import os
import sys
import tempfile
import webbrowser

import requests
from aza_version import APP_CHANNEL, APP_VERSION

UPDATE_MANIFEST_URL = "https://api.aza-medwork.ch/download/version.json"
_MIN_INSTALLER_BYTES = 1_000_000


def _is_newer_version(latest: str, current: str) -> bool:
    def parse(v: str):
        parts = []
        for p in str(v).strip().split("."):
            try:
                parts.append(int(p))
            except Exception:
                parts.append(0)
        while len(parts) < 3:
            parts.append(0)
        return tuple(parts[:3])

    return parse(latest) > parse(current)


def check_for_updates():
    try:
        r = requests.get(UPDATE_MANIFEST_URL, timeout=4)
        if r.status_code != 200:
            return None

        data = r.json()
        latest = str(data.get("version") or "").strip()
        channel = str(data.get("channel") or "stable").strip()
        download_url = str(data.get("download_url") or "").strip()

        if channel != APP_CHANNEL:
            return None

        if latest and _is_newer_version(latest, APP_VERSION):
            return {
                "update_available": True,
                "latest_version": latest,
                "download_url": download_url,
            }

        return None
    except Exception:
        return None


def _download_installer(download_url: str) -> str | None:
    """Downloads installer to TEMP. Returns path on success, None on failure."""
    try:
        target = os.path.join(tempfile.gettempdir(), "aza_desktop_setup_latest.exe")
        with requests.get(download_url, stream=True, timeout=60) as r:
            if r.status_code != 200:
                return None
            with open(target, "wb") as f:
                for chunk in r.iter_content(chunk_size=512 * 1024):
                    if chunk:
                        f.write(chunk)
        if os.path.isfile(target) and os.path.getsize(target) >= _MIN_INSTALLER_BYTES:
            return target
        return None
    except Exception:
        return None


def prompt_update_if_available():
    """Prueft auf Update, zeigt Dialog, laedt Installer herunter und startet ihn."""
    info = check_for_updates()
    if not info or not info.get("update_available"):
        return

    download_url = info.get("download_url", "")
    latest_version = info.get("latest_version", "")

    try:
        import tkinter as tk
        from tkinter import messagebox

        root = tk.Tk()
        root.withdraw()

        answer = messagebox.askyesno(
            "Update verfuegbar",
            f"AZA {latest_version} ist verfuegbar.\n\n"
            f"Ihre Version: {APP_VERSION}\n\n"
            "Moechten Sie das Update jetzt installieren?",
            parent=root,
        )

        if not answer:
            root.destroy()
            return

        root.destroy()

        installer_path = _download_installer(download_url)

        if installer_path:
            os.startfile(installer_path)
            sys.exit(0)

        _root2 = tk.Tk()
        _root2.withdraw()
        retry = messagebox.askyesno(
            "Download fehlgeschlagen",
            "Das Update konnte nicht heruntergeladen werden.\n\n"
            "Moechten Sie die Download-Seite im Browser oeffnen?",
            parent=_root2,
        )
        if retry and download_url:
            webbrowser.open(download_url)
        _root2.destroy()

    except Exception:
        pass


if __name__ == "__main__":
    result = check_for_updates()
    print(result)