"""Non-blocking controls for the system Syncthing instance."""
import queue
import subprocess
import threading
from tkinter import ttk, messagebox

SERVICE = "syncthing.service"
SYSTEMCTL = ("systemctl", "--user", "--no-ask-password")


def service_status():
    result = subprocess.run(
        [*SYSTEMCTL, "show", SERVICE, "--property=ActiveState", "--value"],
        capture_output=True, text=True, timeout=10,
    )
    if result.returncode:
        raise RuntimeError(result.stderr.strip() or "Statut indisponible")
    return result.stdout.strip() or "unknown"


def control_service(action):
    if action == "ensure" and service_status() == "active":
        return "active"
    command = "start" if action == "ensure" else action
    result = subprocess.run(
        [*SYSTEMCTL, command, SERVICE],
        capture_output=True, text=True, timeout=60,
    )
    if result.returncode:
        raise RuntimeError(result.stderr.strip() or f"Échec de systemctl {command}")
    status = service_status()
    if command == "start" and status != "active":
        raise RuntimeError(f"Syncthing n’est pas actif : {status}")
    return status


class SyncthingPanel(ttk.Frame):
    def __init__(self, parent):
        super().__init__(parent)
        self.events = queue.Queue()
        self.busy = False
        self.pending_export = None
        self.status = ttk.Label(self, text=f"{SERVICE} : vérification…")
        self.status.pack(anchor="w")
        controls = ttk.Frame(self)
        controls.pack(anchor="w", pady=4)
        self.start_button = ttk.Button(controls, text="Démarrer Syncthing",
                                       command=lambda: self.request("start"))
        self.start_button.pack(side="left")
        self.stop_button = ttk.Button(controls, text="Arrêter Syncthing",
                                      command=lambda: self.request("stop"))
        self.stop_button.pack(side="left", padx=6)
        self.timer = self.after(100, self.poll)
        self.refresh_timer = None
        self.bind("<Destroy>", self.cleanup, add=True)
        self.request("status")

    def ensure_started(self, callback):
        self.pending_export = callback
        if not self.busy:
            self.request("ensure")

    def request(self, action):
        if self.busy:
            return
        self.busy = True
        self.start_button.configure(state="disabled")
        self.stop_button.configure(state="disabled")
        if action != "status":
            self.status.configure(text=f"{SERVICE} : opération en cours…")

        def work():
            try:
                status = service_status() if action == "status" else control_service(action)
                self.events.put((action, status, None))
            except (OSError, RuntimeError, subprocess.TimeoutExpired) as exc:
                self.events.put((action, None, str(exc)))

        threading.Thread(target=work, daemon=True).start()

    def poll(self):
        try:
            action, status, error = self.events.get_nowait()
        except queue.Empty:
            pass
        else:
            self.busy = False
            self.start_button.configure(state="normal")
            self.stop_button.configure(state="normal")
            self.status.configure(text=f"{SERVICE} : {error or status}")
            if action == "ensure":
                callback, self.pending_export = self.pending_export, None
                if error:
                    messagebox.showwarning(
                        "Syncthing",
                        f"Impossible de démarrer Syncthing : {error}\n\n"
                        "L’export va continuer.",
                    )
                if callback:
                    callback()
            elif error and action != "status":
                messagebox.showerror("Syncthing", error)
            elif self.pending_export:
                self.request("ensure")
        if self.winfo_exists():
            self.timer = self.after(100, self.poll)
            if self.refresh_timer is None:
                self.refresh_timer = self.after(5000, self.refresh)

    def refresh(self):
        self.refresh_timer = None
        self.request("status")

    def cleanup(self, event):
        if event.widget == self:
            self.pending_export = None
            for timer in (self.timer, self.refresh_timer):
                if timer:
                    self.after_cancel(timer)