import warnings
warnings.filterwarnings("ignore", "apt API not stable yet", FutureWarning)
import apt
import os

class MyCache(apt.Cache):
    def __init__(self, progress=None):
        apt.Cache.__init__(self, progress)
        # cache the arch we use
        pipe = os.popen("dpkg --print-architecture")
        self._arch = pipe.read().strip()
        del pipe
    
    def pkgDependsOn(self, pkgname, depends_name):
        """ check if a given pkg depends on a given dependencie """
        if not self.has_key(pkgname):
            return False
        pkg = self[pkgname]
        candver = self._depcache.GetCandidateVer(pkg._pkg)
	if candver == None:
		return False
	dependslist = candver.DependsList
	for dep in dependslist.keys():
            if dep == "Depends" or dep == "PreDepends":
                # get the list of each dependency object
                for depVerList in dependslist[dep]:
                    for z in depVerList:
                        # get all TargetVersions of
                        # the dependency object
                        for tpkg in z.AllTargets():
                            if depends_name == tpkg.ParentPkg.Name:
                                return True
        return False
    def clean(self):
        self._depcache.Init()
    def getArch(self):
        """ Return the cpu architecture of the system"""
        return self._arch
    def getDependantAutoDeps(self, to_rm):
        """ return the installed automatic dependencies for the selected set
            of packages that are going to be removed """
        auto_deps = set()
        for pkg in to_rm:
            self[pkg].markDelete()
        for pkg in self:
            if not pkg.markedDelete and self._depcache.IsGarbage(pkg._pkg):
                #print "%s is garbage" % pkg.name
                for rm_package in to_rm:
                    # check if pkg.name is a dependency of rm_package
                    if self.pkgDependsOn(rm_package, pkg.name):
                        print "%s is garbage and a dep of %s" % (pkg.name, rm_package)
                        auto_deps.add(pkg.name)
        #print auto_deps
        return auto_deps