/**
 * Copyright 1993-2013 NVIDIA Corporation.  All rights reserved.
 *
 * Please refer to the NVIDIA end user license agreement (EULA) associated
 * with this source code for terms and conditions that govern your use of
 * this software. Any use, reproduction, disclosure, or distribution of
 * this software and related documentation outside the terms of the EULA
 * is strictly prohibited.
 *
 */

/*
 *
 * Utility functions for compiling shaders and programs
 *
 * Author: Evan Hart
 * Copyright (c) NVIDIA Corporation. All rights reserved.
 *
 */


#ifndef NV_SHADER_UTILS_H
#define NV_SHADER_UTILS_H

#include <stdio.h>
#include <string.h>

#include <GL/glew.h>

namespace nv
{


    //
    //
    ////////////////////////////////////////////////////////////
    inline GLuint CompileGLSLShader(GLenum target, const char *shader)
    {
        GLuint object;

        object = glCreateShader(target);

        if (!object)
        {
            return object;
        }

        glShaderSource(object, 1, &shader, NULL);

        glCompileShader(object);

        // check if shader compiled
        GLint compiled = 0;
        glGetShaderiv(object, GL_COMPILE_STATUS, &compiled);

        if (!compiled)
        {
#ifdef NV_REPORT_COMPILE_ERRORS
            char temp[256] = "";
            glGetShaderInfoLog(object, 256, NULL, temp);
            fprintf(stderr, "Compile failed:\n%s\n", temp);
#endif
            glDeleteShader(object);
            return 0;
        }

        return object;
    }

    //
    //
    ////////////////////////////////////////////////////////////
    inline GLuint CompileGLSLShaderFromFile(GLenum target, const char *filename)
    {
        FILE *shaderFile;
        char *text;
        long size;
        size_t fsize = 0;

        // read files as binary to prevent problems from newline translation
#ifdef _WIN32

        if (fopen_s(&shaderFile, filename, "rb") != 0)
#else
        if ((shaderFile = fopen(filename, "rb")) == 0)
#endif
        {
            return 0;
        }

        // Get the length of the file
        fseek(shaderFile, 0, SEEK_END);
        size = ftell(shaderFile);

        // Read the file contents from the start, then close file and add a null terminator
        fseek(shaderFile, 0, SEEK_SET);
        text = new char[size+1];
        fsize = fread(text, size, 1, shaderFile);
        fclose(shaderFile);

        if (fsize == 0)
        {
            printf("CompileGLSLShaderFromFile(), error... fsize = 0\n");
        }

        text[size] = '\0';

        GLuint object = CompileGLSLShader(target, text);

        delete []text;

        return object;
    }


    // Create a program composed of vertex and fragment shaders.
    inline GLuint LinkGLSLProgram(GLuint vertexShader, GLuint fragmentShader)
    {
        GLuint program = glCreateProgram();
        glAttachShader(program, vertexShader);
        glAttachShader(program, fragmentShader);
        glLinkProgram(program);

#ifdef NV_REPORT_COMPILE_ERRORS
        // Get error log.
        GLint charsWritten, infoLogLength;
        glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLogLength);

        char *infoLog = new char[infoLogLength];
        glGetProgramInfoLog(program, infoLogLength, &charsWritten, infoLog);
        printf(infoLog);
        delete [] infoLog;
#endif

        // Test linker result.
        GLint linkSucceed = GL_FALSE;
        glGetProgramiv(program, GL_LINK_STATUS, &linkSucceed);

        if (linkSucceed == GL_FALSE)
        {
            glDeleteProgram(program);
            return 0;
        }

        return program;
    }


    // Create a program composed of vertex, geometry and fragment shaders.
    inline GLuint LinkGLSLProgram(GLuint vertexShader, GLuint geometryShader, GLint inputType, GLint vertexOut, GLint outputType, GLuint fragmentShader)
    {
        GLuint program = glCreateProgram();
        glAttachShader(program, vertexShader);
        glAttachShader(program, geometryShader);
        glProgramParameteriEXT(program, GL_GEOMETRY_INPUT_TYPE_EXT, inputType);
        glProgramParameteriEXT(program, GL_GEOMETRY_VERTICES_OUT_EXT, vertexOut);
        glProgramParameteriEXT(program, GL_GEOMETRY_OUTPUT_TYPE_EXT, outputType);
        glAttachShader(program, fragmentShader);
        glLinkProgram(program);

#ifdef NV_REPORT_COMPILE_ERRORS
        // Get error log.
        GLint charsWritten, infoLogLength;
        glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLogLength);

        char *infoLog = new char[infoLogLength];
        glGetProgramInfoLog(program, infoLogLength, &charsWritten, infoLog);
        printf(infoLog);
        delete [] infoLog;
#endif

        // Test linker result.
        GLint linkSucceed = GL_FALSE;
        glGetProgramiv(program, GL_LINK_STATUS, &linkSucceed);

        if (linkSucceed == GL_FALSE)
        {
            glDeleteProgram(program);
            return 0;
        }

        return program;
    }

    //
    //
    ////////////////////////////////////////////////////////////
    inline GLuint CompileASMShader(GLenum program_type, const char *code)
    {
        GLuint program_id;
        glGenProgramsARB(1, &program_id);
        glBindProgramARB(program_type, program_id);
        glProgramStringARB(program_type, GL_PROGRAM_FORMAT_ASCII_ARB, (GLsizei) strlen(code), (GLubyte *) code);

        GLint error_pos;
        glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &error_pos);

        if (error_pos != -1)
        {
#ifdef NV_REPORT_COMPILE_ERRORS
            const GLubyte *error_string;
            error_string = glGetString(GL_PROGRAM_ERROR_STRING_ARB);
            fprintf(stderr, "Program error at position: %d\n%s\n", (int)error_pos, error_string);
#endif
            return 0;
        }

        return program_id;
    }

    //
    //
    ////////////////////////////////////////////////////////////
    inline GLuint CompileASMShaderFromFile(GLenum target, const char *filename)
    {
        FILE *shaderFile;
        char *text;
        long size;
        size_t fsize = 0;

        // read files as binary to prevent problems from newline translation
#ifdef _WIN32

        if (fopen_s(&shaderFile, filename, "rb") != 0)
#else
        if ((shaderFile = fopen(filename, "rb")) == 0)
#endif
        {
            return 0;
        }

        // Get the length of the file
        fseek(shaderFile, 0, SEEK_END);
        size = ftell(shaderFile);

        // Read the file contents from the start, then close file and add a null terminator
        fseek(shaderFile, 0, SEEK_SET);
        text = new char[size+1];
        fsize = fread(text, size, 1, shaderFile);
        fclose(shaderFile);

        if (fsize == 0)
        {
            printf("CompileGLSLShaderFromFile(), error... fsize = 0\n");
        }

        text[size] = '\0';

        GLuint program_id = CompileASMShader(target, text);

        delete []text;

        return program_id;
    }

} // nv namespace

#endif

