"""Starting with the session, the way the desktop expects.

Two mechanisms, because the two desktops disagree about which is canonical:

* a `.desktop` file in `~/.config/autostart` — the XDG standard, honoured by
  KDE, GNOME, XFCE and friends;
* a **systemd user unit**, which is what you actually want on a modern box: it
  restarts the app if it dies and keeps its logs in the journal.

Either can be switched on alone; the app only ever touches files under the
user's own config, never system paths.
"""

from __future__ import annotations

import logging
import os
import shutil
import subprocess
import sys
from pathlib import Path

log = logging.getLogger(__name__)

DESKTOP_FILE_NAME = "kadence.desktop"
SERVICE_NAME = "kadence-desktop.service"


def _autostart_dir() -> Path:
    base = os.environ.get("XDG_CONFIG_HOME") or str(Path.home() / ".config")
    path = Path(base) / "autostart"
    path.mkdir(parents=True, exist_ok=True)
    return path


def _systemd_user_dir() -> Path:
    base = os.environ.get("XDG_CONFIG_HOME") or str(Path.home() / ".config")
    path = Path(base) / "systemd" / "user"
    path.mkdir(parents=True, exist_ok=True)
    return path


def launch_command() -> str:
    """How to start this app again, whether installed or run from a checkout."""
    executable = shutil.which("kadence-desktop")
    if executable:
        return executable
    return f"{sys.executable} -m kadence_desktop"


# --------------------------------------------------------------------------
# XDG autostart
# --------------------------------------------------------------------------
def autostart_enabled() -> bool:
    return (_autostart_dir() / DESKTOP_FILE_NAME).exists()


def set_autostart(enabled: bool, *, minimized: bool = True) -> None:
    path = _autostart_dir() / DESKTOP_FILE_NAME
    if not enabled:
        path.unlink(missing_ok=True)
        return
    command = launch_command() + (" --minimized" if minimized else "")
    path.write_text(
        "\n".join(
            [
                "[Desktop Entry]",
                "Type=Application",
                "Name=Kadence",
                "Comment=Pomodoro timer, task list and focus guard",
                f"Exec={command}",
                "Icon=kadence",
                "Terminal=false",
                "Categories=Utility;Office;",
                "X-GNOME-Autostart-enabled=true",
                "",
            ]
        ),
        "utf-8",
    )
    log.info("autostart entry written to %s", path)


# --------------------------------------------------------------------------
# systemd user service
# --------------------------------------------------------------------------
def service_installed() -> bool:
    return (_systemd_user_dir() / SERVICE_NAME).exists()


def service_enabled() -> bool:
    if not shutil.which("systemctl"):
        return False
    result = subprocess.run(
        ["systemctl", "--user", "is-enabled", SERVICE_NAME],
        capture_output=True,
        text=True,
        check=False,
    )
    return result.stdout.strip() == "enabled"


def install_service(*, enable: bool = True) -> str:
    """Write (and optionally enable) the user unit. Returns a status line."""
    path = _systemd_user_dir() / SERVICE_NAME
    path.write_text(
        "\n".join(
            [
                "[Unit]",
                "Description=Kadence desktop client",
                "PartOf=graphical-session.target",
                "After=graphical-session.target",
                "",
                "[Service]",
                "Type=simple",
                f"ExecStart={launch_command()} --minimized",
                "Restart=on-failure",
                "RestartSec=5",
                "",
                "[Install]",
                "WantedBy=graphical-session.target",
                "",
            ]
        ),
        "utf-8",
    )
    if not shutil.which("systemctl"):
        return f"unit written to {path} (systemctl not found)"
    subprocess.run(["systemctl", "--user", "daemon-reload"], check=False)
    if enable:
        subprocess.run(["systemctl", "--user", "enable", SERVICE_NAME], check=False)
    return f"unit written to {path}" + (" and enabled" if enable else "")


def remove_service() -> None:
    if shutil.which("systemctl"):
        subprocess.run(["systemctl", "--user", "disable", "--now", SERVICE_NAME], check=False)
    (_systemd_user_dir() / SERVICE_NAME).unlink(missing_ok=True)
    if shutil.which("systemctl"):
        subprocess.run(["systemctl", "--user", "daemon-reload"], check=False)