package main

import (
	"fmt"
	"os"

	"github.com/BurntSushi/xgb/xproto"
	"github.com/BurntSushi/xgbutil"
	"github.com/BurntSushi/xgbutil/ewmh"
)

// RealX11Resolver lit _NET_WM_PID via la connexion X11.
type RealX11Resolver struct {
	xu *xgbutil.XUtil
}

// NewRealX11Resolver ouvre une connexion X11. Retourne une erreur si $DISPLAY est absent.
func NewRealX11Resolver() (*RealX11Resolver, error) {
	if os.Getenv("DISPLAY") == "" {
		return nil, fmt.Errorf("DISPLAY not set, cannot resolve X11 PIDs")
	}
	xu, err := xgbutil.NewConn()
	if err != nil {
		return nil, fmt.Errorf("X11 connection failed: %w", err)
	}
	return &RealX11Resolver{xu: xu}, nil
}

func (r *RealX11Resolver) GetPID(windowID int64) (int, error) {
	pid, err := ewmh.WmPidGet(r.xu, xproto.Window(windowID))
	if err != nil {
		return 0, err
	}
	return int(pid), nil
}

// Close ferme la connexion X11.
func (r *RealX11Resolver) Close() {
	if r.xu != nil {
		r.xu.Conn().Close()
	}
}