component amounts which have
-- the same commodity and the same price. Also removes zero amounts,
-- or adds a single zero amount if there are no amounts at all.
normaliseMixedAmount :: MixedAmount -> MixedAmount
normaliseMixedAmount (Mixed as) = Mixed as''
where
as'' = map sumSamePricedAmountsPreservingPrice \$ group \$ sort as'
sort = sortBy cmpsymbolandprice
cmpsymbolandprice a1 a2 = compare (sym a1,price a1) (sym a2,price a2)
group = groupBy samesymbolandprice
samesymbolandprice a1 a2 = (sym a1 == sym a2) && (price a1 == price a2)
sym = symbol . commodity
as' | null nonzeros = [head \$ zeros ++ [nullamt]]
| otherwise = nonzeros
(zeros,nonzeros) = partition isReallyZeroAmount as

-- | Set a mixed amount's commodity to the canonicalised commodity from
-- the provided commodity map.
canonicaliseMixedAmount :: Maybe (Map.Map String Commodity) -> MixedAmount -> MixedAmount
canonicaliseMixedAmount canonicalcommoditymap (Mixed as) = Mixed \$ map (canonicaliseAmount canonicalcommoditymap) as

-- | Set an amount's commodity to the canonicalised commodity from
-- the provided commodity map.
canonicaliseAmount :: Maybe (Map.Map String Commodity) -> Amount -> Amount
canonicaliseAmount Nothing                      = id
canonicaliseAmount (Just canonicalcommoditymap) = fixamount
where
-- like journalCanonicaliseAmounts
fixamount a@Amount{commodity=c} = a{commodity=fixcommodity c}
fixcommodity c@Commodity{symbol=s} = findWithDefault c s canonicalcommoditymap

-- various sum variants..

sumSamePricedAmountsPreservingPrice [] = nullamt
sumSamePricedAmountsPreservingPrice as = (sum as){price=price \$ head as}

-- | Simplify a mixed amount by combining any component amounts which have
-- the same commodity, ignoring and discarding their unit prices if any.
-- Also removes zero amounts, or adds a single zero amount if there are no
-- amounts at all.
normaliseMixedAmountIgnoringPrice :: MixedAmount -> MixedAmount
normaliseMixedAmountIgnoringPrice (Mixed as) = Mixed as''
where
as'' = map sumAmountsDiscardingPrice \$ group \$ sort as'
group = groupBy samesymbol where samesymbol a1 a2 = sym a1 == sym a2
sort = sortBy (comparing sym)
sym = symbol . commodity
as' | null nonzeros = [head \$ zeros ++ [nullamt]]
| otherwise = nonzeros
where (zeros,nonzeros) = partition isZeroAmount as

sumMixedAmountsPreservingHighestPrecision :: [MixedAmount] -> MixedAmount
sumMixedAmountsPreservingHighestPrecision ms = foldl' (+~) 0 ms
where (+~) (Mixed as) (Mixed bs) = normaliseMixedAmountPreservingHighestPrecision \$ Mixed \$ as ++ bs

normaliseMixedAmountPreservingHighestPrecision :: MixedAmount -> MixedAmount
normaliseMixedAmountPreservingHighestPrecision (Mixed as) = Mixed as''
where
as'' = map sumSamePricedAmountsPreservingPriceAndHighestPrecision \$ group \$ sort as'
sort = sortBy cmpsymbolandprice
cmpsymbolandprice a1 a2 = compare (sym a1,price a1) (sym a2,price a2)
group = groupBy samesymbolandprice
samesymbolandprice a1 a2 = (sym a1 == sym a2) && (price a1 == price a2)
sym = symbol . commodity
as' | null nonzeros = [head \$ zeros ++ [nullamt]]
| otherwise = nonzeros
(zeros,nonzeros) = partition isReallyZeroAmount as

sumSamePricedAmountsPreservingPriceAndHighestPrecision [] = nullamt
sumSamePricedAmountsPreservingPriceAndHighestPrecision as = (sumAmountsPreservingHighestPrecision as){price=price \$ head as}

sumAmountsPreservingHighestPrecision :: [Amount] -> Amount
sumAmountsPreservingHighestPrecision as = foldl' (+~) 0 as
where (+~) = amountopPreservingHighestPrecision (+)

amountopPreservingHighestPrecision :: (Double -> Double -> Double) -> Amount -> Amount -> Amount
amountopPreservingHighestPrecision op a@(Amount ac@Commodity{precision=ap} _ _) (Amount bc@Commodity{precision=bp} bq _) =
Amount c q Nothing
where
q = quantity (convertAmountTo bc a) `op` bq
c = if ap > bp then ac else bc
--

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

-- | The empty simple amount.
nullamt :: Amount
nullamt = Amount unknown 0 Nothing

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

-- | A temporary value for parsed transactions which had no amount specified.
missingamt :: MixedAmount
missingamt = Mixed [Amount Commodity {symbol="AUTO",side=L,spaced=False,comma=False,precision=0} 0 Nothing]

tests_Amount = TestList [

"showMixedAmount" ~: do
showMixedAmount (Mixed [Amount dollar 0 Nothing]) `is` "\$0.00"
showMixedAmount (Mixed []) `is` "0"
showMixedAmount missingamt `is` ""

,"showMixedAmountOrZero" ~: do
showMixedAmountOrZero (Mixed [Amount dollar 0 Nothing]) `is` "0"
showMixedAmountOrZero (Mixed []) `is` "0"
showMixedAmountOrZero missingamt `is` ""

,"amount arithmetic" ~: do
let a1 = dollars 1.23
let a2 = Amount (comm "\$") (-1.23) Nothing
let a3 = Amount (comm "\$") (-1.23) Nothing
(a1 + a2) `is` Amount (comm "\$") 0 Nothing
(a1 + a3) `is` Amount (comm "\$") 0 Nothing
(a2 + a3) `is` Amount (comm "\$") (-2.46) Nothing
(a3 + a3) `is` Amount (comm "\$") (-2.46) Nothing
sum [a2,a3] `is` Amount (comm "\$") (-2.46) Nothing
sum [a3,a3] `is` Amount (comm "\$") (-2.46) Nothing
sum [a1,a2,a3,-a3] `is` Amount (comm "\$") 0 Nothing
let dollar0 = dollar{precision=0}
(sum [Amount dollar 1.25 Nothing, Amount dollar0 (-1) Nothing, Amount dollar (-0.25) Nothing])
`is` (Amount dollar 0 Nothing)

,"mixed amount arithmetic" ~: do
let dollar0 = dollar{precision=0}
(sum \$ map (Mixed . (\a -> [a]))
[Amount dollar 1.25 Nothing,
Amount dollar0 (-1) Nothing,
Amount dollar (-0.25) Nothing])
`is` Mixed [Amount dollar 0 Nothing]

]
```