#!/usr/bin/python
# Recurring Transactions for Ledger (dklrt).
# (c) Kevin Keegan 2011-07-20.
# (c) David Keegan 2011-08-06.

import sys, os, re
import Time, Misc

class Transaction:
   _ReTxStart = re.compile('^(%s)(\s*)\((%s)\)' %\
    (Time.ReDate, Time.RePeriod))

   _ReComment = re.compile('^\s*;')
   _ReWhitespace = re.compile('^\s*$')

   def __init__(self, Parent, Line=None):
      self._Parent = Parent
      self._Date = None     # Date String.
      self._Dis = None      # Date in Seconds (since epoch).
      self._Ds = None       # Actual Date Separator.
      self._Period = None   # Period String.
      self._Al = []         # Additional Lines (after date).
      if not Line is None: self._Set(Line)

   def __repr__(self):
      return Misc.Repr('Date=%r,Dis=%r,Ds=%r,Period=%r,Al=%r' %\
       (self._Date, self._Dis, self._Ds, self._Period, self._Al), self)

   def __str__(self):
      """As a string, including the period."""
      return self._DateLine() + self._RemainderLines()

   def TransactionText(self):
      """As a string, excluding the period."""
      return '\n' + self._DateLine(True) + self._RemainderLines(True)

   def _DateLine(self, ExcludePeriod=False):
      """The Date line."""
      Pt = '' if ExcludePeriod else '%s(%s)' % (self._Ds, self._Period)
      return '%s%s%s' % (self._Date, Pt, self._Al[0])

   def _RemainderLines(self, Exclude=False):
      Rv = ''
      if Exclude:
         for Rl in self._Al[1:]:
            if not re.match(self._ReComment, Rl) and\
             not re.match(self._ReWhitespace, Rl):
               Rv = Rv + Rl
      else:
         Rv = ''.join(self._Al[1:]) 
      return Rv

   def __nonzero__(self):
      return self._Date is not None

   def _Log(self, Msg): Misc.Log(Msg, self)
   def _Throw(self, Msg): Misc.Throw(Msg, self)

   def _Set(self, Line):
      self.__init__(self._Parent)
      Match = re.match(self._ReTxStart, Line)
      if Match:
         self._Date = Match.group(1)
         self._Dis = Time.DateTimeParse(self._Date)
         self._Ds = Match.group(2)
         self._Period = Match.group(3)
         Dlen = len(Match.group(0))
         self.Add(Line[Dlen:])

   def Add(self, Line):
      self._Al.append(Line)

   def Generate(self):
      """Generates transactions up to and including the target date.
         Returns a list of strings ready for sorting and output to a
         ledger file.
      """
      Rv = []
      Tdis = self._Parent._Tdis
      Done = False
      while not Done:
         if self._Dis > Tdis: Done = True
         else:
            # Append transaction text.
            Rv.append(self.TransactionText())

            # Evaluate next posting date.
            NewDis = Time.DateAddPeriod(self._Dis, self._Period)
            if NewDis <= self._Dis:
               _Throw("Period is negative or zero!")
            self._Dis = NewDis
            self._Date = Time.DateToText(self._Dis)
      return Rv
       
class Transactions:
   def __init__\
   (self,
    LedgerFileName=None,
    TargetDateInSeconds=None,
    ConfigFileName=None):
      self._Lfn = LedgerFileName
      self._Cfn = ConfigFileName
      self._Tdis = TargetDateInSeconds
      if self._Tdis is None:
         self._Tdis = Time.DateToday()
      self._Nrt = 0            # No of Recurring Transactions.
      self._Preamble = ''
      self._Rtl = []           # Recurring Transaction List.
      self._ReadConfig()

   def __repr__(self):
      return Misc.Repr('Lfn=%r,Cfn=%r,Tdis=%r,Nrt=%r,Preamble=%r,Rtl=%r' %\
       (self._Lfn, self._Cfn, self._Tdis, self._Nrt, self._Preamble,
        self._Rtl), self)

   def __str__(self):
      Rv = self._Preamble
      for Rt in self._Rtl:
         Rv = Rv + str(Rt)
      return Rv

   def _Log(self, Msg): Misc.Log(Msg, self)
   def _Throw(self, Msg): Misc.Throw(Msg, self)

   def _ReadConfig(self):
      Rt = None
      Af = open(self._Cfn)
      for Line in Af:
         RtNew = Transaction(self, Line)
         if RtNew:
            # Line is start of new transaction.
            self._Nrt = self._Nrt + 1
            if Rt is not None: self._Rtl.append(Rt)
            Rt = RtNew
         else:
            # Line does not start a transaction.
            if self._Nrt <= 0:
               # Append to preamble.
               self._Preamble = self._Preamble + Line
            else:
               # Line continues a transaction.
               Rt.Add(Line)
      if Rt is not None: self._Rtl.append(Rt)
      Af.close()

   def _WriteConfig(self):
      """Saves the current state to the file."""
      Af = open(self._Cfn, 'w')

   def Generate(self):
      """Generates transactions up to and including the target date.
         Returns a list of strings ready for sorting and output to a
         ledger file.
      """
      Rv = []
      for Rt in self._Rtl:
         Rv.extend(Rt.Generate())
      return sorted(Rv)

   def Post(self):
      """Generates recurring transactions and posts to ledger file."""
      Posts = self.Generate()

      if len(Posts):
         # Best attempt to ensure either both writes succeed or none.
         Cf = open(self._Cfn, 'w')
         Lf = open(self._Lfn, 'a')
         Cf.write(self.__str__())
         Lf.writelines(Posts)
         Lf.close()
         Cf.close()

def main(Argv=None):
   if Argv is None: Argv = sys.argv
   Lfn = None if len(Argv) < 1 else Argv[0]
   Tdis = None if len(Argv) < 2 else Time.DateTimeParse(Argv[1])
   Cfn = None if len(Argv) < 3 else Argv[2]
   Rts = Transactions(Lfn, Tdis, Cfn)
   Rts.Post()
   return 0

if __name__ == "__main__":
   sys.exit(main(sys.argv[1:]))