package main

import "errors"

type alphaCmd struct {
}

func (c alphaCmd) Run(args []string, g globalCmd) error {
	if len(args) != 1 {
		return errors.New("an argument is required")
	}

	alpha := toInt(args[0], 255)

	style, _, _ := getWindowLong.Call(uintptr(g.targetHandle), GWL_EXSTYLE)
	setWindowLong.Call(uintptr(g.targetHandle), GWL_EXSTYLE, style|WS_EX_LAYERED)

	setLayeredWindowAttributes.Call(uintptr(g.targetHandle), 0, uintptr(alpha), LWA_ALPHA)
	if alpha == 255 {
		setWindowLong.Call(uintptr(g.targetHandle), GWL_EXSTYLE, style&^WS_EX_LAYERED)
	}

	return nil
}