ASMR/src/main/kotlin/net/shadowfacts/cacao/util/RenderHelper.kt

package net.shadowfacts.cacao.util

import com.mojang.blaze3d.platform.GlStateManager
import net.minecraft.client.MinecraftClient
import net.minecraft.client.gui.DrawableHelper
import net.minecraft.client.render.Tessellator
import net.minecraft.client.render.VertexFormats
import net.minecraft.client.sound.PositionedSoundInstance
import net.minecraft.sound.SoundEvent
import net.shadowfacts.cacao.geometry.Rect
import org.lwjgl.opengl.GL11

/**
 * Helper methods for rendering using Minecraft's utilities from Cacao views.
 * For unit testing, all drawing and OpenGL interaction can be disabled by setting the `cacao.drawing.disabled` JVM property to `true`.
 *
 * @author shadowfacts
 */
object RenderHelper {

	val disabled = (System.getProperty("cacao.drawing.disabled") ?: "false").toBoolean()

	// TODO: find a better place for this
	fun playSound(event: SoundEvent) {
		if (disabled) return
		MinecraftClient.getInstance().soundManager.play(PositionedSoundInstance.master(event, 1f))
	}

	/**
	 * Draws a solid [rect] filled with the given [color].
	 */
	fun fill(rect: Rect, color: Color) {
		if (disabled) return
		DrawableHelper.fill(rect.left.toInt(), rect.top.toInt(), rect.right.toInt(), rect.bottom.toInt(), color.argb)
	}

	/**
	 * Binds and draws the given [texture] filling the [rect].
	 */
	fun draw(rect: Rect, texture: Texture) {
		if (disabled) return
		color(1f, 1f, 1f, 1f)
		MinecraftClient.getInstance().textureManager.bindTexture(texture.location)
		draw(rect.left, rect.top, texture.u, texture.v, rect.width, rect.height, texture.width, texture.height)
	}

	/**
	 * Draws the bound texture with the given screen and texture position and size.
	 */
	fun draw(x: Double, y: Double, u: Int, v: Int, width: Double, height: Double, textureWidth: Int, textureHeight: Int) {
		if (disabled) return
		val uStart = u.toDouble() / textureWidth
		val uEnd = (u + width) / textureWidth
		val vStart = v.toDouble() / textureHeight
		val vEnd = (v + height) / textureHeight
		innerBlit(x, x + width, y, y + height, 0.0, uStart, uEnd, vStart, vEnd)
	}

	// Copied from net.minecraft.client.gui.DrawableHelper
	private fun innerBlit(xStart: Double, xEnd: Double, yStart: Double, yEnd: Double, z: Double, uStart: Double, uEnd: Double, vStart: Double, vEnd: Double) {
		val tessellator = Tessellator.getInstance()
		val buffer = tessellator.bufferBuilder
		buffer.begin(GL11.GL_QUADS, VertexFormats.POSITION_UV)
		buffer.vertex(xStart, yEnd, z).texture(uStart, vEnd).next()
		buffer.vertex(xEnd, yEnd, z).texture(uEnd, vEnd).next()
		buffer.vertex(xEnd, yStart, z).texture(uEnd, vStart).next()
		buffer.vertex(xStart, yStart, z).texture(uStart, vStart).next()
		tessellator.draw()
	}

	/**
	 * @see org.lwjgl.opengl.GL11.glPushMatrix
	 */
	fun pushMatrix() {
		if (disabled) return
		GlStateManager.pushMatrix()
	}

	/**
	 * @see org.lwjgl.opengl.GL11.glPopMatrix
	 */
	fun popMatrix() {
		if (disabled) return
		GlStateManager.popMatrix()
	}

	/**
	 * @see org.lwjgl.opengl.GL11.glTranslated
	 */
	fun translate(x: Double, y: Double, z: Double = 0.0) {
		if (disabled) return
		GlStateManager.translated(x, y, z)
	}

	/**
	 * @see org.lwjgl.opengl.GL11.glColor4f
	 */
	fun color(r: Float, g: Float, b: Float, alpha: Float) {
		if (disabled) return
		GlStateManager.color4f(r, g, b, alpha)
	}

}