{-|

A reader for the "timedot" file format.
Example:

@
#DATE
#ACCT DOTS  # Each dot represents 15m, spaces are ignored

# on 2/1, 1h was spent on FOSS haskell work, 0.25h on research, etc.
2/1
fos.haskell   .... ..
biz.research  .
inc.client1   .... .... .... .... .... ....

2/2
biz.research  .
inc.client1   .... .... ..

@

-}

{-# LANGUAGE OverloadedStrings #-}

module Hledger.Read.TimedotReader (
  -- * Reader
  reader,
  -- * Misc other exports
  timedotfilep,
  -- * Tests
  tests_Hledger_Read_TimedotReader
)
where
import Prelude ()
import Prelude.Compat
import Control.Monad
import Control.Monad.Except (ExceptT)
import Control.Monad.State.Strict
import Data.Char (isSpace)
import Data.List (foldl')
import Data.Maybe
import Data.Text (Text)
import Test.HUnit
import Text.Megaparsec.Compat hiding (parse)

import Hledger.Data
import Hledger.Read.Common
import Hledger.Utils hiding (ptrace)

-- easier to toggle this here sometimes
-- import qualified Hledger.Utils (ptrace)
-- ptrace = Hledger.Utils.ptrace
ptrace :: Monad m => a -> m a
ptrace = return

reader :: Reader
reader = Reader
  {rFormat     = "timedot"
  ,rExtensions = ["timedot"]
  ,rParser     = parse
  ,rExperimental = False
  }

-- | Parse and post-process a "Journal" from the timedot format, or give an error.
parse :: Maybe FilePath -> Bool -> FilePath -> Text -> ExceptT String IO Journal
parse _ = parseAndFinaliseJournal timedotfilep

timedotfilep :: JournalParser m ParsedJournal
timedotfilep = do many timedotfileitemp
                  eof
                  get
    where
      timedotfileitemp :: JournalParser m ()
      timedotfileitemp = do
        ptrace "timedotfileitemp"
        choice [
          void emptyorcommentlinep
         ,timedotdayp >>= \ts -> modify' (addTransactions ts)
         ] <?> "timedot day entry, or default year or comment line or blank line"

addTransactions :: [Transaction] -> Journal -> Journal
addTransactions ts j = foldl' (flip ($)) j (map addTransaction ts)

-- | Parse timedot day entries to zero or more time transactions for that day.
-- @
-- 2/1
-- fos.haskell  .... ..
-- biz.research .
-- inc.client1  .... .... .... .... .... ....
-- @
timedotdayp :: JournalParser m [Transaction]
timedotdayp = do
  ptrace " timedotdayp"
  d <- datep <* lift eolof
  es <- catMaybes <$> many (const Nothing <$> try emptyorcommentlinep <|>
                            Just <$> (notFollowedBy datep >> timedotentryp))
  return $ map (\t -> t{tdate=d}) es -- <$> many timedotentryp

-- | Parse a single timedot entry to one (dateless) transaction.
-- @
-- fos.haskell  .... ..
-- @
timedotentryp :: JournalParser m Transaction
timedotentryp = do
  ptrace "  timedotentryp"
  pos <- genericSourcePos <$> getPosition
  lift (many spacenonewline)
  a <- modifiedaccountnamep
  lift (many spacenonewline)
  hours <-
    try (followingcommentp >> return 0)
    <|> (timedotdurationp <*
         (try followingcommentp <|> (newline >> return "")))
  let t = nulltransaction{
        tsourcepos = pos,
        tstatus    = Cleared,
        tpostings  = [
          nullposting{paccount=a
                     ,pamount=Mixed [setAmountPrecision 2 $ num hours]  -- don't assume hours; do set precision to 2
                     ,ptype=VirtualPosting
                     ,ptransaction=Just t
                     }
          ]
        }
  return t

timedotdurationp :: JournalParser m Quantity
timedotdurationp = try timedotnumberp <|> timedotdotsp

-- | Parse a duration written as a decimal number of hours (optionally followed by the letter h).
-- @
-- 1.5h
-- @
timedotnumberp :: JournalParser m Quantity
timedotnumberp = do
   (q, _, _, _) <- lift numberp
   lift (many spacenonewline)
   optional $ char 'h'
   lift (many spacenonewline)
   return q

-- | Parse a quantity written as a line of dots, each representing 0.25.
-- @
-- .... ..
-- @
timedotdotsp :: JournalParser m Quantity
timedotdotsp = do
  dots <- filter (not.isSpace) <$> many (oneOf (". " :: [Char]))
  return $ (/4) $ fromIntegral $ length dots

tests_Hledger_Read_TimedotReader = TestList [
 ]