# MyCache.py
# -*- Mode: Python; indent-tabs-mode: nil; tab-width: 4; coding: utf-8 -*-
#
#  Copyright (c) 2004-2008 Canonical
#
#  Author: Michael Vogt <mvo@debian.org>
#
#  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 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

import warnings

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

from urllib.error import HTTPError
from urllib.request import urlopen
from urllib.parse import urlsplit
from http.client import BadStatusLine
import socket
import subprocess
import re
import DistUpgrade.DistUpgradeCache
from gettext import gettext as _

try:
    from launchpadlib.launchpad import Launchpad
except ImportError:
    Launchpad = None

SYNAPTIC_PINFILE = "/var/lib/synaptic/preferences"
CHANGELOGS_POOL = "https://changelogs.ubuntu.com/changelogs/pool/"
CHANGELOGS_URI = CHANGELOGS_POOL + "%s/%s/%s/%s_%s/%s"


class HttpsChangelogsUnsupportedError(Exception):
    """https changelogs with credentials are unsupported because of the
    lack of certitifcation validation in urllib2 which allows MITM
    attacks to steal the credentials
    """

    pass


class MyCache(DistUpgrade.DistUpgradeCache.MyCache):

    CHANGELOG_ORIGIN = "Ubuntu"

    def __init__(self, progress, rootdir=None):
        apt.Cache.__init__(self, progress, rootdir)
        # save for later
        self.rootdir = rootdir
        # raise if we have packages in reqreinst state
        # and let the caller deal with that (runs partial upgrade)
        assert len(self.req_reinstall_pkgs) == 0
        # check if the dpkg journal is ok (we need to do that here
        # too because libapt will only do it when it tries to lock
        # the packaging system)
        assert not self._dpkgJournalDirty()
        # init the regular cache
        self._initDepCache()
        self.all_changes = {}
        self.all_news = {}
        self.pro_versions = {}
        # on broken packages, try to fix via saveDistUpgrade()
        if self._depcache.broken_count > 0:
            self.saveDistUpgrade()
        assert (
            self._depcache.broken_count == 0 and self._depcache.del_count == 0
        )
        self.launchpad = None
        # generate versioned_kernel_pkgs_regexp for later use
        apt_versioned_kernel_pkgs = apt_pkg.config.value_list(
            "APT::VersionedKernelPackages"
        )
        if apt_versioned_kernel_pkgs:
            self.versioned_kernel_pkgs_regexp = re.compile(
                "("
                + "|".join(["^" + p for p in apt_versioned_kernel_pkgs])
                + ")"
            )
            running_kernel_version = subprocess.check_output(
                ["uname", "-r"], universal_newlines=True
            ).rstrip()
            self.running_kernel_pkgs_regexp = re.compile(
                "("
                + "|".join(
                    [
                        ("^" + p + ".*" + running_kernel_version)
                        if not p.startswith(".*")
                        else (running_kernel_version + p)
                        for p in apt_versioned_kernel_pkgs
                    ]
                )
                + ")"
            )
        else:
            self.versioned_kernel_pkgs_regexp = None
            self.running_kernel_pkgs_regexp = None

    def _dpkgJournalDirty(self):
        """
        test if the dpkg journal is dirty
        (similar to debSystem::CheckUpdates)
        """
        d = (
            os.path.dirname(apt_pkg.config.find_file("Dir::State::status"))
            + "/updates"
        )
        for f in os.listdir(d):
            if re.match("[0-9]+", f):
                return True
        return False

    def _initDepCache(self):
        # apt_pkg.config.set("Debug::pkgPolicy","1")
        # self.depcache = apt_pkg.GetDepCache(self.cache)
        # self._depcache = apt_pkg.GetDepCache(self._cache)
        self._depcache.read_pinfile()
        if os.path.exists(SYNAPTIC_PINFILE):
            self._depcache.read_pinfile(SYNAPTIC_PINFILE)
        self._depcache.init()

    def clear(self):
        self._initDepCache()

    @property
    def required_download(self):
        """get the size of the packages that are required to download"""
        pm = apt_pkg.PackageManager(self._depcache)
        fetcher = apt_pkg.Acquire()
        pm.get_archives(fetcher, self._list, self._records)
        return fetcher.fetch_needed

    @property
    def install_count(self):
        return self._depcache.inst_count

    def keep_count(self):
        return self._depcache.keep_count

    @property
    def del_count(self):
        return self._depcache.del_count

    def _check_dependencies(self, target, deps):
        """Return True if any of the dependencies in deps match target."""
        # TODO: handle virtual packages
        for dep_or in deps:
            if not dep_or:
                continue
            match = True
            for base_dep in dep_or:
                if (
                    base_dep.name != target.package.shortname
                    or not apt_pkg.check_dep(
                        target.version, base_dep.relation, base_dep.version
                    )
                ):
                    match = False
            if match:
                return True
        return False

    def find_removal_justification(self, pkg):
        target = pkg.installed
        if not target:
            return False
        for cpkg in self:
            candidate = cpkg.candidate
            if candidate is not None:
                if self._check_dependencies(
                    target, candidate.get_dependencies("Conflicts")
                ) and self._check_dependencies(
                    target, candidate.get_dependencies("Replaces")
                ):
                    logging.info(
                        "%s Conflicts/Replaces %s; allowing removal"
                        % (candidate.package.shortname, pkg.shortname)
                    )
                    return True
        return False

    def saveDistUpgrade(self):
        """this functions mimics a upgrade but will never remove anything"""
        # self._apply_dselect_upgrade()
        self._depcache.upgrade(True)
        wouldDelete = self._depcache.del_count
        if wouldDelete > 0:
            deleted_pkgs = [pkg for pkg in self if pkg.marked_delete]
            assert wouldDelete == len(deleted_pkgs)
            for pkg in deleted_pkgs:
                if self.find_removal_justification(pkg):
                    wouldDelete -= 1
        if wouldDelete > 0:
            self.clear()
            assert (
                self._depcache.broken_count == 0
                and self._depcache.del_count == 0
            )
        else:
            assert self._depcache.broken_count == 0
        # self._apply_dselect_upgrade()
        self._depcache.upgrade()
        return wouldDelete

    def _strip_epoch(self, verstr):
        "strip of the epoch"
        vers_no_epoch = verstr.split(":")
        if len(vers_no_epoch) > 1:
            verstr = "".join(vers_no_epoch[1:])
        return verstr

    def _get_changelog_or_news(
        self, name, fname, strict_versioning=False, changelogs_uri=None
    ):
        "helper that fetches the file in question"
        # don't touch the gui in this function, it needs to be thread-safe
        pkg = self[name]

        # get the src package name
        srcpkg = pkg.candidate.source_name

        # assume "main" section
        src_section = "main"
        # use the section of the candidate as a starting point
        section = pkg._pcache._depcache.get_candidate_ver(pkg._pkg).section

        # get the source version
        srcver_epoch = pkg.candidate.source_version
        srcver = self._strip_epoch(srcver_epoch)

        split_section = section.split("/")
        if len(split_section) > 1:
            src_section = split_section[0]

        # lib is handled special
        prefix = srcpkg[0]
        if srcpkg.startswith("lib"):
            prefix = "lib" + srcpkg[3]

        # the changelogs_uri argument overrides the default changelogs_uri,
        # this is useful for e.g. PPAs where we construct the changelogs
        # path differently
        if changelogs_uri:
            uri = changelogs_uri
        else:
            uri = CHANGELOGS_URI % (
                src_section,
                prefix,
                srcpkg,
                srcpkg,
                srcver,
                fname,
            )

        # https uris are not supported when they contain a username/password
        # because the urllib2 https implementation will not check certificates
        # and so its possible to do a man-in-the-middle attack to steal the
        # credentials
        res = urlsplit(uri)
        if res.scheme == "https" and res.username:
            raise HttpsChangelogsUnsupportedError(
                "https locations with username/password are not"
                "supported to fetch changelogs"
            )

        # print("Trying: %s " % uri)
        changelog = urlopen(uri)
        # print(changelog.read())
        # do only get the lines that are new
        alllines = ""
        regexp = "^%s \\((.*)\\)(.*)$" % (re.escape(srcpkg))

        while True:
            line = changelog.readline().decode("UTF-8", "replace")
            if line == "":
                break
            match = re.match(regexp, line)
            if match:
                # strip epoch from installed version
                # and from changelog too
                installed = getattr(pkg.installed, "version", None)
                if installed and ":" in installed:
                    installed = installed.split(":", 1)[1]
                changelogver = match.group(1)
                if changelogver and ":" in changelogver:
                    changelogver = changelogver.split(":", 1)[1]
                # we test for "==" here for changelogs
                # to ensure that the version
                # is actually really in the changelog - if not
                # just display it all, this catches cases like:
                # gcc-defaults with "binver=4.3.1" and srcver=1.76
                #
                # for NEWS.Debian we do require the changelogver > installed
                if strict_versioning:
                    if (
                        installed
                        and apt_pkg.version_compare(changelogver, installed)
                        < 0
                    ):
                        break
                else:
                    if (
                        installed
                        and apt_pkg.version_compare(changelogver, installed)
                        == 0
                    ):
                        break
            alllines = alllines + line
        return alllines

    def _extract_ppa_changelog_uri(self, name):
        """Return the changelog URI from the Launchpad API

        Return None in case of an error.
        """
        if not Launchpad:
            logging.warning(
                "Launchpadlib not available, cannot retrieve PPA changelog"
            )
            return None

        cdt = self[name].candidate
        for uri in cdt.uris:
            if urlsplit(uri).hostname != "ppa.launchpad.net":
                continue
            match = re.search("http.*/(.*)/(.*)/ubuntu/.*", uri)
            if match is not None:
                user, ppa = match.group(1), match.group(2)
                break
        else:
            logging.error("Unable to find a valid PPA candidate URL.")
            return

        # Login on launchpad if we are not already
        if self.launchpad is None:
            self.launchpad = Launchpad.login_anonymously(
                "update-manager", "production", version="devel"
            )

        archive = self.launchpad.archives.getByReference(
            reference="~%s/ubuntu/%s" % (user, ppa)
        )
        if archive is None:
            logging.error(
                "Unable to retrieve the archive from the Launchpad API."
            )
            return

        spphs = archive.getPublishedSources(
            source_name=cdt.source_name,
            exact_match=True,
            version=cdt.source_version,
        )
        if not spphs:
            logging.error(
                "No published sources were retrieved from the "
                "Launchpad API."
            )
            return

        return spphs[0].changelogUrl()

    def _guess_third_party_changelogs_uri_by_source(self, name):
        pkg = self[name]
        deb_uri = pkg.candidate.uri
        if deb_uri is None:
            return None
        srcrec = pkg.candidate.record.get("Source")
        if not srcrec:
            return None
        # srcpkg can be "apt" or "gcc-default (1.0)"
        srcpkg = srcrec.split("(")[0].strip()
        if "(" in srcrec:
            srcver = srcrec.split("(")[1].rstrip(")")
        else:
            srcver = pkg.candidate.source_version
        base_uri = deb_uri.rpartition("/")[0]
        return base_uri + "/%s_%s.changelog" % (srcpkg, srcver)

    def _guess_third_party_changelogs_uri_by_binary(self, name):
        """guess changelogs uri based on ArchiveURI by replacing .deb
        with .changelog
        """
        # there is always a pkg and a pkg.candidate, no need to add
        # check here
        pkg = self[name]
        deb_uri = pkg.candidate.uri
        if deb_uri:
            return "%s.changelog" % deb_uri.rsplit(".", 1)[0]
        return None

    def get_news_and_changelog(self, name, lock):
        self.get_news(name)
        self.get_changelog(name)
        try:
            lock.release()
        except Exception:
            pass

    def get_news(self, name):
        "get the NEWS.Debian file from the changelogs location"
        try:
            news = self._get_changelog_or_news(name, "NEWS.Debian", True)
        except Exception:
            return
        if news:
            self.all_news[name] = news

    def _fetch_changelog_for_third_party_package(self, name, origins):
        # Special case for PPAs
        changelogs_uri_ppa = None
        for origin in origins:
            if origin.origin.startswith("LP-PPA-"):
                try:
                    changelogs_uri_ppa = self._extract_ppa_changelog_uri(name)
                    break
                except Exception:
                    logging.exception(
                        "Unable to connect to the Launchpad API."
                    )
        # Try non official changelog location
        changelogs_uri_binary = (
            self._guess_third_party_changelogs_uri_by_binary(name)
        )
        changelogs_uri_source = (
            self._guess_third_party_changelogs_uri_by_source(name)
        )
        error_message = ""
        for changelogs_uri in [
            changelogs_uri_ppa,
            changelogs_uri_binary,
            changelogs_uri_source,
        ]:
            if changelogs_uri:
                try:
                    changelog = self._get_changelog_or_news(
                        name, "changelog", False, changelogs_uri
                    )
                    self.all_changes[name] += changelog
                except (HTTPError, HttpsChangelogsUnsupportedError):
                    # no changelogs_uri or 404
                    error_message = _(
                        "This update does not come from a "
                        "source that supports changelogs."
                    )
                except (IOError, BadStatusLine, socket.error):
                    # network errors and others
                    logging.exception("error on changelog fetching")
                    error_message = _(
                        "Failed to download the list of changes. \n"
                        "Please check your Internet connection."
                    )
        self.all_changes[name] += error_message

    # If the machine is not attached to Ubuntu Pro, Update Manager advertises
    # the upgrades that would be available if it were attached.
    # As that is unbeknownst to Apt, we need this map to show the correct
    # version of each upgradable-if-pro-subscribed package.
    def create_pro_cache(self, pro_pkgs):
        for (name, version, _a, _a) in pro_pkgs:
            self.pro_versions[name] = version

    def get_changelog(self, name):
        "get the changelog file from the changelog location"
        origins = self[name].candidate.origins
        version = self.pro_versions.get(name, self[name].candidate.version)
        self.all_changes[name] = _(
            "Changes for %s versions:\n"
            "Installed version: %s\n"
            "Available version: %s\n\n"
        ) % (
            name,
            getattr(self[name].installed, "version", None),
            version,
        )
        if self.CHANGELOG_ORIGIN not in [o.origin for o in origins]:
            self._fetch_changelog_for_third_party_package(name, origins)
            return
        # fixup epoch handling version
        srcpkg = self[name].candidate.source_name
        srcver_epoch = self[name].candidate.source_version.replace(":", "%3A")
        try:
            changelog = self._get_changelog_or_news(name, "changelog")
            if len(changelog) == 0:
                changelog = _(
                    "The changelog does not contain any relevant changes.\n\n"
                    "Please use http://launchpad.net/ubuntu/+source/"
                    "%s/%s/+changelog\n"
                    "until the changes become available or try again later."
                ) % (srcpkg, srcver_epoch)
        except HTTPError:
            changelog = _(
                "The list of changes is not available yet.\n\n"
                "Please use http://launchpad.net/ubuntu/+source/"
                "%s/%s/+changelog\n"
                "until the changes become available or try again later."
            ) % (srcpkg, srcver_epoch)
        except (IOError, BadStatusLine, socket.error) as e:
            print("caught exception: ", e)
            changelog = _(
                "Failed to download the list of changes. \n"
                "Please check your Internet connection."
            )
        self.all_changes[name] += changelog
