{-|

A 'TimeLog' is a parsed timelog file (generated by timeclock.el),
containing zero or more 'TimeLogEntry's. It can be converted to a
'RawLedger' for querying.

-}

module Ledger.TimeLog
where

import Ledger.Utils
import Ledger.Types
import Ledger.Currency
import Ledger.Amount
import Ledger.RawTransaction
import Ledger.Entry
import Ledger.RawLedger

instance Show TimeLogEntry where 
    show t = printf "%s %s %s" (show $ tlcode t) (tldatetime t) (tlcomment t)

instance Show TimeLog where
    show tl = printf "TimeLog with %d entries" $ length $ timelog_entries tl

-- | Convert a time log to a ledger.
ledgerFromTimeLog :: TimeLog -> RawLedger
ledgerFromTimeLog tl = RawLedger [] [] (entriesFromTimeLogEntries $ timelog_entries tl) ""

-- | Convert time log entries to ledger entries.
entriesFromTimeLogEntries :: [TimeLogEntry] -> [Entry]
entriesFromTimeLogEntries [] = []
entriesFromTimeLogEntries [i] = entriesFromTimeLogEntries [i, clockoutFor i]
entriesFromTimeLogEntries (i:o:rest) = [entryFromTimeLogInOut i o] ++ entriesFromTimeLogEntries rest

-- | When there is a trailing clockin entry, provide the missing clockout.
-- "Now" would be preferable but requires IO, for now use the clockin time.
clockoutFor (TimeLogEntry _ t _) = TimeLogEntry 'o' t ""

-- | Convert a timelog clockin and clockout entry to an equivalent ledger
-- entry, representing the time expenditure.
entryFromTimeLogInOut :: TimeLogEntry -> TimeLogEntry -> Entry
entryFromTimeLogInOut i o =
    Entry {
      edate         = indate, -- ledger uses outdate
      estatus       = True,
      ecode         = "",
      edescription  = acctname,
      ecomment      = "",
      etransactions = txns,
      epreceding_comment_lines=""
    }
    where
      acctname = tlcomment i
      indate   = showDateFrom intime
      outdate  = showDateFrom outtime
      intime   = parsedatetime $ tldatetime i
      outtime  = parsedatetime $ tldatetime o
      hours    = fromRational (toRational (diffUTCTime outtime intime) / 3600) -- whatever..
      amount   = Amount (getcurrency "h") hours 1
      txns     = [RawTransaction acctname amount "", RawTransaction "assets:TIME" (-amount) ""]

showDateFrom :: UTCTime -> String
showDateFrom = formatTime defaultTimeLocale "%Y/%m/%d"