# PyKota
# -*- coding: ISO-8859-15 -*-
#
# PyKota - Print Quotas for CUPS and LPRng
#
# (c) 2003-2004 Jerome Alet <alet@librelogiciel.com>
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
#
# $Id$
#
# $Log$
# Revision 1.5  2004/06/10 22:42:06  jalet
# Better messages in logs
#
# Revision 1.4  2004/05/24 22:45:49  jalet
# New 'enforcement' directive added
# Polling loop improvements
#
# Revision 1.3  2004/05/24 14:36:40  jalet
# Revert to old polling loop. Will need optimisations
#
# Revision 1.2  2004/05/18 14:49:22  jalet
# Big code changes to completely remove the need for "requester" directives,
# jsut use "hardware(... your previous requester directive's content ...)"
#
# Revision 1.1  2004/05/13 13:59:30  jalet
# Code simplifications
#
#
#

import sys
import os
import popen2
from pykota.accounter import AccounterBase, PyKotaAccounterError

class Accounter(AccounterBase) :
    def __init__(self, kotabackend, arguments) :
        """Initializes querying accounter."""
        AccounterBase.__init__(self, kotabackend, arguments)
        
    def getPrinterInternalPageCounter(self) :    
        """Returns the printer's internal page counter."""
        self.filter.logdebug("Reading printer's internal page counter...")
        try :
            counter = self.askPrinterPageCounter(self.filter.printerhostname)
        except PyKotaAccounterError, msg :
            # can't get actual page counter, assume printer is off or warming up
            # log the message anyway.
            self.filter.logger.log_message("%s" % msg, "warn")
            counter = None
        self.filter.logdebug("Printer's internal page counter value is : %s" % str(counter))
        return counter    
        
    def beginJob(self, userpquota) :    
        """Saves printer internal page counter at start of job."""
        # save page counter before job
        self.LastPageCounter = self.counterbefore = self.getPrinterInternalPageCounter()
        
    def endJob(self, userpquota) :    
        """Saves printer internal page counter at end of job."""
        # save page counter after job
        self.LastPageCounter = self.counterafter = self.getPrinterInternalPageCounter()
        
    def getJobSize(self) :    
        """Returns the actual job size."""
        try :
            jobsize = (self.counterafter - self.counterbefore)    
            if jobsize < 0 :
                # Try to take care of HP printers 
                # Their internal page counter is saved to NVRAM
                # only every 10 pages. If the printer was switched
                # off then back on during the job, and that the
                # counters difference is negative, we know 
                # the formula (we can't know if more than eleven
                # pages were printed though) :
                if jobsize > -10 :
                    jobsize += 10
                else :    
                    # here we may have got a printer being replaced
                    # DURING the job. This is HIGHLY improbable !
                    jobsize = 0
        except :    
            # takes care of the case where one counter (or both) was never set.
            jobsize = 0
        return jobsize
        
    def askPrinterPageCounter(self, printer) :
        """Returns the page counter from the printer via an external command.
        
           The external command must report the life time page number of the printer on stdout.
        """
        commandline = self.arguments.strip() % locals()
        if printer is None :
            raise PyKotaAccounterError, _("Unknown printer address in HARDWARE(%s) for printer %s") % (commandline, self.filter.printername)
        self.filter.logger.log_message(_("Launching HARDWARE(%s)...") % commandline, "info")
        error = 1
        pagecounter = None
        child = popen2.Popen4(commandline)    
        try :
            line = child.fromchild.readline()
            pagecounter = int(line.strip())
        except ValueError :    
            self.filter.logger.log_message(_("Incorrect answer : %s") % repr(line), "error")
        except IOError :    
            # we were interrupted by a signal, certainely a SIGTERM
            # caused by the user cancelling the current job
            try :
                os.kill(child.pid, signal.SIGTERM)
            except :    
                pass # already killed ?
            self.filter.logger.log_message(_("SIGTERM was sent to hardware accounter %s (pid: %s)") % (commandline, child.pid), "info")
        else :    
            error = 0
        child.fromchild.close()    
        child.tochild.close()
        try :
            status = child.wait()
        except OSError, msg :    
            self.filter.logdebug("Error while waiting for hardware accounter pid %s : %s" % (child.pid, msg))
            error = 1
        if (not error) and os.WIFEXITED(status) and (not os.WEXITSTATUS(status)) :
            return pagecounter
        else :    
            raise PyKotaAccounterError, _("Unable to query printer %s via HARDWARE(%s)") % (printer, commandline)