# author: Jonathan Dieter <jdieter@gmail.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 Library 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.
# Copyright 2005 Duke University

import os
import deltarpm

def find_available_drpms(conduit, newpkg):
    """Find any applicable drpms for newpkg
       newpkg is a TransactionMember"""
    
    rpmdb = conduit.getRpmDB()
    
    # Saves us some typing
    p_repo = newpkg.po.repo.p_repo
    chosen_drpm = None
    
    if p_repo.enabled:
        # Don't try to download deltarpm if full rpm already exists
        if not os.path.exists(newpkg.po.localpath):
            # First part of key when matching drpms
            key1 = "%s*%s*%i*%s*%s" % (newpkg.name, newpkg.arch, int(newpkg.epoch), newpkg.version, newpkg.release)
            
            # Find any installed packages that match the ones we want to download
            installed = rpmdb.searchNevra(newpkg.name, None, None, None, newpkg.arch)

            for oldpkg in installed:
                # Generate second part of key for matching drpms, then full key
                key2 = "%s*%s*%i*%s*%s" % (oldpkg.name, oldpkg.arch, int(oldpkg.epoch), oldpkg.version, oldpkg.release)
                key = "%s!!%s" % (key1, key2)
                
                # Check whether we have a matching drpm
                if p_repo.deltalist.has_key(key):
                    # Check whether or not we already have a matching drpm, then choose smallest of the two if we do
                    if chosen_drpm == None or p_repo.deltalist[key]['size'] < chosen_drpm['size']:
                    
                        # Get sequence code for drpm
                        sequence = p_repo.deltalist[key]['sequence']
                        if int(oldpkg.epoch) == 0:
                            seq = "%s-%s-%s-%s" % (oldpkg.name, oldpkg.version, oldpkg.release, sequence)
                        else:
                            seq = "%s-%i:%s-%s-%s" % (oldpkg.name, int(oldpkg.epoch), oldpkg.version, oldpkg.release, sequence)
                        drpm = deltarpm.DeltaRpmWrapper(conduit)
                        
                        # Attempt to apply sequence code for drpm. If this fails, drpm will not apply cleanly, so
                        # don't even try to download it.
                        try:
                            drpm.verifySequence(seq)
                            chosen_drpm = p_repo.deltalist[key]
                            chosen_drpm['baseurl'] = p_repo.baseurl[0]
                        except:
                            conduit.info(5, "Verification of %s failed" % seq)
    return chosen_drpm