from __future__ import annotations

import os
from pathlib import Path
import subprocess
import sys
import threading
import time
import urllib.request

from tkinter import Tk, messagebox


INSTALL_ROOT = Path(__file__).resolve().parent
DATA_DIR = INSTALL_ROOT / "data"
SUPERVISOR_LOCK = DATA_DIR / "supervisor.lock"
SUPERVISOR_SCRIPT = INSTALL_ROOT / "ERPAgentSupervisor.pyw"
URL = "http://127.0.0.1:8788"


def _create_no_window() -> int:
    return getattr(subprocess, "CREATE_NO_WINDOW", 0)


def _popup(title: str, message: str, error: bool = False) -> None:
    root = Tk()
    root.withdraw()
    if error:
        messagebox.showerror(title, message)
    else:
        messagebox.showinfo(title, message)
    root.destroy()


def _pid_alive(pid: int) -> bool:
    if pid <= 0:
        return False
    try:
        os.kill(pid, 0)
        return True
    except OSError:
        return False


def _supervisor_running() -> bool:
    try:
        if not SUPERVISOR_LOCK.exists():
            return False
        return _pid_alive(int(SUPERVISOR_LOCK.read_text(encoding="utf-8").strip()))
    except Exception:
        return False


def _pythonw() -> Path:
    pyw = INSTALL_ROOT / ".venv" / "Scripts" / "pythonw.exe"
    if pyw.exists():
        return pyw
    py = INSTALL_ROOT / ".venv" / "Scripts" / "python.exe"
    if py.exists():
        return py
    raise RuntimeError("ERP Local Agent Python environment was not found.")


def _ensure_supervisor() -> None:
    if _supervisor_running():
        return
    subprocess.Popen(
        [str(_pythonw()), str(SUPERVISOR_SCRIPT), "--background"],
        cwd=str(INSTALL_ROOT),
        stdout=subprocess.DEVNULL,
        stderr=subprocess.DEVNULL,
        creationflags=_create_no_window(),
        close_fds=True,
    )
    deadline = time.time() + 20
    while time.time() < deadline:
        if _supervisor_running():
            return
        time.sleep(0.5)
    raise RuntimeError("ERP Local Agent supervisor did not start.")


def _ready(timeout: float = 1.5) -> bool:
    try:
        with urllib.request.urlopen(URL + "/api/status", timeout=timeout) as response:
            return int(getattr(response, "status", 200)) < 500
    except Exception:
        return False


def _wait_ready(seconds: int = 75) -> bool:
    deadline = time.time() + seconds
    while time.time() < deadline:
        if _ready():
            return True
        time.sleep(0.75)
    return False


def main() -> None:
    try:
        _ensure_supervisor()
    except Exception as exc:
        _popup("ERP Local Agent", str(exc), error=True)
        return

    if not _wait_ready():
        _popup(
            "ERP Local Agent",
            "The Local Agent supervisor is running, but the dashboard did not become ready.\n\n"
            f"Check logs under:\n{INSTALL_ROOT / 'logs'}",
            error=True,
        )
        return

    try:
        import webview
    except Exception as exc:
        _popup(
            "ERP Local Agent Dashboard",
            "Desktop dashboard dependency could not be loaded.\n\n"
            f"{exc}\n\nRun the Local Agent updater/installer again.",
            error=True,
        )
        return

    window = webview.create_window(
        "ERP Local Agent Dashboard",
        URL,
        width=1180,
        height=820,
        min_size=(980, 650),
        confirm_close=False,
    )

    def monitor():
        was_ready = True
        outage_seen = False
        while True:
            try:
                current = _ready()
                if was_ready and not current:
                    outage_seen = True
                if outage_seen and current:
                    try:
                        window.load_url(URL)
                    except Exception:
                        pass
                    outage_seen = False
                was_ready = current
                time.sleep(1.5)
            except Exception:
                time.sleep(2)

    webview.start(monitor)


if __name__ == "__main__":
    main()