package x

import "image"
import "git.tebibyte.media/tomo/tomo"
import "git.tebibyte.media/tomo/tomo/input"
import "git.tebibyte.media/tomo/tomo/canvas"

type boxSet map[anyBox] struct { }

func (set boxSet) Empty () bool {
	return set == nil || len(set) == 0
}

func (set boxSet) Has (box anyBox) bool {
	if set == nil { return false }
	_, ok := set[box]
	return ok
}

func (set *boxSet) Add (box anyBox) {
	if *set == nil {
		*set = make(boxSet)
	}
	(*set)[box] = struct { } { }
}

func (set *boxSet) Pop () anyBox {
	for box := range *set {
		delete(*set, box)
		return box
	}
	return nil
}

type parent interface {
	window                  () *window
	canvas                  () canvas.Canvas
	notifyMinimumSizeChange (anyBox)
}

type anyBox interface {
	tomo.Box
	doDraw        ()
	doLayout      ()
	setParent     (parent)
	recursiveRedo ()
	canBeFocused  () bool
	boxUnder      (image.Point) anyBox
	recalculateMinimumSize ()

	handleFocusEnter ()
	handleFocusLeave ()
	// handleDndEnter   ()
	// handleDndLeave   ()
	// handleDndDrop    (data.Data)
	// handleMouseEnter ()
	// handleMouseLeave ()
	// handleMouseMove  ()
	handleMouseDown  (input.Button)
	handleMouseUp    (input.Button)
	// handleScroll     (float64, float64)
	// handleKeyDown    (input.Key, bool)
	// handleKeyUp      (input.Key, bool)
}

func assertAnyBox (unknown tomo.Box) anyBox {
	if box, ok := unknown.(anyBox); ok {
		return box
	} else {
		panic("foregin box implementation, i did not make this!")
	}
}

func (window *window) SetRoot (root tomo.Object) {
	if window.root != nil {
		window.root.setParent(nil)
	}
	if root == nil {
		window.root = nil
	} else {
		box := assertAnyBox(root.Box())
		box.setParent(window)
		window.invalidateLayout(box)
		window.root = box
	}
	window.recalculateMinimumSize()
}

func (window *window) window () *window {
	return window
}

func (window *window) canvas () canvas.Canvas {
	return window.xCanvas
}

func (window *window) notifyMinimumSizeChange (anyBox) {
	window.recalculateMinimumSize()
}

func (window *window) invalidateDraw (box anyBox) {
	window.needDraw.Add(box)
}

func (window *window) invalidateLayout (box anyBox) {
	// TODO: use a priority queue for this and have the value be the amount
	// of parents a box has
	window.needLayout.Add(box)
	window.invalidateDraw(box)
}

func (window *window) focus (box anyBox) {
	if window.focused == box { return }
	
	previous := window.focused
	window.focused = box
	
	if previous != nil {
		window.invalidateDraw(previous)
		previous.handleFocusLeave()
	}
	if box != nil {
		window.invalidateDraw(box)
		box.handleFocusEnter()
	}
}

func (this *window) boxUnder (point image.Point) anyBox {
	if this.root == nil { return nil }
	return this.root.boxUnder(point)
}

func (window *window) afterEvent () {
	if window.xCanvas == nil { return }

	if window.needRedo {
		// set child bounds
		childBounds := window.metrics.bounds
		childBounds = childBounds.Sub(childBounds.Min)
		window.root.SetBounds(childBounds)

		// full relayout/redraw		
		if window.root != nil {
			window.root.recursiveRedo()
		}
		window.pushAll()
		window.needRedo = false
		return
	}

	for len(window.needLayout) > 0 {
		window.needLayout.Pop().doLayout()
	}
	var toPush image.Rectangle
	for len(window.needDraw) > 0 {
		box := window.needDraw.Pop()
		box.doDraw()
		toPush = toPush.Union(box.Bounds())
	}
	if !toPush.Empty() {
		window.pushRegion(toPush)
	}
}