package com.loomcom.symon.ui;

import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Pointer;
import com.sun.jna.ptr.IntByReference;
import com.sun.jna.ptr.PointerByReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class X11ResourceReader {

    private final static Logger logger = LoggerFactory.getLogger(X11ResourceReader.class.getName());


    public interface X11 extends Library {
        X11 INSTANCE = Native.load("X11", X11.class);

        Pointer XOpenDisplay(String display);
        Pointer XResourceManagerString(Pointer display);
        void XCloseDisplay(Pointer display);
    }

    public static Double readXftDpiScale() {
        Pointer display = null;
        try {
            display = X11.INSTANCE.XOpenDisplay(null);
            if (display == null) {
                return null; // não conseguimos ligar ao X server (ex: Wayland puro sem XWayland)
            }

            Pointer resourceString = X11.INSTANCE.XResourceManagerString(display);
            if (resourceString == null) {
                return null;
            }

            String resources = resourceString.getString(0);
            for (String line : resources.split("\n")) {
                if (line.startsWith("Xft.dpi:")) {
                    int dpi = Integer.parseInt(line.split(":")[1].trim());
                    return Math.round((dpi / 96.0) * 4) / 4.0;
                }
            }
            return null;
        } catch (UnsatisfiedLinkError | Exception e) {
            logger.debug("Could not read X11 resource manager (libX11 unavailable?)", e);
            return null;
        } finally {
            if (display != null) {
                X11.INSTANCE.XCloseDisplay(display);
            }
        }
    }
}