ocelot-desktop/src/main/scala/ocelot/desktop/ui/widget/Widget.scala

package ocelot.desktop.ui.widget

import ocelot.desktop.geometry.{Rect2D, Size2D, Vector2D}
import ocelot.desktop.graphics.Graphics
import ocelot.desktop.ui.EventHandlers
import ocelot.desktop.ui.event.Event
import ocelot.desktop.ui.layout.{Layout, LinearLayout}

class Widget {
  val eventHandlers = new EventHandlers

  protected var _children: Array[Widget] = Array[Widget]()
  protected var parent: Option[Widget] = None
  protected val layout: Layout = new LinearLayout(this)

  private var shouldRelayoutParent = false

  def relayoutParent(): Unit = {
    shouldRelayoutParent = true
  }

  def minimumSize: Size2D = layout.minimumSize

  def maximumSize: Size2D = layout.maximumSize

  protected var _position: Vector2D = Vector2D(0, 0)

  def position: Vector2D = _position

  def position_=(value: Vector2D): Unit = {
    if (value == _position) return

    _position = value
    relayout()
  }

  protected var _size: Size2D = Size2D(0, 0)

  def size: Size2D = _size

  def size_=(value: Size2D): Unit = {
    val clamped = value.clamped(minimumSize, maximumSize)

    if (clamped != _size) {
      recalculateBounds()
      _size = clamped.copy()
      relayout()
      shouldRelayoutParent = true
    }
  }

  def width: Float = size.width

  def height: Float = size.height

  def width_=(value: Float): Unit = {
    size = size.copy(width = value)
  }

  def height_=(value: Float): Unit = {
    size = size.copy(height = value)
  }

  def bounds: Rect2D = Rect2D(position, size)

  def children: Array[Widget] = _children

  def children_=(value: Array[Widget]): Unit = {
    _children = value

    for (child <- _children)
      child.parent = Some(this)

    recalculateBounds()
    size = _size
    relayout()
  }

  def recalculateBounds(): Unit = layout.recalculateBounds()

  def relayout(): Unit = layout.relayout()

  def draw(g: Graphics): Unit = {
    drawChildren(g)
  }

  protected def drawChildren(g: Graphics): Unit = {
    for (child <- children) {
      g.save()
      child.draw(g)
      g.restore()
    }
  }

  def update(): Unit = {
    if (shouldRelayoutParent) {
      parent.foreach(_.recalculateBounds())
      parent.foreach(_.relayout())
      shouldRelayoutParent = false
    }

    updateChildren()
  }

  protected def updateChildren(): Unit = {
    for (child <- children)
      child.update()
  }

  def handleEvent(event: Event): Unit = {
    eventHandlers(event)

    for (child <- children)
      child.handleEvent(event)
  }
}