#! /usr/bin/env python
# -*- coding: ISO-8859-15 -*-
#
# pkpgcounter : a generic Page Description Language parser
#
# (c) 2003, 2004, 2005, 2006, 2007 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 3 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, see <http://www.gnu.org/licenses/>.
#
# $Id$
#

"""This modules implements a page counter for ZjStream documents."""

import struct

import pdlparser

class Parser(pdlparser.PDLParser) :
    """A parser for ZjStream documents."""
    def isValid(self) :    
        """Returns True if data is ZjStream, else False."""
        if self.firstblock[:4] == "ZJZJ" :
            self.logdebug("DEBUG: Input file is in the Zenographics ZjStream (little endian) format.")
            return self.littleEndian()
        elif self.firstblock[:4] == "JZJZ" :    
            self.logdebug("DEBUG: Input file is in the Zenographics ZjStream (big endian) format.")
            return self.bigEndian()
        else :    
            return False
        
    def littleEndian(self) :
        """Toggles to little endianness."""
        self.unpackHeader = "<IIIHH"
        return True
        
    def bigEndian(self) :
        """Toggles to big endianness."""
        self.unpackHeader = ">IIIHH"
        return True
        
    def getJobSize(self) :
        """Computes the number of pages in a ZjStream document."""
        unpack = struct.unpack
        self.infile.seek(4, 0) # Skip ZJZJ/JZJZ header
        startpagecount = endpagecount = 0
        while True :
            header = self.infile.read(16)
            if not header :
                break
            try :    
                (totalChunkSize,
                 chunkType,
                 numberOfItems,
                 reserved,
                 signature) = unpack(self.unpackHeader, header)
            except struct.error :
                raise pdlparser.PDLParserError, "This file doesn't seem to be valid ZjStream datas."
            self.infile.seek(totalChunkSize - len(header), 1)
            if chunkType == 2 :    
                #self.logdebug("startPage")
                startpagecount += 1
            elif chunkType == 3 :
                #self.logdebug("endPage")
                endpagecount += 1
            #elif chunkType == 0 :
            #    self.logdebug("startDoc")
            #elif chunkType == 1 :    
            #    self.logdebug("endDoc")
                
            #self.logdebug("Chunk size : %s" % totalChunkSize)
            #self.logdebug("Chunk type : 0x%08x" % chunkType)
            #self.logdebug("# items : %s" % numberOfItems)
            #self.logdebug("reserved : 0x%04x" % reserved)
            #self.logdebug("signature : 0x%04x" % signature)
            #self.logdebug("\n")
            
        # Number of endpage commands should be sufficient,
        # but we never know : someone could try to cheat the printer
        # by starting a page but not ending it, and ejecting it manually
        # later on. Not sure if the printers would support this, but
        # taking the max value works around the problem in any case.
        self.logdebug("StartPage : %i    EndPage : %i" % (startpagecount, endpagecount))
        return max(startpagecount, endpagecount)