package net.minecraft.client.renderer.block.model;

import com.mojang.math.Quadrant;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import net.fabricmc.api.EnvType;
import net.fabricmc.api.Environment;
import net.minecraft.client.renderer.block.model.TextureSlots.Data.Builder;
import net.minecraft.client.renderer.texture.SpriteContents;
import net.minecraft.client.resources.model.Material;
import net.minecraft.client.resources.model.ModelBaker;
import net.minecraft.client.resources.model.ModelDebugName;
import net.minecraft.client.resources.model.ModelState;
import net.minecraft.client.resources.model.QuadCollection;
import net.minecraft.client.resources.model.SpriteGetter;
import net.minecraft.client.resources.model.UnbakedGeometry;
import net.minecraft.client.resources.model.UnbakedModel;
import net.minecraft.core.Direction;
import net.minecraft.resources.ResourceLocation;
import org.jetbrains.annotations.Nullable;
import org.joml.Vector3f;

@Environment(EnvType.CLIENT)
public class ItemModelGenerator implements UnbakedModel {
	public static final ResourceLocation GENERATED_ITEM_MODEL_ID = ResourceLocation.withDefaultNamespace("builtin/generated");
	public static final List<String> LAYERS = List.of("layer0", "layer1", "layer2", "layer3", "layer4");
	private static final float MIN_Z = 7.5F;
	private static final float MAX_Z = 8.5F;
	private static final TextureSlots.Data TEXTURE_SLOTS = new Builder().addReference("particle", "layer0").build();
	private static final BlockElementFace.UVs SOUTH_FACE_UVS = new BlockElementFace.UVs(0.0F, 0.0F, 16.0F, 16.0F);
	private static final BlockElementFace.UVs NORTH_FACE_UVS = new BlockElementFace.UVs(16.0F, 0.0F, 0.0F, 16.0F);

	@Override
	public TextureSlots.Data textureSlots() {
		return TEXTURE_SLOTS;
	}

	@Override
	public UnbakedGeometry geometry() {
		return ItemModelGenerator::bake;
	}

	@Nullable
	@Override
	public UnbakedModel.GuiLight guiLight() {
		return UnbakedModel.GuiLight.FRONT;
	}

	private static QuadCollection bake(TextureSlots textureSlots, ModelBaker baker, ModelState modelState, ModelDebugName debugName) {
		return bake(textureSlots, baker.sprites(), modelState, debugName);
	}

	private static QuadCollection bake(TextureSlots textureSlots, SpriteGetter sprites, ModelState modelState, ModelDebugName debugName) {
		List<BlockElement> list = new ArrayList();

		for (int i = 0; i < LAYERS.size(); i++) {
			String string = (String)LAYERS.get(i);
			Material material = textureSlots.getMaterial(string);
			if (material == null) {
				break;
			}

			SpriteContents spriteContents = sprites.get(material, debugName).contents();
			list.addAll(processFrames(i, string, spriteContents));
		}

		return SimpleUnbakedGeometry.bake(list, textureSlots, sprites, modelState, debugName);
	}

	private static List<BlockElement> processFrames(int tintIndex, String texture, SpriteContents sprite) {
		Map<Direction, BlockElementFace> map = Map.of(
			Direction.SOUTH,
			new BlockElementFace(null, tintIndex, texture, SOUTH_FACE_UVS, Quadrant.R0),
			Direction.NORTH,
			new BlockElementFace(null, tintIndex, texture, NORTH_FACE_UVS, Quadrant.R0)
		);
		List<BlockElement> list = new ArrayList();
		list.add(new BlockElement(new Vector3f(0.0F, 0.0F, 7.5F), new Vector3f(16.0F, 16.0F, 8.5F), map));
		list.addAll(createSideElements(sprite, texture, tintIndex));
		return list;
	}

	private static List<BlockElement> createSideElements(SpriteContents sprite, String texture, int tintIndex) {
		float f = sprite.width();
		float g = sprite.height();
		List<BlockElement> list = new ArrayList();

		for (ItemModelGenerator.Span span : getSpans(sprite)) {
			float h = 0.0F;
			float i = 0.0F;
			float j = 0.0F;
			float k = 0.0F;
			float l = 0.0F;
			float m = 0.0F;
			float n = 0.0F;
			float o = 0.0F;
			float p = 16.0F / f;
			float q = 16.0F / g;
			float r = span.getMin();
			float s = span.getMax();
			float t = span.getAnchor();
			ItemModelGenerator.SpanFacing spanFacing = span.getFacing();
			switch (spanFacing) {
				case UP:
					l = r;
					h = r;
					j = m = s + 1.0F;
					n = t;
					i = t;
					k = t;
					o = t + 1.0F;
					break;
				case DOWN:
					n = t;
					o = t + 1.0F;
					l = r;
					h = r;
					j = m = s + 1.0F;
					i = t + 1.0F;
					k = t + 1.0F;
					break;
				case LEFT:
					l = t;
					h = t;
					j = t;
					m = t + 1.0F;
					o = r;
					i = r;
					k = n = s + 1.0F;
					break;
				case RIGHT:
					l = t;
					m = t + 1.0F;
					h = t + 1.0F;
					j = t + 1.0F;
					o = r;
					i = r;
					k = n = s + 1.0F;
			}

			h *= p;
			j *= p;
			i *= q;
			k *= q;
			i = 16.0F - i;
			k = 16.0F - k;
			l *= p;
			m *= p;
			n *= q;
			o *= q;
			Map<Direction, BlockElementFace> map = Map.of(
				spanFacing.getDirection(), new BlockElementFace(null, tintIndex, texture, new BlockElementFace.UVs(l, n, m, o), Quadrant.R0)
			);
			switch (spanFacing) {
				case UP:
					list.add(new BlockElement(new Vector3f(h, i, 7.5F), new Vector3f(j, i, 8.5F), map));
					break;
				case DOWN:
					list.add(new BlockElement(new Vector3f(h, k, 7.5F), new Vector3f(j, k, 8.5F), map));
					break;
				case LEFT:
					list.add(new BlockElement(new Vector3f(h, i, 7.5F), new Vector3f(h, k, 8.5F), map));
					break;
				case RIGHT:
					list.add(new BlockElement(new Vector3f(j, i, 7.5F), new Vector3f(j, k, 8.5F), map));
			}
		}

		return list;
	}

	private static List<ItemModelGenerator.Span> getSpans(SpriteContents sprite) {
		int i = sprite.width();
		int j = sprite.height();
		List<ItemModelGenerator.Span> list = new ArrayList();
		sprite.getUniqueFrames().forEach(k -> {
			for (int l = 0; l < j; l++) {
				for (int m = 0; m < i; m++) {
					boolean bl = !isTransparent(sprite, k, m, l, i, j);
					checkTransition(ItemModelGenerator.SpanFacing.UP, list, sprite, k, m, l, i, j, bl);
					checkTransition(ItemModelGenerator.SpanFacing.DOWN, list, sprite, k, m, l, i, j, bl);
					checkTransition(ItemModelGenerator.SpanFacing.LEFT, list, sprite, k, m, l, i, j, bl);
					checkTransition(ItemModelGenerator.SpanFacing.RIGHT, list, sprite, k, m, l, i, j, bl);
				}
			}
		});
		return list;
	}

	private static void checkTransition(
		ItemModelGenerator.SpanFacing spanFacing,
		List<ItemModelGenerator.Span> listSpans,
		SpriteContents contents,
		int frameIndex,
		int pixelX,
		int pixelY,
		int spriteWidth,
		int spriteHeight,
		boolean transparent
	) {
		boolean bl = isTransparent(contents, frameIndex, pixelX + spanFacing.getXOffset(), pixelY + spanFacing.getYOffset(), spriteWidth, spriteHeight)
			&& transparent;
		if (bl) {
			createOrExpandSpan(listSpans, spanFacing, pixelX, pixelY);
		}
	}

	private static void createOrExpandSpan(List<ItemModelGenerator.Span> listSpans, ItemModelGenerator.SpanFacing spanFacing, int pixelX, int pixelY) {
		ItemModelGenerator.Span span = null;

		for (ItemModelGenerator.Span span2 : listSpans) {
			if (span2.getFacing() == spanFacing) {
				int i = spanFacing.isHorizontal() ? pixelY : pixelX;
				if (span2.getAnchor() == i) {
					span = span2;
					break;
				}
			}
		}

		int j = spanFacing.isHorizontal() ? pixelY : pixelX;
		int k = spanFacing.isHorizontal() ? pixelX : pixelY;
		if (span == null) {
			listSpans.add(new ItemModelGenerator.Span(spanFacing, k, j));
		} else {
			span.expand(k);
		}
	}

	private static boolean isTransparent(SpriteContents sprite, int frameIndex, int pixelX, int pixelY, int spriteWidth, int spriteHeight) {
		return pixelX >= 0 && pixelY >= 0 && pixelX < spriteWidth && pixelY < spriteHeight ? sprite.isTransparent(frameIndex, pixelX, pixelY) : true;
	}

	@Environment(EnvType.CLIENT)
	static class Span {
		private final ItemModelGenerator.SpanFacing facing;
		private int min;
		private int max;
		private final int anchor;

		public Span(ItemModelGenerator.SpanFacing facing, int minMax, int anchor) {
			this.facing = facing;
			this.min = minMax;
			this.max = minMax;
			this.anchor = anchor;
		}

		public void expand(int pos) {
			if (pos < this.min) {
				this.min = pos;
			} else if (pos > this.max) {
				this.max = pos;
			}
		}

		public ItemModelGenerator.SpanFacing getFacing() {
			return this.facing;
		}

		public int getMin() {
			return this.min;
		}

		public int getMax() {
			return this.max;
		}

		public int getAnchor() {
			return this.anchor;
		}
	}

	@Environment(EnvType.CLIENT)
	static enum SpanFacing {
		UP(Direction.UP, 0, -1),
		DOWN(Direction.DOWN, 0, 1),
		LEFT(Direction.EAST, -1, 0),
		RIGHT(Direction.WEST, 1, 0);

		private final Direction direction;
		private final int xOffset;
		private final int yOffset;

		private SpanFacing(final Direction direction, final int xOffset, final int yOffset) {
			this.direction = direction;
			this.xOffset = xOffset;
			this.yOffset = yOffset;
		}

		/**
		 * Gets the direction of the block's facing.
		 */
		public Direction getDirection() {
			return this.direction;
		}

		public int getXOffset() {
			return this.xOffset;
		}

		public int getYOffset() {
			return this.yOffset;
		}

		boolean isHorizontal() {
			return this == DOWN || this == UP;
		}
	}
}