/*
 * Copyright (c) 2009 Sun Microsystems, Inc. All Rights Reserved.
 * 
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 * modification, are permitted provided that the following conditions are
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 * - Redistribution of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
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 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
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package com.jogamp.opengl.util.glsl;

import java.io.PrintStream;
import java.nio.*;
import java.util.*;

import javax.media.opengl.*;

import com.jogamp.common.nio.Buffers;

public class ShaderUtil {
    public static String getShaderInfoLog(GL _gl, int shaderObj) {
        final GL2ES2 gl = _gl.getGL2ES2();
        int[] infoLogLength=new int[1];
        gl.glGetShaderiv(shaderObj, GL2ES2.GL_INFO_LOG_LENGTH, infoLogLength, 0);

        if(infoLogLength[0]==0) {
            return "(no info log)";
        }
        int[] charsWritten=new int[1];
        byte[] infoLogBytes = new byte[infoLogLength[0]];
        gl.glGetShaderInfoLog(shaderObj, infoLogLength[0], charsWritten, 0, infoLogBytes, 0);

        return new String(infoLogBytes, 0, charsWritten[0]);
    }

    public static String getProgramInfoLog(GL _gl, int programObj) {
        final GL2ES2 gl = _gl.getGL2ES2();
        int[] infoLogLength=new int[1];
        gl.glGetProgramiv(programObj, GL2ES2.GL_INFO_LOG_LENGTH, infoLogLength, 0);

        if(infoLogLength[0]==0) {
            return "(no info log)";
        }
        int[] charsWritten=new int[1];
        byte[] infoLogBytes = new byte[infoLogLength[0]];
        gl.glGetProgramInfoLog(programObj, infoLogLength[0], charsWritten, 0, infoLogBytes, 0);

        return new String(infoLogBytes, 0, charsWritten[0]);
    }

    public static boolean isShaderStatusValid(GL _gl, int shaderObj, int name, PrintStream verboseOut) {
        final GL2ES2 gl = _gl.getGL2ES2();
        int[] ires = new int[1];
        gl.glGetShaderiv(shaderObj, name, ires, 0);

        boolean res = ires[0]==1;
        if(!res && null!=verboseOut) {
            verboseOut.println("Shader status invalid: "+ getShaderInfoLog(gl, shaderObj));
        }
        return res;
    }

    public static boolean isShaderStatusValid(GL _gl, IntBuffer shaders, int name, PrintStream verboseOut) {
        boolean res = true;
        for (int i = shaders.position(); i < shaders.limit(); i++) {
            res = isShaderStatusValid(_gl, shaders.get(i), name, verboseOut) && res;
        }
        return res;
    }

    public static boolean isProgramStatusValid(GL _gl, int programObj, int name) {
        final GL2ES2 gl = _gl.getGL2ES2();
        int[] ires = new int[1];
        gl.glGetProgramiv(programObj, name, ires, 0);

        return ires[0]==1;
    }

    public static boolean isProgramLinkStatusValid(GL _gl, int programObj, PrintStream verboseOut) {
        final GL2ES2 gl = _gl.getGL2ES2();
        if(!gl.glIsProgram(programObj)) {
            if(null!=verboseOut) {
                verboseOut.println("Program name invalid: "+programObj);
            }
            return false;
        }
        if(!isProgramStatusValid(gl, programObj, GL2ES2.GL_LINK_STATUS)) {
            if(null!=verboseOut) {
                verboseOut.println("Program link failed: "+programObj+"\n\t"+ getProgramInfoLog(gl, programObj));
            }
            return false;
        }
        return true;
    }
    
    /**
     * Performs {@link GL2ES2#glValidateProgram(int)}
     * <p>
     * One shall only call this method while debugging and only if all required 
     * resources by the shader are set.
     * </p>
     * <p>
     * Note: It is possible that a working shader program will fail validation.
     * This has been experienced on NVidia APX2500 and Tegra2.
     * </p>
     * @see GL2ES2#glValidateProgram(int)
     **/
    public static boolean isProgramExecStatusValid(GL _gl, int programObj, PrintStream verboseOut) {
        final GL2ES2 gl = _gl.getGL2ES2();
        gl.glValidateProgram(programObj);
        if(!isProgramStatusValid(gl, programObj, GL2ES2.GL_VALIDATE_STATUS)) {
            if(null!=verboseOut) {
                verboseOut.println("Program validation failed: "+programObj+"\n\t"+ getProgramInfoLog(gl, programObj));
            }
            return false;
        }
        return true;
    }

    public static void createShader(GL _gl, int type, IntBuffer shaders) {
        final GL2ES2 gl = _gl.getGL2ES2();
        for (int i = shaders.position(); i < shaders.limit(); i++) {
            shaders.put(i, gl.glCreateShader(type));
        }
    }

    /**
     * If supported, queries the natively supported shader binary formats using 
     * {@link GL2ES2#GL_NUM_SHADER_BINARY_FORMATS} and {@link GL2ES2#GL_SHADER_BINARY_FORMATS}
     * via {@link GL2ES2#glGetIntegerv(int, int[], int)}.
     */
    public static Set<Integer> getShaderBinaryFormats(GL _gl) {
        final GL2ES2 gl = _gl.getGL2ES2();
        final ProfileInformation info = getProfileInformation(gl);
        if(null == info.shaderBinaryFormats) {
            info.shaderBinaryFormats = new HashSet<Integer>();
            if (gl.isGLES2Compatible()) {
                final int[] param = new int[1];
                gl.glGetIntegerv(GL2ES2.GL_NUM_SHADER_BINARY_FORMATS, param, 0);
                int numFormats = param[0];
                if(numFormats>0) {
                    int[] formats = new int[numFormats];
                    gl.glGetIntegerv(GL2ES2.GL_SHADER_BINARY_FORMATS, formats, 0);
                    for(int i=0; i<numFormats; i++) {
                        info.shaderBinaryFormats.add(new Integer(formats[i]));
                    }
                }
            }
        }
        return info.shaderBinaryFormats;
    }

    /** Returns true if a hader compiler is available, otherwise false. */
    public static boolean isShaderCompilerAvailable(GL _gl) {
        final GL2ES2 gl = _gl.getGL2ES2();
        final ProfileInformation info = getProfileInformation(gl);
        if(null==info.shaderCompilerAvailable) {
            if(gl.isGLES2()) {
                final byte[] param = new byte[1];
                gl.glGetBooleanv(GL2ES2.GL_SHADER_COMPILER, param, 0);
                boolean v = param[0]!=(byte)0x00;
                if(!v) {
                    final Set<Integer> bfs = getShaderBinaryFormats(gl);
                    if(bfs.size()==0) {
                        // no supported binary formats, hence a compiler must be available!
                        v = true;
                    }
                }
                info.shaderCompilerAvailable = new Boolean(v);
            } else if( gl.isGL2ES2() ) {
                info.shaderCompilerAvailable = new Boolean(true);
            } else {
                throw new GLException("Invalid OpenGL profile");
            }
        }
        return info.shaderCompilerAvailable.booleanValue();
    }

    public static void shaderSource(GL _gl, int shader, java.lang.String[] source)
    {
        final GL2ES2 gl = _gl.getGL2ES2();
        if(!isShaderCompilerAvailable(_gl)) {
            throw new GLException("No compiler is available");
        }

        int count = (null!=source)?source.length:0;
        if(count==0) {
            throw new GLException("No sources specified");
        }

        IntBuffer lengths = Buffers.newDirectIntBuffer(count);
        for(int i=0; i<count; i++) {
            lengths.put(i, source[i].length());
        }
        gl.glShaderSource(shader, count, source, lengths);
    }

    public static void shaderSource(GL _gl, IntBuffer shaders, java.lang.String[][] sources)
    {
        int sourceNum = (null!=sources)?sources.length:0;
        int shaderNum = (null!=shaders)?shaders.remaining():0;
        if(shaderNum<=0 || sourceNum<=0 || shaderNum!=sourceNum) {
            throw new GLException("Invalid number of shaders and/or sources: shaders="+
                                  shaderNum+", sources="+sourceNum);
        }
        for(int i=0; i<sourceNum; i++) {
            shaderSource(_gl, shaders.get(shaders.position() + i), sources[i]);
        }
    }

    public static void shaderBinary(GL _gl, IntBuffer shaders, int binFormat, java.nio.Buffer bin)
    {
        final GL2ES2 gl = _gl.getGL2ES2();
        if(getShaderBinaryFormats(gl).size()<=0) {
            throw new GLException("No binary formats are supported");
        }

        int shaderNum = shaders.remaining();
        if(shaderNum<=0) {
            throw new GLException("No shaders specified");
        }
        if(null==bin) {
            throw new GLException("Null shader binary");
        }
        int binLength = bin.remaining();
        if(0>=binLength) {
            throw new GLException("Empty shader binary (remaining == 0)");
        }
        gl.glShaderBinary(shaderNum, shaders, binFormat, bin, binLength);
    }

    public static void compileShader(GL _gl, IntBuffer shaders)
    {
        final GL2ES2 gl = _gl.getGL2ES2();
        for (int i = shaders.position(); i < shaders.limit(); i++) {
            gl.glCompileShader(shaders.get(i));
        }
    }

    public static void attachShader(GL _gl, int program, IntBuffer shaders)
    {
        final GL2ES2 gl = _gl.getGL2ES2();
        for (int i = shaders.position(); i < shaders.limit(); i++) {
            gl.glAttachShader(program, shaders.get(i));
        }
    }

    public static void detachShader(GL _gl, int program, IntBuffer shaders)
    {
        final GL2ES2 gl = _gl.getGL2ES2();
        for (int i = shaders.position(); i < shaders.limit(); i++) {
            gl.glDetachShader(program, shaders.get(i));
        }
    }

    public static void deleteShader(GL _gl, IntBuffer shaders)
    {
        final GL2ES2 gl = _gl.getGL2ES2();
        for (int i = shaders.position(); i < shaders.limit(); i++) {
            gl.glDeleteShader(shaders.get(i));

        }
    }

    public static boolean createAndLoadShader(GL _gl, IntBuffer shader, int shaderType,
                                              int binFormat, java.nio.Buffer bin,
                                              PrintStream verboseOut)
    {
        final GL2ES2 gl = _gl.getGL2ES2();
        int err = gl.glGetError(); // flush previous errors ..
        if(err!=GL.GL_NO_ERROR && null!=verboseOut) {
            verboseOut.println("createAndLoadShader: Pre GL Error: 0x"+Integer.toHexString(err));
        }

        createShader(gl, shaderType, shader);
        err = gl.glGetError(); 
        if(err!=GL.GL_NO_ERROR) {
            throw new GLException("createAndLoadShader: CreateShader failed, GL Error: 0x"+Integer.toHexString(err));
        }

        shaderBinary(gl, shader, binFormat, bin);

        err = gl.glGetError();
        if(err!=GL.GL_NO_ERROR && null!=verboseOut) {
            verboseOut.println("createAndLoadShader: ShaderBinary failed, GL Error: 0x"+Integer.toHexString(err));
        }
        return err == GL.GL_NO_ERROR;
    }

    public static boolean createAndCompileShader(GL _gl, IntBuffer shader, int shaderType,
                                                 java.lang.String[][] sources, 
                                                 PrintStream verboseOut)
    {
        final GL2ES2 gl = _gl.getGL2ES2();
        int err = gl.glGetError(); // flush previous errors ..
        if(err!=GL.GL_NO_ERROR && null!=verboseOut) {
            verboseOut.println("createAndCompileShader: Pre GL Error: 0x"+Integer.toHexString(err));
        }

        createShader(gl, shaderType, shader);
        err = gl.glGetError(); 
        if(err!=GL.GL_NO_ERROR) {
            throw new GLException("createAndCompileShader: CreateShader failed, GL Error: 0x"+Integer.toHexString(err));
        }

        shaderSource(gl, shader, sources);
        err = gl.glGetError(); 
        if(err!=GL.GL_NO_ERROR) {
            throw new GLException("createAndCompileShader: ShaderSource failed, GL Error: 0x"+Integer.toHexString(err));
        }

        compileShader(gl, shader);
        err = gl.glGetError(); 
        if(err!=GL.GL_NO_ERROR && null!=verboseOut) {
            verboseOut.println("createAndCompileShader: CompileShader failed, GL Error: 0x"+Integer.toHexString(err));
        }

        return isShaderStatusValid(gl, shader, GL2ES2.GL_COMPILE_STATUS, verboseOut) && err == GL.GL_NO_ERROR;
    }
    
    private static final String implObjectKey = "com.jogamp.opengl.util.glsl.ShaderUtil" ;
    
    private static class ProfileInformation {
        Boolean shaderCompilerAvailable = null;
        Set<Integer> shaderBinaryFormats = null;
    }    

    private static ProfileInformation getProfileInformation(GL gl) {
        final GLContext context = gl.getContext();
        context.validateCurrent();
        ProfileInformation data = (ProfileInformation) context.getAttachedObject(implObjectKey);
        if (data == null) {
            data = new ProfileInformation();
            context.attachObject(implObjectKey, data);
        }
        return data;
    }
}