{-|

A 'Transaction' consists of two or more related 'Posting's which balance
to zero, representing a movement of some commodity(ies) between accounts,
plus a date and optional metadata like description and cleared status.

-}

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

import Hledger.Data.Utils
import Hledger.Data.Types
import Hledger.Data.Dates
import Hledger.Data.Posting
import Hledger.Data.Amount
import Hledger.Data.Commodity (dollars, dollar, unknown)

instance Show Transaction where show = showTransactionUnelided

instance Show ModifierTransaction where 
    show t = "= " ++ mtvalueexpr t ++ "\n" ++ unlines (map show (mtpostings t))

instance Show PeriodicTransaction where 
    show t = "~ " ++ ptperiodicexpr t ++ "\n" ++ unlines (map show (ptpostings t))

nulltransaction :: Transaction
nulltransaction = Transaction {
                    tdate=nulldate,
                    teffectivedate=Nothing, 
                    tstatus=False, 
                    tcode="", 
                    tdescription="", 
                    tcomment="",
                    tmetadata=[],
                    tpostings=[],
                    tpreceding_comment_lines=""
                  }

{-|
Show a journal transaction, formatted for the print command. ledger 2.x's
standard format looks like this:

@
yyyy/mm/dd[ *][ CODE] description.........          [  ; comment...............]
    account name 1.....................  ...$amount1[  ; comment...............]
    account name 2.....................  ..$-amount1[  ; comment...............]

pcodewidth    = no limit -- 10          -- mimicking ledger layout.
pdescwidth    = no limit -- 20          -- I don't remember what these mean,
pacctwidth    = 35 minimum, no maximum  -- they were important at the time.
pamtwidth     = 11
pcommentwidth = no limit -- 22
@
-}
showTransaction :: Transaction -> String
showTransaction = showTransaction' True False

showTransactionUnelided :: Transaction -> String
showTransactionUnelided = showTransaction' False False

showTransactionForPrint :: Bool -> Transaction -> String
showTransactionForPrint effective = showTransaction' False effective

showTransaction' :: Bool -> Bool -> Transaction -> String
showTransaction' elide effective t =
    unlines $ [description] ++ showpostings (tpostings t) ++ [""]
    where
      description = concat [date, status, code, desc, comment]
      date | effective = showdate $ fromMaybe (tdate t) $ teffectivedate t
           | otherwise = showdate (tdate t) ++ maybe "" showedate (teffectivedate t)
      status = if tstatus t then " *" else ""
      code = if length (tcode t) > 0 then printf " (%s)" $ tcode t else ""
      desc = ' ' : tdescription t
      comment = if null com then "" else "  ; " ++ com where com = tcomment t
      showdate = printf "%-10s" . showDate
      showedate = printf "=%s" . showdate
      showpostings ps
          | elide && length ps > 1 && isTransactionBalanced Nothing t -- imprecise balanced check
              = map showposting (init ps) ++ [showpostingnoamt (last ps)]
          | otherwise = map showposting ps
          where
            showpostingnoamt p = rstrip $ showacct p ++ "              " ++ showcomment (pcomment p)
            showposting p = concatTopPadded [showacct p
                                            ,"  "
                                            ,showamt (pamount p)
                                            ,showcomment (pcomment p)
                                            ]
            showacct p = "    " ++ showstatus p ++ printf (printf "%%-%ds" w) (showAccountName Nothing (ptype p) (paccount p))
                where w = maximum $ map (length . paccount) ps
                      showstatus p = if pstatus p then "* " else ""
            showamt =
                padleft 12 . showMixedAmountOrZero
            showcomment s = if null s then "" else "  ; "++s

-- | Show an account name, clipped to the given width if any, and
-- appropriately bracketed/parenthesised for the given posting type.
showAccountName :: Maybe Int -> PostingType -> AccountName -> String
showAccountName w = fmt
    where
      fmt RegularPosting = take w'
      fmt VirtualPosting = parenthesise . reverse . take (w'-2) . reverse
      fmt BalancedVirtualPosting = bracket . reverse . take (w'-2) . reverse
      w' = fromMaybe 999999 w
      parenthesise s = "("++s++")"
      bracket s = "["++s++"]"

realPostings :: Transaction -> [Posting]
realPostings = filter isReal . tpostings

virtualPostings :: Transaction -> [Posting]
virtualPostings = filter isVirtual . tpostings

balancedVirtualPostings :: Transaction -> [Posting]
balancedVirtualPostings = filter isBalancedVirtual . tpostings

-- | Get the sums of a transaction's real, virtual, and balanced virtual postings.
transactionPostingBalances :: Transaction -> (MixedAmount,MixedAmount,MixedAmount)
transactionPostingBalances t = (sumPostings $ realPostings t
                               ,sumPostings $ virtualPostings t
                               ,sumPostings $ balancedVirtualPostings t)

-- | Is this transaction balanced ? A balanced transaction's real
-- (non-virtual) postings sum to 0, and any balanced virtual postings
-- also sum to 0.
isTransactionBalanced :: Maybe (Map.Map String Commodity) -> Transaction -> Bool
isTransactionBalanced canonicalcommoditymap t =
    -- isReallyZeroMixedAmountCost rsum && isReallyZeroMixedAmountCost bvsum
    isZeroMixedAmount rsum' && isZeroMixedAmount bvsum'
    where
      (rsum, _, bvsum) = transactionPostingBalances t
      rsum'  = canonicaliseMixedAmount canonicalcommoditymap $ costOfMixedAmount rsum
      bvsum' = canonicaliseMixedAmount canonicalcommoditymap $ costOfMixedAmount bvsum

canonicaliseMixedAmount :: Maybe (Map.Map String Commodity) -> MixedAmount -> MixedAmount
canonicaliseMixedAmount Nothing                      = id
canonicaliseMixedAmount (Just canonicalcommoditymap) = fixmixedamount
    where
      -- like journalCanonicaliseAmounts
      fixmixedamount (Mixed as) = Mixed $ map fixamount as
      fixamount a@Amount{commodity=c} = a{commodity=fixcommodity c}
      fixcommodity c@Commodity{symbol=s} = findWithDefault c s canonicalcommoditymap

-- | Ensure that this entry is balanced, possibly auto-filling a missing
-- amount first. We can auto-fill if there is just one non-virtual
-- transaction without an amount. The auto-filled balance will be
-- converted to cost basis if possible. If the entry can not be balanced,
-- return an error message instead.
balanceTransaction :: Maybe (Map.Map String Commodity) -> Transaction -> Either String Transaction
balanceTransaction canonicalcommoditymap t@Transaction{tpostings=ps}
    | length rwithoutamounts > 1 || length bvwithoutamounts > 1
        = Left $ printerr "could not balance this transaction (too many missing amounts)"
    | not $ isTransactionBalanced canonicalcommoditymap t' = Left $ printerr $ nonzerobalanceerror t'
    | otherwise = Right t'
    where
      rps = filter isReal ps
      bvps = filter isBalancedVirtual ps
      (rwithamounts, rwithoutamounts) = partition hasAmount rps
      (bvwithamounts, bvwithoutamounts) = partition hasAmount bvps
      t' = t{tpostings=map balance ps}
          where 
            balance p | not (hasAmount p) && isReal p
                          = p{pamount = (-(sum $ map pamount rwithamounts))}
                      | not (hasAmount p) && isBalancedVirtual p
                          = p{pamount = (-(sum $ map pamount bvwithamounts))}
                      | otherwise = p
      printerr s = intercalate "\n" [s, showTransactionUnelided t]

nonzerobalanceerror :: Transaction -> String
nonzerobalanceerror t = printf "could not balance this transaction (%s%s%s)" rmsg sep bvmsg
    where
      (rsum, _, bvsum) = transactionPostingBalances t
      rmsg | isReallyZeroMixedAmountCost rsum = ""
           | otherwise = "real postings are off by " ++ show (costOfMixedAmount rsum)
      bvmsg | isReallyZeroMixedAmountCost bvsum = ""
            | otherwise = "balanced virtual postings are off by " ++ show (costOfMixedAmount bvsum)
      sep = if not (null rmsg) && not (null bvmsg) then "; " else ""

-- | Convert the primary date to either the actual or effective date.
journalTransactionWithDate :: WhichDate -> Transaction -> Transaction
journalTransactionWithDate ActualDate t = t
journalTransactionWithDate EffectiveDate t = txnTieKnot t{tdate=fromMaybe (tdate t) (teffectivedate t)}
    

-- | Ensure a transaction's postings refer back to it.
txnTieKnot :: Transaction -> Transaction
txnTieKnot t@Transaction{tpostings=ps} = t{tpostings=map (settxn t) ps}

-- | Set a posting's parent transaction.
settxn :: Transaction -> Posting -> Posting
settxn t p = p{ptransaction=Just t}

tests_Transaction = TestList [
  "showTransaction" ~: do
     assertEqual "show a balanced transaction, eliding last amount"
       (unlines
        ["2007/01/28 coopportunity"
        ,"    expenses:food:groceries        $47.18"
        ,"    assets:checking"
        ,""
        ])
       (let t = Transaction (parsedate "2007/01/28") Nothing False "" "coopportunity" "" []
                [Posting False "expenses:food:groceries" (Mixed [dollars 47.18]) "" RegularPosting [] (Just t)
                ,Posting False "assets:checking" (Mixed [dollars (-47.18)]) "" RegularPosting [] (Just t)
                ] ""
        in showTransaction t)

  ,"showTransaction" ~: do
     assertEqual "show a balanced transaction, no eliding"
       (unlines
        ["2007/01/28 coopportunity"
        ,"    expenses:food:groceries        $47.18"
        ,"    assets:checking               $-47.18"
        ,""
        ])
       (let t = Transaction (parsedate "2007/01/28") Nothing False "" "coopportunity" "" []
                [Posting False "expenses:food:groceries" (Mixed [dollars 47.18]) "" RegularPosting [] (Just t)
                ,Posting False "assets:checking" (Mixed [dollars (-47.18)]) "" RegularPosting [] (Just t)
                ] ""
        in showTransactionUnelided t)

     -- document some cases that arise in debug/testing:
  ,"showTransaction" ~: do
     assertEqual "show an unbalanced transaction, should not elide"
       (unlines
        ["2007/01/28 coopportunity"
        ,"    expenses:food:groceries        $47.18"
        ,"    assets:checking               $-47.19"
        ,""
        ])
       (showTransaction
        (txnTieKnot $ Transaction (parsedate "2007/01/28") Nothing False "" "coopportunity" "" []
         [Posting False "expenses:food:groceries" (Mixed [dollars 47.18]) "" RegularPosting [] Nothing
         ,Posting False "assets:checking" (Mixed [dollars (-47.19)]) "" RegularPosting [] Nothing
         ] ""))

  ,"showTransaction" ~: do
     assertEqual "show an unbalanced transaction with one posting, should not elide"
       (unlines
        ["2007/01/28 coopportunity"
        ,"    expenses:food:groceries        $47.18"
        ,""
        ])
       (showTransaction
        (txnTieKnot $ Transaction (parsedate "2007/01/28") Nothing False "" "coopportunity" "" []
         [Posting False "expenses:food:groceries" (Mixed [dollars 47.18]) "" RegularPosting [] Nothing
         ] ""))

  ,"showTransaction" ~: do
     assertEqual "show a transaction with one posting and a missing amount"
       (unlines
        ["2007/01/28 coopportunity"
        ,"    expenses:food:groceries              "
        ,""
        ])
       (showTransaction
        (txnTieKnot $ Transaction (parsedate "2007/01/28") Nothing False "" "coopportunity" "" []
         [Posting False "expenses:food:groceries" missingamt "" RegularPosting [] Nothing
         ] ""))

  ,"showTransaction" ~: do
     assertEqual "show a transaction with a priced commodityless amount"
       (unlines
        ["2010/01/01 x"
        ,"    a        1 @ $2"
        ,"    b              "
        ,""
        ])
       (showTransaction
        (txnTieKnot $ Transaction (parsedate "2010/01/01") Nothing False "" "x" "" []
         [Posting False "a" (Mixed [Amount unknown 1 (Just $ Mixed [Amount dollar{precision=0} 2 Nothing])]) "" RegularPosting [] Nothing
         ,Posting False "b" missingamt "" RegularPosting [] Nothing
         ] ""))

  ]