package net.coderbot.iris.shaderpack;

import com.google.common.collect.ImmutableList;
import com.google.gson.Gson;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import com.google.gson.stream.JsonReader;
import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
import it.unimi.dsi.fastutil.objects.Object2ObjectMap;
import it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap;
import lombok.Getter;
import net.coderbot.iris.Iris;
import net.coderbot.iris.features.FeatureFlags;
import net.coderbot.iris.gl.buffer.ShaderStorageInfo;
import net.coderbot.iris.gl.image.ImageInformation;
import net.coderbot.iris.gl.texture.TextureDefinition;
import net.coderbot.iris.shaderpack.include.AbsolutePackPath;
import net.coderbot.iris.shaderpack.include.IncludeGraph;
import net.coderbot.iris.shaderpack.include.IncludeProcessor;
import net.coderbot.iris.shaderpack.include.ShaderPackSourceNames;
import net.coderbot.iris.shaderpack.option.ProfileSet;
import net.coderbot.iris.shaderpack.option.ShaderPackOptions;
import net.coderbot.iris.shaderpack.option.menu.OptionMenuContainer;
import net.coderbot.iris.shaderpack.option.values.MutableOptionValues;
import net.coderbot.iris.shaderpack.option.values.OptionValues;
import net.coderbot.iris.shaderpack.preprocessor.JcppProcessor;
import net.coderbot.iris.shaderpack.preprocessor.PropertiesPreprocessor;
import net.coderbot.iris.shaderpack.texture.CustomTextureData;
import net.coderbot.iris.shaderpack.texture.TextureFilteringData;
import net.coderbot.iris.shaderpack.texture.TextureStage;
import net.coderbot.iris.uniforms.custom.CustomUniforms;
import net.irisshaders.iris.api.v0.IrisApi;
import org.jetbrains.annotations.Nullable;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StringReader;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Collections;
import java.util.EnumMap;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.Properties;
import java.util.Set;
import java.util.function.Function;
import java.util.stream.Collectors;

public class ShaderPack {
	private static final Gson GSON = new Gson();
	private static final Set<String> PINNED_DIMENSIONS = Set.of("Overworld", "Nether", "The End");
	// Configurable via -Diris.dimensionCacheSize=X (default: 12)
	// Set to 0 to disable caching entirely (only vanilla dimensions kept)
	// Minimum effective cache size is 3
	private static final int MAX_DIMENSION_CACHE;
	static {
		int configured = Math.max(0, Integer.getInteger("iris.dimensionCacheSize", 12));
		MAX_DIMENSION_CACHE = configured == 0 ? 0 : Math.max(PINNED_DIMENSIONS.size(), configured);
	}

    public final CustomUniforms.Builder customUniforms;

	private final ProgramSet base;

	private final Map<String, String> dimensionMap;
	private final Map<String, ProgramSet> dimensionProgramSets;
	private final Set<String> foldersWithShaderFiles;
	private final Function<AbsolutePackPath, String> sourceProvider;
	private final ShaderProperties shaderProperties;
	private boolean hasLoggedCacheLimitReached = false;

	@Getter private final IdMap idMap;
	@Getter private final LanguageMap languageMap;
	@Getter private final EnumMap<TextureStage, Object2ObjectMap<String, CustomTextureData>> customTextureDataMap = new EnumMap<>(TextureStage.class);
	@Getter private final Object2ObjectMap<String, CustomTextureData> irisCustomTextureDataMap = new Object2ObjectOpenHashMap<>();
	private final CustomTextureData customNoiseTexture;
	@Getter private final Object2ObjectMap<String, ImageInformation> customImages;
	@Getter private final Int2ObjectMap<ShaderStorageInfo> bufferObjects;
	@Getter private final ShaderPackOptions shaderPackOptions;
	@Getter private final OptionMenuContainer menuContainer;

	private final ProfileSet.ProfileResult profile;
	private final String profileInfo;

	public ShaderPack(Path root, Iterable<StringPair> environmentDefines) throws IOException, IllegalStateException {
		this(root, Collections.emptyMap(), environmentDefines);
	}

	/**
	 * Reads a shader pack from the disk.
	 *
	 * @param root The path to the "shaders" directory within the shader pack. The created ShaderPack will not retain
	 *             this path in any form; once the constructor exits, all disk I/O needed to load this shader pack will
	 *             have completed, and there is no need to hold on to the path for that reason.
	 * @throws IOException if there are any IO errors during shader pack loading.
	 */
	public ShaderPack(Path root, Map<String, String> changedConfigs, Iterable<StringPair> environmentDefines) throws IOException, IllegalStateException {
		// A null path is not allowed.
		Objects.requireNonNull(root);


		final ImmutableList.Builder<AbsolutePackPath> starts = ImmutableList.builder();
		final ImmutableList<String> potentialFileNames = ShaderPackSourceNames.POTENTIAL_STARTS;

		ShaderPackSourceNames.findPresentSources(starts, root, AbsolutePackPath.fromAbsolutePath("/"), potentialFileNames);

		// Parse dimension.properties to get dimension name -> folder mappings
		this.dimensionMap = new HashMap<>();
		this.foldersWithShaderFiles = new HashSet<>();

		Iris.logger.info("Dimension shader cache size: {} (3 vanilla pinned + {} modded), configurable via -Diris.dimensionCacheSize",
			MAX_DIMENSION_CACHE, Math.max(0, MAX_DIMENSION_CACHE - PINNED_DIMENSIONS.size()));

		// LRU cache to prevent memory leaks in modpacks with many dimensions (Mystcraft, Galacticraft, etc.)
		// Vanilla dimensions (Overworld, Nether, End) are pinned and never evicted
		this.dimensionProgramSets = new LinkedHashMap<>(Math.max(12, MAX_DIMENSION_CACHE), 0.75f, true);

		Optional<Properties> dimensionProperties = loadPropertiesFile(root, "dimension.properties");
		boolean hasDimensionProperties = dimensionProperties.isPresent();

		List<String> dimensionFolders = new ArrayList<>();

		if (hasDimensionProperties) {
			// Extract folder names from dimension.properties (e.g., "world0", "world-1", "custom_dim")
			dimensionFolders.addAll(parseDimensionMap(dimensionProperties.get(), "dimension."));
		}

		if (!dimensionFolders.isEmpty()) {
			for (String folderName : dimensionFolders) {
				boolean folderExists = checkAndAddDimensionFolder(starts, root, potentialFileNames, folderName);
				if (folderExists) {
					foldersWithShaderFiles.add(folderName);
				} else {
					Iris.logger.warn("dimension.properties references folder '{}' but it doesn't exist or has no shader files", folderName);
				}
			}

			// Warn if dimension.properties has no wildcard and no explicit Overworld/Nether/End mappings
			if (!dimensionMap.containsKey("*") && !dimensionMap.containsKey("Overworld")
				&& !dimensionMap.containsKey("Nether") && !dimensionMap.containsKey("The End")) {
				Iris.logger.warn("dimension.properties exists but doesn't define mappings for vanilla dimensions (Overworld/Nether/End) or a wildcard (*)");
			}
		} else {
            // No dimension.properties or it has no valid dimension mappings
			if (hasDimensionProperties) {
				Iris.logger.warn("dimension.properties exists but has no valid dimension mappings, falling back to legacy folder detection");
			}

			// Scan for all world{ID} folders to support old OptiFine packs with dimension IDs
			Set<String> foundFolders = new HashSet<>();
			try {
				Files.list(root)
					.filter(Files::isDirectory)
					.map(Path::getFileName)
					.map(Path::toString)
					.filter(name -> name.matches("world-?\\d+"))
					.forEach(folderName -> {
						try {
							boolean exists = checkAndAddDimensionFolder(starts, root, potentialFileNames, folderName);
							if (exists) {
								foundFolders.add(folderName);
								foldersWithShaderFiles.add(folderName);
							}
						} catch (IOException e) {
							Iris.logger.warn("Failed to scan dimension folder: {}", folderName, e);
						}
					});
			} catch (IOException e) {
				Iris.logger.warn("Failed to scan for dimension folders", e);
			}

			// Set up dimension mappings
            // If world0 folder exists with shader files, use it for Overworld. Otherwise use base for all oher dims.
			if (foundFolders.contains("world0")) {
				dimensionMap.put("Overworld", "world0");
			}
			if (foundFolders.contains("world-1")) {
				dimensionMap.put("Nether", "world-1");
			}
			if (foundFolders.contains("world1")) {
				dimensionMap.put("The End", "world1");
			}
		}

		// Read all files and included files recursively
		IncludeGraph graph = new IncludeGraph(root, starts.build());

		if (!graph.getFailures().isEmpty()) {
			graph.getFailures().forEach((path, error) -> {
				Iris.logger.error("{}", error.toString());
			});

			throw new IOException("Failed to resolve some #include directives, see previous messages for details");
		}

		this.languageMap = new LanguageMap(root.resolve("lang"));

		// Discover, merge, and apply shader pack options
		this.shaderPackOptions = new ShaderPackOptions(graph, changedConfigs);
		graph = this.shaderPackOptions.getIncludes();

		List<StringPair> finalEnvironmentDefines = new ArrayList<>();
		environmentDefines.forEach(finalEnvironmentDefines::add);
		for (FeatureFlags flag : FeatureFlags.values()) {
			if (flag.isUsable()) {
				finalEnvironmentDefines.add(new StringPair("IRIS_FEATURE_" + flag.name(), ""));
			}
		}

		this.shaderProperties = Optional.ofNullable(readProperties(root, "shaders.properties"))
				.map(source -> new ShaderProperties(source, shaderPackOptions, finalEnvironmentDefines))
				.orElseGet(ShaderProperties::empty);

		List<FeatureFlags> invalidFlagList = shaderProperties.getRequiredFeatureFlags().stream().filter(FeatureFlags::isInvalid).map(FeatureFlags::getValue).collect(Collectors.toList());
		List<String> invalidFeatureFlags = invalidFlagList.stream().map(FeatureFlags::getHumanReadableName).collect(Collectors.toList());

		if (!invalidFeatureFlags.isEmpty()) {
            // TODO: GUI
//			if (Minecraft.getMinecraft().screen instanceof ShaderPackScreen) {
//				Minecraft.getMinecraft().setScreen(new FeatureMissingErrorScreen(Minecraft.getMinecraft().screen, I18n.format("iris.unsupported.pack"), I18n.format("iris.unsupported.pack.description", FeatureFlags.getInvalidStatus(invalidFlagList), invalidFeatureFlags.stream()
//					.collect(Collectors.joining(", ", ": ", ".")))));
//			}
			IrisApi.getInstance().getConfig().setShadersEnabledAndApply(false);
		}

		ProfileSet profiles = ProfileSet.fromTree(shaderProperties.getProfiles(), this.shaderPackOptions.getOptionSet());
		this.profile = profiles.scan(this.shaderPackOptions.getOptionSet(), this.shaderPackOptions.getOptionValues());

		// Get programs that should be disabled from the detected profile
		List<String> disabledPrograms = new ArrayList<>();
		this.profile.current.ifPresent(profile -> disabledPrograms.addAll(profile.disabledPrograms));
		// Add programs that are disabled by shader options
		shaderProperties.getConditionallyEnabledPrograms().forEach((program, shaderOption) -> {
			if ("true".equals(shaderOption)) return;

			if ("false".equals(shaderOption) || !this.shaderPackOptions.getOptionValues().getBooleanValueOrDefault(shaderOption)) {
				disabledPrograms.add(program);
			}
		});

		this.menuContainer = new OptionMenuContainer(shaderProperties, this.shaderPackOptions, profiles);

		{
			String profileName = getCurrentProfileName();
			OptionValues profileOptions = new MutableOptionValues(
					this.shaderPackOptions.getOptionSet(), this.profile.current.map(p -> p.optionValues).orElse(new HashMap<>()));

			int userOptionsChanged = this.shaderPackOptions.getOptionValues().getOptionsChanged() - profileOptions.getOptionsChanged();

			this.profileInfo = "Profile: " + profileName + " (+" + userOptionsChanged + " option" + (userOptionsChanged == 1 ? "" : "s") + " changed by user)";
		}

		Iris.logger.info(this.profileInfo);

		// Prepare our include processor
		IncludeProcessor includeProcessor = new IncludeProcessor(graph);

		// Set up our source provider for creating ProgramSets
		Iterable<StringPair> finalEnvironmentDefines1 = finalEnvironmentDefines;
		this.sourceProvider = (path) -> {
			String pathString = path.getPathString();
			// Removes the first "/" in the path if present, and the file
			// extension in order to represent the path as its program name
			String programString = pathString.substring(pathString.indexOf("/") == 0 ? 1 : 0, pathString.lastIndexOf("."));

			// Return an empty program source if the program is disabled by the current profile
			if (disabledPrograms.contains(programString)) {
				return null;
			}

			ImmutableList<String> lines = includeProcessor.getIncludedFile(path);

			if (lines == null) {
				return null;
			}

			StringBuilder builder = new StringBuilder();

			for (String line : lines) {
				builder.append(line);
				builder.append('\n');
			}

			// Apply GLSL preprocessor to source, while making environment defines available.
			//
			// This uses similar techniques to the *.properties preprocessor to avoid actually putting
			// #define statements in the actual source - instead, we tell the preprocessor about them
			// directly. This removes one obstacle to accurate reporting of line numbers for errors,
			// though there exist many more (such as relocating all #extension directives and similar things)
			String source = builder.toString();
			source = JcppProcessor.glslPreprocessSource(source, finalEnvironmentDefines1);

			return source;
		};

		this.base = new ProgramSet(AbsolutePackPath.fromAbsolutePath("/"), sourceProvider, shaderProperties, this);

		this.idMap = new IdMap(root, shaderPackOptions, environmentDefines);

		customNoiseTexture = shaderProperties.getNoiseTexturePath().map(path -> {
			try {
				return readTexture(root, path);
			} catch (IOException e) {
				Iris.logger.error("Unable to read the custom noise texture at " + path, e);

				return null;
			}
		}).orElse(null);

		shaderProperties.getCustomTextures().forEach((textureStage, customTexturePropertiesMap) -> {
			Object2ObjectMap<String, CustomTextureData> innerCustomTextureDataMap = new Object2ObjectOpenHashMap<>();
			customTexturePropertiesMap.forEach((samplerName, definition) -> {
				try {
					innerCustomTextureDataMap.put(samplerName, readTexture(root, definition));
				} catch (IOException e) {
					Iris.logger.error("Unable to read the custom texture at " + definition.getName(), e);
				}
			});

			customTextureDataMap.put(textureStage, innerCustomTextureDataMap);
		});

		// Process irisCustomTextures (direct custom textures via customTexture.<name>=<path>)
		shaderProperties.getIrisCustomTextures().forEach((samplerName, definition) -> {
			try {
				irisCustomTextureDataMap.put(samplerName, readTexture(root, definition));
				Iris.logger.debug("[CustomTextures] Loaded customTexture.{} from {}", samplerName, definition.getName());
			} catch (IOException e) {
				Iris.logger.error("Unable to read custom texture for sampler " + samplerName + " at " + definition.getName(), e);
			}
		});

        this.customUniforms = shaderProperties.getCustomUniforms();
		this.customImages = shaderProperties.getCustomImages();
		this.bufferObjects = shaderProperties.getBufferObjects();
	}

	private String getCurrentProfileName() {
		return profile.current.map(p -> p.name).orElse("Custom");
	}

	public String getProfileInfo() {
		return profileInfo;
	}

    // TODO: Copy-paste from IdMap, find a way to deduplicate this
	private static Optional<Properties> loadPropertiesFile(Path shaderPath, String name) {
		String fileContents = readProperties(shaderPath, name);
		if (fileContents == null) {
			return Optional.empty();
		}

		StringReader propertiesReader = new StringReader(fileContents);

		Properties properties = new OrderBackedProperties();
		try {
			properties.load(propertiesReader);
		} catch (IOException e) {
			Iris.logger.error("Error loading " + name + " at " + shaderPath, e);
			return Optional.empty();
		}

		return Optional.of(properties);
	}

  /**
   * Parses dimension mappings from dimension.properties and populates the dimensionMap field.
   *
   * Format: dimension.<folder> = <dimension names...>
   * Example: dimension.world0 = Overworld "Twilight Forest" minecraft:overworld
   *
   * For each entry, creates mappings from each dimension name to its folder name in dimensionMap.
   *
   * @param properties The properties to parse
   * @param keyPrefix The prefix to filter keys by (typically "dimension.")
   * @return List of folder names found in the properties (e.g., ["world0", "world-1", "custom_dim"])
   */
	private List<String> parseDimensionMap(Properties properties, String keyPrefix) {
		List<String> folderNames = new ArrayList<>();

		properties.forEach((keyObject, valueObject) -> {
			String key = (String) keyObject;
			String value = (String) valueObject;

			if (!key.startsWith(keyPrefix)) {
				return;
			}

			// Extract folder name (e.g., "world0" from "dimension.world0")
			String folderName = key.substring(keyPrefix.length());

			// Skip empty folder names
			if (folderName.isEmpty()) {
				Iris.logger.warn("Ignoring dimension.properties entry with empty folder name: {}", key);
				return;
			}

			// Parse dimension names
			List<String> dimensionNames = IdMap.parseIdentifierList(value, "dimension.properties", key);

			// Skip if no dimension names are specified
			if (dimensionNames.isEmpty()) {
				Iris.logger.warn("Ignoring dimension.properties entry '{}' with no dimension names", key);
				return;
			}

			folderNames.add(folderName);

			for (String dimensionName : dimensionNames) {
				dimensionMap.put(dimensionName, folderName);
			}
		});

		return folderNames;
	}

	/**
	 * Checks if a dimension folder exists and adds it to the starts list
	 */
	private boolean checkAndAddDimensionFolder(ImmutableList.Builder<AbsolutePackPath> starts, Path root,
											   ImmutableList<String> potentialFileNames, String folderName) throws IOException {
		return ShaderPackSourceNames.findPresentSources(starts, root,
				AbsolutePackPath.fromAbsolutePath("/" + folderName), potentialFileNames);
	}

	/**
	 * Reads a texture from a TextureDefinition. Handles both PNG and raw texture types.
	 */
	public CustomTextureData readTexture(Path root, TextureDefinition definition) throws IOException {
		if (definition instanceof TextureDefinition.RawDefinition rawDef) {
			return readRawTexture(root, rawDef);
		} else {
			// PNG definition - use the path-based method
			return readTexture(root, definition.getName());
		}
	}

	/**
	 * Reads a raw texture from a RawDefinition.
	 */
	private CustomTextureData readRawTexture(Path root, TextureDefinition.RawDefinition rawDef) throws IOException {
		String path = rawDef.getName();

		if (path.startsWith("/")) {
			path = path.substring(1);
		}

		// Read mcmeta for filtering data
		boolean blur = false;
		boolean clamp = false;

		String mcMetaPath = path + ".mcmeta";
		Path mcMetaResolvedPath = root.resolve(mcMetaPath);

		if (Files.exists(mcMetaResolvedPath)) {
			try {
				JsonObject meta = loadMcMeta(mcMetaResolvedPath);
				if (meta.get("texture") != null) {
					if (meta.get("texture").getAsJsonObject().get("blur") != null) {
						blur = meta.get("texture").getAsJsonObject().get("blur").getAsBoolean();
					}
					if (meta.get("texture").getAsJsonObject().get("clamp") != null) {
						clamp = meta.get("texture").getAsJsonObject().get("clamp").getAsBoolean();
					}
				}
			} catch (IOException e) {
				Iris.logger.error("Unable to read the custom texture mcmeta at " + mcMetaPath + ", ignoring: " + e);
			}
		}

		byte[] content = Files.readAllBytes(root.resolve(path));
		TextureFilteringData filteringData = new TextureFilteringData(blur, clamp);

		return switch (rawDef.getTarget()) {
			case TEXTURE_1D -> new CustomTextureData.RawData1D(content, filteringData,
					rawDef.getInternalFormat(), rawDef.getFormat(), rawDef.getPixelType(),
					rawDef.getSizeX());
			case TEXTURE_2D -> new CustomTextureData.RawData2D(content, filteringData,
					rawDef.getInternalFormat(), rawDef.getFormat(), rawDef.getPixelType(),
					rawDef.getSizeX(), rawDef.getSizeY());
			case TEXTURE_3D -> new CustomTextureData.RawData3D(content, filteringData,
					rawDef.getInternalFormat(), rawDef.getFormat(), rawDef.getPixelType(),
					rawDef.getSizeX(), rawDef.getSizeY(), rawDef.getSizeZ());
			case TEXTURE_RECTANGLE -> new CustomTextureData.RawDataRect(content, filteringData,
					rawDef.getInternalFormat(), rawDef.getFormat(), rawDef.getPixelType(),
					rawDef.getSizeX(), rawDef.getSizeY());
		};
	}

	/**
	 * Reads a texture from a path string (for PNG textures and resource locations).
	 */
	public CustomTextureData readTexture(Path root, String path) throws IOException {
		CustomTextureData customTextureData;
		if (path.contains(":")) {
			String[] parts = path.split(":");

			if (parts.length > 2) {
				Iris.logger.warn("Resource location " + path + " contained more than two parts?");
			}

			if (parts[0].equals("minecraft") && (parts[1].equals("dynamic/lightmap_1") || parts[1].equals("dynamic/light_map_1"))) {
				customTextureData = new CustomTextureData.LightmapMarker();
			} else {
				customTextureData = new CustomTextureData.ResourceData(parts[0], parts[1]);
			}
		} else {
			if (path.startsWith("/")) {
				// NB: This does not guarantee the resulting path is in the shaderpack as a double slash could be used,
				// this just fixes shaderpacks like Continuum 2.0.4 that use a leading slash in texture paths
				path = path.substring(1);
			}

			boolean blur = false;
			boolean clamp = false;

			String mcMetaPath = path + ".mcmeta";
			Path mcMetaResolvedPath = root.resolve(mcMetaPath);

			if (Files.exists(mcMetaResolvedPath)) {
				try {
					JsonObject meta = loadMcMeta(mcMetaResolvedPath);
					if (meta.get("texture") != null) {
						if (meta.get("texture").getAsJsonObject().get("blur") != null) {
							blur = meta.get("texture").getAsJsonObject().get("blur").getAsBoolean();
						}
						if (meta.get("texture").getAsJsonObject().get("clamp") != null) {
							clamp = meta.get("texture").getAsJsonObject().get("clamp").getAsBoolean();
						}
					}
				} catch (IOException e) {
					Iris.logger.error("Unable to read the custom texture mcmeta at " + mcMetaPath + ", ignoring: " + e);
				}
			}

			byte[] content = Files.readAllBytes(root.resolve(path));

			customTextureData = new CustomTextureData.PngData(new TextureFilteringData(blur, clamp), content);
		}
		return customTextureData;
	}

	private JsonObject loadMcMeta(Path mcMetaPath) throws IOException, JsonParseException {
		try (BufferedReader reader = new BufferedReader(new InputStreamReader(Files.newInputStream(mcMetaPath), StandardCharsets.UTF_8))) {
			JsonReader jsonReader = new JsonReader(reader);
			return GSON.getAdapter(JsonObject.class).read(jsonReader);
		}
	}

	private static String readProperties(Path shaderPath, String name) {
		try {
			// Property files should be encoded in ISO_8859_1.
			return new String(Files.readAllBytes(shaderPath.resolve(name)), StandardCharsets.ISO_8859_1);
		} catch (NoSuchFileException e) {
			Iris.logger.debug("An " + name + " file was not found in the current shaderpack");

			return null;
		} catch (IOException e) {
			Iris.logger.error("An IOException occurred reading " + name + " from the current shaderpack", e);

			return null;
		}
	}

	/**
	 * Evicts the least recently used non-pinned dimension from the cache if it exceeds the size limit.
	 * Pinned dimensions (Overworld, Nether, The End) are never evicted.
	 * The LinkedHashMap maintains access order, so oldest entries are at the front.
	 */
	private void evictOldDimensions() {
		// Build set of pinned folders (folders that vanilla dimensions map to)
		Set<String> pinnedFolders = new HashSet<>();
		for (String pinnedDimName : PINNED_DIMENSIONS) {
			String folder = dimensionMap.get(pinnedDimName);
			if (folder != null) {
				pinnedFolders.add(folder);
			}
		}

		// If cache is disabled, evict everything except pinned folders
		if (MAX_DIMENSION_CACHE == 0) {
			dimensionProgramSets.entrySet().removeIf(e -> !pinnedFolders.contains(e.getKey()));
			return;
		}

		// Count non-pinned entries
		long nonPinnedCount = dimensionProgramSets.entrySet().stream()
			.filter(e -> !pinnedFolders.contains(e.getKey()))
			.count();

		int maxNonPinned = Math.max(0, MAX_DIMENSION_CACHE - PINNED_DIMENSIONS.size());

		// Evict oldest non-pinned dimensions until we're at the limit
		while (nonPinnedCount > maxNonPinned) {
			// Log once when we first hit the limit
			if (!hasLoggedCacheLimitReached) {
				Iris.logger.info("Dimension shader cache limit reached (max {} total: {} vanilla + {} modded). Now evicting least recently used dimensions.",
					MAX_DIMENSION_CACHE, PINNED_DIMENSIONS.size(), maxNonPinned);
				hasLoggedCacheLimitReached = true;
			}

			// Find the first (oldest/least recently used) non-pinned entry
			String toEvict = null;
			for (Map.Entry<String, ProgramSet> entry : dimensionProgramSets.entrySet()) {
				if (!pinnedFolders.contains(entry.getKey())) {
					toEvict = entry.getKey();
					break;
				}
			}

			if (toEvict != null) {
				dimensionProgramSets.remove(toEvict);
				nonPinnedCount--;
			} else {
				// Shouldn't happen, but break to avoid infinite loop
				break;
			}
		}
	}

    /**
     * Gets or creates the appropriate ProgramSet for the given dimension.
     *
     * Resolution order:
     *
     *   Exact match in dimension.properties (dimension.<folder> = dimensionName)
     *   Wildcard match (dimension.<folder> = *)
     *   Legacy world{ID} folder (e.g., world0, world-1)
     *   Fallback to base ProgramSet
     *
     *
     * ProgramSets are lazily created and cached. When cache exceeds limit,
     * least recently used non-vanilla dimensions are evicted.
     *
     * @param dimensionName The dimension name from WorldProvider.getDimensionName()
     * @return The ProgramSet for this dimension, or base ProgramSet if no override exists
     */
    public ProgramSet getProgramSet(String dimensionName) {
		int dimensionId = Iris.getCurrentDimensionId();

		// First, try to find an exact match in the dimension map
		String folderName = dimensionMap.get(dimensionName);
		boolean foundExactMatch = folderName != null;

		// If no exact match, try wildcard
		if (folderName == null) {
			folderName = dimensionMap.get("*");
		}

		// If still no match, try world{ID} folder as fallback for backward compatibility
		// But only if that folder actually has shader files!
		if (folderName == null) {
			String worldFolder = "world" + dimensionId;
			if (foldersWithShaderFiles.contains(worldFolder)) {
				folderName = worldFolder;
			}
		}

		// If we have a folder name that contains shader files, try to get or create its ProgramSet
		if (folderName != null && foldersWithShaderFiles.contains(folderName)) {
			ProgramSet programSet = dimensionProgramSets.get(folderName);

			if (programSet == null) {
				// Create ProgramSet on-demand for dimension folder
				try {
					programSet = new ProgramSet(
						AbsolutePackPath.fromAbsolutePath("/" + folderName),
						sourceProvider,
						shaderProperties,
						this
					);
					dimensionProgramSets.put(folderName, programSet);

					// Check cache size limit and evict LRU dimensions if needed
					evictOldDimensions();
				} catch (Exception e) {
					// This shouldn't happen but just in case.
					Iris.logger.error("Failed to create ProgramSet for dimension folder '{}', falling back to base", folderName, e);
					programSet = null;
				}
			}

			if (programSet != null) {
				return programSet;
			}
		}

		// Warn if dimension.properties exists but this dimension has no mapping and no wildcard
		if (!dimensionMap.isEmpty() && !foundExactMatch && !dimensionMap.containsKey("*")) {
			Iris.logger.warn("Dimension '{}' has no shader mapping in dimension.properties and no wildcard (*) fallback is defined. " +
					"Falling back to base shaders. Consider adding 'dimension.<folder>={}' or 'dimension.<folder>=*' to dimension.properties",
					dimensionName, dimensionName);
		}

		// NB: If a dimension overrides directory is present, none of the files from the parent directory are "merged"
		//     into the override. Rather, we act as if the overrides directory contains a completely different set of
		//     shader programs unrelated to that of the base shader pack.
		//
		//     This makes sense because if base defined a composite pass and the override didn't, it would make it
		//     impossible to "un-define" the composite pass. It also removes a lot of complexity related to "merging"
		//     program sets. At the same time, this might be desired behavior by shader pack authors. It could make
		//     sense to bring it back as a configurable option, and have a more maintainable set of code backing it.

		return base;
	}

    public Optional<CustomTextureData> getCustomNoiseTexture() {
		return Optional.ofNullable(customNoiseTexture);
	}

}