package ru.betterend.mixin.client;

import java.util.Random;

import org.lwjgl.opengl.GL11;
import org.spongepowered.asm.mixin.Final;
import org.spongepowered.asm.mixin.Mixin;
import org.spongepowered.asm.mixin.Shadow;
import org.spongepowered.asm.mixin.injection.At;
import org.spongepowered.asm.mixin.injection.Inject;
import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;

import com.mojang.blaze3d.systems.RenderSystem;

import net.minecraft.client.MinecraftClient;
import net.minecraft.client.gl.VertexBuffer;
import net.minecraft.client.render.BufferBuilder;
import net.minecraft.client.render.BufferBuilderStorage;
import net.minecraft.client.render.SkyProperties;
import net.minecraft.client.render.Tessellator;
import net.minecraft.client.render.VertexFormat;
import net.minecraft.client.render.VertexFormats;
import net.minecraft.client.render.WorldRenderer;
import net.minecraft.client.texture.TextureManager;
import net.minecraft.client.util.math.MatrixStack;
import net.minecraft.client.util.math.Vector3f;
import net.minecraft.client.world.ClientWorld;
import net.minecraft.util.Identifier;
import net.minecraft.util.math.Quaternion;
import ru.betterend.BetterEnd;
import ru.betterend.util.MHelper;

@Mixin(WorldRenderer.class)
public class WorldRendererMixin {
	private static final Identifier SKY = new Identifier(BetterEnd.MOD_ID, "textures/sky/nebula_2.png");
	private static final Identifier GRADIENT = new Identifier(BetterEnd.MOD_ID, "textures/sky/gradient.png");
	
	private static VertexBuffer customStarsBuffer1;
	private static VertexBuffer customStarsBuffer2;
	private static VertexBuffer customStarsBuffer3;
	private static VertexBuffer farFogBuffer;
	private static VertexBuffer gradient;
	private static Vector3f axis1;
	private static Vector3f axis2;
	private static Vector3f axis3;
	private static float time;
	
	@Shadow
	@Final
	private MinecraftClient client;
	
	@Shadow
	@Final
	private TextureManager textureManager;
	
	@Shadow
	private ClientWorld world;
	
	@Inject(method = "<init>*", at = @At("TAIL"))
	private void onInit(MinecraftClient client, BufferBuilderStorage bufferBuilders, CallbackInfo info) {
		initStars();
		Random random = new Random(131);
		axis1 = new Vector3f(random.nextFloat(), random.nextFloat(), random.nextFloat());
		axis2 = new Vector3f(random.nextFloat(), random.nextFloat(), random.nextFloat());
		axis3 = new Vector3f(random.nextFloat(), random.nextFloat(), random.nextFloat());
		axis1.normalize();
		axis2.normalize();
		axis3.normalize();
	}
	
	@Inject(method = "renderSky", at = @At("HEAD"), cancellable = true)
	private void renderBetterEndSky(MatrixStack matrices, float tickDelta, CallbackInfo info) {
		if (client.world.getSkyProperties().getSkyType() == SkyProperties.SkyType.END) {
			time += tickDelta * 0.001F;
			if (time > 360) time -= 360;
			
			//RenderSystem.clearDepth(0);
			
			RenderSystem.enableAlphaTest();
			RenderSystem.enableBlend();
			RenderSystem.enableTexture();
			//RenderSystem.alphaFunc(GL11.GL_ONE_MINUS_SRC_ALPHA, 0);
			RenderSystem.defaultBlendFunc();
			RenderSystem.defaultAlphaFunc();
			//RenderSystem.blendEquation(mode);
			//RenderSystem.enableDepthTest();
			//GL14.glBlendFuncSeparate(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA, GL11.GL_ONE, GL11.GL_ZERO);
			//GL14.glBlendEquation(GL14.GL_FUNC_ADD);
			//RenderSystem.disableDepthTest();
			//GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);
			
			//RenderSystem.enableFog();
			//BackgroundRenderer.setFogBlack();
			//RenderSystem.fogStart(1F);
			//RenderSystem.fogEnd(10F);
			
			/*Vec3d vec3d = world.method_23777(this.client.gameRenderer.getCamera().getBlockPos(), tickDelta);
			float r = (float) vec3d.x;
			float g = (float) vec3d.y;
			float b = (float) vec3d.z;*/
			
			textureManager.bindTexture(GRADIENT);
			renderBuffer(matrices, gradient, VertexFormats.POSITION_TEXTURE, 0.77F, 0.31F, 0.73F, 1F);
			
			textureManager.bindTexture(SKY);
			renderBuffer(matrices, farFogBuffer, VertexFormats.POSITION_TEXTURE, 0.77F, 0.31F, 0.73F, 0.3F);

			RenderSystem.disableTexture();
			//RenderSystem.disableFog();
			
			//renderBuffer(matrices, gradient, VertexFormats.POSITION_COLOR, 0.77F, 0.31F, 0.73F, 1F);
			
			matrices.push();
			matrices.multiply(new Quaternion(axis1, time * 3, true));
			renderBuffer(matrices, customStarsBuffer1, VertexFormats.POSITION, 1, 1, 1, 0.6F);
			matrices.pop();
			
			matrices.push();
			matrices.multiply(new Quaternion(axis2, time * 2, true));
			renderBuffer(matrices, customStarsBuffer2, VertexFormats.POSITION, 0.95F, 0.64F, 0.93F, 0.6F);
			matrices.pop();
			
			matrices.push();
			matrices.multiply(new Quaternion(axis3, time, true));
			renderBuffer(matrices, customStarsBuffer3, VertexFormats.POSITION, 0.77F, 0.31F, 0.73F, 0.6F);
			matrices.pop();
			
			RenderSystem.enableTexture();
			RenderSystem.depthMask(true);
			
			info.cancel();
		}
	}
	
	private void renderBuffer(MatrixStack matrices, VertexBuffer buffer, VertexFormat format, float r, float g, float b, float a) {
		RenderSystem.color4f(r, g, b, a);
		buffer.bind();
		format.startDrawing(0L);
        buffer.draw(matrices.peek().getModel(), 7);
        VertexBuffer.unbind();
        format.endDrawing();
	}

	private void initStars() {
		BufferBuilder buffer = Tessellator.getInstance().getBuffer();
		customStarsBuffer1 = buildBuffer(buffer, customStarsBuffer1, 0.05, 0.3, 3500, 41315);
		customStarsBuffer2 = buildBuffer(buffer, customStarsBuffer2, 0.07, 0.4, 2000, 35151);
		customStarsBuffer3 = buildBuffer(buffer, customStarsBuffer3, 0.1, 0.5, 1500, 61354);
		farFogBuffer = buildBufferFarFog(buffer, farFogBuffer, 40, 60, 100, 11515);
		gradient = buildBufferGradient(buffer, gradient);
	}
	 
	private VertexBuffer buildBuffer(BufferBuilder bufferBuilder, VertexBuffer buffer, double minSize, double maxSize, int count, long seed) {
		if (buffer != null) {
			buffer.close();
		}

		buffer = new VertexBuffer(VertexFormats.POSITION);
		makeStars(bufferBuilder, minSize, maxSize, count, seed);
		bufferBuilder.end();
		buffer.upload(bufferBuilder);

		return buffer;
	}
	
	private VertexBuffer buildBufferFarFog(BufferBuilder bufferBuilder, VertexBuffer buffer, double minSize, double maxSize, int count, long seed) {
		if (buffer != null) {
			buffer.close();
		}

		buffer = new VertexBuffer(VertexFormats.POSITION_TEXTURE);
		makeFarFog(bufferBuilder, minSize, maxSize, count, seed);
		bufferBuilder.end();
		buffer.upload(bufferBuilder);

		return buffer;
	}
	
	private VertexBuffer buildBufferGradient(BufferBuilder bufferBuilder, VertexBuffer buffer) {
		if (buffer != null) {
			buffer.close();
		}

		buffer = new VertexBuffer(VertexFormats.POSITION_TEXTURE);
		makeGradient(bufferBuilder);
		bufferBuilder.end();
		buffer.upload(bufferBuilder);

		return buffer;
	}
	
	private void makeStars(BufferBuilder buffer, double minSize, double maxSize, int count, long seed) {
		Random random = new Random(seed);
		buffer.begin(7, VertexFormats.POSITION);

		for (int i = 0; i < count; ++i) {
			double posX = random.nextDouble() * 2.0 - 1.0;
			double posY = random.nextDouble() * 2.0 - 1.0;
			double posZ = random.nextDouble() * 2.0 - 1.0;
			double size = MHelper.randRange(minSize, maxSize, random);
			double length = posX * posX + posY * posY + posZ * posZ;
			if (length < 1.0 && length > 0.001) {
				length = 1.0 / Math.sqrt(length);
				posX *= length;
				posY *= length;
				posZ *= length;
				double j = posX * 100.0;
				double k = posY * 100.0;
				double l = posZ * 100.0;
				double m = Math.atan2(posX, posZ);
				double n = Math.sin(m);
				double o = Math.cos(m);
				double p = Math.atan2(Math.sqrt(posX * posX + posZ * posZ), posY);
				double q = Math.sin(p);
				double r = Math.cos(p);
				double s = random.nextDouble() * Math.PI * 2.0;
				double t = Math.sin(s);
				double u = Math.cos(s);

				for (int v = 0; v < 4; ++v) {
					double x = (double) ((v & 2) - 1) * size;
					double y = (double) ((v + 1 & 2) - 1) * size;
					double aa = x * u - y * t;
					double ab = y * u + x * t;
					double ad = aa * q + 0.0 * r;
					double ae = 0.0 * q - aa * r;
					double af = ae * n - ab * o;
					double ah = ab * n + ae * o;
					buffer.vertex(j + af, k + ad, l + ah).next();
				}
			}
		}
	}
	
	private void makeFarFog(BufferBuilder buffer, double minSize, double maxSize, int count, long seed) {
		Random random = new Random(seed);
		buffer.begin(7, VertexFormats.POSITION_TEXTURE);

		for (int i = 0; i < count; ++i) {
			double posX = random.nextDouble() * 2.0 - 1.0;
			double posY = random.nextDouble() * 0.5 - 0.25;
			double posZ = random.nextDouble() * 2.0 - 1.0;
			double size = MHelper.randRange(minSize, maxSize, random);
			double length = posX * posX + posY * posY + posZ * posZ;
			double distance = 2.0;
			double delta = 1.0 / count;
			if (length < 1.0 && length > 0.001) {
				length = distance / Math.sqrt(length);
				size *= distance;
				distance -= delta;
				posX *= length;
				posY *= length;
				posZ *= length;
				double j = posX * 100.0;
				double k = posY * 100.0;
				double l = posZ * 100.0;
				double m = Math.atan2(posX, posZ);
				double n = Math.sin(m);
				double o = Math.cos(m);
				double p = Math.atan2(Math.sqrt(posX * posX + posZ * posZ), posY);
				double q = Math.sin(p);
				double r = Math.cos(p);
				double s = random.nextDouble() * Math.PI * 2.0;
				double t = Math.sin(s);
				double u = Math.cos(s);

				int pos = 0;
				for (int v = 0; v < 4; ++v) {
					double x = (double) ((v & 2) - 1) * size;
					double y = (double) ((v + 1 & 2) - 1) * size;
					double aa = x * u - y * t;
					double ab = y * u + x * t;
					double ad = aa * q + 0.0 * r;
					double ae = 0.0 * q - aa * r;
					double af = ae * n - ab * o;
					double ah = ab * n + ae * o;
					float texU = (pos >> 1) & 1;
					float texV = ((pos + 1) >> 1) & 1;
					pos ++;
					buffer.vertex(j + af, k + ad, l + ah).texture(texU, texV).next();
				}
			}
		}
	}
	
	private void makeGradient(BufferBuilder buffer) {
		buffer.begin(7, VertexFormats.POSITION_TEXTURE);
		for (int i = 0; i < 8; i ++)
		{
			double a1 = (double) i * Math.PI / 4.0;
			double a2 = (double) (i + 1) * Math.PI / 4.0;
			double px1 = Math.sin(a1) * 100;
			double pz1 = Math.cos(a1) * 100;
			double px2 = Math.sin(a2) * 100;
			double pz2 = Math.cos(a2) * 100;
			
			buffer.vertex(px1, -30, pz1).texture(0, 0).next();
			buffer.vertex(px1, 30, pz1).texture(0, 1).next();
			buffer.vertex(px2, 30, pz2).texture(1, 1).next();
			buffer.vertex(px2, -30, pz2).texture(1, 0).next();
			
			/*buffer.vertex(px1, 0, pz1).color(1, 1, 1, 1).next();
			buffer.vertex(px1, 0.1, pz1).color(1, 1, 1, 0).next();
			buffer.vertex(px2, 0.1, pz2).color(1, 1, 1, 0).next();
			buffer.vertex(px2, 0, pz2).color(1, 1, 1, 1).next();
			
			buffer.vertex(px1, 0, pz1).color(1, 1, 1, 1).next();
			buffer.vertex(px1, -0.1, pz1).color(1, 1, 1, 0).next();
			buffer.vertex(px2, -0.1, pz2).color(1, 1, 1, 0).next();
			buffer.vertex(px2, 0, pz2).color(1, 1, 1, 1).next();*/
		}
	}
}