package main

import (
	"os/exec"
	"path/filepath"
)

// relaunchCmd builds the command that starts OpsLog again — after an update, or
// after a database switch.
//
// It exists to hold one fact in one place: a relaunch of OPSLOG ITSELF must not
// suppress the new process's window.
//
// The auto-update relaunch used to go through hideConsole, which sets
// SysProcAttr{HideWindow: true}. On Windows that puts SW_HIDE into the
// STARTUPINFO handed to CreateProcess, and Windows applies it to the first
// top-level window the new process shows. So the updated OpsLog started
// perfectly, took the single-instance mutex, connected the rig — and never
// became visible. Reported by two operators on 0.27.23 as "it goes to reload
// and just fails to load": a process in the task manager, no window, killing it
// and starting it by hand working every time.
//
// It arrived with the removal of the PowerShell helper. PowerShell's
// Start-Process launched the exe with a normal show, and the direct
// exec.Command that replaced it borrowed hideConsole from the console tools
// beside it — where hiding a console window is exactly right, and where every
// other caller still belongs. Two self-relaunches then differed by that one
// line, and only the hidden one was ever reported broken.
//
// So: nothing that touches the WINDOW. RestartApp never called hideConsole and
// the database-switch relaunch never showed the fault, which is what proved it.
// There is no console to suppress either way — OpsLog is linked for the Windows
// GUI subsystem. What SysProcAttr does carry now is detachment, below, which is
// about process parentage and not about the window.
// Two things the PowerShell helper did that the direct launch did not, both
// restored here after operators kept reporting the relaunch failing:
//
//  1. It launched through Start-Process, so the new OpsLog was a child of
//     PowerShell — which then exited. The direct launch makes it a child of
//     the OpsLog that is dying, inside the same process group and console.
//     detachProcess puts it back on its own.
//  2. It slept 400 ms after the old process was gone, before starting
//     anything. See postExitSettle in main.go.
func relaunchCmd(exe string, args ...string) *exec.Cmd {
	cmd := exec.Command(exe, args...)
	cmd.Dir = filepath.Dir(exe)
	detachProcess(cmd)
	return cmd
}