"""
In-place update on Linux.

Detects how the app is installed (deb/rpm package or a standalone binary)
and updates it without a manual download: packages go through the package
manager, a standalone binary is replaced with the release file. Without
write access the install runs through pkexec. Unsupported setups (AUR, pip,
non-amd64, no pkexec) yield None and the caller shows the release page.
"""
from __future__ import annotations

import logging
import os
import platform
import shutil
import subprocess
import sys
import tempfile
from pathlib import Path
from typing import Dict, List, Optional

BINARY_ASSET = "TgWsProxy_linux_amd64"

# install kind -> release asset suffix
ASSET_SUFFIX = {"binary": "", "deb": ".deb", "rpm": ".rpm"}

_INSTALL_TIMEOUT_SEC = 600.0


def _run_quiet(cmd: List[str]) -> bool:
    try:
        return subprocess.run(
            cmd,
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
            timeout=15,
        ).returncode == 0
    except (OSError, subprocess.SubprocessError):
        return False


def exe_path() -> Path:
    return Path(os.path.realpath(sys.executable))


def _is_root() -> bool:
    return hasattr(os, "geteuid") and os.geteuid() == 0


def _can_elevate() -> bool:
    return _is_root() or bool(shutil.which("pkexec"))


def _elevate() -> List[str]:
    return [] if _is_root() else ["pkexec"]


def detect_install_kind(exe: Optional[Path] = None) -> Optional[str]:
    """How the app is installed: "deb", "rpm", "binary" or None."""
    exe = exe or exe_path()
    if platform.machine().lower() not in ("x86_64", "amd64"):
        return None  # releases ship amd64 only
    if shutil.which("pacman") and _run_quiet(["pacman", "-Qo", str(exe)]):
        return None  # AUR install, updated by its own package manager

    can_elevate = _can_elevate()
    if shutil.which("dpkg-query") and _run_quiet(["dpkg-query", "-S", str(exe)]):
        return "deb" if can_elevate else None
    if shutil.which("rpm") and _run_quiet(["rpm", "-qf", str(exe)]):
        return "rpm" if can_elevate else None

    # replacing the binary needs a writable directory or root
    if os.access(str(exe.parent), os.W_OK) or can_elevate:
        return "binary"
    return None


def asset_name(kind: str) -> str:
    return BINARY_ASSET + ASSET_SUFFIX[kind]


def install_cmd(kind: str, path: Path) -> List[str]:
    """Command that installs the downloaded package."""
    elevate = _elevate()
    if kind == "deb":
        if shutil.which("apt-get"):
            return elevate + [
                "apt-get", "install", "-y", "--reinstall",
                "--allow-downgrades", str(path),
            ]
        return elevate + ["dpkg", "-i", str(path)]
    if kind == "rpm":
        if shutil.which("dnf"):
            return elevate + ["dnf", "install", "-y", str(path)]
        return elevate + ["rpm", "-U", "--force", str(path)]
    raise ValueError("no install command for kind: {0}".format(kind))


def replace_binary_cmd(src: Path, exe: Path) -> List[str]:
    """Replace the binary as root; install(1) avoids ETXTBSY on the running file."""
    return _elevate() + ["install", "-m", "755", str(src), str(exe)]


def _run_install(cmd: List[str], log: Optional[logging.Logger] = None) -> Optional[str]:
    if log:
        log.info("Linux update: %s", " ".join(cmd))
    proc = subprocess.run(
        cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
        timeout=_INSTALL_TIMEOUT_SEC,
    )
    if proc.returncode == 0:
        return None
    err = (proc.stderr or proc.stdout or b"").decode("utf-8", "replace").strip()
    return err[-500:] or "exit code {0}".format(proc.returncode)


def apply_update(
    kind: str, url: str, digest: str = "",
    log: Optional[logging.Logger] = None,
) -> Optional[str]:
    """Download and install the update.

    Returns:
        Error text, or None on success.
    """
    from utils.update_check import download_asset

    exe = exe_path()
    suffix = ASSET_SUFFIX[kind] or ".new"
    # with a writable directory download next to the binary and os.replace it
    in_place = kind == "binary" and os.access(str(exe.parent), os.W_OK)
    dest_dir = exe.parent if in_place else Path(tempfile.gettempdir())

    if log:
        log.info("Linux update (%s): downloading %s", kind, url)
    try:
        tmp = download_asset(url, dest_dir, suffix=suffix, digest=digest)
    except Exception as exc:
        return str(exc)

    try:
        if kind != "binary":
            return _run_install(install_cmd(kind, tmp), log=log)
        os.chmod(str(tmp), 0o755)
        if in_place:
            os.replace(str(tmp), str(exe))
            return None
        return _run_install(replace_binary_cmd(tmp, exe), log=log)
    except (OSError, ValueError, subprocess.SubprocessError) as exc:
        return str(exc)
    finally:
        try:
            tmp.unlink(missing_ok=True)
        except OSError:
            pass


def relaunch_env() -> Dict[str, str]:
    """Environment for relaunching without the unpacked PyInstaller bundle."""
    env = {k: v for k, v in os.environ.items() if not k.startswith("_PYI_")}
    env.pop("_MEIPASS", None)
    mei = getattr(sys, "_MEIPASS", None)
    for var in ("PATH", "LD_LIBRARY_PATH", "GI_TYPELIB_PATH", "GTK_PATH",
                "GST_PLUGIN_PATH", "GIO_MODULE_DIR"):
        original = env.pop(var + "_ORIG", None)
        if original is not None:
            env[var] = original
            continue
        if not mei or not env.get(var):
            continue
        target = os.path.normcase(mei.rstrip("\\/"))
        kept = [
            p for p in env[var].split(os.pathsep)
            if os.path.normcase(p.rstrip("\\/")) != target
        ]
        if kept:
            env[var] = os.pathsep.join(kept)
        else:
            env.pop(var, None)
    return env