/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.badlogic.gdx.graphics;

import java.util.HashMap;
import java.util.Map;

import com.badlogic.gdx.Application;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.assets.AssetLoaderParameters.LoadedCallback;
import com.badlogic.gdx.assets.AssetManager;
import com.badlogic.gdx.assets.loaders.AssetLoader;
import com.badlogic.gdx.assets.loaders.TextureLoader.TextureParameter;
import com.badlogic.gdx.files.FileHandle;
import com.badlogic.gdx.graphics.Pixmap.Format;
import com.badlogic.gdx.graphics.glutils.PixmapTextureData;
import com.badlogic.gdx.utils.Array;
import com.badlogic.gdx.utils.GdxRuntimeException;

/** A Texture wraps a standard OpenGL ES texture.
 * <p>
 * A Texture can be managed. If the OpenGL context is lost all managed textures get invalidated. This happens when a user switches
 * to another application or receives an incoming call. Managed textures get reloaded automatically.
 * <p>
 * A Texture has to be bound via the {@link Texture#bind()} method in order for it to be applied to geometry. The texture will be
 * bound to the currently active texture unit specified via {@link GL20#glActiveTexture(int)}.
 * <p>
 * You can draw {@link Pixmap}s to a texture at any time. The changes will be automatically uploaded to texture memory. This is of
 * course not extremely fast so use it with care. It also only works with unmanaged textures.
 * <p>
 * A Texture must be disposed when it is no longer used
 * @author badlogicgames@gmail.com */
public class Texture extends GLTexture {
	private static AssetManager assetManager;
	final static Map<Application, Array<Texture>> managedTextures = new HashMap<Application, Array<Texture>>();

	public enum TextureFilter {
		Nearest(GL20.GL_NEAREST), Linear(GL20.GL_LINEAR), MipMap(GL20.GL_LINEAR_MIPMAP_LINEAR), MipMapNearestNearest(
			GL20.GL_NEAREST_MIPMAP_NEAREST), MipMapLinearNearest(GL20.GL_LINEAR_MIPMAP_NEAREST), MipMapNearestLinear(
			GL20.GL_NEAREST_MIPMAP_LINEAR), MipMapLinearLinear(GL20.GL_LINEAR_MIPMAP_LINEAR);

		final int glEnum;

		TextureFilter (int glEnum) {
			this.glEnum = glEnum;
		}

		public boolean isMipMap () {
			return glEnum != GL20.GL_NEAREST && glEnum != GL20.GL_LINEAR;
		}

		public int getGLEnum () {
			return glEnum;
		}
	}

	public enum TextureWrap {
		MirroredRepeat(GL20.GL_MIRRORED_REPEAT), ClampToEdge(GL20.GL_CLAMP_TO_EDGE), Repeat(GL20.GL_REPEAT);

		final int glEnum;

		TextureWrap (int glEnum) {
			this.glEnum = glEnum;
		}

		public int getGLEnum () {
			return glEnum;
		}
	}

	TextureData data;

	public Texture (String internalPath) {
		this(Gdx.files.internal(internalPath));
	}

	public Texture (FileHandle file) {
		this(file, null, false);
	}

	public Texture (FileHandle file, boolean useMipMaps) {
		this(file, null, useMipMaps);
	}

	public Texture (FileHandle file, Format format, boolean useMipMaps) {
		this(TextureData.Factory.loadFromFile(file, format, useMipMaps));
	}

	public Texture (Pixmap pixmap) {
		this(new PixmapTextureData(pixmap, null, false, false));
	}

	public Texture (Pixmap pixmap, boolean useMipMaps) {
		this(new PixmapTextureData(pixmap, null, useMipMaps, false));
	}

	public Texture (Pixmap pixmap, Format format, boolean useMipMaps) {
		this(new PixmapTextureData(pixmap, format, useMipMaps, false));
	}

	public Texture (int width, int height, Format format) {
		this(new PixmapTextureData(new Pixmap(width, height, format), null, false, true));
	}

	public Texture (TextureData data) {
		this(GL20.GL_TEXTURE_2D, Gdx.gl.glGenTexture(), data);
	}

	protected Texture (int glTarget, int glHandle, TextureData data) {
		super(glTarget, glHandle);
		load(data);
		if (data.isManaged()) addManagedTexture(Gdx.app, this);
	}

	public void load (TextureData data) {
		if (this.data != null && data.isManaged() != this.data.isManaged())
			throw new GdxRuntimeException("New data must have the same managed status as the old data");
		this.data = data;

		if (!data.isPrepared()) data.prepare();

		bind();
		uploadImageData(GL20.GL_TEXTURE_2D, data);

		setFilter(minFilter, magFilter);
		setWrap(uWrap, vWrap);
		Gdx.gl.glBindTexture(glTarget, 0);
	}

	/** Used internally to reload after context loss. Creates a new GL handle then calls {@link #load(TextureData)}. Use this only
	 * if you know what you do! */
	@Override
	protected void reload () {
		if (!isManaged()) throw new GdxRuntimeException("Tried to reload unmanaged Texture");
		glHandle = Gdx.gl.glGenTexture();
		load(data);
	}

	/** Draws the given {@link Pixmap} to the texture at position x, y. No clipping is performed so you have to make sure that you
	 * draw only inside the texture region. Note that this will only draw to mipmap level 0!
	 * 
	 * @param pixmap The Pixmap
	 * @param x The x coordinate in pixels
	 * @param y The y coordinate in pixels */
	public void draw (Pixmap pixmap, int x, int y) {
		if (data.isManaged()) throw new GdxRuntimeException("can't draw to a managed texture");

		bind();
		Gdx.gl.glTexSubImage2D(glTarget, 0, x, y, pixmap.getWidth(), pixmap.getHeight(), pixmap.getGLFormat(), pixmap.getGLType(),
			pixmap.getPixels());
	}

	@Override
	public int getWidth () {
		return data.getWidth();
	}

	@Override
	public int getHeight () {
		return data.getHeight();
	}

	@Override
	public int getDepth () {
		return 0;
	}

	public TextureData getTextureData () {
		return data;
	}

	/** @return whether this texture is managed or not. */
	public boolean isManaged () {
		return data.isManaged();
	}

	/** Disposes all resources associated with the texture */
	public void dispose () {
		// this is a hack. reason: we have to set the glHandle to 0 for textures that are
		// reloaded through the asset manager as we first remove (and thus dispose) the texture
		// and then reload it. the glHandle is set to 0 in invalidateAllTextures prior to
		// removal from the asset manager.
		if (glHandle == 0) return;
		delete();
		if (data.isManaged()) if (managedTextures.get(Gdx.app) != null) managedTextures.get(Gdx.app).removeValue(this, true);
	}

	private static void addManagedTexture (Application app, Texture texture) {
		Array<Texture> managedTextureArray = managedTextures.get(app);
		if (managedTextureArray == null) managedTextureArray = new Array<Texture>();
		managedTextureArray.add(texture);
		managedTextures.put(app, managedTextureArray);
	}

	/** Clears all managed textures. This is an internal method. Do not use it! */
	public static void clearAllTextures (Application app) {
		managedTextures.remove(app);
	}

	/** Invalidate all managed textures. This is an internal method. Do not use it! */
	public static void invalidateAllTextures (Application app) {
		Array<Texture> managedTextureArray = managedTextures.get(app);
		if (managedTextureArray == null) return;

		if (assetManager == null) {
			for (int i = 0; i < managedTextureArray.size; i++) {
				Texture texture = managedTextureArray.get(i);
				texture.reload();
			}
		} else {
			// first we have to make sure the AssetManager isn't loading anything anymore,
			// otherwise the ref counting trick below wouldn't work (when a texture is
			// currently on the task stack of the manager.)
			assetManager.finishLoading();

			// next we go through each texture and reload either directly or via the
			// asset manager.
			Array<Texture> textures = new Array<Texture>(managedTextureArray);
			for (Texture texture : textures) {
				String fileName = assetManager.getAssetFileName(texture);
				if (fileName == null) {
					texture.reload();
				} else {
					// get the ref count of the texture, then set it to 0 so we
					// can actually remove it from the assetmanager. Also set the
					// handle to zero, otherwise we might accidentially dispose
					// already reloaded textures.
					final int refCount = assetManager.getReferenceCount(fileName);
					assetManager.setReferenceCount(fileName, 0);
					texture.glHandle = 0;

					// create the parameters, passing the reference to the texture as
					// well as a callback that sets the ref count.
					TextureParameter params = new TextureParameter();
					params.textureData = texture.getTextureData();
					params.minFilter = texture.getMinFilter();
					params.magFilter = texture.getMagFilter();
					params.wrapU = texture.getUWrap();
					params.wrapV = texture.getVWrap();
					params.genMipMaps = texture.data.useMipMaps(); // not sure about this?
					params.texture = texture; // special parameter which will ensure that the references stay the same.
					params.loadedCallback = new LoadedCallback() {
						@Override
						public void finishedLoading (AssetManager assetManager, String fileName, Class type) {
							assetManager.setReferenceCount(fileName, refCount);
						}
					};

					// unload the texture, create a new gl handle then reload it.
					assetManager.unload(fileName);
					texture.glHandle = Gdx.gl.glGenTexture();
					assetManager.load(fileName, Texture.class, params);
				}
			}
			managedTextureArray.clear();
			managedTextureArray.addAll(textures);
		}
	}

	/** Sets the {@link AssetManager}. When the context is lost, textures managed by the asset manager are reloaded by the manager
	 * on a separate thread (provided that a suitable {@link AssetLoader} is registered with the manager). Textures not managed by
	 * the AssetManager are reloaded via the usual means on the rendering thread.
	 * @param manager the asset manager. */
	public static void setAssetManager (AssetManager manager) {
		Texture.assetManager = manager;
	}

	public static String getManagedStatus () {
		StringBuilder builder = new StringBuilder();
		builder.append("Managed textures/app: { ");
		for (Application app : managedTextures.keySet()) {
			builder.append(managedTextures.get(app).size);
			builder.append(" ");
		}
		builder.append("}");
		return builder.toString();
	}

	/** @return the number of managed textures currently loaded */
	public static int getNumManagedTextures () {
		return managedTextures.get(Gdx.app).size;
	}
}