{-| 

A history-aware add command to help with data entry.

-}

module Commands.Add
where
import Prelude hiding (putStr, putStrLn, getLine, appendFile)
import Ledger
import Options
import Commands.Register (showRegisterReport)
import System.IO.UTF8
import System.IO (stderr, hFlush)
import System.IO.Error
import Text.ParserCombinators.Parsec
import Utils (ledgerFromStringWithOpts)
import qualified Data.Foldable as Foldable (find)

-- | Read ledger transactions from the terminal, prompting for each field,
-- and append them to the ledger file. If the ledger came from stdin, this
-- command has no effect.
add :: [Opt] -> [String] -> Ledger -> IO ()
add opts args l
    | filepath (journal l) == "-" = return ()
    | otherwise = do
  hPutStrLn stderr
    "Enter one or more transactions, which will be added to your ledger file.\n\
    \To complete a transaction, enter . as account name. To quit, press control-c."
  today <- getCurrentDay
  getAndAddTransactions l opts args today `catch` (\e -> unless (isEOFError e) $ ioError e)

-- | Read a number of ledger transactions from the command line,
-- prompting, validating, displaying and appending them to the ledger
-- file, until end of input (then raise an EOF exception). Any
-- command-line arguments are used as the first transaction's description.
getAndAddTransactions :: Ledger -> [Opt] -> [String] -> Day -> IO ()
getAndAddTransactions l opts args defaultDate = do
  (ledgerTransaction,date) <- getTransaction l opts args defaultDate
  l <- ledgerAddTransaction l ledgerTransaction
  getAndAddTransactions l opts args date

-- | Read a transaction from the command line, with history-aware prompting.
getTransaction :: Ledger -> [Opt] -> [String] -> Day -> IO (Transaction,Day)
getTransaction l opts args defaultDate = do
  today <- getCurrentDay
  datestr <- askFor "date" 
            (Just $ showDate defaultDate)
            (Just $ \s -> null s || 
             isRight (parse (smartdate >> many spacenonewline >> eof) "" $ lowercase s))
  description <- askFor "description" Nothing (Just $ not . null) 
  let historymatches = transactionsSimilarTo l args description
      bestmatch | null historymatches = Nothing
                | otherwise = Just $ snd $ head historymatches
      bestmatchpostings = maybe Nothing (Just . tpostings) bestmatch
      date = fixSmartDate today $ fromparse $ (parse smartdate "" . lowercase) datestr
      accept x = x == "." || (not . null) x &&
        if NoNewAccts `elem` opts
            then isJust $ Foldable.find (== x) ant
            else True
        where (ant,_,_,_) = groupPostings . journalPostings . journal $ l
      getpostingsandvalidate = do
        ps <- getPostings accept bestmatchpostings []
        let t = nulltransaction{tdate=date
                               ,tstatus=False
                               ,tdescription=description
                               ,tpostings=ps
                               }
            retry = do
              hPutStrLn stderr $ "\n" ++ nonzerobalanceerror ++ ". Re-enter:"
              getpostingsandvalidate
        either (const retry) (return . flip (,) date) $ balanceTransaction t
  unless (null historymatches) 
       (do
         hPutStrLn stderr "Similar transactions found, using the first for defaults:\n"
         hPutStr stderr $ concatMap (\(n,t) -> printf "[%3d%%] %s" (round $ n*100 :: Int) (show t)) $ take 3 historymatches)
  getpostingsandvalidate

-- | Read postings from the command line until . is entered, using the
-- provided historical postings, if any, to guess defaults.
getPostings :: (AccountName -> Bool) -> Maybe [Posting] -> [Posting] -> IO [Posting]
getPostings accept historicalps enteredps = do
  account <- askFor (printf "account %d" n) defaultaccount (Just accept)
  if account=="."
    then return enteredps
    else do
      amountstr <- askFor (printf "amount  %d" n) defaultamount validateamount
      let amount = fromparse $ parse (someamount <|> return missingamt) "" amountstr
      let p = nullposting{paccount=stripbrackets account,
                          pamount=amount,
                          ptype=postingtype account}
      getPostings accept historicalps $ enteredps ++ [p]
    where
      n = length enteredps + 1
      enteredrealps = filter isReal enteredps
      bestmatch | isNothing historicalps = Nothing
                | n <= length ps = Just $ ps !! (n-1)
                | otherwise = Nothing
                where Just ps = historicalps
      defaultaccount = maybe Nothing (Just . showacctname) bestmatch
      showacctname p = showAccountName Nothing (ptype p) $ paccount p
      defaultamount = maybe balancingamount (Just . show . pamount) bestmatch
          where balancingamount = Just $ show $ negate $ sum $ map pamount enteredrealps
      postingtype ('[':_) = BalancedVirtualPosting
      postingtype ('(':_) = VirtualPosting
      postingtype _ = RegularPosting
      stripbrackets = dropWhile (`elem` "([") . reverse . dropWhile (`elem` "])") . reverse
      validateamount = Just $ \s -> (null s && not (null enteredrealps))
                                   || isRight (parse (someamount>>many spacenonewline>>eof) "" s)

-- | Prompt for and read a string value, optionally with a default value
-- and a validator. A validator causes the prompt to repeat until the
-- input is valid. May also raise an EOF exception if control-d is pressed.
askFor :: String -> Maybe String -> Maybe (String -> Bool) -> IO String
askFor prompt def validator = do
  hPutStr stderr $ prompt ++ maybe "" showdef def ++ ": "
  hFlush stderr
  l <- getLine
  let input = if null l then fromMaybe l def else l
  case validator of
    Just valid -> if valid input
                   then return input
                   else askFor prompt def validator
    Nothing -> return input
    where showdef s = " [" ++ s ++ "]"

-- | Append this transaction to the ledger's file. Also, to the ledger's
-- transaction list, but we don't bother updating the other fields - this
-- is enough to include new transactions in the history matching.
ledgerAddTransaction :: Ledger -> Transaction -> IO Ledger
ledgerAddTransaction l t = do
  appendToLedgerFile l $ show t
  putStrLn $ printf "\nAdded transaction to %s:" (filepath $ journal l)
  putStrLn =<< registerFromString (show t)
  return l{journal=rl{jtxns=ts}}
      where rl = journal l
            ts = jtxns rl ++ [t]

-- | Append data to the ledger's file, ensuring proper separation from any
-- existing data; or if the file is "-", dump it to stdout.
appendToLedgerFile :: Ledger -> String -> IO ()
appendToLedgerFile l s = 
    if f == "-"
    then putStr $ sep ++ s
    else appendFile f $ sep++s
    where 
      f = filepath $ journal l
      -- XXX we are looking at the original raw text from when the ledger
      -- was first read, but that's good enough for now
      t = jtext $ journal l
      sep | null $ strip t = ""
          | otherwise = replicate (2 - min 2 (length lastnls)) '\n'
          where lastnls = takeWhile (=='\n') $ reverse t

-- | Convert a string of ledger data into a register report.
registerFromString :: String -> IO String
registerFromString s = do
  now <- getCurrentLocalTime
  l <- ledgerFromStringWithOpts [] s
  return $ showRegisterReport opts (optsToFilterSpec opts [] now) l
    where opts = [Empty]

-- | Return a similarity measure, from 0 to 1, for two strings.
-- This is Simon White's letter pairs algorithm from
-- http://www.catalysoft.com/articles/StrikeAMatch.html
-- with a modification for short strings.
compareStrings :: String -> String -> Double
compareStrings "" "" = 1
compareStrings (_:[]) "" = 0
compareStrings "" (_:[]) = 0
compareStrings (a:[]) (b:[]) = if toUpper a == toUpper b then 1 else 0
compareStrings s1 s2 = 2.0 * fromIntegral i / fromIntegral u
    where
      i = length $ intersect pairs1 pairs2
      u = length pairs1 + length pairs2
      pairs1 = wordLetterPairs $ uppercase s1
      pairs2 = wordLetterPairs $ uppercase s2
wordLetterPairs = concatMap letterPairs . words
letterPairs (a:b:rest) = [a,b] : letterPairs (b:rest)
letterPairs _ = []

compareLedgerDescriptions :: [Char] -> [Char] -> Double
compareLedgerDescriptions s t = compareStrings s' t'
    where s' = simplify s
          t' = simplify t
          simplify = filter (not . (`elem` "0123456789"))

transactionsSimilarTo :: Ledger -> [String] -> String -> [(Double,Transaction)]
transactionsSimilarTo l apats s =
    sortBy compareRelevanceAndRecency
               $ filter ((> threshold).fst)
               [(compareLedgerDescriptions s $ tdescription t, t) | t <- ts]
    where
      compareRelevanceAndRecency (n1,t1) (n2,t2) = compare (n2,tdate t2) (n1,tdate t1)
      ts = jtxns $ filterJournalTransactionsByAccount apats $ journal l
      threshold = 0