"""SaraSortd's systemd user unit: status, start/stop/restart, autostart, and
its journal. SaraSortd's own log files are read from its LogDir."""

import subprocess
from dataclasses import dataclass
from pathlib import Path

from Core import ChildEnvironment


@dataclass
class ServiceStatus:
    Active: str = "unknown"  # active, inactive, failed, activating, ...
    Sub: str = ""  # running, dead, ...
    Enabled: str = "unknown"  # enabled, disabled, ...
    Pid: str = ""
    Since: str = ""
    Found: bool = False

    @property
    def Running(self) -> bool:
        return self.Active in ("active", "activating", "reloading")


def _Run(Arguments: list[str], Timeout: int = 15) -> subprocess.CompletedProcess:
    return subprocess.run(Arguments, capture_output=True, text=True, timeout=Timeout, env=ChildEnvironment())


def Status(Unit: str) -> ServiceStatus:
    try:
        Result = _Run(["systemctl", "--user", "show", Unit,
                       "-p", "LoadState,ActiveState,SubState,UnitFileState,MainPID,ActiveEnterTimestamp"])
    except (OSError, subprocess.SubprocessError):
        return ServiceStatus()
    Values = dict(Line.split("=", 1) for Line in Result.stdout.splitlines() if "=" in Line)
    return ServiceStatus(
        Active=Values.get("ActiveState", "unknown"),
        Sub=Values.get("SubState", ""),
        Enabled=Values.get("UnitFileState", "") or "unknown",
        Pid=Values.get("MainPID", "") if Values.get("MainPID") != "0" else "",
        Since=Values.get("ActiveEnterTimestamp", ""),
        Found=Values.get("LoadState") == "loaded",
    )


def Control(Unit: str, Action: str) -> str:
    """Action: start, stop, restart, enable, disable. Returns "" or an error."""
    try:
        Result = _Run(["systemctl", "--user", Action, Unit])
    except (OSError, subprocess.SubprocessError) as Error:
        return str(Error)
    return "" if Result.returncode == 0 else (Result.stderr.strip() or f"systemctl {Action} failed")


def RestartIfRunning(Unit: str) -> str:
    """For after a GlobalConf.toml change: SaraSortd only reads it at start."""
    if not Status(Unit).Running:
        return ""
    return Control(Unit, "restart")


def Journal(Unit: str, Lines: int) -> list[str]:
    try:
        Result = _Run(["journalctl", "--user", "-u", Unit, "-n", str(Lines), "--no-pager", "-o", "short-iso"])
    except (OSError, subprocess.SubprocessError) as Error:
        return [f"Couldn't read the journal: {Error}"]
    return Result.stdout.splitlines() or [Result.stderr.strip() or "(empty)"]


def LogFiles(LogDir: Path) -> list[Path]:
    """Newest first."""
    if not LogDir.is_dir():
        return []
    return sorted((Item for Item in LogDir.iterdir() if Item.is_file()), key=lambda Item: Item.stat().st_mtime, reverse=True)


def ReadTail(FilePath: Path, Lines: int) -> list[str]:
    try:
        return FilePath.read_text(encoding="utf-8", errors="replace").splitlines()[-Lines:]
    except OSError as Error:
        return [f"Couldn't read {FilePath}: {Error}"]