from landscape.lib.hashlib import sha1

import apt_pkg


PACKAGE = 1 << 0
PROVIDES = 1 << 1
REQUIRES = 1 << 2
UPGRADES = 1 << 3
CONFLICTS = 1 << 4

DEB_PACKAGE = 1 << 16 | PACKAGE
DEB_PROVIDES = 2 << 16 | PROVIDES
DEB_NAME_PROVIDES = 3 << 16 | PROVIDES
DEB_REQUIRES = 4 << 16 | REQUIRES
DEB_OR_REQUIRES = 5 << 16 | REQUIRES
DEB_UPGRADES = 6 << 16 | UPGRADES
DEB_CONFLICTS = 7 << 16 | CONFLICTS


class PackageTypeError(Exception):
"""Raised when an unsupported package type is passed to build_skeleton."""


class PackageSkeleton(object):

section = None
summary = None
description = None
size = None
installed_size = None
_hash = None

def __init__(self, type, name, version):
self.type = type
self.name = name
self.version = version
self.relations = []

def add_relation(self, type, info):
self.relations.append((type, info))

def get_hash(self):
"""Calculate the package hash.

If C{set_hash} has been used, that hash will be returned and the
hash won't be the calculated value.
"""
if self._hash is not None:
return self._hash
digest = sha1("[%d %s %s]" % (self.type, self.name, self.version))
self.relations.sort()
for pair in self.relations:
digest.update("[%d %s]" % pair)
return digest.digest()

def set_hash(self, package_hash):
"""Set the hash to an explicit value.

This should be used when the hash is previously known and can't
be calculated from the relations anymore.

The only use case for this is package resurrection. We're
planning on getting rid of package resurrection, and this code
can be removed when that is done.
"""
self._hash = package_hash



def relation_to_string(relation_tuple):
"""Convert an apt relation to a string representation.

@param relation_tuple: A tuple, (name, version, relation). version
and relation can be the empty string, if the relation is on a
name only.

Returns something like "name > 1.0"
"""
name, version, relation_type = relation_tuple
relation_string = name
if relation_type:
relation_string += " %s %s" % (relation_type, version)
return relation_string


def parse_record_field(record, record_field, relation_type,
or_relation_type=None):
"""Parse an apt C{Record} field and return skeleton relations

@param record: An C{apt.package.Record} instance with package information.
@param record_field: The name of the record field to parse.
@param relation_type: The deb relation that can be passed to
C{skeleton.add_relation()}
@param or_relation_type: The deb relation that should be used if
there is more than one value in a relation.
"""
relations = set()
values = apt_pkg.parse_depends(record.get(record_field, ""))
for value in values:
value_strings = [relation_to_string(relation) for relation in value]
value_relation_type = relation_type
if len(value_strings) > 1:
value_relation_type = or_relation_type
relation_string = " | ".join(value_strings)
relations.add((value_relation_type, relation_string))
return relations


def build_skeleton_apt(version, with_info=False, with_unicode=False):
"""Build a package skeleton from an apt package.

@param version: An instance of C{apt.package.Version}
@param with_info: Whether to extract extra information about the
package, like description, summary, size.
@param with_unicode: Whether the C{name} and C{version} of the
skeleton should be unicode strings.
"""
name, version_string = version.package.name, version.version
if with_unicode:
name, version_string = unicode(name), unicode(version_string)
skeleton = PackageSkeleton(DEB_PACKAGE, name, version_string)
relations = set()
relations.update(parse_record_field(
version.record, "Provides", DEB_PROVIDES))
relations.add((
DEB_NAME_PROVIDES,
"%s = %s" % (version.package.name, version.version)))
relations.update(parse_record_field(
version.record, "Pre-Depends", DEB_REQUIRES, DEB_OR_REQUIRES))
relations.update(parse_record_field(
version.record, "Depends", DEB_REQUIRES, DEB_OR_REQUIRES))

relations.add((
DEB_UPGRADES, "%s < %s" % (version.package.name, version.version)))

relations.update(parse_record_field(
version.record, "Conflicts", DEB_CONFLICTS))
relations.update(parse_record_field(
version.record, "Breaks", DEB_CONFLICTS))
skeleton.relations = sorted(relations)

if with_info:
skeleton.section = version.section
skeleton.summary = version.summary
skeleton.description = version.description
skeleton.size = version.size
if version.installed_size > 0:
skeleton.installed_size = version.installed_size
if with_unicode:
skeleton.section = skeleton.section.decode("utf-8")
skeleton.summary = skeleton.summary.decode("utf-8")
skeleton.description = skeleton.description.decode("utf-8")
return skeleton