/*
   orxonox - the future of 3D-vertical-scrollers

   Copyright (C) 2004 orx

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   ### File Specific:
   main-programmer: Benjamin Grauer
   co-programmer: ...
*/

//#define DEBUG_SPECIAL_MODULE DEBUG_MODULE_

#include "shader.h"

#include "stdlibincl.h"
#include <stdio.h>
#include "debug.h"


#ifndef PARSELINELENGHT
#define PARSELINELENGHT     512       //!< how many chars to read at once
#endif

using namespace std;


/**
 * standard constructor
*/
Shader::Shader (const char* vertexShaderFile, const char* fragmentShaderFile)
{
   this->setClassID(CL_SHADER, "Shader");

   this->fragmentShaderFile = NULL;
   this->vertexShaderFile = NULL;
   this->shaderProgram = 0;
   this->vertexShader = 0;
   this->fragmentShader = 0;

   if (GLEW_ARB_shader_objects && GLEW_ARB_shading_language_100)
     this->shaderProgram = glCreateProgramObjectARB();

   if (vertexShaderFile != NULL)
     this->loadShaderProgramm(SHADER_VERTEX, vertexShaderFile);
   if (fragmentShaderFile != NULL)
     this->loadShaderProgramm(SHADER_FRAGMENT, fragmentShaderFile);
  try  {
   glLinkProgramARB(this->shaderProgram); }
  catch(GLenum errorCode)  {
   this->printError(this->shaderProgram); }
}


/**
 * standard deconstructor
*/
Shader::~Shader ()
{
  // delete what has to be deleted here
  this->deleteProgram(SHADER_VERTEX);
  this->deleteProgram(SHADER_FRAGMENT);

  glDeleteObjectARB(this->fragmentShader);
  glDeleteObjectARB(this->vertexShader);
  glDeleteObjectARB(this->shaderProgram);
}


bool Shader::loadShaderProgramm(SHADER_TYPE type, const char* fileName)
{
  if (type != SHADER_VERTEX && type != SHADER_FRAGMENT)
    return false;
  this->deleteProgram(type);


  const char* program = fileRead(fileName);
  GLenum shader = 0;
  if (type == SHADER_VERTEX && GLEW_ARB_vertex_shader)
  {
    this->vertexShaderFile = new char[strlen(fileName)+1];
    strcpy(this->vertexShaderFile, fileName);

    shader = this->vertexShader = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB);
  }

  if (type == SHADER_FRAGMENT && GLEW_ARB_fragment_shader)
  {
    this->fragmentShaderFile = new char[strlen(fileName)+1];
    strcpy(this->fragmentShaderFile, fileName);

    shader = this->fragmentShader = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);
  }
  glShaderSourceARB(shader, 1, (const GLcharARB**)&program, NULL);
  try {
    glCompileShaderARB(shader);
  }
  catch (...)
  {
    this->printError(shader);
  }
  glAttachObjectARB(this->shaderProgram, shader);
  delete[] program;
}


char* Shader::fileRead(const char* fileName)
{
  FILE* fileHandle;
  char* content = NULL;

  int count = 0;

  if (fileName != NULL) {
    fileHandle = fopen(fileName, "rt");

    if (fileHandle != NULL) {

      fseek(fileHandle, 0, SEEK_END);
      count = ftell(fileHandle);
      rewind(fileHandle);

      if (count > 0) {
        content = new char[count+1];
        count = fread(content, sizeof(char), count, fileHandle);
        content[count] = '\0';
      }
      fclose(fileHandle);
    }
  }
  return content;
}

void Shader::activateShader()
{
  glUseProgramObjectARB(this->shaderProgram);
}

void Shader::deactivateShader()
{
  glUseProgramObjectARB(0);
}


void Shader::deleteProgram(SHADER_TYPE type)
{
  if (type == SHADER_VERTEX)
  {
    delete[] this->vertexShaderFile;
    this->vertexShaderFile = NULL;
    glDeleteObjectARB(this->vertexShader);
    this->vertexShader = 0;
  }
  else if (type == SHADER_FRAGMENT)
  {
    delete[] this->fragmentShaderFile;
    this->fragmentShaderFile = NULL;
    glDeleteObjectARB(this->fragmentShader);
    this->fragmentShader = 0;
  }
  else
    return;
}


void Shader::printError(GLenum program)
{
  int infologLength = 0;
  int charsWritten  = 0;
  char *infoLog;

  glGetObjectParameterivARB(program, GL_OBJECT_INFO_LOG_LENGTH_ARB,
                            &infologLength);

  if (infologLength > 0)
  {
    infoLog = (char *)malloc(sizeof(char) * (infologLength+1));
    glGetInfoLogARB(program, infologLength, &charsWritten, infoLog);
    printf("%s\n", infoLog);
    free(infoLog);
  }
}



void Shader::debug() const
{
  PRINT(3)("Shader info: (SHADER: %d)\n", this->shaderProgram);
  if (this->vertexShader != 0)
  {
/*    PRINT(3)("VertexShaderProgramm: number=%d, file='%s'\n", this->vertexShader, this->vertexShaderFile);
    if (this->vertexShaderSource != NULL)
      for (unsigned int i = 0; i < this->vertexShaderSource->getCount(); i++)
        PRINT(3)("%d: %s\n", i, this->vertexShaderSource->getEntry(i));
  }
  if (this->fragmentShader != 0)
  {
    PRINT(3)("FragmentShaderProgramm: number=%d, file='%s'\n", this->fragmentShader, this->fragmentShaderFile);
    if (this->fragmentShaderSource != NULL)
      for (unsigned int i = 0; i < this->fragmentShaderSource->getCount(); i++)
        PRINT(3)("%d: %s\n", i, this->fragmentShaderSource->getEntry(i));*/
  }


}