package electrosphere.renderer.model;

import electrosphere.engine.Globals;
import electrosphere.logger.LoggerInterface;
import electrosphere.renderer.OpenGLState;
import electrosphere.renderer.texture.Texture;
import electrosphere.util.FileUtils;

import org.lwjgl.PointerBuffer;
import org.lwjgl.assimp.AIMaterial;
import org.lwjgl.assimp.AIMaterialProperty;
import org.lwjgl.assimp.AIScene;
import org.lwjgl.assimp.AIString;
import org.lwjgl.assimp.AITexture;
import org.lwjgl.assimp.Assimp;
import org.lwjgl.opengl.GL45;

import java.io.File;
import java.nio.IntBuffer;
import java.nio.file.Path;

/**
 * A material
 */
public class Material {
    

    /**
     * The path of the diffuse texture when using texture lookups
     */
    private String diffuse;

    /**
     * The path of the specular texture when using texture lookups
     */
    private String specular;

    /**
     * Tracks whether this material has transparency or not
     */
    public boolean hasTransparency = false;
    
    /**
     * Sets whether this material should get its texture pointers from the assetManager by looking up diffuse and specular paths
     * or whether it should have a manually set texturePointer and not look up while binding
     */
    private boolean usesFetch = true;
    
    /**
     * texture pointer for the specular
     */
    private int texturePointer;

    /**
     * texture pointer for the normal
     */
    private int normalPointer;
    
    /**
     * A material that contains textures
     */
    public Material(){
    }

    /**
     * Creates a material with a diffuse texture
     * @param diffuse The path to the diffuse texture
     */
    public Material(String diffuse){
        this.diffuse = diffuse;
    }

    /**
     * Loads materials from the ai material object
     * @param path The path to the file we're loading materials from
     * @param input The input scene
     * @param input The input ai material
     * @return The resulting engine material
     */
    public static Material loadMaterialFromAIMaterial(String path, AIScene scene, AIMaterial input){
        Material rVal = new Material();

        AIString aiPathString = AIString.calloc();

        //read props

        //read textures
        PointerBuffer texturePtrBuff = scene.mTextures();
        String[] texPaths = new String[scene.mNumTextures()];
        for(int i = 0; i < scene.mNumTextures(); i++){
            AITexture tex = AITexture.create(texturePtrBuff.get());
            texPaths[i] = tex.mFilename().dataString();
        }
        //discover diffuse
        boolean foundDiffuse = false;
        int textureCount = Assimp.aiGetMaterialTextureCount(input, Assimp.aiTextureType_DIFFUSE);
        if(textureCount > 0){
            //for the time being, only load the first diffuse
            int textureIndex = 0;
            int retCode = Assimp.aiGetMaterialTexture(input, Assimp.aiTextureType_DIFFUSE, textureIndex, aiPathString, (IntBuffer)null, null, null, null, null, null);
            if(retCode != Assimp.aiReturn_SUCCESS){
                throw new Error("Failed to read diffuse! " + textureCount + " " + Assimp.aiGetErrorString());
            }
            String texturePath = aiPathString.dataString();
            if(texturePath == null || texturePath.length() <= 0){
                throw new Error("Texture path is empty " + texturePath);
            }
            if(texturePath.length() == 2 && texturePath.startsWith("*")){
                //older versions of Assimp require you to read the INDEX of the texture from the material, then look up that texture in the scene itself
                //format looks like "*<index>"   ie "*0"
                int indexInLoadedTexturePaths = Integer.parseInt(texturePath.substring(1));
                if(indexInLoadedTexturePaths >= texPaths.length){
                    throw new Error("Index discovered is outside the array's length " + indexInLoadedTexturePaths + " " + texPaths.length);
                }
                String resolved = Material.resolveTexturePath(path, texPaths[indexInLoadedTexturePaths]);
                if(resolved != null && resolved.length() > 0){
                    rVal.usesFetch = true;
                    rVal.diffuse = resolved;
                    Globals.assetManager.addTexturePathtoQueue(rVal.diffuse);
                    foundDiffuse = true;
                }
            } else {
                String resolved = Material.resolveTexturePath(path, texturePath);
                if(resolved != null && resolved.length() > 0){
                    rVal.usesFetch = true;
                    rVal.diffuse = resolved;
                    Globals.assetManager.addTexturePathtoQueue(rVal.diffuse);
                    foundDiffuse = true;
                }
            }
        }
        if(!foundDiffuse){
            textureCount = Assimp.aiGetMaterialTextureCount(input, Assimp.aiTextureType_BASE_COLOR);
            if(textureCount > 0){
                //for the time being, only load the first diffuse
                int textureIndex = 0;
                int retCode = Assimp.aiGetMaterialTexture(input, Assimp.aiTextureType_BASE_COLOR, textureIndex, aiPathString, (IntBuffer)null, null, null, null, null, null);
                if(retCode != Assimp.aiReturn_SUCCESS){
                    throw new Error("Failed to read diffuse! " + textureCount + " " + Assimp.aiGetErrorString());
                }
                String texturePath = aiPathString.dataString();
                if(texturePath == null || texturePath.length() <= 0){
                    throw new Error("Texture path is empty " + texturePath);
                }
                if(texturePath.length() == 2 && texturePath.startsWith("*")){
                    //older versions of Assimp require you to read the INDEX of the texture from the material, then look up that texture in the scene itself
                    //format looks like "*<index>"   ie "*0"
                    int indexInLoadedTexturePaths = Integer.parseInt(texturePath.substring(1));
                    if(indexInLoadedTexturePaths >= texPaths.length){
                        throw new Error("Index discovered is outside the array's length " + indexInLoadedTexturePaths + " " + texPaths.length);
                    }
                    String resolved = Material.resolveTexturePath(path, texPaths[indexInLoadedTexturePaths]);
                    if(resolved != null && resolved.length() > 0){
                        rVal.usesFetch = true;
                        rVal.diffuse = resolved;
                        Globals.assetManager.addTexturePathtoQueue(rVal.diffuse);
                        foundDiffuse = true;
                    }
                } else {
                    String resolved = Material.resolveTexturePath(path, texturePath);
                    if(resolved != null && resolved.length() > 0){
                        rVal.usesFetch = true;
                        rVal.diffuse = resolved;
                        Globals.assetManager.addTexturePathtoQueue(rVal.diffuse);
                        foundDiffuse = true;
                    }
                }
            }
        }

        //free mem
        aiPathString.free();

        return rVal;
    }

    /**
     * Describes the properties of a material
     * @param material The material
     */
    public static void listMaterialProps(AIMaterial material){
        LoggerInterface.loggerRenderer.WARNING("Describing material");
        for(int i = 0; i < material.mNumProperties(); i++){
            AIMaterialProperty prop = AIMaterialProperty.create(material.mProperties().get(i));
            String key = prop.mKey().dataString();
            int propType = prop.mSemantic();
            if(propType == Assimp.aiTextureType_NONE){
                //non-texture prop
                LoggerInterface.loggerRenderer.WARNING("Prop \"" + key + "\" is not a texture");
            } else {
                LoggerInterface.loggerRenderer.WARNING("Prop \"" + key + "\" is a texture");
            }
        }
    }

    /**
     * Resolves the filepath of the texture
     * @param path The path of the ai scene itself
     * @param filename The name of the file
     * @return The full path to load
     */
    private static String resolveTexturePath(String path, String filename){
        File fileObj = FileUtils.getAssetFile(path);
        File parentDir = fileObj.getParentFile();
        File[] contents = parentDir.listFiles();
        File discovered = null;
        for(File child : contents){
            String name = child.getName();
            String nameNoExt = child.getName().replaceFirst("[.][^.]+$", "");
            if(name.equals(filename) || nameNoExt.equals(filename)){
                discovered = child;
            }
        }

        if(discovered == null){
            LoggerInterface.loggerRenderer.WARNING("Failed to find texture \"" + filename + "\" for model " + path);
            return null;
        } else {
            Path relative = new File("./assets").toPath().relativize(discovered.toPath());
            return relative.toString().replace("\\","/");
        }
    }

    /**
     * Gets the path for the diffuse of the material
     * @return The path for the diffuse texture
     */
    public String getDiffuse(){
        return diffuse;
    }

    /**
     * Gets the path for the specular of the material
     * @return The path for the specular texture
     */
    public String getSpecular(){
        return specular;
    }

    /**
     * Sets the diffuse texture
     * @param t The texture path
     */
    public void setDiffuse(String t){
        diffuse = t;
    }

    /**
     * Sets the specular texture path
     * @param t The specular texture path
     */
    public void setSpecular(String t){
        specular = t;
    }
    
    /**
     * Sets the texture pointer
     * @param pointer The texture pointer
     */
    public void setTexturePointer(int pointer){
        texturePointer = pointer;
        usesFetch = false;
    }

    /**
     * Sets the in-material pointer for the normal
     * @param pointer the normal texture
     */
    public void setNormalTexturePointer(int pointer){
        normalPointer = pointer;
        usesFetch = false;
    }
    
    /**
     * Applies the material
     */
    public void applyMaterial(OpenGLState openGLState){
        //Controls whether the texturePointer should be resolved by looking up the diffuse in asset manager or using the texture pointer already set in this material
        if(usesFetch){
            if(diffuse != null){
                Texture diffuseTexture = Globals.assetManager.fetchTexture(diffuse);
                if(diffuseTexture != null){
                    diffuseTexture.bind(openGLState,0);
                    Globals.renderingEngine.checkError();
                    openGLState.getActiveShader().setUniform(openGLState, "material.diffuse", 0);
                    Globals.renderingEngine.checkError();
                }
            }
            if(specular != null){
                Texture specularTexture = Globals.assetManager.fetchTexture(specular);
                if(specularTexture != null){
                    specularTexture.bind(openGLState,1);
                    Globals.renderingEngine.checkError();
                    openGLState.getActiveShader().setUniform(openGLState, "material.specular", 1);
                    Globals.renderingEngine.checkError();
                }
            }
        } else {
            openGLState.glBindTextureUnit(GL45.GL_TEXTURE0, texturePointer, GL45.GL_TEXTURE_2D);
            Globals.renderingEngine.checkError();
        }
    }
    
    /**
     * Checks if this material has transparency
     * @return true if there is transparency, false otherwise
     */
    public boolean isTransparent(){
        boolean rVal = false;
        Texture diffuseTexture = Globals.assetManager.fetchTexture(diffuse);
        if(diffuseTexture != null && diffuseTexture.isTransparent()){
            rVal = true;
        }
        Texture specularTexture = Globals.assetManager.fetchTexture(specular);
        if(specularTexture != null && specularTexture.isTransparent()){
            rVal = true;
        }
        return rVal;
    }

    /**
     * Frees the material
     */
    public void free(){
        GL45.glDeleteTextures(new int[]{
            this.texturePointer,
            this.normalPointer,
        });
    }
}