package net.shadowfacts.cacao

import net.shadowfacts.cacao.geometry.Point
import net.shadowfacts.cacao.view.View
import no.birkett.kiwi.Solver
import java.util.*

/**
 * A Window is the object at the top of a Cacao view hierarchy. It occupies the entirety of the Minecraft screen size
 * and provides the base coordinate system for its view hierarchy.
 *
 * The Window owns the Kiwi [Solver] object used for layout by all of its views.
 *
 * @author shadowfacts
 */
class Window {

	var solver = Solver()

	// _views is the internal, mutable object, since we only want it to be mutated by the add/removeView methods
	private val _views = LinkedList<View>()
	/**
	 * The list of top-level views in this window.
	 * This list should never be modified directly, only by calling the [addView]/[removeView] methods.
	 */
	val views: List<View> = _views

	/**
	 * Adds the given view as a top-level view in this window.
	 *
	 * @param view The view to add.
	 * @return The same view, as a convenience.
	 */
	fun <T: View> addView(view: T): T {
		_views.add(view)
		view.solver = solver

		view.wasAdded()

		return view
	}

	/**
	 * Instructs the solver to solve all of the provided constraints.
	 * Should be called after the view hierarchy is setup.
	 */
	fun layout() {
		solver.updateVariables()
		views.forEach(View::didLayout)
	}

	/**
	 * Draws this window and all of its views.
	 * This method is called by [CacaoScreen] and generally shouldn't be called directly.
	 *
	 * @param mouse The point in the coordinate system of the window.
	 * @param delta The time elapsed since the last frame.
	 */
	fun draw(mouse: Point, delta: Float) {
		views.forEach(View::draw)
	}

}