package x

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

type containerBox struct {
	*box

	hOverflow, vOverflow bool
	hAlign, vAlign       tomo.Align
	contentBounds image.Rectangle
	scroll        image.Point
	
	gap             image.Point
	children        []tomo.Box
	layout          tomo.Layout
	propagateEvents bool

	on struct {
		contentBoundsChange event.FuncBroadcaster
	}
}

func (backend *Backend) NewContainerBox() tomo.ContainerBox {
	this    := &containerBox { propagateEvents: true }
	this.box = backend.newBox(this)
	return this
}

func (this *containerBox) SetOverflow (horizontal, vertical bool) {
	if this.hOverflow == horizontal && this.vOverflow == vertical { return }
	this.hOverflow = horizontal
	this.vOverflow = vertical
	this.invalidateLayout()
}

func (this *containerBox) SetAlign (x, y tomo.Align) {
	if this.hAlign == x && this.vAlign == y { return }
	this.hAlign = x
	this.vAlign = y
	this.invalidateLayout()
}

func (this *containerBox) ContentBounds () image.Rectangle {
	return this.contentBounds
}

func (this *containerBox) ScrollTo (point image.Point) {
	// TODO: constrain scroll
	this.scroll = point
	this.invalidateLayout()
}

func (this *containerBox) OnContentBoundsChange (callback func()) event.Cookie {
	return this.on.contentBoundsChange.Connect(callback)
}

func (this *containerBox) SetPropagateEvents (propagate bool) {
	this.propagateEvents = propagate
}

func (this *containerBox) SetGap (gap image.Point) {
	if this.gap == gap { return }
	this.gap = gap
	this.invalidateLayout()
	this.invalidateMinimum()
}

func (this *containerBox) Add (child tomo.Object) {
	box := assertAnyBox(child.GetBox())
	if indexOf(this.children, tomo.Box(box)) > -1 { return }
	
	box.setParent(this)
	box.flushActionQueue()
	this.children = append(this.children, box)
	this.invalidateLayout()
	this.invalidateMinimum()
}

func (this *containerBox) Delete (child tomo.Object) {
	box := assertAnyBox(child.GetBox())
	index := indexOf(this.children, tomo.Box(box))
	if index < 0 { return }
	
	box.setParent(nil)
	this.children = remove(this.children, index)
	this.invalidateLayout()
	this.invalidateMinimum()
}

func (this *containerBox) Insert (child, before tomo.Object) {
	box := assertAnyBox(child.GetBox())
	if indexOf(this.children, tomo.Box(box)) > -1 { return }

	beforeBox := assertAnyBox(before.GetBox())
	index     := indexOf(this.children, tomo.Box(beforeBox))
	if index < 0 { return }
	
	box.setParent(this)
	this.children = insert(this.children, index, tomo.Box(box))
	this.invalidateLayout()
	this.invalidateMinimum()
}

func (this *containerBox) Clear () {
	for _, box := range this.children {
		box.(anyBox).setParent(nil)
	}
	this.children = nil
	this.invalidateLayout()
	this.invalidateMinimum()
}

func (this *containerBox) Length () int {
	return len(this.children)
}

func (this *containerBox) At (index int) tomo.Object {
	if index < 0 || index >= len(this.children) {
		return nil
	}
	return this.children[index]
}

func (this *containerBox) SetLayout (layout tomo.Layout) {
	this.layout = layout
	this.invalidateLayout()
	this.invalidateMinimum()
}

func (this *containerBox) Draw (can canvas.Canvas) {
	if can == nil { return }

	rocks := make([]image.Rectangle, len(this.children))
	for index, box := range this.children {
		rocks[index] = box.Bounds()
	}
	for _, tile := range canvas.Shatter(this.bounds, rocks...) {
		clipped := can.Clip(tile)
		if this.transparent() && this.parent != nil {
			this.parent.drawBackgroundPart(clipped)
		}
		if clipped == nil { continue }
		pen := clipped.Pen()
		pen.Fill(this.color)
		pen.Texture(this.texture)
		pen.Rectangle(this.innerClippingBounds)
	}
}

func (this *containerBox) drawBackgroundPart (can canvas.Canvas) {
	if can == nil { return }
	pen := can.Pen()
	pen.Fill(this.color)
	pen.Texture(this.texture)
	
	if this.transparent() && this.parent != nil {
		this.parent.drawBackgroundPart(can)
	}
	pen.Rectangle(this.innerClippingBounds)
}

func (this *containerBox) flushActionQueue () {
	for _, box := range this.children {
		box.(anyBox).flushActionQueue()
	}
	this.box.flushActionQueue()
}

func (this *containerBox) window () *window {
	if this.parent == nil { return nil }
	return this.parent.window()
}

func (this *containerBox) canvas () canvas.Canvas {
	return this.box.canvas
}

func (this *containerBox) notifyMinimumSizeChange (child anyBox) {
	this.invalidateMinimum()
	size   := child.MinimumSize()
	bounds := child.Bounds()
	if bounds.Dx() < size.X || bounds.Dy() < size.Y {
		this.invalidateLayout()
	}
}

func (this *containerBox) layoutHints () tomo.LayoutHints {
	innerBounds := this.InnerBounds().Sub(this.scroll)
	return tomo.LayoutHints {
		Bounds:    innerBounds,
		OverflowX: this.hOverflow,
		OverflowY: this.vOverflow,
		AlignX:    this.hAlign,
		AlignY:    this.vAlign,
		Gap:       this.gap,
	}
}

func (this *containerBox) contentMinimum () image.Point {
	minimum := this.box.contentMinimum()
	if this.layout != nil {
		minimum = minimum.Add (
			this.layout.MinimumSize (
				this.layoutHints(),
				this.children))
	}
	return minimum
}

func (this *containerBox) doLayout () {
	this.box.doLayout()
	previousContentBounds := this.contentBounds
	if this.layout != nil {
		this.layout.Arrange(this.layoutHints(), this.children)
	}
	if previousContentBounds != this.contentBounds {
		this.on.contentBoundsChange.Broadcast()
	}
}

func (this *containerBox) recursiveRedo () {
	this.doLayout()
	this.doDraw()
	for _, child := range this.children {
		child.(anyBox).recursiveRedo()
	}
}

func (this *containerBox) boxUnder (point image.Point) anyBox {
	if this.propagateEvents {
		for _, box := range this.children {
			candidate := box.(anyBox).boxUnder(point)
			if candidate != nil { return candidate }
		}
	}

	return this.box.boxUnder(point)
}

func (this *containerBox) propagate (callback func (anyBox) bool) bool {
	for _, box := range this.children {
		box := box.(anyBox)
		if !box.propagate(callback) { return false }
	}

	return callback(this)
}

func (this *containerBox) propagateAlt (callback func (anyBox) bool) bool {
	if !callback(this) { return false}
	
	for _, box := range this.children {
		box := box.(anyBox)
		if !box.propagateAlt(callback) { return false }
	}
	
	return true
}