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

	on struct {
		contentBoundsChange event.FuncBroadcaster
	}
}

func (backend *Backend) NewContainerBox() tomo.ContainerBox {
	box := &containerBox {
		box: backend.NewBox().(*box),
	}
	box.drawer = box
	box.outer  = box
	return box
}

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

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

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

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

	beforeBox := assertAnyBox(before.Box())
	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.recalculateMinimumSize()
}

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

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.recalculateMinimumSize()
}

func (this *containerBox) Draw (can canvas.Canvas) {
	if can == nil { return }
	this.drawBorders(can)
	pen := can.Pen()
	pen.Fill(this.color)

	// TODO: do this in doLayout and save the result
	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...) {
		pen.Rectangle(tile)
	}
}

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.recalculateMinimumSize()

	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) recalculateMinimumSize () {
	if this.layout == nil {
		this.SetMinimumSize(image.Point { })
		return
	}
	minimum := this.layout.MinimumSize(this.layoutHints(), this.children)
	minimum.X += this.padding.Horizontal()
	minimum.Y += this.padding.Vertical()
	borderSum := this.borderSum()
	minimum.X += borderSum.Horizontal()
	minimum.Y += borderSum.Vertical()
	this.SetMinimumSize(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()
	}
}