package net.shadowfacts.cacao.util

import net.shadowfacts.cacao.LayoutVariable
import net.shadowfacts.cacao.geometry.Rect
import net.shadowfacts.cacao.view.View

/**
 * A layout guide is a non-view object that represents a rectangular area for the purposes of constraint-based layout.
 * It allows you to define complex layouts without needing empty container views.
 *
 * A layout guide is always owned by a view. The owning view's dimensions are not necessarily tied to the layout guide's.
 *
 * To create a layout guide, call [View.addLayoutGuide] on the owning view.
 *
 * @author shadowfacts
 */
class LayoutGuide(
	val owningView: View,
) {

	val leftAnchor: LayoutVariable = LayoutVariable(this, "left")
	val rightAnchor: LayoutVariable = LayoutVariable(this, "right")
	val topAnchor: LayoutVariable = LayoutVariable(this, "top")
	val bottomAnchor: LayoutVariable = LayoutVariable(this, "bottom")
	val widthAnchor: LayoutVariable = LayoutVariable(this, "width")
	val heightAnchor: LayoutVariable = LayoutVariable(this, "height")
	val centerXAnchor: LayoutVariable = LayoutVariable(this, "centerX")
	val centerYAnchor: LayoutVariable = LayoutVariable(this, "centerY")

	val frame: Rect
		get() = Rect(leftAnchor.value - owningView.leftAnchor.value, topAnchor.value - owningView.topAnchor.value, widthAnchor.value, heightAnchor.value)

}