package com.jozufozu.flywheel.backend;

import static org.lwjgl.opengl.GL20.GL_TEXTURE0;
import static org.lwjgl.opengl.GL20.GL_TEXTURE4;
import static org.lwjgl.opengl.GL20.GL_TEXTURE_2D;
import static org.lwjgl.opengl.GL20.glActiveTexture;
import static org.lwjgl.opengl.GL20.glBindTexture;

import java.util.ArrayList;
import java.util.BitSet;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.SortedSet;
import java.util.Vector;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.lwjgl.opengl.GL;
import org.lwjgl.opengl.GLCapabilities;

import com.jozufozu.flywheel.backend.core.CrumblingRenderer;
import com.jozufozu.flywheel.backend.core.WorldContext;
import com.jozufozu.flywheel.backend.core.WorldTileRenderer;
import com.jozufozu.flywheel.backend.core.shader.ProgramSpec;
import com.jozufozu.flywheel.backend.core.shader.WorldProgram;
import com.jozufozu.flywheel.backend.gl.shader.GlProgram;
import com.jozufozu.flywheel.backend.gl.versioned.GlCompat;
import com.jozufozu.flywheel.backend.instancing.IFlywheelWorld;
import com.jozufozu.flywheel.backend.instancing.InstanceData;
import com.jozufozu.flywheel.backend.instancing.MaterialSpec;
import com.jozufozu.flywheel.util.WorldAttached;
import com.simibubi.create.foundation.config.AllConfigs;

import it.unimi.dsi.fastutil.longs.Long2ObjectMap;
import net.minecraft.client.Minecraft;
import net.minecraft.client.renderer.ActiveRenderInfo;
import net.minecraft.client.renderer.DestroyBlockProgress;
import net.minecraft.client.renderer.RenderType;
import net.minecraft.client.renderer.WorldRenderer;
import net.minecraft.client.renderer.model.ModelBakery;
import net.minecraft.client.renderer.texture.Texture;
import net.minecraft.client.renderer.texture.TextureManager;
import net.minecraft.client.world.ClientWorld;
import net.minecraft.entity.Entity;
import net.minecraft.inventory.container.PlayerContainer;
import net.minecraft.resources.IReloadableResourceManager;
import net.minecraft.resources.IResourceManager;
import net.minecraft.tileentity.TileEntity;
import net.minecraft.util.LazyValue;
import net.minecraft.util.ResourceLocation;
import net.minecraft.util.math.BlockPos;
import net.minecraft.util.math.vector.Matrix4f;
import net.minecraft.world.World;
import net.minecraftforge.resource.ISelectiveResourceReloadListener;

public class Backend {
	public static final Logger log = LogManager.getLogger(Backend.class);

	public static final ShaderLoader shaderLoader = new ShaderLoader();
	public static final FlywheelListeners listeners = new FlywheelListeners();

	public static GLCapabilities capabilities;
	public static GlCompat compat;

	public static WorldAttached<WorldTileRenderer<WorldProgram>> tileRenderer = new WorldAttached<>(() -> new WorldTileRenderer<>(WorldContext.INSTANCE));
	public static LazyValue<Vector<CrumblingRenderer>> blockBreaking = new LazyValue<>(() -> {
		Vector<CrumblingRenderer> renderers = new Vector<>(10);
		for (int i = 0; i < 10; i++) {
			renderers.add(new CrumblingRenderer());
		}
		return renderers;
	});

	private static Matrix4f projectionMatrix = new Matrix4f();
	private static boolean instancingAvailable;
	private static boolean enabled;

	static final Map<ResourceLocation, MaterialSpec<?>> materialRegistry = new HashMap<>();
	static final List<ShaderContext<?>> contexts = new ArrayList<>();
	static final Map<ResourceLocation, ProgramSpec> programSpecRegistry = new HashMap<>();

	static {
		register(WorldContext.INSTANCE);
		register(WorldContext.CRUMBLING);

		listeners.refreshListener(world -> {
			if (canUseInstancing() && world != null) {
				WorldTileRenderer<WorldProgram> tileRenderer = Backend.tileRenderer.get(world);
				tileRenderer.invalidate();
				world.loadedTileEntityList.forEach(tileRenderer::add);
			}
		});

		listeners.setupFrameListener((world, stack, info, gameRenderer, lightTexture) -> {
			Backend.tileRenderer.get(world)
					.beginFrame(info);
		});

		listeners.renderLayerListener(Backend::renderLayer);
	}

	public Backend() {
		throw new IllegalStateException();
	}

	/**
	 * Register a shader program.
	 */
	public static ProgramSpec register(ProgramSpec spec) {
		ResourceLocation name = spec.name;
		if (programSpecRegistry.containsKey(name)) {
			throw new IllegalStateException("Program spec '" + name + "' already registered.");
		}
		programSpecRegistry.put(name, spec);
		return spec;
	}

	/**
	 * Register a shader context.
	 */
	public static <P extends GlProgram> ShaderContext<P> register(ShaderContext<P> spec) {
		contexts.add(spec);
		return spec;
	}

	/**
	 * Register an instancing material.
	 */
	public static <D extends InstanceData> MaterialSpec<D> register(MaterialSpec<D> spec) {
		ResourceLocation name = spec.name;
		if (materialRegistry.containsKey(name)) {
			throw new IllegalStateException("Material spec '" + name + "' already registered.");
		}
		materialRegistry.put(name, spec);
		return spec;
	}

	public static boolean isFlywheelWorld(World world) {
		return world == Minecraft.getInstance().world || (world instanceof IFlywheelWorld && ((IFlywheelWorld) world).supportsFlywheel());
	}

	public static boolean available() {
		return canUseVBOs();
	}

	public static boolean canUseInstancing() {
		return enabled && instancingAvailable;
	}

	public static boolean canUseVBOs() {
		return enabled && gl20();
	}

	public static boolean gl33() {
		return capabilities.OpenGL33;
	}

	public static boolean gl20() {
		return capabilities.OpenGL20;
	}

	public static void init() {
		// Can be null when running datagenerators due to the unfortunate time we call this
		Minecraft mc = Minecraft.getInstance();
		if (mc == null) return;

		IResourceManager manager = mc.getResourceManager();

		if (manager instanceof IReloadableResourceManager) {
			ISelectiveResourceReloadListener listener = shaderLoader::onResourceManagerReload;
			((IReloadableResourceManager) manager).addReloadListener(listener);
		}
	}

	public static void refresh() {
		capabilities = GL.createCapabilities();

		compat = new GlCompat(capabilities);

		instancingAvailable = compat.vertexArrayObjectsSupported() &&
				compat.drawInstancedSupported() &&
				compat.instancedArraysSupported();

		enabled = AllConfigs.CLIENT.experimentalRendering.get() && !OptifineHandler.usingShaders();
	}

	public static void tick() {
		Minecraft mc = Minecraft.getInstance();
		ClientWorld world = mc.world;

		WorldTileRenderer<WorldProgram> instancer = tileRenderer.get(world);

		Entity renderViewEntity = mc.renderViewEntity;
		instancer.tick(renderViewEntity.getX(), renderViewEntity.getY(), renderViewEntity.getZ());
	}

	public static void renderLayer(ClientWorld world, RenderType layer, Matrix4f viewProjection, double cameraX, double cameraY, double cameraZ) {
		if (!canUseInstancing(world)) return;
		WorldTileRenderer<WorldProgram> renderer = tileRenderer.get(world);

		layer.startDrawing();

		renderer.render(layer, viewProjection, cameraX, cameraY, cameraZ);

		layer.endDrawing();
	}

	private static final RenderType CRUMBLING = ModelBakery.BLOCK_DESTRUCTION_RENDER_LAYERS.get(0);

	public static void renderBreaking(ClientWorld world, Matrix4f viewProjection, double cameraX, double cameraY, double cameraZ) {
		if (!canUseInstancing(world)) return;

		WorldRenderer worldRenderer = Minecraft.getInstance().worldRenderer;
		Long2ObjectMap<SortedSet<DestroyBlockProgress>> breakingProgressions = worldRenderer.blockBreakingProgressions;

		if (breakingProgressions.isEmpty()) return;
		Vector<CrumblingRenderer> renderers = blockBreaking.getValue();

		BitSet bitSet = new BitSet(10);

		for (Long2ObjectMap.Entry<SortedSet<DestroyBlockProgress>> entry : breakingProgressions.long2ObjectEntrySet()) {
			BlockPos breakingPos = BlockPos.fromLong(entry.getLongKey());

			SortedSet<DestroyBlockProgress> progresses = entry.getValue();
			if (progresses != null && !progresses.isEmpty()) {
				int blockDamage = progresses.last().getPartialBlockDamage();
				bitSet.set(blockDamage);
				renderers.get(blockDamage).add(world.getTileEntity(breakingPos));
			}
		}

		TextureManager textureManager = Minecraft.getInstance().textureManager;
		ActiveRenderInfo info = Minecraft.getInstance().gameRenderer.getActiveRenderInfo();

		glActiveTexture(GL_TEXTURE0);
		glBindTexture(GL_TEXTURE_2D, textureManager.getTexture(PlayerContainer.BLOCK_ATLAS_TEXTURE).getGlTextureId());

		glActiveTexture(GL_TEXTURE4);

		CRUMBLING.startDrawing();
		bitSet.stream().forEach(i -> {
			Texture breaking = textureManager.getTexture(ModelBakery.BLOCK_DESTRUCTION_STAGE_TEXTURES.get(i));
			CrumblingRenderer renderer = renderers.get(i);
			renderer.beginFrame(info);

			if (breaking != null) {
				glBindTexture(GL_TEXTURE_2D, breaking.getGlTextureId());
				renderer.render(RenderType.getCutoutMipped(), viewProjection, cameraX, cameraY, cameraZ, program -> program.setTextureScale(64, 64));
			}

			renderer.invalidate();
		});
		CRUMBLING.endDrawing();

		glActiveTexture(GL_TEXTURE0);
		Texture breaking = textureManager.getTexture(ModelBakery.BLOCK_DESTRUCTION_STAGE_TEXTURES.get(0));
		if (breaking != null)
			glBindTexture(GL_TEXTURE_2D, breaking.getGlTextureId());
	}

	public static void enqueueUpdate(TileEntity te) {
		tileRenderer.get(te.getWorld()).queueUpdate(te);
	}

	public static void reloadWorldRenderers() {
		RenderWork.enqueue(Minecraft.getInstance().worldRenderer::loadRenderers);
	}

	public static boolean canUseInstancing(World world) {
		return canUseInstancing() && isFlywheelWorld(world);
	}

	public static Collection<MaterialSpec<?>> allMaterials() {
		return materialRegistry.values();
	}

	public static Collection<ProgramSpec> allPrograms() {
		return programSpecRegistry.values();
	}

	public static Matrix4f getProjectionMatrix() {
		return projectionMatrix;
	}

	public static void setProjectionMatrix(Matrix4f projectionMatrix) {
		Backend.projectionMatrix = projectionMatrix;
	}
}