"""Unix."""

from __future__ import annotations

import os
import re
import stat
import sys
from pathlib import Path
from tempfile import gettempdir
from typing import TYPE_CHECKING, Final, NoReturn

from ._xdg import XDGMixin, _xdg_dir
from .api import PlatformDirsABC

if TYPE_CHECKING:
    from collections.abc import Iterator

if sys.platform == "win32":

    def getuid() -> NoReturn:
        msg = "should only be used on Unix"
        raise RuntimeError(msg)

else:
    from os import getuid


class _UnixDefaults(PlatformDirsABC):  # ruff:ignore[too-many-public-methods]
    """Default directories for Unix/Linux without XDG environment variable overrides.

    The XDG env var handling is in :class:`~platformdirs._xdg.XDGMixin`.

    """

    @property
    def _use_site(self) -> bool:
        return self.use_site_for_root and getuid() == 0

    @property
    def user_data_dir(self) -> str:
        """Data directory tied to the user, e.g. ``~/.local/share/$appname/$version`` or ``$XDG_DATA_HOME/$appname/$version``."""
        return self._append_app_name_and_version(os.path.expanduser("~/.local/share"))  # ruff:ignore[os-path-expanduser]

    @property
    def _site_data_dirs(self) -> list[str]:
        return [self._join_app_name_and_version("/usr/local/share"), self._join_app_name_and_version("/usr/share")]

    @property
    def user_config_dir(self) -> str:
        """Config directory tied to the user, e.g. ``~/.config/$appname/$version`` or ``$XDG_CONFIG_HOME/$appname/$version``."""
        return self._append_app_name_and_version(os.path.expanduser("~/.config"))  # ruff:ignore[os-path-expanduser]

    @property
    def _site_config_dirs(self) -> list[str]:
        return [self._join_app_name_and_version("/etc/xdg")]

    @property
    def user_cache_dir(self) -> str:
        """Cache directory tied to the user, e.g. ``~/.cache/$appname/$version`` or ``$XDG_CACHE_HOME/$appname/$version``."""
        return self._append_app_name_and_version(os.path.expanduser("~/.cache"))  # ruff:ignore[os-path-expanduser]

    @property
    def site_cache_dir(self) -> str:
        """Cache directory shared by users, e.g. ``/var/cache/$appname/$version``."""
        return self._append_app_name_and_version("/var/cache")

    @property
    def user_state_dir(self) -> str:
        """State directory tied to the user, e.g. ``~/.local/state/$appname/$version`` or ``$XDG_STATE_HOME/$appname/$version``."""
        return self._append_app_name_and_version(os.path.expanduser("~/.local/state"))  # ruff:ignore[os-path-expanduser]

    @property
    def site_state_dir(self) -> str:
        """State directory shared by users, e.g. ``/var/lib/$appname/$version``."""
        return self._append_app_name_and_version("/var/lib")

    @property
    def user_log_dir(self) -> str:
        """Log directory tied to the user, same as `user_state_dir` if not opinionated else ``log`` in it."""
        path = self.user_state_dir
        if self.opinion:
            path = os.path.join(path, "log")  # ruff:ignore[os-path-join]
            self._optionally_create_directory(path)
        return path

    @property
    def site_log_dir(self) -> str:
        """Log directory shared by users, e.g. ``/var/log/$appname/$version``.

        Unlike `user_log_dir`, ``opinion`` has no effect since ``/var/log`` is inherently a log directory.

        """
        return self._append_app_name_and_version("/var/log")

    @property
    def user_documents_dir(self) -> str:
        """Documents directory tied to the user, e.g. ``~/Documents``."""
        return self._user_media_dir("XDG_DOCUMENTS_DIR", "~/Documents")

    @property
    def user_downloads_dir(self) -> str:
        """Downloads directory tied to the user, e.g. ``~/Downloads``."""
        return self._user_media_dir("XDG_DOWNLOAD_DIR", "~/Downloads")

    @property
    def user_pictures_dir(self) -> str:
        """Pictures directory tied to the user, e.g. ``~/Pictures``."""
        return self._user_media_dir("XDG_PICTURES_DIR", "~/Pictures")

    @property
    def user_videos_dir(self) -> str:
        """Videos directory tied to the user, e.g. ``~/Videos``."""
        return self._user_media_dir("XDG_VIDEOS_DIR", "~/Videos")

    @property
    def user_music_dir(self) -> str:
        """Music directory tied to the user, e.g. ``~/Music``."""
        return self._user_media_dir("XDG_MUSIC_DIR", "~/Music")

    @property
    def user_desktop_dir(self) -> str:
        """Desktop directory tied to the user, e.g. ``~/Desktop``."""
        return self._user_media_dir("XDG_DESKTOP_DIR", "~/Desktop")

    @property
    def user_projects_dir(self) -> str:
        """Projects directory tied to the user, e.g. ``~/Projects``."""
        return self._user_media_dir("XDG_PROJECTS_DIR", "~/Projects")

    @property
    def user_publicshare_dir(self) -> str:
        """Public share directory tied to the user, e.g. ``~/Public``."""
        return self._user_media_dir("XDG_PUBLICSHARE_DIR", "~/Public")

    @property
    def user_templates_dir(self) -> str:
        """Templates directory tied to the user, e.g. ``~/Templates``."""
        return self._user_media_dir("XDG_TEMPLATES_DIR", "~/Templates")

    def _user_media_dir(self, key: str, default: str) -> str:
        if path := _get_user_dirs_folder(key):
            self._optionally_create_media_directory(path)
            return path
        return os.path.expanduser(default)  # ruff:ignore[os-path-expanduser]

    @property
    def user_fonts_dir(self) -> str:
        """Fonts directory tied to the user, e.g. ``~/.local/share/fonts``."""
        return f"{os.path.expanduser('~/.local/share')}/fonts"  # ruff:ignore[os-path-expanduser]  # API returns str, not Path

    @property
    def user_preference_dir(self) -> str:
        """Preference directory tied to the user, same as ``user_config_dir``."""
        return self.user_config_dir

    @property
    def user_bin_dir(self) -> str:
        """Bin directory tied to the user, e.g. ``~/.local/bin``."""
        return os.path.expanduser("~/.local/bin")  # ruff:ignore[os-path-expanduser]

    @property
    def site_bin_dir(self) -> str:
        """Bin directory shared by users, e.g. ``/usr/local/bin``."""
        return "/usr/local/bin"

    @property
    def user_applications_dir(self) -> str:
        """Applications directory tied to the user, e.g. ``~/.local/share/applications``."""
        return os.path.join(os.path.expanduser("~/.local/share"), "applications")  # ruff:ignore[os-path-expanduser, os-path-join]

    @property
    def _site_applications_dirs(self) -> list[str]:
        return [os.path.join(p, "applications") for p in ["/usr/local/share", "/usr/share"]]  # ruff:ignore[os-path-join]

    @property
    def site_applications_dir(self) -> str:
        """Applications directory shared by users, e.g. ``/usr/share/applications``."""
        dirs = self._site_applications_dirs
        return os.pathsep.join(dirs) if self.multipath else dirs[0]

    @property
    def user_runtime_dir(self) -> str:
        """Runtime directory tied to the user, e.g. ``$XDG_RUNTIME_DIR/$appname/$version``.

        If ``$XDG_RUNTIME_DIR`` is unset, tries the platform default (``/tmp/run/user/$(id -u)`` on OpenBSD,
        ``/var/run/user/$(id -u)`` on FreeBSD/NetBSD, ``/run/user/$(id -u)`` otherwise). If the default is not writable,
        falls back to ``runtime-$(id -u)`` in the temporary directory, with mode ``0700`` under ``ensure_exists``.

        :raises PermissionError: if another user owns the temporary fallback directory.

        """
        if sys.platform.startswith("openbsd"):
            path = f"/tmp/run/user/{getuid()}"  # ruff:ignore[hardcoded-temp-file]
        elif sys.platform.startswith(("freebsd", "netbsd")):
            path = f"/var/run/user/{getuid()}"
        else:
            path = f"/run/user/{getuid()}"
        if not os.access(path, os.W_OK):
            path = self._temp_runtime_dir()
        return self._append_app_name_and_version(path)

    def _temp_runtime_dir(self) -> str:
        # Another user can pre-create this predictable name, and XDG requires an owned runtime dir with mode 0700.
        path = f"{gettempdir()}/runtime-{(uid := getuid())}"
        if self.ensure_exists:
            Path(path).mkdir(mode=0o700, exist_ok=True)
        try:
            info = Path(path).lstat()
        except FileNotFoundError:
            return path
        if info.st_uid != uid:
            msg = f"runtime directory {path} is owned by uid {info.st_uid}, not {uid}; set XDG_RUNTIME_DIR instead"
            raise PermissionError(msg)
        # Earlier releases created this directory with the default 0755.
        if self.ensure_exists and stat.S_IMODE(info.st_mode) & 0o077:
            Path(path).chmod(0o700)
        return path

    @property
    def site_runtime_dir(self) -> str:
        """Runtime directory shared by users, e.g. ``/run/$appname/$version`` or ``$XDG_RUNTIME_DIR/$appname/$version``.

        Note that this behaves almost exactly like `user_runtime_dir` if ``$XDG_RUNTIME_DIR`` is set, but will fall back
        to paths associated to the root user instead of a regular logged-in user if it's not set.

        If you wish to ensure that a logged-in root user path is returned e.g. ``/run/user/0``, use `user_runtime_dir`
        instead.

        For FreeBSD/OpenBSD/NetBSD, it would return ``/var/run/$appname/$version`` if ``$XDG_RUNTIME_DIR`` is not set.

        """
        if sys.platform.startswith(("freebsd", "openbsd", "netbsd")):
            path = "/var/run"
        else:
            path = "/run"
        return self._append_app_name_and_version(path)

    @property
    def site_data_path(self) -> Path:
        """Data path shared by users. Only return the first item, even if ``multipath`` is set to ``True``."""
        return self._first_site_dir_as_path(self._site_data_dirs)

    @property
    def site_config_path(self) -> Path:
        """Config path shared by users, returns the first item, even if ``multipath`` is set to ``True``."""
        return self._first_site_dir_as_path(self._site_config_dirs)

    def _iter_config_dirs(self) -> Iterator[str]:
        # Under multipath the user dir is an os.pathsep-joined string that no single site entry matches, so the
        # dedupe in iter_config_dirs cannot drop it. Skip it here instead.
        if not self._use_site:
            yield self.user_config_dir
        yield from self._create_as_yielded(self._site_config_dirs)

    def _iter_data_dirs(self) -> Iterator[str]:
        if not self._use_site:
            yield self.user_data_dir
        yield from self._create_as_yielded(self._site_data_dirs)

    def _iter_cache_dirs(self) -> Iterator[str]:
        if not self._use_site:
            yield self.user_cache_dir
        yield self.site_cache_dir

    def _iter_state_dirs(self) -> Iterator[str]:
        if not self._use_site:
            yield self.user_state_dir
        yield self.site_state_dir

    def _iter_log_dirs(self) -> Iterator[str]:
        if not self._use_site:
            yield self.user_log_dir
        yield self.site_log_dir

    def _iter_runtime_dirs(self) -> Iterator[str]:
        yield self.user_runtime_dir
        if not self._use_site:
            yield self.site_runtime_dir


class Unix(XDGMixin, _UnixDefaults):
    """On Unix/Linux, we follow the `XDG Basedir Spec <https://specifications.freedesktop.org/basedir/latest/>`_.

    The spec allows overriding directories with environment variables. The examples shown are the default values,
    alongside the name of the environment variable that overrides them. Makes use of the `appname
    <platformdirs.api.PlatformDirsABC.appname>`, `version <platformdirs.api.PlatformDirsABC.version>`, `multipath
    <platformdirs.api.PlatformDirsABC.multipath>`, `opinion <platformdirs.api.PlatformDirsABC.opinion>`, `ensure_exists
    <platformdirs.api.PlatformDirsABC.ensure_exists>`.

    """

    @property
    def user_data_dir(self) -> str:
        """Data directory tied to the user, or site equivalent when root with ``use_site_for_root``."""
        return self.site_data_dir if self._use_site else super().user_data_dir

    @property
    def user_config_dir(self) -> str:
        """Config directory tied to the user, or site equivalent when root with ``use_site_for_root``."""
        return self.site_config_dir if self._use_site else super().user_config_dir

    @property
    def user_cache_dir(self) -> str:
        """Cache directory tied to the user, or site equivalent when root with ``use_site_for_root``."""
        return self.site_cache_dir if self._use_site else super().user_cache_dir

    @property
    def user_state_dir(self) -> str:
        """State directory tied to the user, or site equivalent when root with ``use_site_for_root``."""
        return self.site_state_dir if self._use_site else super().user_state_dir

    @property
    def user_log_dir(self) -> str:
        """Log directory tied to the user, or site equivalent when root with ``use_site_for_root``."""
        return self.site_log_dir if self._use_site else super().user_log_dir

    @property
    def user_applications_dir(self) -> str:
        """Applications directory tied to the user, or site equivalent when root with ``use_site_for_root``."""
        return self.site_applications_dir if self._use_site else super().user_applications_dir

    @property
    def user_runtime_dir(self) -> str:
        """Runtime directory tied to the user, or site equivalent when root with ``use_site_for_root``."""
        # XDGMixin.site_runtime_dir reads $XDG_RUNTIME_DIR, which belongs to the user who started the root process.
        return super(XDGMixin, self).site_runtime_dir if self._use_site else super().user_runtime_dir

    @property
    def user_bin_dir(self) -> str:
        """Bin directory tied to the user, or site equivalent when root with ``use_site_for_root``."""
        return self.site_bin_dir if self._use_site else super().user_bin_dir

    @property
    def user_data_path(self) -> Path:
        """Data path tied to the user, or the first site entry when root with ``use_site_for_root``."""
        return self.site_data_path if self._use_site else super().user_data_path

    @property
    def user_config_path(self) -> Path:
        """Config path tied to the user, or the first site entry when root with ``use_site_for_root``."""
        return self.site_config_path if self._use_site else super().user_config_path

    @property
    def user_preference_path(self) -> Path:
        """Preference path tied to the user, or the first site config entry when root with ``use_site_for_root``."""
        return self.site_config_path if self._use_site else super().user_preference_path

    @property
    def user_applications_path(self) -> Path:
        """Applications path tied to the user, or the first site entry when root with ``use_site_for_root``."""
        return self.site_applications_path if self._use_site else super().user_applications_path


_USER_DIRS_LINE: Final = re.compile(
    r"""
    [ \t]*(?P<key>\w+)[ \t]*=[ \t]*  # KEY=, blanks allowed around the key and after the =
    (?:
        "(?P<quoted>(?:[^"\\]|\\.)*)"  # a double-quoted value with backslash escapes, text after it ignored
        |(?P<bare>[^"\s].*?)          # or an unquoted value, up to
        (?:[ \t]+\#.*|[ \t]*)$         # a comment, which sh starts at a word-initial #, or the line end
    )
    """,
    re.VERBOSE,
)


def _get_user_dirs_folder(key: str) -> str | None:
    """Return directory from user-dirs.dirs config file.

    ``xdg-user-dirs-update`` writes shell assignments, so match each line like ``xdg-user-dir`` does and keep the last
    valid assignment to ``key``.

    See https://freedesktop.org/wiki/Software/xdg-user-dirs/.

    """
    config_home = _xdg_dir("XDG_CONFIG_HOME") or os.path.expanduser("~/.config")  # ruff:ignore[os-path-expanduser]
    user_dirs_config_path = Path(config_home) / "user-dirs.dirs"
    if not user_dirs_config_path.exists():
        return None
    folder = None
    # the file holds raw path bytes, and surrogateescape round-trips undecodable ones like os.fsdecode
    with user_dirs_config_path.open(encoding=sys.getfilesystemencoding(), errors="surrogateescape") as stream:
        for line in stream:
            if (entry := _USER_DIRS_LINE.match(line)) and entry["key"] == key:
                folder = _resolve_user_dirs_value(entry) or folder
    return folder


def _resolve_user_dirs_value(entry: re.Match[str]) -> str | None:
    value = entry["bare"] if entry["quoted"] is None else entry["quoted"]
    if value == "$HOME" or value.startswith("$HOME/"):
        prefix, value = os.path.expanduser("~"), value.removeprefix("$HOME")  # ruff:ignore[os-path-expanduser]
    elif value.startswith("/"):
        prefix = ""
    else:
        return None
    if entry["quoted"] is not None:
        # xdg-user-dirs-update backslash-escapes $, `, " and \ inside the quotes.
        value = re.sub(r"\\(.)", r"\1", value)
    return prefix + value


__all__ = [
    "Unix",
]