{-|

A compound data type for efficiency. A 'Ledger' caches information derived
from a 'RawLedger' for easier querying. Also it typically has had
uninteresting 'LedgerTransaction's and 'Posting's filtered out. It
contains:

- the original unfiltered 'RawLedger'

- a tree of 'AccountName's

- a map from account names to 'Account's

- the full text of the journal file, when available

This is the main object you'll deal with as a user of the Ledger
library. The most useful functions also have shorter, lower-case
aliases for easier interaction. Here's an example:

> > import Ledger
> > l <- readLedger "sample.ledger"
> > accountnames l
> ["assets","assets:bank","assets:bank:checking","assets:bank:saving",...
> > accounts l
> [Account assets with 0 txns and $-1 balance,Account assets:bank with...
> > topaccounts l
> [Account assets with 0 txns and $-1 balance,Account expenses with...
> > account l "assets"
> Account assets with 0 txns and $-1 balance
> > accountsmatching ["ch"] l
> accountsmatching ["ch"] l
> [Account assets:bank:checking with 4 txns and $0 balance]
> > subaccounts l (account l "assets")
> subaccounts l (account l "assets")
> [Account assets:bank with 0 txns and $1 balance,Account assets:cash...
> > head $ transactions l
> 2008/01/01 income assets:bank:checking $1 RegularPosting
> > accounttree 2 l
> Node {rootLabel = Account top with 0 txns and 0 balance, subForest = [...
> > accounttreeat l (account l "assets")
> Just (Node {rootLabel = Account assets with 0 txns and $-1 balance, ...
> > datespan l
> DateSpan (Just 2008-01-01) (Just 2009-01-01)
> > rawdatespan l
> DateSpan (Just 2008-01-01) (Just 2009-01-01)
> > ledgeramounts l
> [$1,$-1,$1,$-1,$1,$-1,$1,$1,$-2,$1,$-1]
> > commodities l
> [Commodity {symbol = "$", side = L, spaced = False, comma = False, ...


-}

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


instance Show Ledger where
    show l = printf "Ledger with %d transactions, %d accounts\n%s"
             ((length $ ledger_txns $ rawledger l) +
              (length $ modifier_txns $ rawledger l) +
              (length $ periodic_txns $ rawledger l))
             (length $ accountnames l)
             (showtree $ accountnametree l)

-- | Convert a raw ledger to a more efficient cached type, described above.  
cacheLedger :: [String] -> RawLedger -> Ledger
cacheLedger apats l = Ledger{rawledgertext="",rawledger=l,accountnametree=ant,accountmap=acctmap}
    where
      (ant,txnsof,_,inclbalof) = groupTransactions $ filtertxns apats $ rawLedgerTransactions l
      acctmap = Map.fromList [(a, mkacct a) | a <- flatten ant]
          where mkacct a = Account a (txnsof a) (inclbalof a)

-- | Given a list of transactions, return an account name tree and three
-- query functions that fetch transactions, balance, and
-- subaccount-including balance by account name. 
-- This is to factor out common logic from cacheLedger and
-- summariseTransactionsInDateSpan.
groupTransactions :: [Transaction] -> (Tree AccountName,
                                     (AccountName -> [Transaction]), 
                                     (AccountName -> MixedAmount), 
                                     (AccountName -> MixedAmount))
groupTransactions ts = (ant,txnsof,exclbalof,inclbalof)
    where
      txnanames = sort $ nub $ map taccount ts
      ant = accountNameTreeFrom $ expandAccountNames $ txnanames
      allanames = flatten ant
      txnmap = Map.union (transactionsByAccount ts) (Map.fromList [(a,[]) | a <- allanames])
      balmap = Map.fromList $ flatten $ calculateBalances ant txnsof
      txnsof = (txnmap !) 
      exclbalof = fst . (balmap !)
      inclbalof = snd . (balmap !)
-- debug
--       txnsof a = (txnmap ! (trace ("ts "++a) a))
--       exclbalof a = fst $ (balmap ! (trace ("eb "++a) a))
--       inclbalof a = snd $ (balmap ! (trace ("ib "++a) a))

-- | Add subaccount-excluding and subaccount-including balances to a tree
-- of account names somewhat efficiently, given a function that looks up
-- transactions by account name.
calculateBalances :: Tree AccountName -> (AccountName -> [Transaction]) -> Tree (AccountName, (MixedAmount, MixedAmount))
calculateBalances ant txnsof = addbalances ant
    where 
      addbalances (Node a subs) = Node (a,(bal,bal+subsbal)) subs'
          where
            bal         = sumTransactions $ txnsof a
            subsbal     = sum $ map (snd . snd . root) subs'
            subs'       = map addbalances subs

-- | Convert a list of transactions to a map from account name to the list
-- of all transactions in that account. 
transactionsByAccount :: [Transaction] -> Map.Map AccountName [Transaction]
transactionsByAccount ts = m'
    where
      sortedts = sortBy (comparing taccount) ts
      groupedts = groupBy (\t1 t2 -> taccount t1 == taccount t2) sortedts
      m' = Map.fromList [(taccount $ head g, g) | g <- groupedts]
-- The special account name "top" can be used to look up all transactions. ?
--      m' = Map.insert "top" sortedts m

filtertxns :: [String] -> [Transaction] -> [Transaction]
filtertxns apats ts = filter (matchpats apats . taccount) ts

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

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

-- | List a ledger's accounts, in tree order
ledgerAccounts :: Ledger -> [Account]
ledgerAccounts l = drop 1 $ flatten $ ledgerAccountTree 9999 l

-- | List a ledger's top-level accounts, in tree order
ledgerTopAccounts :: Ledger -> [Account]
ledgerTopAccounts l = map root $ branches $ ledgerAccountTree 9999 l

-- | Accounts in ledger whose name matches the pattern, in tree order.
ledgerAccountsMatching :: [String] -> Ledger -> [Account]
ledgerAccountsMatching pats l = filter (matchpats pats . aname) $ accounts l

-- | List a ledger account's immediate subaccounts
ledgerSubAccounts :: Ledger -> Account -> [Account]
ledgerSubAccounts l Account{aname=a} = 
    map (ledgerAccount l) $ filter (`isSubAccountNameOf` a) $ accountnames l

-- | List a ledger's "transactions", ie postings with transaction info attached.
ledgerTransactions :: Ledger -> [Transaction]
ledgerTransactions l = rawLedgerTransactions $ rawledger l

-- | Get a ledger's tree of accounts to the specified depth.
ledgerAccountTree :: Int -> Ledger -> Tree Account
ledgerAccountTree depth l = treemap (ledgerAccount l) $ treeprune depth $ accountnametree l

-- | Get a ledger's tree of accounts rooted at the specified account.
ledgerAccountTreeAt :: Ledger -> Account -> Maybe (Tree Account)
ledgerAccountTreeAt l acct = subtreeat acct $ ledgerAccountTree 9999 l

-- | The (fully specified) date span containing all the ledger's (filtered) transactions,
-- or DateSpan Nothing Nothing if there are none.
ledgerDateSpan :: Ledger -> DateSpan
ledgerDateSpan l
    | null ts = DateSpan Nothing Nothing
    | otherwise = DateSpan (Just $ tdate $ head ts) (Just $ addDays 1 $ tdate $ last ts)
    where
      ts = sortBy (comparing tdate) $ ledgerTransactions l

-- | Convenience aliases.
accountnames :: Ledger -> [AccountName]
accountnames = ledgerAccountNames

account :: Ledger -> AccountName -> Account
account = ledgerAccount

accounts :: Ledger -> [Account]
accounts = ledgerAccounts

topaccounts :: Ledger -> [Account]
topaccounts = ledgerTopAccounts

accountsmatching :: [String] -> Ledger -> [Account]
accountsmatching = ledgerAccountsMatching

subaccounts :: Ledger -> Account -> [Account]
subaccounts = ledgerSubAccounts

transactions :: Ledger -> [Transaction]
transactions = ledgerTransactions

commodities :: Ledger -> [Commodity]
commodities = nub . rawLedgerCommodities . rawledger

accounttree :: Int -> Ledger -> Tree Account
accounttree = ledgerAccountTree

accounttreeat :: Ledger -> Account -> Maybe (Tree Account)
accounttreeat = ledgerAccountTreeAt

datespan :: Ledger -> DateSpan
datespan = ledgerDateSpan

rawdatespan :: Ledger -> DateSpan
rawdatespan = rawLedgerDateSpan . rawledger

ledgeramounts :: Ledger -> [MixedAmount]
ledgeramounts = rawLedgerAmounts . rawledger