{-|

A 'Ledger' stores, for efficiency, a 'RawLedger' plus its tree of account
names, a map from account names to 'Account's, and the display precision.
Typically it has also has had the uninteresting 'Entry's filtered out.
In addition, it stores the account filter pattern and a second set of fields
providing the filtered entries & transactions.

-}

module Ledger.Ledger
where
import qualified Data.Map as Map
import Data.Map ((!))
import Ledger.Utils
import Ledger.Types
import Ledger.Amount
import Ledger.Account
import Ledger.AccountName
import Ledger.Transaction
import Ledger.RawLedger
import Ledger.Entry


instance Show Ledger where
    show l = printf "Ledger with %d entries, %d accounts: %s"
             ((length $ entries $ rawledger l) +
              (length $ modifier_entries $ rawledger l) +
              (length $ periodic_entries $ rawledger l))
             (length $ accountnames l)
             (show $ accountnames l)
             ++ "\n" ++ (showtree $ accountnametree l)
             ++ "\n" ++ (showtree $ filteredaccountnametree l)

-- | Convert a raw ledger to a more efficient cached type, described above.  
cacheLedger :: Regex -> RawLedger -> Ledger
cacheLedger acctpat l = 
    let 
        ant = rawLedgerAccountNameTree l
        anames = flatten ant
        ts = rawLedgerTransactions l
        sortedts = sortBy (comparing account) ts
        groupedts = groupBy (\t1 t2 -> account t1 == account t2) sortedts
        txnmap = Map.union 
               (Map.fromList [(account $ head g, g) | g <- groupedts])
               (Map.fromList [(a,[]) | a <- anames])
        txnsof = (txnmap !)
        subacctsof a = filter (isAccountNamePrefixOf a) anames
        subtxnsof a = concat [txnsof a | a <- [a] ++ subacctsof a]
        balmap = Map.union 
               (Map.fromList [(a, (sumTransactions $ subtxnsof a){precision=maxprecision}) | a <- anames])
               (Map.fromList [(a,nullamt) | a <- anames])
        amap = Map.fromList [(a, Account a (txnmap ! a) (balmap ! a)) | a <- anames]
        -- the same again, considering only accounts and transactions matching the account pattern
        matchacct :: AccountName -> Bool
        matchacct = containsRegex acctpat . accountLeafName
        filteredant = treefilter matchacct ant
        -- rebuild the tree after filtering to include all parents
        filteredanames = flatten $ accountNameTreeFrom $ filter matchacct anames
        filteredts = filter (matchacct . account) ts
        filteredsortedts = sortBy (comparing account) filteredts
        filteredgroupedts = groupBy (\t1 t2 -> account t1 == account t2) filteredsortedts
        filteredtxnmap = Map.union 
               (Map.fromList [(account $ head g, g) | g <- filteredgroupedts])
               (Map.fromList [(a,[]) | a <- filteredanames])
        filteredtxnsof = (filteredtxnmap !)
        filteredsubacctsof a = filter (isAccountNamePrefixOf a) filteredanames
        filteredsubtxnsof a = concat [filteredtxnsof a | a <- [a] ++ filteredsubacctsof a]
        filteredbalmap = Map.union 
               (Map.fromList [(a, (sumTransactions $ filteredsubtxnsof a){precision=maxprecision}) | a <- filteredanames])
               (Map.fromList [(a,nullamt) | a <- filteredanames])
        filteredamap = Map.fromList [(a, Account a (filteredtxnmap ! a) (filteredbalmap ! a)) | a <- filteredanames]

        maxprecision = maximum $ map (precision . amount) ts
    in
      Ledger l ant amap maxprecision acctpat filteredant filteredamap

-- | Remove ledger entries we are not interested in.
-- Keep only those which fall between the begin and end dates, match the
-- description patterns, or transact with an account matching the account
-- patterns.
filterLedgerEntries :: String -> String -> Regex -> Regex -> RawLedger -> RawLedger
filterLedgerEntries begin end acctpat descpat = 
    filterLedgerEntriesByDate begin end .
    filterLedgerEntriesByDescription descpat

-- | Keep only entries whose description matches the description pattern.
filterLedgerEntriesByDescription :: Regex -> RawLedger -> RawLedger
filterLedgerEntriesByDescription descpat (RawLedger ms ps es f) = 
    RawLedger ms ps (filter matchdesc es) f
    where
      matchdesc :: Entry -> Bool
      matchdesc e = case matchRegex descpat (edescription e) of
                      Nothing -> False
                      otherwise -> True

-- | Keep only entries which fall between begin and end dates. 
-- We include entries on the begin date and exclude entries on the end
-- date, like ledger.  An empty date string means no restriction.
filterLedgerEntriesByDate :: String -> String -> RawLedger -> RawLedger
filterLedgerEntriesByDate begin end (RawLedger ms ps es f) = 
    RawLedger ms ps (filter matchdate es) f
    where
      matchdate :: Entry -> Bool
      matchdate e = (begin == "" || entrydate >= begindate) && 
                    (end == "" || entrydate < enddate)
                    where 
                      begindate = parsedate begin :: UTCTime
                      enddate   = parsedate end
                      entrydate = parsedate $ edate e

-- | List a 'Ledger' 's account names.
accountnames :: Ledger -> [AccountName]
accountnames l = drop 1 $ flatten $ accountnametree l

-- | List a 'Ledger' 's account names filtered by the account match pattern.
filteredaccountnames :: Ledger -> [AccountName]
filteredaccountnames l = filter (containsRegex (acctpat l) . accountLeafName) $ accountnames l

-- | Get the named account from a ledger.
ledgerAccount :: Ledger -> AccountName -> Account
ledgerAccount l a = (accounts l) ! a

-- | Get the named filtered account from a ledger.
ledgerFilteredAccount :: Ledger -> AccountName -> Account
ledgerFilteredAccount l a = (filteredaccounts l) ! a

-- | List a ledger's transactions.
--
-- NB this sets the amount precisions to that of the highest-precision
-- amount, to help with report output. It should perhaps be done in the
-- display functions, but those are far removed from the ledger. Keep in
-- mind if doing more arithmetic with these.
ledgerTransactions :: Ledger -> [Transaction]
ledgerTransactions l = 
    setprecisions $ rawLedgerTransactions $ rawledger l
    where
      setprecisions = map (transactionSetPrecision (lprecision l))

-- | Get a ledger's tree of accounts to the specified depth.
ledgerAccountTree :: Int -> Ledger -> Tree Account
ledgerAccountTree depth l = 
    addDataToAccountNameTree l depthpruned
    where
      nametree = filteredaccountnametree l --
      depthpruned = treeprune depth nametree

-- | Get a ledger's tree of accounts to the specified depth, filtered by
-- the account pattern.
ledgerFilteredAccountTree :: Int -> Regex -> Ledger -> Tree Account
ledgerFilteredAccountTree depth acctpat l = 
    addFilteredDataToAccountNameTree l $ treeprune depth $ filteredaccountnametree l

-- | Convert a tree of account names into a tree of accounts, using their
-- parent ledger.
addDataToAccountNameTree :: Ledger -> Tree AccountName -> Tree Account
addDataToAccountNameTree = treemap . ledgerAccount

-- | Convert a tree of account names into a tree of accounts, using their
-- parent ledger's filtered account data.
addFilteredDataToAccountNameTree :: Ledger -> Tree AccountName -> Tree Account
addFilteredDataToAccountNameTree l = treemap (ledgerFilteredAccount l)

-- | Print a print report.
printentries :: Ledger -> IO ()
printentries l = putStr $ showEntries $ setprecisions $ entries $ rawledger l
    where setprecisions = map (entrySetPrecision (lprecision l))
      
-- | Print a register report.
printregister :: Ledger -> IO ()
printregister l = putStr $ showTransactionsWithBalances 
                  (sortBy (comparing date) $ ledgerTransactions l)
                  nullamt{precision=lprecision l}

{-| 
This and the helper functions below generate ledger-compatible balance
report output. Here's how it should work:

A sample account tree (as in the sample.ledger file):

@
 assets
  cash
  checking
  saving
 expenses
  food
  supplies
 income
  gifts
  salary
 liabilities
  debts
@

The balance command shows top-level accounts by default:

@
 \> ledger balance
 $-1  assets
  $2  expenses
 $-2  income
  $1  liabilities
@

With -s (--showsubs), also show the subaccounts:

@
 $-1  assets
 $-2    cash
  $1    saving
  $2  expenses
  $1    food
  $1    supplies
 $-2  income
 $-1    gifts
 $-1    salary
  $1  liabilities:debts
@

- @checking@ is not shown because it has a zero balance and no interesting
  subaccounts.  

- @liabilities@ is displayed only as a prefix because it has no transactions
  of its own and only one subaccount.

With an account pattern, show only the accounts with matching names:

@
 \> ledger balance o
  $1  expenses:food
 $-2  income
--------------------
 $-1  
@

- The o matched @food@ and @income@, so they are shown.

- Parents of matched accounts are also shown for context (@expenses@).

- This time the grand total is also shown, because it is not zero.

Again, -s adds the subaccounts:

@
\> ledger -s balance o
  $1  expenses:food
 $-2  income
 $-1    gifts
 $-1    salary
--------------------
 $-1  
@

- @food@ has no subaccounts. @income@ has two, so they are shown. 

- We do not add the subaccounts of parents included for context (@expenses@).

Here are some rules for account balance display, as seen above:

- grand total is omitted if it is 0

- leaf accounts and branches with 0 balance or 0 transactions are omitted

- inner accounts with 0 transactions and 1 subaccount are displayed inline

- in a filtered report, matched accounts are displayed with their parents
  inline (a consequence of the above)

- in a showsubs report, all subaccounts of matched accounts are displayed

-}
showLedgerAccountBalances :: Ledger -> Int -> String
showLedgerAccountBalances l maxdepth = 
    concatMap (showAccountTree l maxdepth) acctbranches
    ++
    if isZeroAmount total 
    then ""
    else printf "--------------------\n%20s\n" $ showAmountRounded total
    where 
      acctbranches = branches $ ledgerAccountTree maxdepth l
      filteredacctbranches = branches $ ledgerFilteredAccountTree maxdepth (acctpat l) l
      total = sum $ map (abalance . root) filteredacctbranches

-- | Get the string representation of a tree of accounts.
-- The ledger from which the accounts come is also required, so that
-- we can check for boring accounts.
showAccountTree :: Ledger -> Int -> Tree Account -> String
showAccountTree l maxdepth = showAccountTree' l maxdepth 0 ""

showAccountTree' :: Ledger -> Int -> Int -> String -> Tree Account -> String
showAccountTree' l maxdepth indentlevel prefix t
    -- merge boring inner account names with the next line
    | isBoringInnerAccount l maxdepth acct = subsindented 0 (fullname++":")
    -- ditto with unmatched parent accounts when filtering by account
    |  filtering && doesnotmatch = subsindented 0 (fullname++":")
    -- otherwise show this account's name & balance
    | otherwise = bal ++ "  " ++ indent ++ prefix ++ leafname ++ "\n" ++ (subsindented 1 "")
    where
      acct = root t
      subs = branches t
      subsindented i p = concatMap (showAccountTree' l maxdepth (indentlevel+i) p) subs
      bal = printf "%20s" $ show $ abalance $ acct
      indent = replicate (indentlevel * 2) ' '
      fullname = aname acct
      leafname = accountLeafName fullname
      filtering = filteredaccountnames l /= (accountnames l)
      doesnotmatch = not (containsRegex (acctpat l) leafname)

-- | Is this account a boring inner account in this ledger ? 
-- Boring inner accounts have no transactions, one subaccount,
-- and depth less than the maximum display depth.
-- Also, they are unmatched parent accounts when account matching is in effect.
isBoringInnerAccount :: Ledger -> Int -> Account -> Bool
isBoringInnerAccount l maxdepth a
    | name == "top" = False
    | depth < maxdepth && numtxns == 0 && numsubs == 1 = True
    | otherwise = False
    where      
      name = aname a
      depth = accountNameLevel name
      numtxns = length $ atransactions a
      -- how many (filter-matching) subaccounts has this account ?
      numsubs = length $ subAccountNamesFrom (filteredaccountnames l) name

-- | Is the named account a boring inner account in this ledger ?
isBoringInnerAccountName :: Ledger -> Int -> AccountName -> Bool
isBoringInnerAccountName l maxdepth = isBoringInnerAccount l maxdepth . ledgerAccount l