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

package ocelot.desktop.ui.widget

import ocelot.desktop.ColorScheme
import ocelot.desktop.audio.{SoundSource, SoundSources}
import ocelot.desktop.color.Color
import ocelot.desktop.geometry.Size2D
import ocelot.desktop.graphics.Graphics
import ocelot.desktop.ui.event.handlers.{ClickHandler, HoverHandler}
import ocelot.desktop.ui.event.{HoverEvent, MouseEvent}
import ocelot.desktop.ui.widget.IconButton.Mode
import ocelot.desktop.ui.widget.tooltip.LabelTooltip
import ocelot.desktop.util.animation.{ColorAnimation, ValueAnimation}
import ocelot.desktop.util.{DrawUtils, Spritesheet}

class IconButton(
  releasedIcon: String,
  pressedIcon: String,
  releasedColor: Color = Color.White,
  pressedColor: Color = Color.White,
  sizeMultiplier: Float = 1,
  mode: Mode = Mode.Regular,
  drawBackground: Boolean = false,
  padding: Float = 0,
  tooltip: Option[String] = None,
  val model: IconButton.Model = IconButton.DefaultModel(false),
) extends Widget
    with ClickHandler
    with HoverHandler
    with ClickSoundSource {

  private val speed = 10f

  override def receiveMouseEvents = true

  private var prevModelValue = model.pressed

  eventHandlers += {
    case HoverEvent(HoverEvent.State.Enter) => onHoverEnter()
    case HoverEvent(HoverEvent.State.Leave) => onHoverLeave()

    case MouseEvent(MouseEvent.State.Press, MouseEvent.Button.Left) =>
      mode match {
        case Mode.Switch if model.pressed => handleRelease()
        case Mode.Radio if model.pressed =>
        case _ => handlePress()
      }

      clickSoundSource.play()

    case MouseEvent(MouseEvent.State.Release, MouseEvent.Button.Left) =>
      mode match {
        case Mode.Regular => handleRelease()
        case Mode.Switch =>
        case Mode.Radio =>
      }
  }

  def onPressed(): Unit = {}

  def onReleased(): Unit = {}

  private def onHoverEnter(): Unit = {
    for (tooltip <- labelTooltip) {
      root.get.tooltipPool.addTooltip(tooltip)
    }
  }

  private def onHoverLeave(): Unit = {
    for (tooltip <- labelTooltip) {
      root.get.tooltipPool.closeTooltip(tooltip)
    }
  }

  private def targetColor: Color = if (model.pressed) pressedColor else releasedColor
  private def targetAlpha: Float = if (model.pressed) 1f else 0f

  private val colorAnimation = new ColorAnimation(targetColor, speed)
  private val alphaAnimation = new ValueAnimation(targetAlpha, speed)

  private def handlePress(): Unit = {
    model.pressed = true
    onPressed()
  }

  private def handleRelease(): Unit = {
    model.pressed = false
    onReleased()
  }

  size = minimumSize

  private def releasedIconSize: Size2D = Spritesheet.spriteSize(releasedIcon) * sizeMultiplier

  private def pressedIconSize: Size2D = Spritesheet.spriteSize(pressedIcon) * sizeMultiplier

  override def minimumSize: Size2D = releasedIconSize.max(pressedIconSize) + (padding * 2.0f)
  override def maximumSize: Size2D = minimumSize

  private val labelTooltip = tooltip.map(label => new LabelTooltip(label))

  override def draw(g: Graphics): Unit = {
    if (drawBackground) {
      g.rect(bounds, ColorScheme("ButtonBackground"))
      DrawUtils.ring(g, position.x, position.y, width, height, 2, ColorScheme("ButtonBorder"))
    }

    if (alphaAnimation.value < 1f) {
      g.sprite(
        releasedIcon,
        position + (size - releasedIconSize) / 2f,
        releasedIconSize,
        releasedColor.toRGBANorm.mapA(_ * (1f - alphaAnimation.value)),
      )
    }

    if (alphaAnimation.value > 0f) {
      g.sprite(
        pressedIcon,
        position + (size - pressedIconSize) / 2f,
        pressedIconSize,
        pressedColor.toRGBANorm.mapA(_ * alphaAnimation.value),
      )
    }
  }

  override def update(): Unit = {
    super.update()

    val nextModelValue = model.pressed

    if (prevModelValue != nextModelValue) {
      prevModelValue = nextModelValue
      colorAnimation.goto(targetColor)
      alphaAnimation.goto(targetAlpha)
    }

    colorAnimation.update()
    alphaAnimation.update()
  }

  override protected def clickSoundSource: SoundSource = SoundSources.InterfaceClick
}

object IconButton {
  sealed trait Mode

  object Mode {
    /**
      * Your regular, run-of-the-mill button you love.
      *
      * When the LMB is depressed, [[IconButton.onPressed]] is called.
      * After it's released, [[IconButton.onReleased]] is called.
      */
    case object Regular extends Mode

    /**
      * A toggleable button, or a switch.
      *
      * Pressing the LMB while the button is pressed releases it, and [[IconButton.onReleased]] is called.
      * Pressing the LMB while the button is released depresses it, and [[IconButton.onPressed]] is called.
      */
    case object Switch extends Mode

    /**
      * A radio button is like a switch except clicking on it while it's depressed doesn't do anything.
      *
      * [[IconButton.onReleased]] is never called (unless you do it yourself).
      *
      * Managing a group of radio buttons is your responsibility.
      */
    case object Radio extends Mode
  }

  /**
    * This is the visible button state.
    *
    * When [[IconButton.update]] notices a state change, it runs its animations.
    *
    * Note that callbacks are run after running the setter regardless of whether it does anything.
    */
  trait Model {
    /**
      * Whether to display the pressed button state.
      */
    def pressed: Boolean

    /**
      * This setter is used by [[IconButton]] to respond to user interaction.
      *
      * You may want to override this method to do nothing
      * if you're proxying another model and updating it in callbacks.
      */
    def pressed_=(newValue: Boolean): Unit
  }

  /**
    * This is the default model that simply reads from a variable and writes to it.
    */
  case class DefaultModel(override var pressed: Boolean) extends Model

  /**
    * This is a model that ignores user input (presumably you handle it in callbacks).
    */
  class ReadOnlyModel(f: () => Boolean) extends Model {
    override def pressed: Boolean = f()

    override def pressed_=(newValue: Boolean): Unit = {}
  }

  object ReadOnlyModel {
    /**
      * A utility method to create a new instance of [[ReadOnlyModel]].
      *
      * The value returned by [[ReadOnlyModel.pressed]] is obtained
      * by evaluating the provided expression '''every time'''.
      */
    def apply(value: => Boolean): ReadOnlyModel = new ReadOnlyModel(value _)
  }
}