149 lines
		
	
	
		
			6.6 KiB
		
	
	
	
		
			Haskell
		
	
	
	
	
	
			
		
		
	
	
			149 lines
		
	
	
		
			6.6 KiB
		
	
	
	
		
			Haskell
		
	
	
	
	
	
{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE ViewPatterns #-}
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{-# LANGUAGE CPP #-}
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{-|
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A 'TransactionModifier' is a rule that modifies certain 'Transaction's,
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typically adding automated postings to them.
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-}
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module Hledger.Data.TransactionModifier (
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   modifyTransactions
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)
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where
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import Control.Applicative ((<|>))
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import Data.Maybe
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#if !(MIN_VERSION_base(4,11,0))
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import Data.Monoid ((<>))
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#endif
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import qualified Data.Text as T
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import Data.Time.Calendar
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import Hledger.Data.Types
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import Hledger.Data.Dates
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import Hledger.Data.Amount
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import Hledger.Data.Transaction
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import Hledger.Query
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import Hledger.Data.Posting (commentJoin, commentAddTag)
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import Hledger.Utils.UTF8IOCompat (error')
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import Hledger.Utils.Debug
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-- $setup
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-- >>> :set -XOverloadedStrings
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-- >>> import Hledger.Data.Posting
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-- >>> import Hledger.Data.Transaction
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-- >>> import Hledger.Data.Journal
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-- | Apply all the given transaction modifiers, in turn, to each transaction.
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modifyTransactions :: [TransactionModifier] -> [Transaction] -> [Transaction]
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modifyTransactions tmods = map applymods
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  where
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    applymods t = taggedt'
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      where
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        t' = foldr (flip (.) . transactionModifierToFunction) id tmods t
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        taggedt'
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          -- PERF: compares txns to see if any modifier had an effect, inefficient ?
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          | t' /= t   = t'{tcomment = tcomment t' `commentAddTag` ("modified","")
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                          ,ttags    = ("modified","") : ttags t'
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                          }
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          | otherwise = t'
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-- | Converts a 'TransactionModifier' to a 'Transaction'-transforming function,
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-- which applies the modification(s) specified by the TransactionModifier.
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-- Currently this means adding automated postings when certain other postings are present.
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-- The postings of the transformed transaction will reference it in the usual
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-- way (ie, 'txnTieKnot' is called).
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--
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-- >>> putStr $ showTransaction $ transactionModifierToFunction (TransactionModifier "" ["pong" `post` usd 2]) nulltransaction{tpostings=["ping" `post` usd 1]}
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-- 0000/01/01
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--     ping           $1.00
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--     pong           $2.00
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-- <BLANKLINE>
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-- >>> putStr $ showTransaction $ transactionModifierToFunction (TransactionModifier "miss" ["pong" `post` usd 2]) nulltransaction{tpostings=["ping" `post` usd 1]}
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-- 0000/01/01
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--     ping           $1.00
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-- <BLANKLINE>
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-- >>> putStr $ showTransaction $ transactionModifierToFunction (TransactionModifier "ping" ["pong" `post` amount{aismultiplier=True, aquantity=3}]) nulltransaction{tpostings=["ping" `post` usd 2]}
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-- 0000/01/01
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--     ping           $2.00
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--     pong           $6.00
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-- <BLANKLINE>
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--
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transactionModifierToFunction :: TransactionModifier -> (Transaction -> Transaction)
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transactionModifierToFunction mt =
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  \t@(tpostings -> ps) -> txnTieKnot t{ tpostings=generatePostings ps }
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  where
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    q = simplifyQuery $ tmParseQuery mt (error' "a transaction modifier's query cannot depend on current date")
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    mods = map (tmPostingRuleToFunction (tmquerytxt mt)) $ tmpostingrules mt
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    generatePostings ps = [p' | p <- ps
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                              , p' <- if q `matchesPosting` p then p:[ m p | m <- mods] else [p]]
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-- | Parse the 'Query' from a 'TransactionModifier's 'tmquerytxt',
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-- and return it as a function requiring the current date.
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--
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-- >>> tmParseQuery (TransactionModifier "" []) undefined
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-- Any
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-- >>> tmParseQuery (TransactionModifier "ping" []) undefined
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-- Acct "ping"
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-- >>> tmParseQuery (TransactionModifier "date:2016" []) undefined
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-- Date (DateSpan 2016)
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-- >>> tmParseQuery (TransactionModifier "date:today" []) (read "2017-01-01")
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-- Date (DateSpan 2017/01/01)
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tmParseQuery :: TransactionModifier -> (Day -> Query)
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tmParseQuery mt = fst . flip parseQuery (tmquerytxt mt)
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-- | Converts a 'TransactionModifier''s posting rule to a 'Posting'-generating function,
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-- which will be used to make a new posting based on the old one (an "automated posting").
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-- The new posting's amount can optionally be the old posting's amount multiplied by a constant.
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-- If the old posting had a total-priced amount, the new posting's multiplied amount will be unit-priced.
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-- The new posting will have two tags added: a normal generated-posting: tag which also appears in the comment,
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-- and a hidden _generated-posting: tag which does not.
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-- The TransactionModifier's query text is also provided, and saved
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-- as the tags' value.
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tmPostingRuleToFunction :: T.Text -> TMPostingRule -> (Posting -> Posting)
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tmPostingRuleToFunction querytxt pr =
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  \p -> renderPostingCommentDates $ pr
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      { pdate    = pdate  pr <|> pdate  p
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      , pdate2   = pdate2 pr <|> pdate2 p
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      , pamount  = amount' p
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      , pcomment = pcomment pr `commentAddTag` ("generated-posting",qry)
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      , ptags    = ("generated-posting", qry) :
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                   ("_generated-posting",qry) :
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                   ptags pr
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      }
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  where
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    qry = "= " <> querytxt
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    amount' = case postingRuleMultiplier pr of
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        Nothing -> const $ pamount pr
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        Just n  -> \p ->
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          -- Multiply the old posting's amount by the posting rule's multiplier.
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          let
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            pramount = dbg6 "pramount" $ head $ amounts $ pamount pr
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            matchedamount = dbg6 "matchedamount" $ pamount p
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            -- Handle a matched amount with a total price carefully so as to keep the transaction balanced (#928).
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            -- Approach 1: convert to a unit price and increase the display precision slightly
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            -- Mixed as = dbg6 "multipliedamount" $ n `multiplyMixedAmount` mixedAmountTotalPriceToUnitPrice matchedamount
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            -- Approach 2: multiply the total price (keeping it positive) as well as the quantity
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            Mixed as = dbg6 "multipliedamount" $ n `multiplyMixedAmountAndPrice` matchedamount
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          in
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            case acommodity pramount of
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              "" -> Mixed as
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              -- TODO multipliers with commodity symbols are not yet a documented feature.
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              -- For now: in addition to multiplying the quantity, it also replaces the
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              -- matched amount's commodity, display style, and price with those of the posting rule.
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              c  -> Mixed [a{acommodity = c, astyle = astyle pramount, aprice = aprice pramount} | a <- as]
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postingRuleMultiplier :: TMPostingRule -> Maybe Quantity
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postingRuleMultiplier p =
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    case amounts $ pamount p of
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        [a] | aismultiplier a -> Just $ aquantity a
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        _                   -> Nothing
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renderPostingCommentDates :: Posting -> Posting
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renderPostingCommentDates p = p { pcomment = comment' }
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    where
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        dates = T.concat $ catMaybes [T.pack . showDate <$> pdate p, ("=" <>) . T.pack . showDate <$> pdate2 p]
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        comment'
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            | T.null dates = pcomment p
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            | otherwise    = ("[" <> dates <> "]") `commentJoin` pcomment p
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