hledger/hledger-lib/Hledger/Data/TransactionModifier.hs
2018-11-13 11:25:36 -08:00

109 lines
4.3 KiB
Haskell

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE CPP #-}
{-|
A 'TransactionModifier' is a rule that modifies certain 'Transaction's,
typically adding automated postings to them.
-}
module Hledger.Data.TransactionModifier (
transactionModifierToFunction
)
where
import Data.Maybe
#if !(MIN_VERSION_base(4,11,0))
import Data.Monoid ((<>))
#endif
import qualified Data.Text as T
import Data.Time.Calendar
import Hledger.Data.Types
import Hledger.Data.Dates
import Hledger.Data.Amount
import Hledger.Data.Transaction
import Hledger.Query
import Hledger.Utils.UTF8IOCompat (error')
-- import Hledger.Utils.Debug
-- $setup
-- >>> :set -XOverloadedStrings
-- >>> import Hledger.Data.Posting
-- >>> import Hledger.Data.Transaction
-- >>> import Hledger.Data.Journal
-- | Converts a 'TransactionModifier' to a 'Transaction'-transforming function,
-- which applies the modification(s) specified by the TransactionModifier.
-- Currently this means adding automated postings when certain other postings are present.
-- The postings of the transformed transaction will reference it in the usual
-- way (ie, 'txnTieKnot' is called).
--
-- >>> putStr $ showTransaction $ transactionModifierToFunction (TransactionModifier "" ["pong" `post` usd 2]) nulltransaction{tpostings=["ping" `post` usd 1]}
-- 0000/01/01
-- ping $1.00
-- pong $2.00
-- <BLANKLINE>
-- >>> putStr $ showTransaction $ transactionModifierToFunction (TransactionModifier "miss" ["pong" `post` usd 2]) nulltransaction{tpostings=["ping" `post` usd 1]}
-- 0000/01/01
-- ping $1.00
-- <BLANKLINE>
-- >>> putStr $ showTransaction $ transactionModifierToFunction (TransactionModifier "ping" ["pong" `post` amount{amultiplier=True, aquantity=3}]) nulltransaction{tpostings=["ping" `post` usd 2]}
-- 0000/01/01
-- ping $2.00
-- pong $6.00
-- <BLANKLINE>
--
transactionModifierToFunction :: TransactionModifier -> (Transaction -> Transaction)
transactionModifierToFunction mt =
\t@(tpostings -> ps) -> txnTieKnot t{ tpostings=generatePostings ps } -- TODO add modifier txn comment/tags ?
where
q = simplifyQuery $ tmParseQuery mt (error' "a transaction modifier's query cannot depend on current date")
mods = map tmPostingToFunction $ tmpostings mt
generatePostings ps = [p' | p <- ps
, p' <- if q `matchesPosting` p then p:[ m p | m <- mods] else [p]]
-- | Parse the 'Query' from a 'TransactionModifier's 'tmquerytxt',
-- and return it as a function requiring the current date.
--
-- >>> tmParseQuery (TransactionModifier "" []) undefined
-- Any
-- >>> tmParseQuery (TransactionModifier "ping" []) undefined
-- Acct "ping"
-- >>> tmParseQuery (TransactionModifier "date:2016" []) undefined
-- Date (DateSpan 2016)
-- >>> tmParseQuery (TransactionModifier "date:today" []) (read "2017-01-01")
-- Date (DateSpan 2017/01/01)
tmParseQuery :: TransactionModifier -> (Day -> Query)
tmParseQuery mt = fst . flip parseQuery (tmquerytxt mt)
-- | Converts a 'TransactionModifier''s posting to a 'Posting'-generating function,
-- which will be used to make a new posting based on the old one (an "automated posting").
tmPostingToFunction :: Posting -> (Posting -> Posting)
tmPostingToFunction p' =
\p -> renderPostingCommentDates $ p'
{ pdate = pdate p
, pdate2 = pdate2 p
, pamount = amount' p
}
where
amount' = case postingScale p' of
Nothing -> const $ pamount p'
Just n -> \p -> withAmountType (head $ amounts $ pamount p') $ pamount p `divideMixedAmount` (1/n)
withAmountType amount (Mixed as) = case acommodity amount of
"" -> Mixed as
c -> Mixed [a{acommodity = c, astyle = astyle amount, aprice = aprice amount} | a <- as]
postingScale :: Posting -> Maybe Quantity
postingScale p =
case amounts $ pamount p of
[a] | amultiplier a -> Just $ aquantity a
_ -> Nothing
renderPostingCommentDates :: Posting -> Posting
renderPostingCommentDates p = p { pcomment = comment' }
where
datesComment = T.concat $ catMaybes [T.pack . showDate <$> pdate p, ("=" <>) . T.pack . showDate <$> pdate2 p]
comment'
| T.null datesComment = pcomment p
| otherwise = T.intercalate "\n" $ filter (not . T.null) [T.strip $ pcomment p, "[" <> datesComment <> "]"]