{-|

A 'TimeclockEntry' is a clock-in, clock-out, or other directive in a timeclock
file (see timeclock.el or the command-line version). These can be
converted to 'Transactions' and queried like a ledger.

-}

{-# LANGUAGE OverloadedStrings #-}

module Hledger.Data.Timeclock (
   timeclockEntriesToTransactions
  ,tests_Timeclock
)
where

import Data.Maybe
-- import Data.Text (Text)
import qualified Data.Text as T
import Data.Time.Calendar
import Data.Time.Clock
import Data.Time.Format
import Data.Time.LocalTime
import Text.Printf

import Hledger.Utils
import Hledger.Data.Types
import Hledger.Data.Dates
import Hledger.Data.Amount
import Hledger.Data.Posting
import Hledger.Data.Transaction

instance Show TimeclockEntry where
    show t = printf "%s %s %s  %s" (show $ tlcode t) (show $ tldatetime t) (tlaccount t) (tldescription t)

instance Show TimeclockCode where
    show SetBalance = "b"
    show SetRequiredHours = "h"
    show In = "i"
    show Out = "o"
    show FinalOut = "O"

instance Read TimeclockCode where
    readsPrec _ ('b' : xs) = [(SetBalance, xs)]
    readsPrec _ ('h' : xs) = [(SetRequiredHours, xs)]
    readsPrec _ ('i' : xs) = [(In, xs)]
    readsPrec _ ('o' : xs) = [(Out, xs)]
    readsPrec _ ('O' : xs) = [(FinalOut, xs)]
    readsPrec _ _ = []

-- | Convert time log entries to journal transactions. When there is no
-- clockout, add one with the provided current time. Sessions crossing
-- midnight are split into days to give accurate per-day totals.
timeclockEntriesToTransactions :: LocalTime -> [TimeclockEntry] -> [Transaction]
timeclockEntriesToTransactions _ [] = []
timeclockEntriesToTransactions now [i]
    | tlcode i /= In = errorExpectedCodeButGot In i
    | odate > idate = entryFromTimeclockInOut i o' : timeclockEntriesToTransactions now [i',o]
    | otherwise = [entryFromTimeclockInOut i o]
    where
      o = TimeclockEntry (tlsourcepos i) Out end "" ""
      end = if itime > now then itime else now
      (itime,otime) = (tldatetime i,tldatetime o)
      (idate,odate) = (localDay itime,localDay otime)
      o' = o{tldatetime=itime{localDay=idate, localTimeOfDay=TimeOfDay 23 59 59}}
      i' = i{tldatetime=itime{localDay=addDays 1 idate, localTimeOfDay=midnight}}
timeclockEntriesToTransactions now (i:o:rest)
    | tlcode i /= In = errorExpectedCodeButGot In i
    | tlcode o /= Out =errorExpectedCodeButGot Out o
    | odate > idate = entryFromTimeclockInOut i o' : timeclockEntriesToTransactions now (i':o:rest)
    | otherwise = entryFromTimeclockInOut i o : timeclockEntriesToTransactions now rest
    where
      (itime,otime) = (tldatetime i,tldatetime o)
      (idate,odate) = (localDay itime,localDay otime)
      o' = o{tldatetime=itime{localDay=idate, localTimeOfDay=TimeOfDay 23 59 59}}
      i' = i{tldatetime=itime{localDay=addDays 1 idate, localTimeOfDay=midnight}}
{- HLINT ignore timeclockEntriesToTransactions -}

errorExpectedCodeButGot expected actual = errorWithSourceLine line $ "expected timeclock code " ++ (show expected) ++ " but got " ++ show (tlcode actual)
    where
        line = case tlsourcepos actual of
                  GenericSourcePos _ l _ -> l
                  JournalSourcePos _ (l, _) -> l

errorWithSourceLine line msg = error $ "line " ++ show line ++ ": " ++ msg

-- | Convert a timeclock clockin and clockout entry to an equivalent journal
-- transaction, representing the time expenditure. Note this entry is  not balanced,
-- since we omit the \"assets:time\" transaction for simpler output.
entryFromTimeclockInOut :: TimeclockEntry -> TimeclockEntry -> Transaction
entryFromTimeclockInOut i o
    | otime >= itime = t
    | otherwise = error' . T.unpack $
        "clock-out time less than clock-in time in:\n" <> showTransaction t  -- PARTIAL:
    where
      t = Transaction {
            tindex       = 0,
            tsourcepos   = tlsourcepos i,
            tdate        = idate,
            tdate2       = Nothing,
            tstatus      = Cleared,
            tcode        = "",
            tdescription = desc,
            tcomment     = "",
            ttags        = [],
            tpostings    = ps,
            tprecedingcomment=""
          }
      itime    = tldatetime i
      otime    = tldatetime o
      itod     = localTimeOfDay itime
      otod     = localTimeOfDay otime
      idate    = localDay itime
      desc     | T.null (tldescription i) = T.pack $ showtime itod ++ "-" ++ showtime otod
               | otherwise                = tldescription i
      showtime = take 5 . show
      hours    = elapsedSeconds (toutc otime) (toutc itime) / 3600 where toutc = localTimeToUTC utc
      acctname = tlaccount i
      amount   = Mixed [hrs hours]
      ps       = [posting{paccount=acctname, pamount=amount, ptype=VirtualPosting, ptransaction=Just t}]


-- tests

tests_Timeclock = tests "Timeclock" [
  testCaseSteps "timeclockEntriesToTransactions tests" $ \step -> do
      step "gathering data"
      today <- getCurrentDay
      now' <- getCurrentTime
      tz <- getCurrentTimeZone
      let now = utcToLocalTime tz now'
          nowstr = showtime now
          yesterday = prevday today
          clockin = TimeclockEntry nullsourcepos In
          mktime d = LocalTime d . fromMaybe midnight .
                     parseTimeM True defaultTimeLocale "%H:%M:%S"
          showtime = formatTime defaultTimeLocale "%H:%M"
          txndescs = map (T.unpack . tdescription) . timeclockEntriesToTransactions now
          future = utcToLocalTime tz $ addUTCTime 100 now'
          futurestr = showtime future
      step "started yesterday, split session at midnight"
      txndescs [clockin (mktime yesterday "23:00:00") "" ""] @?= ["23:00-23:59","00:00-"++nowstr]
      step "split multi-day sessions at each midnight"
      txndescs [clockin (mktime (addDays (-2) today) "23:00:00") "" ""] @?= ["23:00-23:59","00:00-23:59","00:00-"++nowstr]
      step "auto-clock-out if needed"
      txndescs [clockin (mktime today "00:00:00") "" ""] @?= ["00:00-"++nowstr]
      step "use the clockin time for auto-clockout if it's in the future"
      txndescs [clockin future "" ""] @?= [printf "%s-%s" futurestr futurestr]
 ]