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

# Tea4CUPS : Tee for CUPS
#
# (c) 2005 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.
#
# $Id$
#
#

import sys
import os
import errno
import md5
import cStringIO
import shlex
import tempfile
import ConfigParser

class TeeError(Exception):
    """Base exception for Tea4CUPS related stuff."""
    def __init__(self, message = ""):
        self.message = message
        Exception.__init__(self, message)
    def __repr__(self):
        return self.message
    __str__ = __repr__
    
class ConfigError(TeeError) :    
    """Configuration related exceptions."""
    pass 
    
class FakeConfig :    
    """Fakes a configuration file parser."""
    def get(self, section, option, raw=0) :
        """Fakes the retrieval of a global option."""
        raise ConfigError, "Invalid configuration file : no option %s in section [%s]" % (option, section)
        
class CupsBackend :
    """Base class for tools with no database access."""
    def __init__(self) :
        """Initializes the CUPS backend wrapper."""
        self.MyName = "Tea4CUPS"
        self.myname = "tea4cups"
        self.pid = os.getpid()
        confdir = os.environ.get("CUPS_SERVERROOT", ".") 
        self.conffile = os.path.join(confdir, "%s.conf" % self.myname)
        if os.path.isfile(self.conffile) :
            self.config = ConfigParser.ConfigParser()
            self.config.read([self.conffile])
            self.debug = self.isTrue(self.getGlobalOption("debug", ignore=1))
        else :    
            self.config = FakeConfig()
            self.debug = 1      # no config, so force debug mode !
        
    def logDebug(self, message) :    
        """Logs something to debug output if debug is enabled."""
        if self.debug :
            sys.stderr.write("DEBUG: %s (PID %i) : %s\n" % (self.MyName, self.pid, message))
            sys.stderr.flush()
            
    def logInfo(self, message, level="info") :        
        """Logs a message to CUPS' error_log file."""
        sys.stderr.write("%s: %s (PID %i) : %s\n" % (level.upper(), self.MyName, self.pid, message))
        sys.stderr.flush()
        
    def isTrue(self, option) :        
        """Returns 1 if option is set to true, else 0."""
        if (option is not None) and (option.upper().strip() in ['Y', 'YES', '1', 'ON', 'T', 'TRUE']) :
            return 1
        else :    
            return 0
                        
    def getGlobalOption(self, option, ignore=0) :    
        """Returns an option from the global section, or raises a ConfigError if ignore is not set, else returns None."""
        try :
            return self.config.get("global", option, raw=1)
        except (ConfigParser.NoSectionError, ConfigParser.NoOptionError) :    
            if not ignore :
                raise ConfigError, "Option %s not found in section global of %s" % (option, self.conffile)
                
    def getPrintQueueOption(self, printqueuename, option, ignore=0) :    
        """Returns an option from the printer section, or the global section, or raises a ConfigError."""
        globaloption = self.getGlobalOption(option, ignore=1)
        try :
            return self.config.get(printqueuename, option, raw=1)
        except (ConfigParser.NoSectionError, ConfigParser.NoOptionError) :    
            if globaloption is not None :
                return globaloption
            elif not ignore :
                raise ConfigError, "Option %s not found in section [%s] of %s" % (option, printqueuename, self.conffile)
                
    def enumTeeBranches(self, printqueuename) :
        """Returns the list of branches for a particular section's Tee."""
        try :
            globalbranches = [ (k, v) for (k, v) in self.config.items("global") if k.startswith("tee_") ]
        except ConfigParser.NoSectionError, msg :    
            self.printInfo("Invalid configuration file : %s" % msg, "error")
            globalbranches = []
        try :
            sectionbranches = [ (k, v) for (k, v) in self.config.items(printqueuename) if k.startswith("tee_") ]
        except ConfigParser.NoSectionError, msg :    
            self.printInfo("Invalid configuration file : %s" % msg, "error")
            sectionbranches = []
        branches = {}
        for (k, v) in globalbranches :
            value = v.strip()
            if value :
                branches[k] = value
        for (k, v) in sectionbranches :    
            value = v.strip()
            if value :
                branches[k] = value # overwrite any global option or set a new value
            else :    
                del branches[k] # empty value disables a global option
        return branches
        
    def discoverOtherBackends(self) :    
        """Discovers the other CUPS backends.
        
           Executes each existing backend in turn in device enumeration mode.
           Returns the list of available backends.
        """
        # Unfortunately this method can't output any debug information
        # to stdout or stderr, else CUPS considers that the device is
        # not available.
        available = []
        (directory, myname) = os.path.split(sys.argv[0])
        tmpdir = tempfile.gettempdir()
        lockfilename = os.path.join(tmpdir, "%s..LCK" % myname)
        if os.path.exists(lockfilename) :
            lockfile = open(lockfilename, "r")
            pid = int(lockfile.read())
            lockfile.close()
            try :
                # see if the pid contained in the lock file is still running
                os.kill(pid, 0)
            except OSError, e :    
                if e.errno != errno.EPERM :
                    # process doesn't exist anymore
                    os.remove(lockfilename)
            
        if not os.path.exists(lockfilename) :
            lockfile = open(lockfilename, "w")
            lockfile.write("%i" % self.pid)
            lockfile.close()
            allbackends = [ os.path.join(directory, b) \
                                for b in os.listdir(directory) 
                                    if os.access(os.path.join(directory, b), os.X_OK) \
                                        and (b != myname)] 
            for backend in allbackends :                            
                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(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]
                            available.append('%s %s:%s "%s+%s" "%s managed %s"' \
                                                 % (devicetype, self.myname, device, self.MyName, name, self.MyName, fullname))
            os.remove(lockfilename)
        return available
                        
    def initBackend(self) :    
        """Initializes the backend's attributes."""
        # check that the DEVICE_URI environment variable's value is 
        # prefixed with self.myname otherwise don't touch it.
        # If this is the case, we have to remove the prefix from 
        # the environment before launching the real backend 
        muststartwith = "%s:" % self.myname
        device_uri = os.environ.get("DEVICE_URI", "")
        if device_uri.startswith(muststartwith) :
            fulldevice_uri = device_uri[:]
            device_uri = fulldevice_uri[len(muststartwith):]
            if device_uri.startswith("//") :  
                device_uri = device_uri[2:]
        try :
            (backend, destination) = device_uri.split(":", 1) 
        except ValueError :    
            raise TeeError, "Invalid DEVICE_URI : %s\n" % device_uri
        
        self.JobId = sys.argv[1].strip()
        self.UserName = sys.argv[2].strip()
        self.Title = sys.argv[3].strip()
        self.Copies = int(sys.argv[4].strip())
        self.Options = sys.argv[5].strip()
        if len(sys.argv) == 7 :
            self.InputFile = sys.argv[6] # read job's datas from file
        else :    
            self.InputFile = None        # read job's datas from stdin
            
        self.RealBackend = backend
        self.DeviceURI = device_uri
        self.PrinterName = os.environ.get("PRINTER", "")
        self.Directory = self.getPrintQueueOption(self.PrinterName, "directory")
        self.DataFile = os.path.join(self.Directory, "%s-%s-%s" % (self.myname, self.PrinterName, self.JobId))
            
    def exportAttributes(self) :    
        """Exports our backend's attributes to the environment."""
        os.environ["DEVICE_URI"] = self.DeviceURI       # WARNING !
        os.environ["TEAPRINTERNAME"] = self.PrinterName
        os.environ["TEADIRECTORY"] = self.Directory
        os.environ["TEADATAFILE"] = self.DataFile
        os.environ["TEAJOBSIZE"] = self.JobSize
        os.environ["TEAMD5SUM"] = self.JobMD5Sum
        os.environ["TEAJOBID"] = self.JobId
        os.environ["TEAUSERNAME"] = self.UserName
        os.environ["TEATITLE"] = self.Title
        os.environ["TEACOPIES"] = str(self.Copies)
        os.environ["TEAOPTIONS"] = self.Options
        os.environ["TEAINPUTFILE"] = self.InputFile or ""
        
    def saveDatasAndCheckSum(self) :
        """Saves the input datas into a static file."""
        self.logDebug("Duplicating data stream to %s" % self.DataFile)
        mustclose = 0
        if self.InputFile is not None :
            infile = open(self.InputFile, "rb")
            mustclose = 1
        else :    
            infile = sys.stdin
        CHUNK = 64*1024         # read 64 Kb at a time
        dummy = 0
        sizeread = 0
        checksum = md5.new()
        outfile = open(self.DataFile, "wb")    
        while 1 :
            data = infile.read(CHUNK) 
            if not data :
                break
            sizeread += len(data)    
            outfile.write(data)
            checksum.update(data)    
            if not (dummy % 32) : # Only display every 2 Mb
                self.logDebug("%s bytes saved..." % sizeread)
            dummy += 1    
        outfile.close()
        if mustclose :    
            self.infile.close()
        self.JobSize = sizeread    
        self.JobMD5Sum = checksum.hexdigest()
        self.logDebug("Job %s is %s bytes long." % (self.JobId, self.JobSize))
        self.logDebug("Job %s MD5 sum is %s" % (self.JobId, self.JobMD5Sum))

    def cleanUp(self) :
        """Cleans up the place."""
        if not self.isTrue(self.getPrintQueueOption(self.PrinterName, "keepfiles", ignore=1)) :
            os.remove(self.DataFile)
        
if __name__ == "__main__" :    
    # This is a CUPS backend, we should act and die like a CUPS backend
    wrapper = CupsBackend()
    if len(sys.argv) == 1 :
        print "\n".join(wrapper.discoverOtherBackends())
        sys.exit(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])
        sys.exit(1)
    else :    
        wrapper.initBackend()
        wrapper.saveDatasAndCheckSum()
        wrapper.exportAttributes()
        wrapper.cleanUp()
        sys.stderr.write("ERROR: Not Yet !\n")
        sys.exit(1)