package net.shadowfacts.cacao.view.button

import net.minecraft.util.Identifier
import net.shadowfacts.cacao.geometry.Point
import net.shadowfacts.cacao.util.MouseButton
import net.shadowfacts.cacao.util.NinePatchTexture
import net.shadowfacts.cacao.util.RenderHelper
import net.shadowfacts.cacao.util.Texture
import net.shadowfacts.cacao.view.NinePatchView
import net.shadowfacts.cacao.view.View
import net.shadowfacts.kiwidsl.dsl

/**
 * A abstract button class. Cannot be constructed directly, used for creating button implementations with their own logic.
 * Use [Button] for a generic no-frills button.
 *
 * @author shadowfacts
 * @param Impl The type of the concrete implementation of the button.
 * 				Used to allow the [handler] to receive the exact button type that was constructed.
 * @param content The [View] that provides the content of this button.
 * 					Will be added as a subview of the button and laid out using constraints.
 * @param padding The padding between the [content] and the edges of the button.
 */
abstract class AbstractButton<Impl: AbstractButton<Impl>>(val content: View, val padding: Double = 4.0): View() {

	companion object {
		val DEFAULT_BG = NinePatchTexture(Texture(Identifier("textures/gui/widgets.png"), 0, 66), 3, 3, 194, 14)
		val HOVERED_BG = NinePatchTexture(Texture(Identifier("textures/gui/widgets.png"), 0, 86), 3, 3, 194, 14)
		val DISABLED_BG = NinePatchTexture(Texture(Identifier("textures/gui/widgets.png"), 0, 46), 3, 3, 194, 14)
	}

	/**
	 * The function that handles when this button is clicked.
	 * The parameter is the type of the concrete button implementation that was used.
	 */
	var handler: ((Impl) -> Unit)? = null

	/**
	 * Whether the button is disabled.
	 * Disabled buttons have a different background ([disabledBackground]) and do not receive click events.
	 */
	var disabled = false

	/**
	 * The normal background view to draw behind the button content. It will be added as a subview during [wasAdded],
	 * so all background view properties must be specified prior to the button being added to a view hierarchy.
	 *
	 * The background will fill the entire button (going beneath the content [padding]).
	 * There are also [hoveredBackground] and [disabledBackground] for those states.
	 * If a [backgroundColor] is specified, it will be drawn behind the background View and thus not visible
	 * unless the background view is not fully opaque.
	 */
	var background: View? = NinePatchView(DEFAULT_BG)
	/**
	 * The background to draw when the button is hovered over by the mouse.
	 * If `null`, the normal [background] will be used.
	 * @see background
	 */
	var hoveredBackground: View? = NinePatchView(HOVERED_BG)
	/**
	 * The background to draw when the button is [disabled].
	 * If `null`, the normal [background] will be used.
	 * @see background
	 */
	var disabledBackground: View? = NinePatchView(DISABLED_BG)

	override fun wasAdded() {
		solver.dsl {
			addSubview(content)
			content.leftAnchor equalTo (leftAnchor + padding)
			content.rightAnchor equalTo (rightAnchor - padding)
			content.topAnchor equalTo (topAnchor + padding)
			content.bottomAnchor equalTo (bottomAnchor - padding)

			listOfNotNull(background, hoveredBackground, disabledBackground).forEach {
				addSubview(it)
				it.leftAnchor equalTo leftAnchor
				it.rightAnchor equalTo rightAnchor
				it.topAnchor equalTo topAnchor
				it.bottomAnchor equalTo bottomAnchor
			}
		}

		super.wasAdded()
	}

	override fun draw(mouse: Point, delta: Float) {
		RenderHelper.pushMatrix()
		RenderHelper.translate(frame.left, frame.top)

		RenderHelper.fill(bounds, backgroundColor)

		var currentBackground: View? = background
		if (mouse in bounds) {
			currentBackground = hoveredBackground ?: currentBackground
		}
		if (disabled) {
			currentBackground = disabledBackground ?: currentBackground
		}
		// don't need to convert mouse to background coordinate system
		// the edges are all pinned, so the coordinate space is the same
		currentBackground?.draw(mouse, delta)

		val mouseInContent = convert(mouse, to = content)
		content.draw(mouseInContent, delta)

		// don't draw subviews, otherwise all background views + content will get drawn

		RenderHelper.popMatrix()
	}

	override fun mouseClicked(point: Point, mouseButton: MouseButton): Boolean {
		if (disabled) return false

		// We can perform an unchecked cast here because we are certain that Impl will be the concrete implementation
		// of AbstractButton.
		// For example, an implementing class may be defined as such: `class Button: AbstractButton<Button>`
		@Suppress("UNCHECKED_CAST")
		handler?.invoke(this as Impl)

		return true
	}

}