//go:build windows

package procscan

import (
	"fmt"
	"path/filepath"
	"syscall"

	"golang.org/x/sys/windows"
)

// ResolvePID returns the exe basename for a given PID, or an error
// if the PID has already exited or we lack the rights to query it.
//
// Used by the engine's socketLoop to do a lazy lookup when SOCKET
// Connect events arrive for processes we haven't yet seen via the
// 2-second procscan tick — Update.exe's full lifecycle (spawn →
// connect → exit) routinely fits inside one tick window, so without
// this lookup the engine would miss its connections entirely and
// Discord's "Checking for updates" would hit its 30 s timeout.
func ResolvePID(pid uint32) (string, error) {
	h, err := windows.OpenProcess(windows.PROCESS_QUERY_LIMITED_INFORMATION, false, pid)
	if err != nil {
		return "", fmt.Errorf("OpenProcess pid=%d: %w", pid, err)
	}
	defer windows.CloseHandle(h)

	buf := make([]uint16, windows.MAX_PATH)
	size := uint32(len(buf))
	if err := windows.QueryFullProcessImageName(h, 0, &buf[0], &size); err != nil {
		return "", fmt.Errorf("QueryFullProcessImageName pid=%d: %w", pid, err)
	}
	full := syscall.UTF16ToString(buf[:size])
	return filepath.Base(full), nil
}