#  sourceslist.py - Provide an abstraction of the sources.list
#
#  Copyright (c) 2004-2023 Canonical Ltd.
#  Copyright (c) 2004 Michiel Sikkes
#  Copyright (c) 2006-2007 Sebastian Heinlein
#
#  Authors: Michiel Sikkes <michiel@eyesopened.nl>
#           Michael Vogt <mvo@debian.org>
#           Sebastian Heinlein <glatzor@ubuntu.com>
#
#  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 builtins
import glob
import io
import logging
import os.path
import re
import shutil
import time
import weakref
from collections.abc import Callable, Iterable, Iterator
from typing import Any, Generic, Optional, TypeVar, Union

import apt_pkg

from . import _deb822
from .distinfo import DistInfo, Template

# from apt_pkg import gettext as _

T = TypeVar("T")

# some global helpers

__all__ = [
    "is_mirror",
    "Deb822SourceEntry",
    "SourceEntry",
    "NullMatcher",
    "SourcesList",
    "SourceEntryMatcher",
]


def is_mirror(master_uri: str, compare_uri: str) -> bool:
    """check if the given add_url is idential or a mirror of orig_uri e.g.:
    master_uri = archive.ubuntu.com
    compare_uri = de.archive.ubuntu.com
    -> True
    """
    # remove traling spaces and "/"
    compare_uri = compare_uri.rstrip("/ ")
    master_uri = master_uri.rstrip("/ ")
    # uri is identical
    if compare_uri == master_uri:
        # print "Identical"
        return True
    # add uri is a master site and orig_uri has the from "XX.mastersite"
    # (e.g. de.archive.ubuntu.com)
    try:
        compare_srv = compare_uri.split("//")[1]
        master_srv = master_uri.split("//")[1]
        # print "%s == %s " % (add_srv, orig_srv)
    except IndexError:  # ok, somethings wrong here
        # print "IndexError"
        return False
    # remove the leading "<country>." (if any) and see if that helps
    if "." in compare_srv and compare_srv[compare_srv.index(".") + 1 :] == master_srv:
        # print "Mirror"
        return True
    return False


def uniq(s: Iterable[T]) -> list[T]:
    """simple and efficient way to return uniq collection

    This is not intended for use with a SourceList. It is provided
    for internal use only. It does not have a leading underscore to
    not break any old code that uses it; but it should not be used
    in new code (and is not listed in __all__)."""
    return list(set(s))


class SingleValueProperty(property):
    def __init__(self, key: str, doc: str):
        self.key = key
        self.__doc__ = doc

    def __get__(
        self, obj: Optional["Deb822SourceEntry"], objtype: type | None = None
    ) -> str | None:
        if obj is None:
            return self  # type: ignore
        return obj.section.get(self.key, None)

    def __set__(self, obj: "Deb822SourceEntry", value: str | None) -> None:
        if value is None:
            del obj.section[self.key]
        else:
            obj.section[self.key] = value


class MultiValueProperty(property):
    def __init__(self, key: str, doc: str):
        self.key = key
        self.__doc__ = doc

    def __get__(
        self, obj: Optional["Deb822SourceEntry"], objtype: type | None = None
    ) -> list[str]:
        if obj is None:
            return self  # type: ignore
        return SourceEntry.mysplit(obj.section.get(self.key, ""))

    def __set__(self, obj: "Deb822SourceEntry", values: list[str]) -> None:
        obj.section[self.key] = " ".join(values)


class ExplodedEntryProperty(property, Generic[T]):
    def __init__(self, parent: T):
        self.parent = parent

    def __get__(
        self, obj: Optional["ExplodedDeb822SourceEntry"], objtype: type | None = None
    ) -> T:
        if obj is None:
            return self  # type: ignore
        return self.parent.__get__(obj.parent)  # type: ignore

    def __set__(self, obj: "ExplodedDeb822SourceEntry", value: T) -> None:
        obj.split_out()
        self.parent.__set__(obj.parent, value)  # type: ignore


def DeprecatedProperty(prop: T) -> T:
    return prop


def _null_weakref() -> None:
    """Behaves like an expired weakref.ref, returning None"""
    return None


class Deb822SourceEntry:
    def __init__(
        self,
        section: _deb822.Section | str | None,
        file: str,
        list: Optional["SourcesList"] = None,
    ):
        if section is None:
            self.section = _deb822.Section("")
        elif isinstance(section, str):
            self.section = _deb822.Section(section)
        else:
            self.section = section

        self._line = str(self.section)
        self.file = file
        self.template: Template | None = None  # type DistInfo.Suite
        self.may_merge = False
        self._children = weakref.WeakSet["ExplodedDeb822SourceEntry"]()

        if list:
            self._list: Callable[[], SourcesList | None] = weakref.ref(list)
        else:
            self._list = _null_weakref

    def __eq__(self, other: Any) -> Any:
        #  FIXME: Implement plurals more correctly
        """equal operator for two sources.list entries"""
        return (
            self.disabled == other.disabled
            and self.type == other.type
            and self.uri
            and self.uri.rstrip("/") == other.uri.rstrip("/")
            and self.dist == other.dist
            and self.comps == other.comps
        )

    architectures = MultiValueProperty("Architectures", "The list of architectures")
    types = MultiValueProperty("Types", "The list of types")
    type = DeprecatedProperty(SingleValueProperty("Types", "The list of types"))
    uris = MultiValueProperty("URIs", "URIs in the source")
    uri = DeprecatedProperty(SingleValueProperty("URIs", "URIs in the source"))
    suites = MultiValueProperty("Suites", "Suites in the source")
    dist = DeprecatedProperty(SingleValueProperty("Suites", "Suites in the source"))
    comps = MultiValueProperty("Components", "Components in the source")

    @property
    def comment(self) -> str:
        """Legacy attribute describing the paragraph header."""
        return self.section.header

    @comment.setter
    def comment(self, comment: str) -> None:
        """Legacy attribute describing the paragraph header."""
        self.section.header = comment

    @property
    def trusted(self) -> bool | None:
        """Return the value of the Trusted field"""
        try:
            return apt_pkg.string_to_bool(self.section["Trusted"])
        except KeyError:
            return None

    @trusted.setter
    def trusted(self, value: bool | None) -> None:
        if value is None:
            try:
                del self.section["Trusted"]
            except KeyError:
                pass
        else:
            self.section["Trusted"] = "yes" if value else "no"

    @property
    def disabled(self) -> bool:
        """Check if Enabled: no is set."""
        return not apt_pkg.string_to_bool(self.section.get("Enabled", "yes"))

    @disabled.setter
    def disabled(self, value: bool) -> None:
        if value:
            self.section["Enabled"] = "no"
        else:
            try:
                del self.section["Enabled"]
            except KeyError:
                pass

    @property
    def invalid(self) -> bool:
        """A section is invalid if it doesn't have proper entries."""
        return not self.section

    @property
    def line(self) -> str:
        """The entire (original) paragraph."""
        return self._line

    def __str__(self) -> str:
        return self.str().strip()

    def str(self) -> str:
        """Section as a string, newline terminated."""
        return str(self.section)

    def set_enabled(self, enabled: bool) -> None:
        """Deprecated (for deb822) accessor for .disabled"""
        self.disabled = not enabled

    def merge(self, other: "AnySourceEntry") -> bool:
        """Merge the two entries if they are compatible."""
        if (
            not self.may_merge
            and self.template is None
            and not all(child.template for child in self._children)
        ):
            return False
        if self.file != other.file:
            return False
        if not isinstance(other, Deb822SourceEntry):
            return False
        if self.comment != other.comment and not any(
            "Added by software-properties" in c for c in (self.comment, other.comment)
        ):
            return False

        for tag in list(self.section.tags) + list(other.section.tags):
            if tag.lower() in (
                "types",
                "uris",
                "suites",
                "components",
                "architectures",
                "signed-by",
            ):
                continue
            in_self = self.section.get(tag, None)
            in_other = other.section.get(tag, None)
            if in_self != in_other:
                return False

        if (
            sum(
                [
                    set(self.types) != set(other.types),
                    set(self.uris) != set(other.uris),
                    set(self.suites) != set(other.suites),
                    set(self.comps) != set(other.comps),
                    set(self.architectures) != set(other.architectures),
                ]
            )
            > 1
        ):
            return False

        for typ in other.types:
            if typ not in self.types:
                self.types += [typ]

        for uri in other.uris:
            if uri not in self.uris:
                self.uris += [uri]

        for suite in other.suites:
            if suite not in self.suites:
                self.suites += [suite]

        for component in other.comps:
            if component not in self.comps:
                self.comps += [component]

        for arch in other.architectures:
            if arch not in self.architectures:
                self.architectures += [arch]

        return True

    def _reparent_children(self, to: "Deb822SourceEntry") -> None:
        """If we end up being split, check if any of our children need to be reparented to the new parent."""
        for child in self._children:
            for typ in to.types:
                for uri in to.uris:
                    for suite in to.suites:
                        if (child._type, child._uri, child._suite) == (typ, uri, suite):
                            assert child.parent == self
                            child._parent = weakref.ref(to)


class ExplodedDeb822SourceEntry:
    """This represents a bit of a deb822 paragraph corresponding to a legacy sources.list entry"""

    # Mostly we use slots to prevent accidentally assigning unproxied attributes
    __slots__ = ["_parent", "_type", "_uri", "_suite", "template", "__weakref__"]

    def __init__(self, parent: Deb822SourceEntry, typ: str, uri: str, suite: str):
        self._parent = weakref.ref(parent)
        self._type = typ
        self._uri = uri
        self._suite = suite
        self.template = parent.template
        parent._children.add(self)

    @property
    def parent(self) -> Deb822SourceEntry:
        if self._parent is not None:
            if (parent := self._parent()) is not None:
                return parent
        raise ValueError("The parent entry is no longer valid")

    @property
    def uri(self) -> str:
        self.__check_valid()
        return self._uri

    @uri.setter
    def uri(self, uri: str) -> None:
        self.split_out()
        self.parent.uris = [u if u != self._uri else uri for u in self.parent.uris]
        self._uri = uri

    @property
    def types(self) -> list[str]:
        return [self.type]

    @property
    def suites(self) -> list[str]:
        return [self.dist]

    @property
    def uris(self) -> list[str]:
        return [self.uri]

    @property
    def type(self) -> str:
        self.__check_valid()
        return self._type

    @type.setter
    def type(self, typ: str) -> None:
        self.split_out()
        self.parent.types = [typ]
        self._type = typ
        self.__check_valid()
        assert self._type == typ
        assert self.parent.types == [self._type]

    @property
    def dist(self) -> str:
        self.__check_valid()
        return self._suite

    @dist.setter
    def dist(self, suite: str) -> None:
        self.split_out()
        self.parent.suites = [suite]
        self._suite = suite
        self.__check_valid()
        assert self._suite == suite
        assert self.parent.suites == [self._suite]

    def __check_valid(self) -> None:
        if self.parent._list() is None:
            raise ValueError("The parent entry is dead")
        for type in self.parent.types:
            for uri in self.parent.uris:
                for suite in self.parent.suites:
                    if (type, uri, suite) == (self._type, self._uri, self._suite):
                        return
        raise ValueError(f"Could not find parent of {self}")

    def split_out(self) -> None:
        parent = self.parent
        if (parent.types, parent.uris, parent.suites) == (
            [self._type],
            [self._uri],
            [self._suite],
        ):
            return
        sources_list = parent._list()
        if sources_list is None:
            raise ValueError("The parent entry is dead")

        try:
            index = sources_list.list.index(parent)
        except ValueError as e:
            raise ValueError(
                f"Parent entry for partial deb822 {self} no longer valid"
            ) from e

        sources_list.remove(parent)

        reparented = False
        for type in reversed(parent.types):
            for uri in reversed(parent.uris):
                for suite in reversed(parent.suites):
                    new = Deb822SourceEntry(
                        section=_deb822.Section(parent.section),
                        file=parent.file,
                        list=sources_list,
                    )
                    new.types = [type]
                    new.uris = [uri]
                    new.suites = [suite]
                    new.may_merge = True

                    parent._reparent_children(new)
                    sources_list.list.insert(index, new)
                    if (type, uri, suite) == (self._type, self._uri, self._suite):
                        self._parent = weakref.ref(new)
                        reparented = True
        if not reparented:
            raise ValueError(f"Could not find parent of {self}")

    def __repr__(self) -> str:
        return f"<child {self._type} {self._uri} {self._suite} of {self._parent}"

    architectures = ExplodedEntryProperty(Deb822SourceEntry.architectures)
    comps = ExplodedEntryProperty(Deb822SourceEntry.comps)
    invalid = ExplodedEntryProperty(Deb822SourceEntry.invalid)
    disabled = ExplodedEntryProperty[bool](Deb822SourceEntry.disabled)  # type: ignore
    trusted = ExplodedEntryProperty(Deb822SourceEntry.trusted)
    comment = ExplodedEntryProperty(Deb822SourceEntry.comment)

    def set_enabled(self, enabled: bool) -> None:
        """Set the source to enabled."""
        self.disabled = not enabled

    @property
    def file(self) -> str:
        """Return the file."""
        return self.parent.file


class SourceEntry:
    """single sources.list entry"""

    def __init__(self, line: str, file: str | None = None):
        self.invalid = False  # is the source entry valid
        self.disabled = False  # is it disabled ('#' in front)
        self.type = ""  # what type (deb, deb-src)
        self.architectures: list[str] = []  # architectures
        self.trusted: bool | None = None  # Trusted
        self.uri = ""  # base-uri
        self.dist = ""  # distribution (dapper, edgy, etc)
        self.comps: list[str] = []  # list of available componetns (may empty)
        self.comment = ""  # (optional) comment
        self.line = line  # the original sources.list line
        if file is None:
            file = apt_pkg.config.find_file("Dir::Etc::sourcelist")
        self.file = file  # the file that the entry is located in
        self.parse(line)
        self.template: Template | None = None  # type DistInfo.Suite
        self.children: list[SourceEntry] = []

    def __eq__(self, other: Any) -> Any:
        """equal operator for two sources.list entries"""
        return (
            self.disabled == other.disabled
            and self.type == other.type
            and self.uri.rstrip("/") == other.uri.rstrip("/")
            and self.dist == other.dist
            and self.comps == other.comps
        )

    @staticmethod
    def mysplit(line: str) -> list[str]:
        """a split() implementation that understands the sources.list
        format better and takes [] into account (for e.g. cdroms)"""
        line = line.strip()
        pieces = []
        tmp = ""
        # we are inside a [..] block
        p_found = False
        space_found = False
        for i in range(len(line)):
            if line[i] == "[":
                if space_found:
                    space_found = False
                    p_found = True
                    pieces.append(tmp)
                    tmp = line[i]
                else:
                    p_found = True
                    tmp += line[i]
            elif line[i] == "]":
                p_found = False
                tmp += line[i]
            elif space_found and not line[i].isspace():
                # we skip one or more space
                space_found = False
                pieces.append(tmp)
                tmp = line[i]
            elif line[i].isspace() and not p_found:
                # found a whitespace
                space_found = True
            else:
                tmp += line[i]
        # append last piece
        if len(tmp) > 0:
            pieces.append(tmp)
        return pieces

    def parse(self, line: str) -> None:
        """parse a given sources.list (textual) line and break it up
        into the field we have"""
        self.line = line
        line = line.strip()
        # check if the source is enabled/disabled
        if line == "" or line == "#":  # empty line
            self.invalid = True
            return
        if line[0] == "#":
            self.disabled = True
            pieces = line[1:].strip().split()
            # if it looks not like a disabled deb line return
            if not pieces[0] in ("rpm", "rpm-src", "deb", "deb-src"):
                self.invalid = True
                return
            else:
                line = line[1:]
        # check for another "#" in the line (this is treated as a comment)
        i = line.find("#")
        if i > 0:
            self.comment = line[i + 1 :]
            line = line[:i]
        # source is ok, split it and see what we have
        pieces = self.mysplit(line)
        # Sanity check
        if len(pieces) < 3:
            self.invalid = True
            return
        # Type, deb or deb-src
        self.type = pieces[0].strip()
        # Sanity check
        if self.type not in ("deb", "deb-src", "rpm", "rpm-src"):
            self.invalid = True
            return

        if pieces[1].strip()[0] == "[":
            options = pieces.pop(1).strip("[]").split()
            for option in options:
                try:
                    key, value = option.split("=", 1)
                except Exception:
                    self.invalid = True
                else:
                    if key == "arch":
                        self.architectures = value.split(",")
                    elif key == "trusted":
                        self.trusted = apt_pkg.string_to_bool(value)
                    else:
                        self.invalid = True

        # URI
        self.uri = pieces[1].strip()
        if len(self.uri) < 1:
            self.invalid = True
        # distro and components (optional)
        # Directory or distro
        self.dist = pieces[2].strip()
        if len(pieces) > 3:
            # List of components
            self.comps = pieces[3:]
        else:
            self.comps = []

    def set_enabled(self, new_value: bool) -> None:
        """set a line to enabled or disabled"""
        self.disabled = not new_value
        # enable, remove all "#" from the start of the line
        if new_value:
            self.line = self.line.lstrip().lstrip("#")
        else:
            # disabled, add a "#"
            if self.line.strip()[0] != "#":
                self.line = "#" + self.line

    def __str__(self) -> str:
        """debug helper"""
        return self.str().strip()

    def str(self) -> str:
        """return the current line as string"""
        if self.invalid:
            return self.line
        line = ""
        if self.disabled:
            line = "# "

        line += self.type

        if self.architectures and self.trusted is not None:
            line += " [arch={} trusted={}]".format(
                ",".join(self.architectures),
                "yes" if self.trusted else "no",
            )
        elif self.trusted is not None:
            line += " [trusted=%s]" % ("yes" if self.trusted else "no")
        elif self.architectures:
            line += " [arch=%s]" % ",".join(self.architectures)
        line += f" {self.uri} {self.dist}"
        if len(self.comps) > 0:
            line += " " + " ".join(self.comps)
        if self.comment != "":
            line += " #" + self.comment
        line += "\n"
        return line

    @property
    def types(self) -> list[builtins.str]:
        """deb822 compatible accessor for the type"""
        return [self.type]

    @property
    def uris(self) -> list[builtins.str]:
        """deb822 compatible accessor for the uri"""
        return [self.uri]

    @property
    def suites(self) -> list[builtins.str]:
        """deb822 compatible accessor for the suite"""
        return [self.dist]


AnySourceEntry = Union[SourceEntry, Deb822SourceEntry]
AnyExplodedSourceEntry = Union[
    SourceEntry, Deb822SourceEntry, ExplodedDeb822SourceEntry
]


class NullMatcher:
    """a Matcher that does nothing"""

    def match(self, s: AnyExplodedSourceEntry) -> bool:
        return True


class SourcesList:
    """represents the full sources.list + sources.list.d file"""

    def __init__(
        self,
        withMatcher: bool = True,
        matcherPath: str = "/usr/share/python-apt/templates/",
        *,
        deb822: bool = False,
    ):
        self.list: list[AnySourceEntry] = []  # the actual SourceEntries Type
        self.matcher: NullMatcher | SourceEntryMatcher
        if withMatcher:
            self.matcher = SourceEntryMatcher(matcherPath)
        else:
            self.matcher = NullMatcher()
        self.deb822 = deb822
        self.refresh()

    def refresh(self) -> None:
        """update the list of known entries"""
        self.list = []
        # read sources.list
        file = apt_pkg.config.find_file("Dir::Etc::sourcelist")
        if file != "/dev/null" and os.path.exists(file):
            self.load(file)
        # read sources.list.d
        partsdir = apt_pkg.config.find_dir("Dir::Etc::sourceparts")
        if partsdir != "/dev/null" and os.path.exists(partsdir):
            for file in os.listdir(partsdir):
                if (self.deb822 and file.endswith(".sources")) or file.endswith(
                    ".list"
                ):
                    self.load(os.path.join(partsdir, file))
        # check if the source item fits a predefined template
        for source in self.list:
            if not source.invalid:
                self.matcher.match(source)

    def __iter__(self) -> Iterator[AnySourceEntry]:
        """simple iterator to go over self.list, returns SourceEntry
        types"""
        yield from self.list

    def __find(
        self, *predicates: Callable[[AnyExplodedSourceEntry], bool], **attrs: Any
    ) -> Iterator[AnyExplodedSourceEntry]:
        uri = attrs.pop("uri", None)
        for source in self.exploded_list():
            if uri and source.uri and uri.rstrip("/") != source.uri.rstrip("/"):
                continue
            if all(getattr(source, key) == attrs[key] for key in attrs) and all(
                predicate(source) for predicate in predicates
            ):
                yield source

    def add(
        self,
        type: str,
        uri: str,
        dist: str,
        orig_comps: list[str],
        comment: str = "",
        pos: int = -1,
        file: str | None = None,
        architectures: Iterable[str] = [],
        parent: AnyExplodedSourceEntry | None = None,
    ) -> AnyExplodedSourceEntry:
        """
        Add a new source to the sources.list.
        The method will search for existing matching repos and will try to
        reuse them as far as possible
        """

        type = type.strip()
        disabled = type.startswith("#")
        if disabled:
            type = type[1:].lstrip()
        architectures = set(architectures)
        # create a working copy of the component list so that
        # we can modify it later
        comps = orig_comps[:]
        sources = self.__find(
            lambda s: set(s.architectures) == architectures,
            disabled=disabled,
            invalid=False,
            type=type,
            uri=uri,
            dist=dist,
        )
        # check if we have this source already in the sources.list
        for source in sources:
            for new_comp in comps:
                if new_comp in source.comps:
                    # we have this component already, delete it
                    # from the new_comps list
                    del comps[comps.index(new_comp)]
                    if len(comps) == 0:
                        return source

        sources = self.__find(
            lambda s: set(s.architectures) == architectures,
            invalid=False,
            type=type,
            uri=uri,
            dist=dist,
        )
        for source in sources:
            if source.disabled == disabled:
                # if there is a repo with the same (disabled, type, uri, dist)
                # just add the components
                if set(source.comps) != set(comps):
                    source.comps = uniq(source.comps + comps)
                return source
            elif source.disabled and not disabled:
                # enable any matching (type, uri, dist), but disabled repo
                if set(source.comps) == set(comps):
                    source.disabled = False
                    return source

        new_entry: AnySourceEntry
        if file is not None and file.endswith(".sources"):
            new_entry = Deb822SourceEntry(None, file=file, list=self)
            if parent:
                parent = getattr(parent, "parent", parent)
                assert isinstance(parent, Deb822SourceEntry)
                for k in parent.section.tags:
                    new_entry.section.tags[k] = parent.section.tags[k]
            new_entry.types = [type]
            new_entry.uris = [uri]
            new_entry.suites = [dist]
            new_entry.comps = comps
            if architectures:
                new_entry.architectures = list(architectures)
            new_entry.section.header = comment
            new_entry.disabled = disabled
        else:
            # there isn't any matching source, so create a new line and parse it
            parts = [
                "#" if disabled else "",
                type,
                ("[arch=%s]" % ",".join(architectures)) if architectures else "",
                uri,
                dist,
            ]
            parts.extend(comps)
            if comment:
                parts.append("#" + comment)
            line = " ".join(part for part in parts if part) + "\n"

            new_entry = SourceEntry(line)
            if file is not None:
                new_entry.file = file

        self.matcher.match(new_entry)
        if pos < 0:
            self.list.append(new_entry)
        else:
            self.list.insert(pos, new_entry)
        return new_entry

    def remove(self, source_entry: AnyExplodedSourceEntry) -> None:
        """remove the specified entry from the sources.list"""
        if isinstance(source_entry, ExplodedDeb822SourceEntry):
            source_entry.split_out()
            source_entry = source_entry.parent
        self.list.remove(source_entry)

    def restore_backup(self, backup_ext: str) -> None:
        "restore sources.list files based on the backup extension"
        file = apt_pkg.config.find_file("Dir::Etc::sourcelist")
        if os.path.exists(file + backup_ext) and os.path.exists(file):
            shutil.copy(file + backup_ext, file)
        # now sources.list.d
        partsdir = apt_pkg.config.find_dir("Dir::Etc::sourceparts")
        for file in glob.glob("%s/*" % partsdir):
            if os.path.exists(file + backup_ext):
                shutil.copy(file + backup_ext, file)

    def backup(self, backup_ext: str | None = None) -> str:
        """make a backup of the current source files, if no backup extension
        is given, the current date/time is used (and returned)"""
        already_backuped: Iterable[str] = set()
        if backup_ext is None:
            backup_ext = time.strftime("%y%m%d.%H%M")
        for source in self.list:
            if source.file not in already_backuped and os.path.exists(source.file):
                shutil.copy(source.file, f"{source.file}{backup_ext}")
        return backup_ext

    def load(self, file: str) -> None:
        """(re)load the current sources"""
        try:
            with open(file) as f:
                if file.endswith(".sources"):
                    for section in _deb822.File(f):
                        self.list.append(Deb822SourceEntry(section, file, list=self))
                else:
                    for line in f:
                        source = SourceEntry(line, file)
                        self.list.append(source)
        except Exception as exc:
            logging.warning(f"could not open file '{file}': {exc}\n")

    def index(self, entry: AnyExplodedSourceEntry) -> int:
        if isinstance(entry, ExplodedDeb822SourceEntry):
            return self.list.index(entry.parent)
        return self.list.index(entry)

    def merge(self) -> None:
        """Merge consecutive entries that have been split back together."""
        merged = True
        while merged:
            i = 0
            merged = False
            while i + 1 < len(self.list):
                entry = self.list[i]
                if isinstance(entry, Deb822SourceEntry):
                    j = i + 1
                    while j < len(self.list):
                        if entry.merge(self.list[j]):
                            del self.list[j]
                            merged = True
                        else:
                            j += 1
                i += 1

    def save(self) -> None:
        """save the current sources"""
        files: dict[str, io.TextIOWrapper] = {}
        # write an empty default config file if there aren't any sources
        if len(self.list) == 0:
            path = apt_pkg.config.find_file("Dir::Etc::sourcelist")
            header = (
                "## See sources.list(5) for more information, especialy\n"
                "# Remember that you can only use http, ftp or file URIs\n"
                "# CDROMs are managed through the apt-cdrom tool.\n"
            )

            with open(path, "w") as f:
                f.write(header)
            return

        self.merge()
        try:
            for source in self.list:
                if source.file not in files:
                    files[source.file] = open(source.file, "w")
                elif isinstance(source, Deb822SourceEntry):
                    files[source.file].write("\n")
                files[source.file].write(source.str())
        finally:
            for f in files.values():
                f.close()

    def check_for_relations(
        self, sources_list: Iterable[AnySourceEntry]
    ) -> tuple[list[AnySourceEntry], dict[Template, list[AnySourceEntry]]]:
        """get all parent and child channels in the sources list"""
        parents = []
        used_child_templates: dict[Template, list[AnySourceEntry]] = {}
        for source in sources_list:
            # try to avoid checking uninterressting sources
            if source.template is None:
                continue
            # set up a dict with all used child templates and corresponding
            # source entries
            if source.template.child:
                key = source.template
                if key not in used_child_templates:
                    used_child_templates[key] = []
                temp = used_child_templates[key]
                temp.append(source)
            else:
                # store each source with children aka. a parent :)
                if len(source.template.children) > 0:
                    parents.append(source)
        # print self.used_child_templates
        # print self.parents
        return (parents, used_child_templates)

    def exploded_list(self) -> list[AnyExplodedSourceEntry]:
        """Present an exploded view of the list where each entry corresponds exactly to a Release file.

        A release file is uniquely identified by the triplet (type, uri, suite). Old style entries
        always referred to a single release file, but deb822 entries allow multiple values for each
        of those fields.
        """
        res: list[AnyExplodedSourceEntry] = []
        for entry in self.list:
            if isinstance(entry, SourceEntry):
                res.append(entry)
            elif (
                len(entry.types) == 1
                and len(entry.uris) == 1
                and len(entry.suites) == 1
            ):
                res.append(entry)
            else:
                for typ in entry.types:
                    for uri in entry.uris:
                        for sui in entry.suites:
                            res.append(ExplodedDeb822SourceEntry(entry, typ, uri, sui))
                            self.matcher.match(res[-1])

        return res


class SourceEntryMatcher:
    """matcher class to make a source entry look nice
    lots of predefined matchers to make it i18n/gettext friendly
    """

    def __init__(self, matcherPath: str):
        self.templates: list[Template] = []
        # Get the human readable channel and comp names from the channel .infos
        spec_files = glob.glob("%s/*.info" % matcherPath)
        for f in spec_files:
            f = os.path.basename(f)
            i = f.find(".info")
            f = f[0:i]
            dist = DistInfo(f, base_dir=matcherPath)
            for template in dist.templates:
                if template.match_uri is not None:
                    self.templates.append(template)
        return

    def match(self, source: AnyExplodedSourceEntry) -> bool:
        """Add a matching template to the source"""
        found = False
        for template in self.templates:
            if source.uri is None or source.dist is None:
                continue
            if (
                template.match_uri is not None
                and template.match_name is not None
                and source.uri is not None
                and source.dist is not None
                and re.search(template.match_uri, source.uri)
                and re.match(template.match_name, source.dist)
                and
                # deb is a valid fallback for deb-src (if that is not
                # definied, see #760035
                (source.type == template.type or template.type == "deb")
            ):
                found = True
                source.template = template
                break
            elif (
                template.is_mirror(source.uri)
                and template.match_name is not None
                and source.dist is not None
                and re.match(template.match_name, source.dist)
            ):
                found = True
                source.template = template
                break
        return found


# some simple tests
if __name__ == "__main__":
    apt_pkg.init_config()
    sources = SourcesList()

    for entry in sources:
        logging.info("entry %s" % entry.str())
        # print entry.uri

    mirror = is_mirror(
        "http://archive.ubuntu.com/ubuntu/", "http://de.archive.ubuntu.com/ubuntu/"
    )
    logging.info("is_mirror(): %s" % mirror)

    logging.info(
        is_mirror(
            "http://archive.ubuntu.com/ubuntu", "http://de.archive.ubuntu.com/ubuntu/"
        )
    )
    logging.info(
        is_mirror(
            "http://archive.ubuntu.com/ubuntu/", "http://de.archive.ubuntu.com/ubuntu"
        )
    )
