# author: Jonathan Dieter <jdieter@gmail.com>
#
# mostly taken from deltarpm.py created by 
#         Lars Herrmann <herrmann@redhat.com>
# and modified for Presto by
#          Ahmed Kamal <email.ahmedkamal@googlemail.com>
#          
# license: GPL (see COPYING file in distribution)
#
# this module provides a python wrapper around deltarpm tools written by suse
# 
# TODO: catch exceptions wherever possible and raise useful ones ;)
#    see TODO lines in methods

APPLY='/usr/bin/applydeltarpm'

import popen2
import string
import os

class Process:
    """wrapper class to execute programs and return exitcode and output (stdout and stderr combined)"""
    def __init__(self, conduit):
        self.__stdout=None
        self.__returncode=None
        self.__command=None
        self.__args=None
        self.conduit = conduit

    def run(self, command, *args):
        self.__command=command
        self.__args=args
        cmdline=command+" "+string.join(args, " ")
        self.conduit.info(7, '%s.%s: executing %s' % (self.__class__, 'run', cmdline))
        pipe = popen2.Popen4(cmdline)
        self.__stdout=pipe.fromchild.read()
        retcode = pipe.wait()
        if os.WIFEXITED(retcode):
            self.__returncode = os.WEXITSTATUS(retcode)
        else:
            self.__returncode = retcode
        # fallback to old implementation - works better ?
        #stdoutp = os.popen(cmdline,'r',1)
        #self.__stdout = stdoutp.read()
        #retcode = stdoutp.close()
        #if retcode is None:
        #    self.__returncode = 0
        #else:
        #    self.__returncode = retcode

    def getOutput(self):
        return self.__stdout

    def returnCode(self):
        return self.__returncode

class DeltaRpmWrapper:
    """wrapper around deltarpm binaries - implement methods for applying and verifying delta rpms
    - raises exceptions if exitcode of binaries was != 0"""
    
    def __init__(self, conduit):
        self.conduit = conduit
        self.conduit.info(7, '%s.%s: created' % (self.__class__, '__init__'))

    def apply(self, newrpmfile, deltarpmfile):
        """wraps execution of applydeltarpm [-r oldrpm] deltarpm newrpm -
        constructs file names and paths based on given RpmDescription and instance settings for directories"""
        # TODO: test args for type == instance and __class__ == RpmDescription
        self.conduit.info(7, '%s.apply(%s,%s)' % (self.__class__, newrpmfile, deltarpmfile))
        p=Process(self.conduit)
        # targetrpm filename
        p.run(APPLY, deltarpmfile, newrpmfile)
        if p.returnCode():
            # in case of error, raise exception
            raise Exception("Could not apply deltarpm: %d" % (p.returnCode()))
        return newrpmfile

    def verifySequence(self, sequence):
        """wraps execution of applydeltarpm [-r oldrpm] -s seqfilecontent -
        constructs file names and paths based on given RpmDescription and instance settings for directories"""
        self.conduit.info(7, '%s.verify(%s)' % (self.__class__, sequence))
        p = Process(self.conduit)
        p.run(APPLY, '-s', sequence)
        if p.returnCode():
            # in case of error, raise exception
            raise Exception("Could not verify sequence of deltarpm: %d" % (p.returnCode()))