#! /usr/bin/env python

from __future__ import print_function

import atexit
from collections import namedtuple
import gzip
import optparse
import os
import re
import shutil
import subprocess
import tempfile
try:
    from urllib.parse import unquote
    from urllib.request import urlretrieve
except ImportError:
    from urllib import unquote, urlretrieve

import apt_pkg
from launchpadlib.launchpad import Launchpad


# from dak, more or less
re_no_epoch = re.compile(r"^\d+:")
re_strip_revision = re.compile(r"-[^-]+$")
re_changelog_versions = re.compile(r"^\w[-+0-9a-z.]+ \(([^\(\) \t]+)\)")

default_mirrors = ":".join([
    '/home/ubuntu-archive/mirror/ubuntu',
    '/srv/archive.ubuntu.com/ubuntu',
])
tempdir = None

series_by_name = {}


def ensure_tempdir():
    global tempdir
    if not tempdir:
        tempdir = tempfile.mkdtemp(prefix='copy-report')
        atexit.register(shutil.rmtree, tempdir)


def decompress_open(tagfile):
    if tagfile.startswith('http:') or tagfile.startswith('ftp:'):
        url = tagfile
        tagfile = urlretrieve(url)[0]

    if tagfile.endswith('.gz'):
        ensure_tempdir()
        decompressed = tempfile.mktemp(dir=tempdir)
        fin = gzip.GzipFile(filename=tagfile)
        with open(decompressed, 'wb') as fout:
            fout.write(fin.read())
        return open(decompressed, 'r')
    else:
        return open(tagfile, 'r')


Section = namedtuple("Section", ["version", "directory", "files"])


def tagfiletodict(tagfile):
    suite = {}
    for section in apt_pkg.TagFile(decompress_open(tagfile)):
        files = [s.strip().split()[2] for s in section["Files"].split('\n')]
        suite[section["Package"]] = Section(
            version=section["Version"], directory=section["Directory"],
            files=files)
    return suite


def find_dsc(options, pkg, section):
    dsc_filename = [s for s in section.files if s.endswith('.dsc')][0]
    for mirror in options.mirrors:
        path = '%s/%s/%s' % (mirror, section.directory, dsc_filename)
        if os.path.exists(path):
            yield path
    ensure_tempdir()
    spph = options.archive.getPublishedSources(
        source_name=pkg, version=section.version, exact_match=True)[0]
    outdir = tempfile.mkdtemp(dir=tempdir)
    filenames = []
    for url in spph.sourceFileUrls():
        filename = os.path.join(outdir, unquote(os.path.basename(url)))
        urlretrieve(url, filename)
        filenames.append(filename)
    yield [s for s in filenames if s.endswith('.dsc')][0]


class BrokenSourcePackage(Exception):
    pass


def get_changelog_versions(pkg, dsc, version):
    ensure_tempdir()

    upstream_version = re_no_epoch.sub('', version)
    upstream_version = re_strip_revision.sub('', upstream_version)

    with open(os.devnull, 'w') as devnull:
        ret = subprocess.call(
            ['dpkg-source', '-q', '--no-check', '-sn', '-x', dsc],
            stdout=devnull, cwd=tempdir)

    # It's in the archive, so these assertions must hold.
    if ret != 0:
        raise BrokenSourcePackage(dsc)

    unpacked = '%s/%s-%s' % (tempdir, pkg, upstream_version)
    assert os.path.isdir(unpacked)
    changelog_path = '%s/debian/changelog' % unpacked
    assert os.path.exists(changelog_path)

    with open(changelog_path) as changelog:
        versions = set()
        for line in changelog:
            m = re_changelog_versions.match(line)
            if m:
                versions.add(m.group(1))

    shutil.rmtree(unpacked)

    return versions


def descended_from(options, pkg, section1, section2):
    if apt_pkg.version_compare(section1.version, section2.version) <= 0:
        return False
    exception = None
    for dsc in find_dsc(options, pkg, section1):
        try:
            versions = get_changelog_versions(pkg, dsc, section1.version)
        except BrokenSourcePackage as exception:
            continue
        return section1.version in versions
    raise exception


Candidate = namedtuple(
    "Candidate", ["package", "suite1", "suite2", "version1", "version2"])


def get_series(options, name):
    if name not in series_by_name:
        series_by_name[name] = options.distro.getSeries(name_or_version=name)
    return series_by_name[name]


def already_copied(options, candidate):
    if "-" in candidate.suite2:
        series, pocket = candidate.suite2.split("-", 1)
        pocket = pocket.title()
    else:
        series = candidate.suite2
        pocket = "Release"
    series = get_series(options, series)
    pubs = options.archive.getPublishedSources(
        source_name=candidate.package, version=candidate.version1,
        exact_match=True, distro_series=series, pocket=pocket)
    for pub in pubs:
        if pub.status in ("Pending", "Published"):
            return True
    return False


def copy(options, candidate):
    if "-" in candidate.suite2:
        to_series, to_pocket = candidate.suite2.split("-", 1)
        to_pocket = to_pocket.title()
    else:
        to_series = candidate.suite2
        to_pocket = "Release"
    options.archive.copyPackage(
        source_name=candidate.package, version=candidate.version1,
        from_archive=options.archive, to_pocket=to_pocket, to_series=to_series,
        include_binaries=True, auto_approve=True)


def candidate_string(candidate):
    string = ('copy-package -y -b -s %s --to-suite %s -e %s %s' %
              (candidate.suite1, candidate.suite2, candidate.version1,
               candidate.package))
    if candidate.version2 is not None:
        string += '  # %s: %s' % (candidate.suite2, candidate.version2)
    return string


def main():
    apt_pkg.init_system()

    parser = optparse.OptionParser(usage="usage: %prog [options] [suites]")
    parser.add_option(
        "-l", "--launchpad", dest="launchpad_instance", default="production")
    parser.add_option(
        "--quick", action="store_true", help="don't examine changelogs")
    parser.add_option(
        "--copy-safe", action="store_true",
        help="automatically copy safe candidates")
    parser.add_option(
        "--mirrors", default=default_mirrors,
        help="colon-separated list of local mirrors")
    options, args = parser.parse_args()

    options.launchpad = Launchpad.login_with(
        "copy-report", options.launchpad_instance, version="devel")
    options.distro = options.launchpad.distributions["ubuntu"]
    options.archive = options.distro.main_archive
    options.mirrors = options.mirrors.split(":")

    if args:
        suites = args
    else:
        suites = reversed([
            series.name
            for series in options.launchpad.distributions["ubuntu"].series
            if series.status in ("Supported", "Current Stable Release")])

    yes = []
    maybe = []
    no = []

    for suite in suites:
        for component in 'main', 'restricted', 'universe', 'multiverse':
            tagfile1 = '%s/dists/%s-security/%s/source/Sources.gz' % (
                options.mirrors[0], suite, component)
            tagfile2 = '%s/dists/%s-updates/%s/source/Sources.gz' % (
                options.mirrors[0], suite, component)
            name1 = '%s-security' % suite
            name2 = '%s-updates' % suite

            suite1 = tagfiletodict(tagfile1)
            suite2 = tagfiletodict(tagfile2)

            for package in sorted(suite1):
                section1 = suite1[package]
                section2 = suite2.get(package)
                if (section2 is None or
                    (not options.quick and
                     descended_from(options, package, section1, section2))):
                    candidate = Candidate(
                        package=package, suite1=name1, suite2=name2,
                        version1=section1.version, version2=None)
                    if not already_copied(options, candidate):
                        yes.append(candidate)
                elif apt_pkg.version_compare(
                        section1.version, section2.version) > 0:
                    candidate = Candidate(
                        package=package, suite1=name1, suite2=name2,
                        version1=section1.version, version2=section2.version)
                    if already_copied(options, candidate):
                        pass
                    elif not options.quick:
                        no.append(candidate)
                    else:
                        maybe.append(candidate)

    if yes:
        print("The following packages can be copied safely:")
        print("--------------------------------------------")
        print()
        for candidate in yes:
            print(candidate_string(candidate))
        print()

        if options.copy_safe:
            for candidate in yes:
                copy(options, candidate)

    if maybe:
        print("Check that these packages are descendants before copying:")
        print("---------------------------------------------------------")
        print()
        for candidate in maybe:
            print('#%s' % candidate_string(candidate))
        print()

    if no:
        print("The following packages need to be merged by hand:")
        print("-------------------------------------------------")
        print()
        for candidate in no:
            print('#%s' % candidate_string(candidate))
        print()


if __name__ == '__main__':
    main()