# Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
#
# This module is part of GitPython and is released under the
# 3-Clause BSD License: https://opensource.org/license/bsd-3-clause/

import sys

__all__ = [
    "stream_copy",
    "join_path",
    "to_native_path_linux",
    "join_path_native",
    "Stats",
    "IndexFileSHA1Writer",
    "IterableObj",
    "IterableList",
    "BlockingLockFile",
    "LockFile",
    "Actor",
    "get_user_id",
    "assure_directory_exists",
    "RemoteProgress",
    "CallableRemoteProgress",
    "rmtree",
    "unbare_repo",
    "HIDE_WINDOWS_KNOWN_ERRORS",
]

if sys.platform == "win32":
    __all__.append("to_native_path_windows")

from abc import abstractmethod
import contextlib
from functools import wraps
import getpass
import logging
import os
import os.path as osp
import pathlib
import platform
import re
import shutil
import stat
import subprocess
import time
from urllib.parse import urlsplit, urlunsplit
import warnings

# NOTE: Unused imports can be improved now that CI testing has fully resumed. Some of
# these be used indirectly through other GitPython modules, which avoids having to write
# gitdb all the time in their imports. They are not in __all__, at least currently,
# because they could be removed or changed at any time, and so should not be considered
# conceptually public to code outside GitPython. Linters of course do not like it.
from gitdb.util import (
    LazyMixin,  # noqa: F401
    LockedFD,  # noqa: F401
    bin_to_hex,  # noqa: F401
    file_contents_ro,  # noqa: F401
    file_contents_ro_filepath,  # noqa: F401
    hex_to_bin,  # noqa: F401
    make_sha,
    to_bin_sha,  # noqa: F401
    to_hex_sha,  # noqa: F401
)

# typing ---------------------------------------------------------

from typing import (
    Any,
    AnyStr,
    BinaryIO,
    Callable,
    Dict,
    Generator,
    IO,
    Iterator,
    List,
    Optional,
    Pattern,
    Sequence,
    Tuple,
    TYPE_CHECKING,
    TypeVar,
    Union,
    cast,
    overload,
)

if TYPE_CHECKING:
    from git.cmd import Git
    from git.config import GitConfigParser, SectionConstraint
    from git.remote import Remote
    from git.repo.base import Repo

from git.types import (
    Files_TD,
    Has_id_attribute,
    HSH_TD,
    Literal,
    PathLike,
    Protocol,
    SupportsIndex,
    Total_TD,
    runtime_checkable,
)

# ---------------------------------------------------------------------

T_IterableObj = TypeVar("T_IterableObj", bound=Union["IterableObj", "Has_id_attribute"], covariant=True)
# So IterableList[Head] is subtype of IterableList[IterableObj].

_logger = logging.getLogger(__name__)


def _read_env_flag(name: str, default: bool) -> bool:
    """Read a boolean flag from an environment variable.

    :return:
        The flag, or the `default` value if absent or ambiguous.
    """
    try:
        value = os.environ[name]
    except KeyError:
        return default

    _logger.warning(
        "The %s environment variable is deprecated. Its effect has never been documented and changes without warning.",
        name,
    )

    adjusted_value = value.strip().lower()

    if adjusted_value in {"", "0", "false", "no"}:
        return False
    if adjusted_value in {"1", "true", "yes"}:
        return True
    _logger.warning("%s has unrecognized value %r, treating as %r.", name, value, default)
    return default


def _read_win_env_flag(name: str, default: bool) -> bool:
    """Read a boolean flag from an environment variable on Windows.

    :return:
        On Windows, the flag, or the `default` value if absent or ambiguous.
        On all other operating systems, ``False``.

    :note:
        This only accesses the environment on Windows.
    """
    return sys.platform == "win32" and _read_env_flag(name, default)


#: We need an easy way to see if Appveyor TCs start failing,
#: so the errors marked with this var are considered "acknowledged" ones, awaiting remedy,
#: till then, we wish to hide them.
HIDE_WINDOWS_KNOWN_ERRORS = _read_win_env_flag("HIDE_WINDOWS_KNOWN_ERRORS", True)
HIDE_WINDOWS_FREEZE_ERRORS = _read_win_env_flag("HIDE_WINDOWS_FREEZE_ERRORS", True)

# { Utility Methods

T = TypeVar("T")


def unbare_repo(func: Callable[..., T]) -> Callable[..., T]:
    """Methods with this decorator raise :exc:`~git.exc.InvalidGitRepositoryError` if
    they encounter a bare repository."""

    from .exc import InvalidGitRepositoryError

    @wraps(func)
    def wrapper(self: "Remote", *args: Any, **kwargs: Any) -> T:
        if self.repo.bare:
            raise InvalidGitRepositoryError("Method '%s' cannot operate on bare repositories" % func.__name__)
        # END bare method
        return func(self, *args, **kwargs)

    # END wrapper

    return wrapper


@contextlib.contextmanager
def cwd(new_dir: PathLike) -> Generator[PathLike, None, None]:
    """Context manager to temporarily change directory.

    This is similar to :func:`contextlib.chdir` introduced in Python 3.11, but the
    context manager object returned by a single call to this function is not reentrant.
    """
    old_dir = os.getcwd()
    os.chdir(new_dir)
    try:
        yield new_dir
    finally:
        os.chdir(old_dir)


@contextlib.contextmanager
def patch_env(name: str, value: str) -> Generator[None, None, None]:
    """Context manager to temporarily patch an environment variable."""
    old_value = os.getenv(name)
    os.environ[name] = value
    try:
        yield
    finally:
        if old_value is None:
            del os.environ[name]
        else:
            os.environ[name] = old_value


def rmtree(path: PathLike) -> None:
    """Remove the given directory tree recursively.

    :note:
        We use :func:`shutil.rmtree` but adjust its behaviour to see whether files that
        couldn't be deleted are read-only. Windows will not remove them in that case.
    """

    def handler(function: Callable, path: PathLike, _excinfo: Any) -> None:
        """Callback for :func:`shutil.rmtree`.

        This works as either a ``onexc`` or ``onerror`` style callback.
        """
        # Is the error an access error?
        os.chmod(path, stat.S_IWUSR)

        try:
            function(path)
        except PermissionError as ex:
            if HIDE_WINDOWS_KNOWN_ERRORS:
                from unittest import SkipTest

                raise SkipTest(f"FIXME: fails with: PermissionError\n  {ex}") from ex
            raise

    if sys.platform != "win32":
        shutil.rmtree(path)
    elif sys.version_info >= (3, 12):
        shutil.rmtree(path, onexc=handler)
    else:
        shutil.rmtree(path, onerror=handler)


def rmfile(path: PathLike) -> None:
    """Ensure file deleted also on *Windows* where read-only files need special
    treatment."""
    if osp.isfile(path):
        if sys.platform == "win32":
            os.chmod(path, 0o777)
        os.remove(path)


def stream_copy(source: BinaryIO, destination: BinaryIO, chunk_size: int = 512 * 1024) -> int:
    """Copy all data from the `source` stream into the `destination` stream in chunks
    of size `chunk_size`.

    :return:
        Number of bytes written
    """
    br = 0
    while True:
        chunk = source.read(chunk_size)
        destination.write(chunk)
        br += len(chunk)
        if len(chunk) < chunk_size:
            break
    # END reading output stream
    return br


def join_path(a: PathLike, *p: PathLike) -> PathLike:
    R"""Join path tokens together similar to osp.join, but always use ``/`` instead of
    possibly ``\`` on Windows."""
    path = str(a)
    for b in p:
        b = str(b)
        if not b:
            continue
        if b.startswith("/"):
            path += b[1:]
        elif path == "" or path.endswith("/"):
            path += b
        else:
            path += "/" + b
    # END for each path token to add
    return path


if sys.platform == "win32":

    def to_native_path_windows(path: PathLike) -> PathLike:
        path = str(path)
        return path.replace("/", "\\")

    def to_native_path_linux(path: PathLike) -> str:
        path = str(path)
        return path.replace("\\", "/")

    to_native_path = to_native_path_windows
else:
    # No need for any work on Linux.
    def to_native_path_linux(path: PathLike) -> str:
        return str(path)

    to_native_path = to_native_path_linux


def join_path_native(a: PathLike, *p: PathLike) -> PathLike:
    R"""Like :func:`join_path`, but makes sure an OS native path is returned.

    This is only needed to play it safe on Windows and to ensure nice paths that only
    use ``\``.
    """
    return to_native_path(join_path(a, *p))


def assure_directory_exists(path: PathLike, is_file: bool = False) -> bool:
    """Make sure that the directory pointed to by path exists.

    :param is_file:
        If ``True``, `path` is assumed to be a file and handled correctly.
        Otherwise it must be a directory.

    :return:
        ``True`` if the directory was created, ``False`` if it already existed.
    """
    if is_file:
        path = osp.dirname(path)
    # END handle file
    if not osp.isdir(path):
        os.makedirs(path, exist_ok=True)
        return True
    return False


def _get_exe_extensions() -> Sequence[str]:
    PATHEXT = os.environ.get("PATHEXT", None)
    if PATHEXT:
        return tuple(p.upper() for p in PATHEXT.split(os.pathsep))
    elif sys.platform == "win32":
        return (".BAT", "COM", ".EXE")
    else:
        return ()


def py_where(program: str, path: Optional[PathLike] = None) -> List[str]:
    """Perform a path search to assist :func:`is_cygwin_git`.

    This is not robust for general use. It is an implementation detail of
    :func:`is_cygwin_git`. When a search following all shell rules is needed,
    :func:`shutil.which` can be used instead.

    :note:
        Neither this function nor :func:`shutil.which` will predict the effect of an
        executable search on a native Windows system due to a :class:`subprocess.Popen`
        call without ``shell=True``, because shell and non-shell executable search on
        Windows differ considerably.
    """
    # From: http://stackoverflow.com/a/377028/548792
    winprog_exts = _get_exe_extensions()

    def is_exec(fpath: str) -> bool:
        return (
            osp.isfile(fpath)
            and os.access(fpath, os.X_OK)
            and (
                sys.platform != "win32" or not winprog_exts or any(fpath.upper().endswith(ext) for ext in winprog_exts)
            )
        )

    progs = []
    if not path:
        path = os.environ["PATH"]
    for folder in str(path).split(os.pathsep):
        folder = folder.strip('"')
        if folder:
            exe_path = osp.join(folder, program)
            for f in [exe_path] + ["%s%s" % (exe_path, e) for e in winprog_exts]:
                if is_exec(f):
                    progs.append(f)
    return progs


def _cygexpath(drive: Optional[str], path: str) -> str:
    if osp.isabs(path) and not drive:
        # Invoked from `cygpath()` directly with `D:Apps\123`?
        #  It's an error, leave it alone just slashes)
        p = path  # convert to str if AnyPath given
    else:
        p = path and osp.normpath(osp.expandvars(osp.expanduser(path)))
        if osp.isabs(p):
            if drive:
                # Confusing, maybe a remote system should expand vars.
                p = path
            else:
                p = cygpath(p)
        elif drive:
            p = "/proc/cygdrive/%s/%s" % (drive.lower(), p)
    p_str = str(p)  # ensure it is a str and not AnyPath
    return p_str.replace("\\", "/")


_cygpath_parsers: Tuple[Tuple[Pattern[str], Callable, bool], ...] = (
    # See: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
    # and: https://www.cygwin.com/cygwin-ug-net/using.html#unc-paths
    (
        re.compile(r"\\\\\?\\UNC\\([^\\]+)\\([^\\]+)(?:\\(.*))?"),
        (lambda server, share, rest_path: "//%s/%s/%s" % (server, share, rest_path.replace("\\", "/"))),
        False,
    ),
    (re.compile(r"\\\\\?\\(\w):[/\\](.*)"), (_cygexpath), False),
    (re.compile(r"(\w):[/\\](.*)"), (_cygexpath), False),
    (re.compile(r"file:(.*)", re.I), (lambda rest_path: rest_path), True),
    (re.compile(r"(\w{2,}:.*)"), (lambda url: url), False),  # remote URL, do nothing
)


def cygpath(path: str) -> str:
    """Use :meth:`git.cmd.Git.polish_url` instead, that works on any environment."""
    path = str(path)  # Ensure is str and not AnyPath.
    # Fix to use Paths when 3.5 dropped. Or to be just str if only for URLs?
    if not path.startswith(("/cygdrive", "//", "/proc/cygdrive")):
        for regex, parser, recurse in _cygpath_parsers:
            match = regex.match(path)
            if match:
                path = parser(*match.groups())
                if recurse:
                    path = cygpath(path)
                break
        else:
            path = _cygexpath(None, path)

    return path


_decygpath_regex = re.compile(r"(?:/proc)?/cygdrive/(\w)(/.*)?")


def decygpath(path: PathLike) -> str:
    path = str(path)
    m = _decygpath_regex.match(path)
    if m:
        drive, rest_path = m.groups()
        path = "%s:%s" % (drive.upper(), rest_path or "")

    return path.replace("/", "\\")


#: Store boolean flags denoting if a specific Git executable
#: is from a Cygwin installation (since `cache_lru()` unsupported on PY2).
_is_cygwin_cache: Dict[str, Optional[bool]] = {}


def _is_cygwin_git(git_executable: str) -> bool:
    is_cygwin = _is_cygwin_cache.get(git_executable)  # type: Optional[bool]
    if is_cygwin is None:
        is_cygwin = False
        try:
            git_dir = osp.dirname(git_executable)
            if not git_dir:
                res = py_where(git_executable)
                git_dir = osp.dirname(res[0]) if res else ""

            # Just a name given, not a real path.
            uname_cmd = osp.join(git_dir, "uname")
            process = subprocess.Popen([uname_cmd], stdout=subprocess.PIPE, universal_newlines=True)
            uname_out, _ = process.communicate()
            # retcode = process.poll()
            is_cygwin = "CYGWIN" in uname_out
        except Exception as ex:
            _logger.debug("Failed checking if running in CYGWIN due to: %r", ex)
        _is_cygwin_cache[git_executable] = is_cygwin

    return is_cygwin


@overload
def is_cygwin_git(git_executable: None) -> Literal[False]: ...


@overload
def is_cygwin_git(git_executable: PathLike) -> bool: ...


def is_cygwin_git(git_executable: Union[None, PathLike]) -> bool:
    if sys.platform == "win32":  # TODO: See if we can use `sys.platform != "cygwin"`.
        return False
    elif git_executable is None:
        return False
    else:
        return _is_cygwin_git(str(git_executable))


def get_user_id() -> str:
    """:return: String identifying the currently active system user as ``name@node``"""
    return "%s@%s" % (getpass.getuser(), platform.node())


def finalize_process(proc: Union[subprocess.Popen, "Git.AutoInterrupt"], **kwargs: Any) -> None:
    """Wait for the process (clone, fetch, pull or push) and handle its errors
    accordingly."""
    # TODO: No close proc-streams??
    proc.wait(**kwargs)


@overload
def expand_path(p: None, expand_vars: bool = ...) -> None: ...


@overload
def expand_path(p: PathLike, expand_vars: bool = ...) -> str:
    # TODO: Support for Python 3.5 has been dropped, so these overloads can be improved.
    ...


def expand_path(p: Union[None, PathLike], expand_vars: bool = True) -> Optional[PathLike]:
    if isinstance(p, pathlib.Path):
        return p.resolve()
    try:
        p = osp.expanduser(p)  # type: ignore[arg-type]
        if expand_vars:
            p = osp.expandvars(p)
        return osp.normpath(osp.abspath(p))
    except Exception:
        return None


def remove_password_if_present(cmdline: Sequence[str]) -> List[str]:
    """Parse any command line argument and if one of the elements is an URL with a
    username and/or password, replace them by stars (in-place).

    If nothing is found, this just returns the command line as-is.

    This should be used for every log line that print a command line, as well as
    exception messages.
    """
    new_cmdline = []
    for index, to_parse in enumerate(cmdline):
        new_cmdline.append(to_parse)
        try:
            url = urlsplit(to_parse)
            # Remove password from the URL if present.
            if url.password is None and url.username is None:
                continue

            if url.password is not None:
                url = url._replace(netloc=url.netloc.replace(url.password, "*****"))
            if url.username is not None:
                url = url._replace(netloc=url.netloc.replace(url.username, "*****"))
            new_cmdline[index] = urlunsplit(url)
        except ValueError:
            # This is not a valid URL.
            continue
    return new_cmdline


# } END utilities

# { Classes


class RemoteProgress:
    """Handler providing an interface to parse progress information emitted by
    :manpage:`git-push(1)` and :manpage:`git-fetch(1)` and to dispatch callbacks
    allowing subclasses to react to the progress."""

    _num_op_codes: int = 9
    (
        BEGIN,
        END,
        COUNTING,
        COMPRESSING,
        WRITING,
        RECEIVING,
        RESOLVING,
        FINDING_SOURCES,
        CHECKING_OUT,
    ) = [1 << x for x in range(_num_op_codes)]
    STAGE_MASK = BEGIN | END
    OP_MASK = ~STAGE_MASK

    DONE_TOKEN = "done."
    TOKEN_SEPARATOR = ", "

    __slots__ = (
        "_cur_line",
        "_seen_ops",
        "error_lines",  # Lines that started with 'error:' or 'fatal:'.
        "other_lines",  # Lines not denoting progress (i.e.g. push-infos).
    )
    re_op_absolute = re.compile(r"(remote: )?([\w\s]+):\s+()(\d+)()(.*)")
    re_op_relative = re.compile(r"(remote: )?([\w\s]+):\s+(\d+)% \((\d+)/(\d+)\)(.*)")

    def __init__(self) -> None:
        self._seen_ops: List[int] = []
        self._cur_line: Optional[str] = None
        self.error_lines: List[str] = []
        self.other_lines: List[str] = []

    def _parse_progress_line(self, line: AnyStr) -> None:
        """Parse progress information from the given line as retrieved by
        :manpage:`git-push(1)` or :manpage:`git-fetch(1)`.

        - Lines that do not contain progress info are stored in :attr:`other_lines`.
        - Lines that seem to contain an error (i.e. start with ``error:`` or ``fatal:``)
          are stored in :attr:`error_lines`.
        """
        # handle
        # Counting objects: 4, done.
        # Compressing objects:  50% (1/2)
        # Compressing objects: 100% (2/2)
        # Compressing objects: 100% (2/2), done.
        if isinstance(line, bytes):  # mypy argues about ternary assignment.
            line_str = line.decode("utf-8")
        else:
            line_str = line
        self._cur_line = line_str

        if self._cur_line.startswith(("error:", "fatal:")):
            self.error_lines.append(self._cur_line)
            return

        cur_count, max_count = None, None
        match = self.re_op_relative.match(line_str)
        if match is None:
            match = self.re_op_absolute.match(line_str)

        if not match:
            self.line_dropped(line_str)
            self.other_lines.append(line_str)
            return
        # END could not get match

        op_code = 0
        _remote, op_name, _percent, cur_count, max_count, message = match.groups()

        # Get operation ID.
        if op_name == "Counting objects":
            op_code |= self.COUNTING
        elif op_name == "Compressing objects":
            op_code |= self.COMPRESSING
        elif op_name == "Writing objects":
            op_code |= self.WRITING
        elif op_name == "Receiving objects":
            op_code |= self.RECEIVING
        elif op_name == "Resolving deltas":
            op_code |= self.RESOLVING
        elif op_name == "Finding sources":
            op_code |= self.FINDING_SOURCES
        elif op_name == "Checking out files":
            op_code |= self.CHECKING_OUT
        else:
            # Note: On Windows it can happen that partial lines are sent.
            # Hence we get something like "CompreReceiving objects", which is
            # a blend of "Compressing objects" and "Receiving objects".
            # This can't really be prevented, so we drop the line verbosely
            # to make sure we get informed in case the process spits out new
            # commands at some point.
            self.line_dropped(line_str)
            # Note: Don't add this line to the other lines, as we have to silently
            # drop it.
            return
        # END handle op code

        # Figure out stage.
        if op_code not in self._seen_ops:
            self._seen_ops.append(op_code)
            op_code |= self.BEGIN
        # END begin opcode

        if message is None:
            message = ""
        # END message handling

        message = message.strip()
        if message.endswith(self.DONE_TOKEN):
            op_code |= self.END
            message = message[: -len(self.DONE_TOKEN)]
        # END end message handling
        message = message.strip(self.TOKEN_SEPARATOR)

        self.update(
            op_code,
            cur_count and float(cur_count),
            max_count and float(max_count),
            message,
        )

    def new_message_handler(self) -> Callable[[str], None]:
        """
        :return:
            A progress handler suitable for :func:`~git.cmd.handle_process_output`,
            passing lines on to this progress handler in a suitable format.
        """

        def handler(line: AnyStr) -> None:
            return self._parse_progress_line(line.rstrip())

        # END handler

        return handler

    def line_dropped(self, line: str) -> None:
        """Called whenever a line could not be understood and was therefore dropped."""
        pass

    def update(
        self,
        op_code: int,
        cur_count: Union[str, float],
        max_count: Union[str, float, None] = None,
        message: str = "",
    ) -> None:
        """Called whenever the progress changes.

        :param op_code:
            Integer allowing to be compared against Operation IDs and stage IDs.

            Stage IDs are :const:`BEGIN` and :const:`END`. :const:`BEGIN` will only be
            set once for each Operation ID as well as :const:`END`. It may be that
            :const:`BEGIN` and :const:`END` are set at once in case only one progress
            message was emitted due to the speed of the operation. Between
            :const:`BEGIN` and :const:`END`, none of these flags will be set.

            Operation IDs are all held within the :const:`OP_MASK`. Only one Operation
            ID will be active per call.

        :param cur_count:
            Current absolute count of items.

        :param max_count:
            The maximum count of items we expect. It may be ``None`` in case there is no
            maximum number of items or if it is (yet) unknown.

        :param message:
            In case of the :const:`WRITING` operation, it contains the amount of bytes
            transferred. It may possibly be used for other purposes as well.

        :note:
            You may read the contents of the current line in
            :attr:`self._cur_line <_cur_line>`.
        """
        pass


class CallableRemoteProgress(RemoteProgress):
    """A :class:`RemoteProgress` implementation forwarding updates to any callable.

    :note:
        Like direct instances of :class:`RemoteProgress`, instances of this
        :class:`CallableRemoteProgress` class are not themselves directly callable.
        Rather, instances of this class wrap a callable and forward to it. This should
        therefore not be confused with :class:`git.types.CallableProgress`.
    """

    __slots__ = ("_callable",)

    def __init__(self, fn: Callable) -> None:
        self._callable = fn
        super().__init__()

    def update(self, *args: Any, **kwargs: Any) -> None:
        self._callable(*args, **kwargs)


class Actor:
    """Actors hold information about a person acting on the repository. They can be
    committers and authors or anything with a name and an email as mentioned in the git
    log entries."""

    # PRECOMPILED REGEX
    name_only_regex = re.compile(r"<(.*)>")
    name_email_regex = re.compile(r"(.*) <(.*?)>")

    # ENVIRONMENT VARIABLES
    # These are read when creating new commits.
    env_author_name = "GIT_AUTHOR_NAME"
    env_author_email = "GIT_AUTHOR_EMAIL"
    env_committer_name = "GIT_COMMITTER_NAME"
    env_committer_email = "GIT_COMMITTER_EMAIL"

    # CONFIGURATION KEYS
    conf_name = "name"
    conf_email = "email"

    __slots__ = ("name", "email")

    def __init__(self, name: Optional[str], email: Optional[str]) -> None:
        self.name = name
        self.email = email

    def __eq__(self, other: Any) -> bool:
        return self.name == other.name and self.email == other.email

    def __ne__(self, other: Any) -> bool:
        return not (self == other)

    def __hash__(self) -> int:
        return hash((self.name, self.email))

    def __str__(self) -> str:
        return self.name if self.name else ""

    def __repr__(self) -> str:
        return '<git.Actor "%s <%s>">' % (self.name, self.email)

    @classmethod
    def _from_string(cls, string: str) -> "Actor":
        """Create an :class:`Actor` from a string.

        :param string:
            The string, which is expected to be in regular git format::

                John Doe <jdoe@example.com>

        :return:
            :class:`Actor`
        """
        m = cls.name_email_regex.search(string)
        if m:
            name, email = m.groups()
            return Actor(name, email)
        else:
            m = cls.name_only_regex.search(string)
            if m:
                return Actor(m.group(1), None)
            # Assume the best and use the whole string as name.
            return Actor(string, None)
            # END special case name
        # END handle name/email matching

    @classmethod
    def _main_actor(
        cls,
        env_name: str,
        env_email: str,
        config_reader: Union[None, "GitConfigParser", "SectionConstraint"] = None,
    ) -> "Actor":
        actor = Actor("", "")
        user_id = None  # We use this to avoid multiple calls to getpass.getuser().

        def default_email() -> str:
            nonlocal user_id
            if not user_id:
                user_id = get_user_id()
            return user_id

        def default_name() -> str:
            return default_email().split("@")[0]

        for attr, evar, cvar, default in (
            ("name", env_name, cls.conf_name, default_name),
            ("email", env_email, cls.conf_email, default_email),
        ):
            try:
                val = os.environ[evar]
                setattr(actor, attr, val)
            except KeyError:
                if config_reader is not None:
                    try:
                        val = config_reader.get("user", cvar)
                    except Exception:
                        val = default()
                    setattr(actor, attr, val)
                # END config-reader handling
                if not getattr(actor, attr):
                    setattr(actor, attr, default())
            # END handle name
        # END for each item to retrieve
        return actor

    @classmethod
    def committer(cls, config_reader: Union[None, "GitConfigParser", "SectionConstraint"] = None) -> "Actor":
        """
        :return:
            :class:`Actor` instance corresponding to the configured committer. It
            behaves similar to the git implementation, such that the environment will
            override configuration values of `config_reader`. If no value is set at all,
            it will be generated.

        :param config_reader:
            ConfigReader to use to retrieve the values from in case they are not set in
            the environment.
        """
        return cls._main_actor(cls.env_committer_name, cls.env_committer_email, config_reader)

    @classmethod
    def author(cls, config_reader: Union[None, "GitConfigParser", "SectionConstraint"] = None) -> "Actor":
        """Same as :meth:`committer`, but defines the main author. It may be specified
        in the environment, but defaults to the committer."""
        return cls._main_actor(cls.env_author_name, cls.env_author_email, config_reader)


class Stats:
    """Represents stat information as presented by git at the end of a merge. It is
    created from the output of a diff operation.

    Example::

     c = Commit( sha1 )
     s = c.stats
     s.total         # full-stat-dict
     s.files         # dict( filepath : stat-dict )

    ``stat-dict``

    A dictionary with the following keys and values::

      deletions = number of deleted lines as int
      insertions = number of inserted lines as int
      lines = total number of lines changed as int, or deletions + insertions

    ``full-stat-dict``

    In addition to the items in the stat-dict, it features additional information::

     files = number of changed files as int
    """

    __slots__ = ("total", "files")

    def __init__(self, total: Total_TD, files: Dict[PathLike, Files_TD]) -> None:
        self.total = total
        self.files = files

    @classmethod
    def _list_from_string(cls, repo: "Repo", text: str) -> "Stats":
        """Create a :class:`Stats` object from output retrieved by
        :manpage:`git-diff(1)`.

        :return:
            :class:`git.Stats`
        """

        hsh: HSH_TD = {
            "total": {"insertions": 0, "deletions": 0, "lines": 0, "files": 0},
            "files": {},
        }
        for line in text.splitlines():
            (raw_insertions, raw_deletions, filename) = line.split("\t")
            insertions = raw_insertions != "-" and int(raw_insertions) or 0
            deletions = raw_deletions != "-" and int(raw_deletions) or 0
            hsh["total"]["insertions"] += insertions
            hsh["total"]["deletions"] += deletions
            hsh["total"]["lines"] += insertions + deletions
            hsh["total"]["files"] += 1
            files_dict: Files_TD = {
                "insertions": insertions,
                "deletions": deletions,
                "lines": insertions + deletions,
            }
            hsh["files"][filename.strip()] = files_dict
        return Stats(hsh["total"], hsh["files"])


class IndexFileSHA1Writer:
    """Wrapper around a file-like object that remembers the SHA1 of the data written to
    it. It will write a sha when the stream is closed or if asked for explicitly using
    :meth:`write_sha`.

    Only useful to the index file.

    :note:
        Based on the dulwich project.
    """

    __slots__ = ("f", "sha1")

    def __init__(self, f: IO) -> None:
        self.f = f
        self.sha1 = make_sha(b"")

    def write(self, data: AnyStr) -> int:
        self.sha1.update(data)
        return self.f.write(data)

    def write_sha(self) -> bytes:
        sha = self.sha1.digest()
        self.f.write(sha)
        return sha

    def close(self) -> bytes:
        sha = self.write_sha()
        self.f.close()
        return sha

    def tell(self) -> int:
        return self.f.tell()


class LockFile:
    """Provides methods to obtain, check for, and release a file based lock which
    should be used to handle concurrent access to the same file.

    As we are a utility class to be derived from, we only use protected methods.

    Locks will automatically be released on destruction.
    """

    __slots__ = ("_file_path", "_owns_lock")

    def __init__(self, file_path: PathLike) -> None:
        self._file_path = file_path
        self._owns_lock = False

    def __del__(self) -> None:
        self._release_lock()

    def _lock_file_path(self) -> str:
        """:return: Path to lockfile"""
        return "%s.lock" % (self._file_path)

    def _has_lock(self) -> bool:
        """
        :return:
            True if we have a lock and if the lockfile still exists

        :raise AssertionError:
            If our lock-file does not exist.
        """
        return self._owns_lock

    def _obtain_lock_or_raise(self) -> None:
        """Create a lock file as flag for other instances, mark our instance as
        lock-holder.

        :raise IOError:
            If a lock was already present or a lock file could not be written.
        """
        if self._has_lock():
            return
        lock_file = self._lock_file_path()
        if osp.isfile(lock_file):
            raise IOError(
                "Lock for file %r did already exist, delete %r in case the lock is illegal"
                % (self._file_path, lock_file)
            )

        try:
            with open(lock_file, mode="w"):
                pass
        except OSError as e:
            raise IOError(str(e)) from e

        self._owns_lock = True

    def _obtain_lock(self) -> None:
        """The default implementation will raise if a lock cannot be obtained.

        Subclasses may override this method to provide a different implementation.
        """
        return self._obtain_lock_or_raise()

    def _release_lock(self) -> None:
        """Release our lock if we have one."""
        if not self._has_lock():
            return

        # If someone removed our file beforehand, lets just flag this issue instead of
        # failing, to make it more usable.
        lfp = self._lock_file_path()
        try:
            rmfile(lfp)
        except OSError:
            pass
        self._owns_lock = False


class BlockingLockFile(LockFile):
    """The lock file will block until a lock could be obtained, or fail after a
    specified timeout.

    :note:
        If the directory containing the lock was removed, an exception will be raised
        during the blocking period, preventing hangs as the lock can never be obtained.
    """

    __slots__ = ("_check_interval", "_max_block_time")

    def __init__(
        self,
        file_path: PathLike,
        check_interval_s: float = 0.3,
        max_block_time_s: int = sys.maxsize,
    ) -> None:
        """Configure the instance.

        :param check_interval_s:
            Period of time to sleep until the lock is checked the next time.
            By default, it waits a nearly unlimited time.

        :param max_block_time_s:
            Maximum amount of seconds we may lock.
        """
        super().__init__(file_path)
        self._check_interval = check_interval_s
        self._max_block_time = max_block_time_s

    def _obtain_lock(self) -> None:
        """This method blocks until it obtained the lock, or raises :exc:`IOError` if it
        ran out of time or if the parent directory was not available anymore.

        If this method returns, you are guaranteed to own the lock.
        """
        starttime = time.time()
        maxtime = starttime + float(self._max_block_time)
        while True:
            try:
                super()._obtain_lock()
            except IOError as e:
                # synity check: if the directory leading to the lockfile is not
                # readable anymore, raise an exception
                curtime = time.time()
                if not osp.isdir(osp.dirname(self._lock_file_path())):
                    msg = "Directory containing the lockfile %r was not readable anymore after waiting %g seconds" % (
                        self._lock_file_path(),
                        curtime - starttime,
                    )
                    raise IOError(msg) from e
                # END handle missing directory

                if curtime >= maxtime:
                    msg = "Waited %g seconds for lock at %r" % (
                        maxtime - starttime,
                        self._lock_file_path(),
                    )
                    raise IOError(msg) from e
                # END abort if we wait too long
                time.sleep(self._check_interval)
            else:
                break
        # END endless loop


class IterableList(List[T_IterableObj]):
    """List of iterable objects allowing to query an object by id or by named index::

     heads = repo.heads
     heads.master
     heads['master']
     heads[0]

    Iterable parent objects:

    * :class:`Commit <git.objects.Commit>`
    * :class:`Submodule <git.objects.submodule.base.Submodule>`
    * :class:`Reference <git.refs.reference.Reference>`
    * :class:`FetchInfo <git.remote.FetchInfo>`
    * :class:`PushInfo <git.remote.PushInfo>`

    Iterable via inheritance:

    * :class:`Head <git.refs.head.Head>`
    * :class:`TagReference <git.refs.tag.TagReference>`
    * :class:`RemoteReference <git.refs.remote.RemoteReference>`

    This requires an ``id_attribute`` name to be set which will be queried from its
    contained items to have a means for comparison.

    A prefix can be specified which is to be used in case the id returned by the items
    always contains a prefix that does not matter to the user, so it can be left out.
    """

    __slots__ = ("_id_attr", "_prefix")

    def __new__(cls, id_attr: str, prefix: str = "") -> "IterableList[T_IterableObj]":
        return super().__new__(cls)

    def __init__(self, id_attr: str, prefix: str = "") -> None:
        self._id_attr = id_attr
        self._prefix = prefix

    def __contains__(self, attr: object) -> bool:
        # First try identity match for performance.
        try:
            rval = list.__contains__(self, attr)
            if rval:
                return rval
        except (AttributeError, TypeError):
            pass
        # END handle match

        # Otherwise make a full name search.
        try:
            getattr(self, cast(str, attr))  # Use cast to silence mypy.
            return True
        except (AttributeError, TypeError):
            return False
        # END handle membership

    def __getattr__(self, attr: str) -> T_IterableObj:
        attr = self._prefix + attr
        for item in self:
            if getattr(item, self._id_attr) == attr:
                return item
        # END for each item
        return list.__getattribute__(self, attr)

    def __getitem__(self, index: Union[SupportsIndex, int, slice, str]) -> T_IterableObj:  # type: ignore[override]
        assert isinstance(index, (int, str, slice)), "Index of IterableList should be an int or str"

        if isinstance(index, int):
            return list.__getitem__(self, index)
        elif isinstance(index, slice):
            raise ValueError("Index should be an int or str")
        else:
            try:
                return getattr(self, index)
            except AttributeError as e:
                raise IndexError("No item found with id %r" % (self._prefix + index)) from e
        # END handle getattr

    def __delitem__(self, index: Union[SupportsIndex, int, slice, str]) -> None:
        assert isinstance(index, (int, str)), "Index of IterableList should be an int or str"

        delindex = cast(int, index)
        if not isinstance(index, int):
            delindex = -1
            name = self._prefix + index
            for i, item in enumerate(self):
                if getattr(item, self._id_attr) == name:
                    delindex = i
                    break
                # END search index
            # END for each item
            if delindex == -1:
                raise IndexError("Item with name %s not found" % name)
            # END handle error
        # END get index to delete
        list.__delitem__(self, delindex)


@runtime_checkable
class IterableObj(Protocol):
    """Defines an interface for iterable items, so there is a uniform way to retrieve
    and iterate items within the git repository.

    Subclasses:

    * :class:`Submodule <git.objects.submodule.base.Submodule>`
    * :class:`Commit <git.objects.Commit>`
    * :class:`Reference <git.refs.reference.Reference>`
    * :class:`PushInfo <git.remote.PushInfo>`
    * :class:`FetchInfo <git.remote.FetchInfo>`
    * :class:`Remote <git.remote.Remote>`
    """

    __slots__ = ()

    _id_attribute_: str

    @classmethod
    @abstractmethod
    def iter_items(cls, repo: "Repo", *args: Any, **kwargs: Any) -> Iterator[T_IterableObj]:
        # Return-typed to be compatible with subtypes e.g. Remote.
        """Find (all) items of this type.

        Subclasses can specify `args` and `kwargs` differently, and may use them for
        filtering. However, when the method is called with no additional positional or
        keyword arguments, subclasses are obliged to to yield all items.

        :return:
            Iterator yielding Items
        """
        raise NotImplementedError("To be implemented by Subclass")

    @classmethod
    def list_items(cls, repo: "Repo", *args: Any, **kwargs: Any) -> IterableList[T_IterableObj]:
        """Find (all) items of this type and collect them into a list.

        For more information about the arguments, see :meth:`iter_items`.

        :note:
            Favor the :meth:`iter_items` method as it will avoid eagerly collecting all
            items. When there are many items, that can slow performance and increase
            memory usage.

        :return:
            list(Item,...) list of item instances
        """
        out_list: IterableList = IterableList(cls._id_attribute_)
        out_list.extend(cls.iter_items(repo, *args, **kwargs))
        return out_list


class IterableClassWatcher(type):
    """Metaclass that issues :exc:`DeprecationWarning` when :class:`git.util.Iterable`
    is subclassed."""

    def __init__(cls, name: str, bases: Tuple, clsdict: Dict) -> None:
        for base in bases:
            if type(base) is IterableClassWatcher:
                warnings.warn(
                    f"GitPython Iterable subclassed by {name}."
                    " Iterable is deprecated due to naming clash since v3.1.18"
                    " and will be removed in 4.0.0."
                    " Use IterableObj instead.",
                    DeprecationWarning,
                    stacklevel=2,
                )


class Iterable(metaclass=IterableClassWatcher):
    """Deprecated, use :class:`IterableObj` instead.

    Defines an interface for iterable items, so there is a uniform way to retrieve
    and iterate items within the git repository.
    """

    __slots__ = ()

    _id_attribute_ = "attribute that most suitably identifies your instance"

    @classmethod
    def iter_items(cls, repo: "Repo", *args: Any, **kwargs: Any) -> Any:
        """Deprecated, use :class:`IterableObj` instead.

        Find (all) items of this type.

        See :meth:`IterableObj.iter_items` for details on usage.

        :return:
            Iterator yielding Items
        """
        raise NotImplementedError("To be implemented by Subclass")

    @classmethod
    def list_items(cls, repo: "Repo", *args: Any, **kwargs: Any) -> Any:
        """Deprecated, use :class:`IterableObj` instead.

        Find (all) items of this type and collect them into a list.

        See :meth:`IterableObj.list_items` for details on usage.

        :return:
            list(Item,...) list of item instances
        """
        out_list: Any = IterableList(cls._id_attribute_)
        out_list.extend(cls.iter_items(repo, *args, **kwargs))
        return out_list


# } END classes