#! /usr/bin/env python
# -*- coding: ISO-8859-15 -*-

# CUPSPyKota accounting backend
#
# PyKota - Print Quotas for CUPS and LPRng
#
# (c) 2003 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  2003/11/14 18:31:27  jalet
# Not perfect, but seems to work with the poll() loop.
#
# Revision 1.4  2003/11/14 17:04:15  jalet
# More (untested) work on the CUPS backend.
#
# Revision 1.3  2003/11/12 23:27:44  jalet
# More work on new backend. This commit may be unstable.
#
# Revision 1.2  2003/11/12 09:33:34  jalet
# New CUPS backend supports device enumeration
#
# Revision 1.1  2003/11/08 16:05:31  jalet
# CUPS backend added for people to experiment.
#
#
#

import sys
import os
import popen2
import time
import cStringIO
import shlex
import select
import signal

from pykota.tool import PyKotaTool, PyKotaToolError
from pykota.config import PyKotaConfigError
from pykota.storage import PyKotaStorageError
from pykota.accounter import openAccounter, PyKotaAccounterError
from pykota.requester import openRequester, PyKotaRequesterError

class PyKotaPopen3(popen2.Popen3) :
    """Our own class to execute real backends.
    
       Their first argument is different from their path so using
       native popen2.Popen3 would not be feasible.
    """
    def __init__(self, cmd, capturestderr=False, bufsize=-1, arg0=None) :
        self.arg0 = arg0
        popen2.Popen3.__init__(self, cmd, capturestderr, bufsize)
        
    def _run_child(self, cmd):
        for i in range(3, 256): # TODO : MAXFD in original popen2 module
            try:
                os.close(i)
            except OSError:
                pass
        try:
            os.execvpe(cmd[0], [self.arg0 or cmd[0]] + cmd[1:], os.environ)
        finally:
            os._exit(1)
    
class PyKotaBackend(PyKotaTool) :    
    """Class for the PyKota backend."""
    def __init__(self) :
        PyKotaTool.__init__(self)
        (self.printingsystem, \
         self.printerhostname, \
         self.printername, \
         self.username, \
         self.jobid, \
         self.inputfile, \
         self.copies, \
         self.title, \
         self.options, \
         self.originalbackend) = self.extractCUPSInfo()
        self.accounter = openAccounter(self)
    
    def extractCUPSInfo(self) :    
        """Returns a tuple (printingsystem, printerhostname, printername, username, jobid, filename, title, options, backend).
        
           Returns (None, None, None, None, None, None, None, None, None, None) if no printing system is recognized.
        """
        # Try to detect CUPS
        if os.environ.has_key("CUPS_SERVERROOT") and os.path.isdir(os.environ.get("CUPS_SERVERROOT", "")) :
            if len(sys.argv) == 7 :
                inputfile = sys.argv[6]
            else :    
                inputfile = None
                
            # the DEVICE_URI environment variable's value is 
            # prefixed with "cupspykota:" otherwise we wouldn't
            # be called. We have to remove this from the environment 
            # before launching the real backend.
            fulldevice_uri = os.environ.get("DEVICE_URI", "")
            device_uri = fulldevice_uri[len("cupspykota:"):]
            os.environ["DEVICE_URI"] = device_uri
            # TODO : check this for more complex urls than ipp://myprinter.dot.com:631/printers/lp
            try :
                (backend, destination) = device_uri.split(":", 1) 
            except ValueError :    
                raise PyKotaToolError, "Invalid DEVICE_URI : %s\n" % device_uri
            while destination.startswith("/") :
                destination = destination[1:]
            printerhostname = destination.split("/")[0].split(":")[0]
            return ("CUPS", \
                    printerhostname, \
                    os.environ.get("PRINTER"), \
                    sys.argv[2].strip(), \
                    sys.argv[1].strip(), \
                    inputfile, \
                    int(sys.argv[4].strip()), \
                    sys.argv[3], \
                    sys.argv[5], \
                    backend)
        else :    
            self.logger.log_message(_("Printing system unknown, args=%s") % " ".join(sys.argv), "warn")
            return (None, None, None, None, None, None, None, None, None, None)   # Unknown printing system          
        
def format_commandline(prt, usr, cmdline) :            
    """Passes printer and user names on the command line."""
    printer = prt.Name
    user = usr.Name
    # we don't want the external command's standard 
    # output to break the print job's data, but we
    # want to keep its standard error
    return "%s >/dev/null" % (cmdline % locals())

def sigterm_handler(signum, frame) :
    """Handler for SIGTERM."""
    sys.exit(1)
    
def main(thebackend) :    
    """Do it, and do it right !"""
    # first deal with signals
    # CUPS backends ignore SIGPIPE and exit(1) on SIGTERM
    # Fortunately SIGPIPE is already ignored by Python
    # It's there just in case this changes in the future
    signal.signal(signal.SIGPIPE, signal.SIG_IGN)
    signal.signal(signal.SIGTERM, sigterm_handler)
    
    #
    # Get the last page counter and last username from the Quota Storage backend
    printer = thebackend.storage.getPrinter(thebackend.printername)
    if not printer.Exists :
        # The printer is unknown from the Quota Storage perspective
        # we let the job pass through, but log a warning message
        thebackend.logger.log_message(_("Printer %s not registered in the PyKota system") % thebackend.printername, "warn")
        action = "ALLOW"
    else :    
        for dummy in range(2) :
            user = thebackend.storage.getUser(thebackend.username)
            if user.Exists :
                break
            else :    
                # The user is unknown from the Quota Storage perspective
                # Depending on the default policy for this printer, we
                # either let the job pass through or reject it, but we
                # log a message in any case.
                (policy, args) = thebackend.config.getPrinterPolicy(thebackend.printername)
                if policy == "ALLOW" :
                    action = "POLICY_ALLOW"
                elif policy == "EXTERNAL" :    
                    commandline = format_commandline(printer, user, args)
                    thebackend.logger.log_message(_("User %s not registered in the PyKota system, applying external policy (%s) for printer %s") % (thebackend.username, commandline, thebackend.printername), "info")
                    if os.system(commandline) :
                        # if an error occured, we die without error,
                        # so that the job doesn't stop the print queue.
                        thebackend.logger.log_message(_("External policy %s for printer %s produced an error. Job rejected. Please check PyKota's configuration files.") % (commandline, thebackend.printername), "error")
                        return 0
                    else :    
                        # here we try a second time, because the goal
                        # of the external action was to add the user
                        # in the database.
                        continue 
                else :    
                    action = "POLICY_DENY"
                thebackend.logger.log_message(_("User %s not registered in the PyKota system, applying default policy (%s) for printer %s") % (thebackend.username, action, thebackend.printername), "warn")
                if action == "POLICY_DENY" :
                    # if not allowed to print then die, else proceed.
                    # we die without error, so that the job doesn't 
                    # stop the print queue.
                    return 0
                # when we get there, the printer policy allows the job to pass 
                break    
                    
        if user.Exists :
            # Is the current user allowed to print at all ?
            action = thebackend.warnUserPQuota(thebackend.storage.getUserPQuota(user, printer))
        elif policy == "EXTERNAL" :                
            # if the extenal policy produced no error, but the 
            # user still doesn't exist, we die without error,
            # so that the job doesn't stop the print queue.
            thebackend.logger.log_message(_("External policy %s for printer %s couldn't add user %s. Job rejected.") % (commandline, thebackend.printername, thebackend.username), "error")
            return 0
        
    if action not in ["ALLOW", "WARN"] :    
        # if not allowed to print then die, else proceed.
        # we die without error, so that the job doesn't 
        # stop the print queue.
        retcode = 0
    else :
        # pass the job untouched to the underlying layer
        # and starts accounting at the same time
        thebackend.accounter.beginJob(printer, user)
        
        # executes original backend
        mustclose = 0    
        if thebackend.inputfile is not None :    
            if hasattr(thebackend.inputfile, "read") :
                infile = thebackend.inputfile
            else :    
                infile = open(thebackend.inputfile, "rb")
            mustclose = 1
        else :    
            infile = sys.stdin
        realbackend = os.path.join(os.path.split(sys.argv[0])[0], thebackend.originalbackend)
        subprocess = PyKotaPopen3([realbackend] + sys.argv[1:], capturestderr=1, arg0=os.environ["DEVICE_URI"])
        pollster = select.poll()
        pollster.register(infile.fileno(), select.POLLIN)
        pollster.register(subprocess.fromchild.fileno(), select.POLLIN)
        pollster.register(subprocess.childerr.fileno(), select.POLLIN)
        pollster.register(subprocess.tochild.fileno(), select.POLLOUT)
        inputdata = ""
        end = 0
        while not end :
            availablestreams = pollster.poll()
            for (stream, mask) in availablestreams :
                if mask & select.POLLHUP :
                    if stream == infile.fileno() :
                        end = 1
                if mask & select.POLLOUT :
                    if stream == subprocess.tochild.fileno() :
                        if inputdata :
                            os.write(stream, inputdata)    
                            inputdata = ""
                if mask & select.POLLIN :     
                    data = os.read(stream, 256 * 1024)
                    if stream == infile.fileno() :
                        inputdata += data
                    elif stream == subprocess.fromchild.fileno() :
                        sys.stdout.write(data)
                    elif stream == subprocess.childerr.fileno() :    
                        sys.stderr.write(data)
        if inputdata :                
            try :
                os.write(subprocess.tochild.fileno(), inputdata)
            except :    
                pass
        sys.stdout.flush()                
        sys.stderr.flush()
        subprocess.fromchild.close()
        subprocess.childerr.close()
        subprocess.tochild.close()
        if mustclose :
            infile.close()
        status = subprocess.wait()
        if os.WIFEXITED(status) :
            retcode = os.WEXITSTATUS(status)
        else :    
            thebackend.logger.log_message(_("CUPS backend %s died abnormally.") % realbackend, "error")
            retcode = -1
    
    # stops accounting. 
    thebackend.accounter.endJob(printer, user)
        
    # retrieve the job size    
    jobsize = thebackend.accounter.getJobSize()
    
    # update the quota for the current user on this printer 
    if printer.Exists :
        if jobsize :
            userquota = thebackend.storage.getUserPQuota(user, printer)
            if userquota.Exists :
                userquota.increasePagesUsage(jobsize)
        
        # adds the current job to history    
        printer.addJobToHistory(thebackend.jobid, user, thebackend.accounter.getLastPageCounter(), action, jobsize)
    
    return retcode

if __name__ == "__main__" :    
    # This is a CUPS backend, we should act and die like a CUPS backend
    if len(sys.argv) == 1 :
        # we will execute each existing backend in device enumeration mode
        # and generate their PyKota accounting counterpart
        (directory, myname) = os.path.split(sys.argv[0])
        for backend in [os.path.join(directory, b) for b in os.listdir(directory) if os.path.isfile(os.path.join(directory, b)) and (b != myname)] :
            answer = os.popen(backend, "r")
            try :
                devices = [line.strip() for line in answer.readlines()]
            except :    
                devices = []
            status = answer.close()
            if status is None :
                for d in devices :
                    # each line is of the form : 'xxxx xxxx "xxxx xxx" "xxxx xxx"'
                    # so we have to decompose it carefully
                    fdevice = cStringIO.StringIO("%s" % d)
                    tokenizer = shlex.shlex(fdevice)
                    tokenizer.wordchars = tokenizer.wordchars + r".:,?!~/\_$*-+={}[]()#"
                    arguments = []
                    while 1 :
                        token = tokenizer.get_token()
                        if token :
                            arguments.append(token)
                        else :
                            break
                    fdevice.close()
                    try :
                        (devicetype, device, name, fullname) = arguments
                    except ValueError :    
                        pass    # ignore this 'bizarre' device
                    else :    
                        if name.startswith('"') and name.endswith('"') :
                            name = name[1:-1]
                        if fullname.startswith('"') and fullname.endswith('"') :
                            fullname = fullname[1:-1]
                        print '%s cupspykota:%s "PyKota+%s" "PyKota managed %s"' % (devicetype, device, name, fullname)    
        retcode = 0
    elif len(sys.argv) not in (6, 7) :    
        sys.stderr.write("ERROR: %s job-id user title copies options [file]\n" % sys.argv[0])
        retcode = 1
    else :    
        try :
            # Initializes the backend
            kotabackend = PyKotaBackend()    
            retcode = main(kotabackend)
        except (PyKotaToolError, PyKotaConfigError, PyKotaStorageError, PyKotaAccounterError, AttributeError, KeyError, IndexError, ValueError, TypeError, IOError), msg :
            sys.stderr.write("ERROR : cupspykota backend failed (%s)\n" % msg)
            sys.stderr.flush()
            retcode = 1
        
        try :
            kotabackend.storage.close()
        except (TypeError, NameError, AttributeError) :    
            pass
        
    sys.exit(retcode)