#!/usr/bin/python3
# pull-debian-debdiff - find and download a specific version of a Debian
#                       package and its immediate parent to generate a debdiff.
#
# Copyright (C) 2010-2011, Stefano Rivera <stefanor@ubuntu.com>
# Inspired by a tool of the same name by Kees Cook.
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
# OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.

# pylint: disable=invalid-name
# pylint: enable=invalid-name

import argparse
import sys

import debian.changelog

from ubuntutools import getLogger
from ubuntutools.archive import DebianSourcePackage, DownloadError
from ubuntutools.config import UDTConfig
from ubuntutools.version import Version

Logger = getLogger()


def previous_version(package, version, distance):
    "Given an (extracted) package, determine the version distance versions ago"
    upver = Version(version).upstream_version
    filename = f"{package}-{upver}/debian/changelog"
    changelog_file = open(filename, "r", encoding="utf-8")
    changelog = debian.changelog.Changelog(changelog_file.read())
    changelog_file.close()
    seen = 0
    for entry in changelog:
        if entry.distributions == "UNRELEASED":
            continue
        if seen == distance:
            return entry.version.full_version
        seen += 1
    return False


def main():
    parser = argparse.ArgumentParser(usage="%(prog)s [options] <package> <version> [distance]")
    parser.add_argument(
        "-f",
        "--fetch",
        dest="fetch_only",
        default=False,
        action="store_true",
        help="Only fetch the source packages, don't diff.",
    )
    parser.add_argument(
        "-d",
        "--debian-mirror",
        metavar="DEBIAN_MIRROR",
        dest="debian_mirror",
        help="Preferred Debian mirror (default: http://deb.debian.org/debian)",
    )
    parser.add_argument(
        "-s",
        "--debsec-mirror",
        metavar="DEBSEC_MIRROR",
        dest="debsec_mirror",
        help="Preferred Debian Security mirror (default: http://security.debian.org)",
    )
    parser.add_argument(
        "--no-conf",
        dest="no_conf",
        default=False,
        action="store_true",
        help="Don't read config files or environment variables",
    )
    parser.add_argument("package", help=argparse.SUPPRESS)
    parser.add_argument("version", help=argparse.SUPPRESS)
    parser.add_argument("distance", default=1, type=int, nargs="?", help=argparse.SUPPRESS)
    args = parser.parse_args()

    config = UDTConfig(args.no_conf)
    if args.debian_mirror is None:
        args.debian_mirror = config.get_value("DEBIAN_MIRROR")
    if args.debsec_mirror is None:
        args.debsec_mirror = config.get_value("DEBSEC_MIRROR")
    mirrors = [args.debsec_mirror, args.debian_mirror]

    Logger.info("Downloading %s %s", args.package, args.version)

    newpkg = DebianSourcePackage(args.package, args.version, mirrors=mirrors)
    try:
        newpkg.pull()
    except DownloadError as e:
        Logger.error("Failed to download: %s", str(e))
        sys.exit(1)
    newpkg.unpack()

    if args.fetch_only:
        sys.exit(0)

    oldversion = previous_version(args.package, args.version, args.distance)
    if not oldversion:
        Logger.error("No previous version could be found")
        sys.exit(1)
    Logger.info("Downloading %s %s", args.package, oldversion)

    oldpkg = DebianSourcePackage(args.package, oldversion, mirrors=mirrors)
    try:
        oldpkg.pull()
    except DownloadError as e:
        Logger.error("Failed to download: %s", str(e))
        sys.exit(1)
    Logger.info("file://%s", oldpkg.debdiff(newpkg, diffstat=True))


if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        Logger.info("User abort.")