package system

import "image"
import "image/color"
import "git.tebibyte.media/tomo/tomo"
import "git.tebibyte.media/tomo/tomo/data"
import "git.tebibyte.media/tomo/tomo/input"
import "git.tebibyte.media/tomo/tomo/event"
import "git.tebibyte.media/tomo/tomo/canvas"
import "git.tebibyte.media/tomo/backend/internal/util"

type textureMode int; const (
	textureModeTile textureMode = iota
	textureModeCenter
)

type box struct {
	system *System
	parent parent
	outer  anyBox

	role           tomo.Role
	styleCookie    event.Cookie
	lastStyleNonce int
	lastIconsNonce int

	bounds              image.Rectangle
	minSize             image.Point
	userMinSize         image.Point
	innerClippingBounds image.Rectangle
	
	minSizeQueued bool
	focusQueued   *bool

	padding     tomo.Inset
	border      []tomo.Border
	color       color.Color
	texture     canvas.Texture
	textureMode textureMode

	dndData   data.Data
	dndAccept []data.Mime
	focused   bool
	focusable bool

	canvas util.Memo[canvas.Canvas]
	drawer canvas.Drawer

	on struct {
		focusEnter  event.FuncBroadcaster
		focusLeave  event.FuncBroadcaster
		dndEnter    event.FuncBroadcaster
		dndLeave    event.FuncBroadcaster
		dndDrop     event.Broadcaster[func (data.Data)]
		mouseEnter  event.FuncBroadcaster
		mouseLeave  event.FuncBroadcaster
		mouseMove   event.FuncBroadcaster
		mouseDown   event.Broadcaster[func (input.Button)]
		mouseUp     event.Broadcaster[func (input.Button)]
		scroll      event.Broadcaster[func (float64, float64)]
		keyDown     event.Broadcaster[func (input.Key, bool)]
		keyUp       event.Broadcaster[func (input.Key, bool)]
		styleChange event.FuncBroadcaster
		iconsChange event.FuncBroadcaster
	}
}

func (this *System) newBox (outer anyBox) *box {
	box := &box {
		system:  this,
		color:   color.Transparent,
		outer:   outer,
		drawer:  outer,
	}
	box.canvas = util.NewMemo (func () canvas.Canvas {
		if box.parent == nil { return nil }
		parentCanvas := box.parent.getCanvas()
		if parentCanvas == nil { return nil }
		return parentCanvas.SubCanvas(box.bounds)
	})
	if outer == nil {
		box.drawer = box
		box.outer  = box
	}
	box.invalidateMinimum()
	return box

}

func (this *System) NewBox () tomo.Box {
	return this.newBox(nil)
}

func (this *box) GetBox () tomo.Box {
	return this.outer
}

func (this *box) Window () tomo.Window {
	hierarchy := this.getHierarchy()
	if hierarchy == nil { return nil }
	return hierarchy.getWindow()
}

func (this *box) Bounds () image.Rectangle {
	return this.bounds
}

func (this *box) InnerBounds () image.Rectangle {
	return this.padding.Apply(this.innerClippingBounds)
}

func (this *box) MinimumSize () image.Point {
	return this.minSize
}

func (this *box) Role () tomo.Role {
	return this.role
}

func (this *box) borderSum () tomo.Inset {
	sum := tomo.Inset { }
	for _, border := range this.border {
		sum[0] += border.Width[0]
		sum[1] += border.Width[1]
		sum[2] += border.Width[2]
		sum[3] += border.Width[3]
	}
	return sum
}

func (this *box) borderAndPaddingSum () tomo.Inset {
	sum := this.borderSum()
	sum[0] += this.padding[0]
	sum[1] += this.padding[1]
	sum[2] += this.padding[2]
	sum[3] += this.padding[3]
	return sum
}

func (this *box) SetBounds (bounds image.Rectangle) {
	if this.bounds == bounds { return }
	this.bounds = bounds
	this.invalidateLayout()
}

func (this *box) SetColor (c color.Color) {
	if c == nil { c = color.Transparent }
	if this.color == c { return }
	this.color = c
	this.invalidateDraw()
}

func (this *box) SetTextureTile (texture canvas.Texture) {
	if this.texture == texture && this.textureMode == textureModeTile { return }
	this.textureMode = textureModeTile
	this.texture = texture
	this.invalidateDraw()
}

func (this *box) SetTextureCenter (texture canvas.Texture) {
	if this.texture == texture && this.textureMode == textureModeCenter { return }
	this.texture = texture
	this.textureMode = textureModeCenter
	this.invalidateDraw()
}

func (this *box) SetBorder (borders ...tomo.Border) {
	previousBorderSum := this.borderSum()
	previousBorders   := this.border
	this.border = borders

	// only invalidate the layout if the border is sized differently
	if this.borderSum() != previousBorderSum {
		this.invalidateLayout()
		this.invalidateMinimum()
		return
	}

	// if the border takes up the same amount of space, only invalidate the
	// drawing if it looks different
	for index, newBorder := range this.border {
		different :=
			index >= len(previousBorders) ||
			newBorder != previousBorders[index]
		if different {
			this.invalidateDraw()
			return
		}
	}
}

func (this *box) SetMinimumSize (size image.Point) {
	if this.userMinSize == size { return }
	this.userMinSize = size
	this.invalidateMinimum()
}

func (this *box) SetPadding (padding tomo.Inset) {
	if this.padding == padding { return }
	this.padding = padding
	this.invalidateLayout()
	this.invalidateMinimum()
}

func (this *box) SetRole (role tomo.Role) {
	this.role = role
}

func (this *box) SetDNDData (dat data.Data) {
	this.dndData = dat
}

func (this *box) SetDNDAccept (types ...data.Mime) {
	this.dndAccept = types
}

func (this *box) SetFocused (focused bool) {
	hierarchy := this.getHierarchy()
	if hierarchy == nil {
		focusedCopy := focused
		this.focusQueued = &focusedCopy
		return
	}
	if !this.focusable { return }
	
	if this.Focused () && !focused {
		hierarchy.focus(nil)
	} else if !this.Focused() && focused {
		hierarchy.focus(this.outer)
	}
}

func (this *box) SetFocusable (focusable bool) {
	if this.focusable == focusable { return }
	this.focusable = focusable
	if !focusable {
		this.SetFocused(false)
	}
}

func (this *box) Focused () bool {
	hierarchy := this.getHierarchy()
	if hierarchy == nil { return false }
	return hierarchy.isFocused(this.outer)
}

func (this *box) Modifiers () input.Modifiers {
	hierarchy := this.getHierarchy()
	if hierarchy == nil { return input.Modifiers { } }
	return hierarchy.getModifiers()
}

func (this *box) MousePosition () image.Point {
	hierarchy := this.getHierarchy()
	if hierarchy == nil { return image.Point { } }
	return hierarchy.getMousePosition()
}

// ----- event handler setters ---------------------------------------------- //
func (this *box) OnFocusEnter (callback func()) event.Cookie {
	return this.on.focusEnter.Connect(callback)
}
func (this *box) OnFocusLeave (callback func()) event.Cookie {
	return this.on.focusLeave.Connect(callback)
}
func (this *box) OnDNDEnter (callback func()) event.Cookie {
	return this.on.dndEnter.Connect(callback)
}
func (this *box) OnDNDLeave (callback func()) event.Cookie {
	return this.on.dndLeave.Connect(callback)
}
func (this *box) OnDNDDrop (callback func(data.Data)) event.Cookie {
	return this.on.dndDrop.Connect(callback)
}
func (this *box) OnMouseEnter (callback func()) event.Cookie {
	return this.on.mouseEnter.Connect(callback)
}
func (this *box) OnMouseLeave (callback func()) event.Cookie {
	return this.on.mouseLeave.Connect(callback)
}
func (this *box) OnMouseMove (callback func()) event.Cookie {
	return this.on.mouseMove.Connect(callback)
}
func (this *box) OnMouseDown (callback func(input.Button)) event.Cookie {
	return this.on.mouseDown.Connect(callback)
}
func (this *box) OnMouseUp (callback func(input.Button)) event.Cookie {
	return this.on.mouseUp.Connect(callback)
}
func (this *box) OnScroll (callback func(deltaX, deltaY float64)) event.Cookie {
	return this.on.scroll.Connect(callback)
}
func (this *box) OnKeyDown (callback func(key input.Key, numberPad bool)) event.Cookie {
	return this.on.keyDown.Connect(callback)
}
func (this *box) OnKeyUp (callback func(key input.Key, numberPad bool)) event.Cookie {
	return this.on.keyUp.Connect(callback)
}
func (this *box) OnStyleChange (callback func()) event.Cookie {
	return this.on.styleChange.Connect(callback)
}
func (this *box) OnIconsChange (callback func()) event.Cookie {
	return this.on.iconsChange.Connect(callback)
}
func (this *box) handleFocusEnter () {
	this.on.focusEnter.Broadcast()
}
func (this *box) handleFocusLeave () {
	this.on.focusLeave.Broadcast()
}
func (this *box) handleMouseEnter () {
	this.on.mouseEnter.Broadcast()
}
func (this *box) handleMouseLeave () {
	this.on.mouseLeave.Broadcast()
}
func (this *box) handleMouseMove () {
	this.on.mouseMove.Broadcast()
}
func (this *box) handleMouseDown (button input.Button) {
	if this.focusable {
		this.SetFocused(true)
	} else {
		hierarchy := this.getHierarchy()
		if hierarchy == nil { return }
		hierarchy.focus(nil)
	}
	for _, listener := range this.on.mouseDown.Listeners() {
		listener(button)
	}
}
func (this *box) handleMouseUp (button input.Button) {
	for _, listener := range this.on.mouseUp.Listeners() {
		listener(button)
	}
}
func (this *box) handleScroll (x, y float64) {
	for _, listener := range this.on.scroll.Listeners() {
		listener(x, y)
	}
}
func (this *box) handleKeyDown (key input.Key, numberPad bool) {
	for _, listener := range this.on.keyDown.Listeners() {
		listener(key, numberPad)
	}
}
func (this *box) handleKeyUp (key input.Key, numberPad bool) {
	for _, listener := range this.on.keyUp.Listeners() {
		listener(key, numberPad)
	}
}
// -------------------------------------------------------------------------- //

func (this *box) Draw (can canvas.Canvas) {
	if can == nil { return }
	pen := can.Pen()
	bounds := this.Bounds()

	// background
	pen.Fill(this.color)
	if this.textureMode == textureModeTile {
		pen.Texture(this.texture)
	}
	if this.transparent() && this.parent != nil {
		this.parent.drawBackgroundPart(can)
	}
	pen.Rectangle(bounds)

	// centered texture
	if this.textureMode == textureModeCenter && this.texture != nil {
		textureBounds := this.texture.Bounds()
		textureOrigin :=
			bounds.Min.
			Add(image.Pt (
				bounds.Dx() / 2,
				bounds.Dy() / 2)).
			Sub(image.Pt (
				textureBounds.Dx() / 2,
				textureBounds.Dy() / 2))
	
		pen.Fill(color.Transparent)
		pen.Texture(this.texture)
		pen.Rectangle(textureBounds.Sub(textureBounds.Min).Add(textureOrigin))
	}
}

func (this *box) drawBorders (can canvas.Canvas) {
	if can == nil { return }
	pen := can.Pen()
	bounds := this.bounds

	rectangle := func (x0, y0, x1, y1 int, c color.Color) {
		area := image.Rect(x0, y0, x1, y1)
		if util.Transparent(c) && this.parent != nil {
			this.parent.drawBackgroundPart(can.SubCanvas(area))
		}
		pen.Fill(c)
		pen.Rectangle(area)
	}
	
	for _, border := range this.border {
		rectangle (
			bounds.Min.X,
			bounds.Min.Y,
			bounds.Max.X,
			bounds.Min.Y + border.Width[tomo.SideTop],
			border.Color[tomo.SideTop])
		rectangle (
			bounds.Min.X,
			bounds.Max.Y - border.Width[tomo.SideBottom],
			bounds.Max.X,
			bounds.Max.Y,
			border.Color[tomo.SideBottom])
		rectangle (
			bounds.Min.X,
			bounds.Min.Y + border.Width[tomo.SideTop],
			bounds.Min.X + border.Width[tomo.SideLeft],
			bounds.Max.Y - border.Width[tomo.SideBottom],
			border.Color[tomo.SideLeft])
		rectangle (
			bounds.Max.X - border.Width[tomo.SideRight],
			bounds.Min.Y + border.Width[tomo.SideTop],
			bounds.Max.X,
			bounds.Max.Y - border.Width[tomo.SideBottom],
			border.Color[tomo.SideRight])

		bounds = border.Width.Apply(bounds)
	}
}

func (this *box) contentMinimum () image.Point {
	var minimum image.Point
	minimum.X += this.padding.Horizontal()
	minimum.Y += this.padding.Vertical()
	borderSum := this.borderSum()
	minimum.X += borderSum.Horizontal()
	minimum.Y += borderSum.Vertical()
	return minimum
}

func (this *box) doMinimumSize () {
	this.minSize = this.outer.contentMinimum()
	if this.minSize.X < this.userMinSize.X {
		this.minSize.X = this.userMinSize.X
	}
	if this.minSize.Y < this.userMinSize.Y {
		this.minSize.Y = this.userMinSize.Y
	}
	
	if this.parent != nil {
		this.parent.notifyMinimumSizeChange(this)
	}
}

// var drawcnt int
func (this *box) doDraw () {
	// println("DRAW", drawcnt)
	// drawcnt ++

	canvas := this.canvas.Value()
	if canvas == nil { return }
	if this.drawer != nil {
		this.drawBorders(canvas)
		this.drawer.Draw(canvas.SubCanvas(this.innerClippingBounds))
	}
}

// var laycnt int
func (this *box) doLayout () {
	// println("LAYOUT", laycnt)
	// laycnt ++
	
	this.innerClippingBounds = this.borderSum().Apply(this.bounds)
	this.outer.recursiveLoseCanvas()
}

func (this *box) setParent (parent parent) {
	if this.parent != parent && this.Focused() {
		this.SetFocused(false)
	}
	this.parent = parent
	this.outer.recursiveReApply()
}

func (this *box) getParent () parent {
	return this.parent
}

func (this *box) flushActionQueue () {
	if this.getHierarchy() == nil { return }

	if this.minSizeQueued {
		this.invalidateMinimum()
	}
	if this.focusQueued != nil {
		this.SetFocused(*this.focusQueued)
	}
}

func (this *box) recursiveRedo () {
	this.doLayout()
	this.doDraw()
}

func (this *box) recursiveLoseCanvas () {
	this.canvas.InvalidateTo(nil)
}

func (this *box) invalidateLayout () {
	hierarchy := this.getHierarchy()
	if hierarchy == nil { return }
	hierarchy.invalidateLayout(this.outer)
}

func (this *box) invalidateDraw () {
	hierarchy := this.getHierarchy()
	if hierarchy == nil { return }
	hierarchy.invalidateDraw(this.outer)
}

func (this *box) invalidateMinimum () {
	hierarchy := this.getHierarchy()
	if hierarchy == nil {
		this.minSizeQueued = true
	} else {
		hierarchy.invalidateMinimum(this.outer)
	}
}

func (this *box) recursiveReApply () {
	if this.getHierarchy() == nil { return }
	
	// re-apply styling, icons *if needed*

	// style
	hierarchyStyleNonce := this.getStyleNonce()
	if this.lastStyleNonce != hierarchyStyleNonce {
		// remove old style
		this.lastStyleNonce = hierarchyStyleNonce
		if this.styleCookie != nil {
			this.styleCookie.Close()
			this.styleCookie = nil
		}

		// apply new one
		if style := this.getStyle(); style != nil {
			this.styleCookie = style.Apply(this.outer)
		}
		this.on.styleChange.Broadcast()
	}

	// icons
	hierarchyIconsNonce := this.getIconsNonce()
	if this.lastIconsNonce != hierarchyIconsNonce {
		this.lastIconsNonce = hierarchyIconsNonce
		this.on.iconsChange.Broadcast()
	}
}

func (this *box) canBeFocused () bool {
	return this.focusable
}

func (this *box) boxUnder (point image.Point, category eventCategory) anyBox {
	if point.In(this.bounds) {
		return this.outer
	} else {
		return nil
	}
}

func (this *box) propagate (callback func (anyBox) bool) bool {
	return callback(this.outer)
}

func (this *box) propagateAlt (callback func (anyBox) bool) bool {
	return callback(this.outer)
}

func (this *box) transparent () bool {
	// TODO uncomment once we have
	// a way to detect texture transparency
	return util.Transparent(this.color) /*&&
		(this.texture == nil || !this.texture.Opaque())*/
}

func (this *box) getWindow () tomo.Window {
	hierarchy := this.getHierarchy()
	if hierarchy == nil { return nil }
	return hierarchy.getWindow()
}

func (this *box) getStyle () tomo.Style {
	hierarchy := this.getHierarchy()
	if hierarchy == nil { return nil }
	return hierarchy.getStyle()
}

func (this *box) getHierarchy () *Hierarchy {
	if this.parent == nil { return nil }
	return this.parent.getHierarchy()
}

func (this *box) getStyleNonce () int {
	// should panic if not in the tree
	return this.getHierarchy().getStyleNonce()
}

func (this *box) getIconsNonce () int {
	// should panic if not in the tree
	return this.getHierarchy().getIconsNonce()
}