/*
   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_data.h"

#include "stdlibincl.h"
#include "compiler.h"
//#include <stdio.h>
#include <fstream>

#include "debug.h"


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


ObjectListDefinition(ShaderData);

/**
 * standard constructor
*/
ShaderData::ShaderData ()
{
  this->registerObject(this, ShaderData::_objectList);
  this->shaderProgram = 0;
  this->vertexShader = 0;
  this->fragmentShader = 0;
}


/// TODO fix that shaders are unloaded first. then loaded
bool ShaderData::load(const std::string& vertexShaderFile, const std::string& fragmentShaderFile)
{
  if (GLEW_ARB_shader_objects && GLEW_ARB_shading_language_100)
  {
    this->shaderProgram = glCreateProgramObjectARB();

    if (!vertexShaderFile.empty())
      this->loadShaderProgramm(ShaderData::Vertex, vertexShaderFile);
    if (!fragmentShaderFile.empty())
      this->loadShaderProgramm(ShaderData::Fragment, fragmentShaderFile);

    this->linkShaderProgram();

  }
  else
  {
    PRINTF(2)("Shaders are not supported on your hardware\n");
  }
}

/**
 * standard deconstructor
 */
ShaderData::~ShaderData ()
{
  if (this->shaderProgram == glGetHandleARB(GL_PROGRAM_OBJECT_ARB))
    glUseProgramObjectARB(0);

  // delete what has to be deleted here
  this->deleteProgram(ShaderData::Vertex);
  this->deleteProgram(ShaderData::Fragment);

  if (this->fragmentShader != 0)
  {
    glDetachObjectARB(this->shaderProgram, this->fragmentShader);
    glDeleteObjectARB(this->fragmentShader);
  }
  if (this->vertexShader != 0)
  {
    glDetachObjectARB(this->shaderProgram, this->vertexShader);
    glDeleteObjectARB(this->vertexShader);
  }
  if (this->shaderProgram != 0)
  {
    GLint status = 0;
    //glLinkProgramARB(this->shaderProgram);
    glDeleteObjectARB(this->shaderProgram);
    // link error checking
    glGetObjectParameterivARB(this->shaderProgram, GL_OBJECT_DELETE_STATUS_ARB, &status);
    if (status == GL_INVALID_VALUE || status == GL_INVALID_OPERATION)
      this->printError(this->shaderProgram);
  }
}

bool ShaderData::loadShaderProgramm(ShaderData::Type type, const std::string& fileName)
{
  GLhandleARB shader = 0;

  if (type != ShaderData::Vertex && type != ShaderData::Fragment)
    return false;
  this->deleteProgram(type);


  std::string program;
  if (!readShader(fileName, program))
    return false;

  if (type == ShaderData::Vertex && GLEW_ARB_vertex_shader)
  {
    this->vertexShaderFile = fileName;

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

  if (type == ShaderData::Fragment && GLEW_ARB_fragment_shader)
  {
    this->fragmentShaderFile = fileName;

    shader = this->fragmentShader = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);
  }

  if (shader != 0)
  {
    GLint status = 0;
    const char* prog = program.c_str();

    glShaderSourceARB(shader, 1, &prog, NULL);
    glCompileShaderARB(shader);
    // checking on error.
    glGetObjectParameterivARB(shader, GL_OBJECT_COMPILE_STATUS_ARB, &status);
    if (status == GL_INVALID_VALUE || status == GL_INVALID_OPERATION)
      this->printError(shader);
    else
      glAttachObjectARB(this->shaderProgram, shader);
  }
  return true;
}


void ShaderData::linkShaderProgram()
{
  GLint status = 0;

  glLinkProgramARB(this->shaderProgram);
  // link error checking
  glGetObjectParameterivARB(this->shaderProgram, GL_OBJECT_LINK_STATUS_ARB, &status);
  if (status == GL_INVALID_VALUE || status == GL_INVALID_OPERATION)
    this->printError(this->shaderProgram);
}


bool ShaderData::readShader(const std::string& fileName, std::string& output)
{
  char lineBuffer[PARSELINELENGTH];

  std::ifstream shader;
  shader.open(fileName.c_str());
  if (!shader.is_open())
    return false;


  while (!shader.eof())
  {
    shader.getline(lineBuffer, PARSELINELENGTH);
    output += lineBuffer;
    output += "\n";
  }


  shader.close();
  return true;
}

void ShaderData::bindShader(const char* name, const float* value, size_t size)
{
  if (likely (this->shaderProgram != 0))
  {
    glUseProgramObjectARB(this->shaderProgram);

    unsigned int location = glGetUniformLocationARB(this->shaderProgram, name);
    /* This is EXPENSIVE and should be avoided. */

    if      (size == 1)  glUniform1fvARB(location, 1, value);
    else if (size == 2)  glUniform2fvARB(location, 1, value);
    else if (size == 3)  glUniform3fvARB(location, 1, value);
    else if (size == 4)  glUniform4fvARB(location, 1, value);
    else if (size == 9)  glUniformMatrix3fvARB(location, 1, false, value);
    else if (size == 16) glUniformMatrix4fvARB(location, 1, false, value);

  }
}

void ShaderData::deleteProgram(ShaderData::Type type)
{
  GLint status = 0;
  if (type == ShaderData::Vertex && this->vertexShader != 0)
  {
    this->vertexShaderFile = "";
    glDetachObjectARB(this->shaderProgram, this->vertexShader);
    glDeleteObjectARB(this->vertexShader);
    glGetObjectParameterivARB(this->vertexShader, GL_OBJECT_DELETE_STATUS_ARB, &status);
    if (status == GL_INVALID_VALUE || status == GL_INVALID_OPERATION)
      ShaderData::printError(this->vertexShader);
    this->vertexShader = 0;
  }
  else if (type == ShaderData::Fragment && this->fragmentShader != 0)
  {
    this->fragmentShaderFile = "";
    glDetachObjectARB(this->shaderProgram, this->fragmentShader);
    glDeleteObjectARB(this->fragmentShader);
    glGetObjectParameterivARB(this->fragmentShader, GL_OBJECT_DELETE_STATUS_ARB, &status);
    if (status == GL_INVALID_VALUE || status == GL_INVALID_OPERATION)
      ShaderData::printError(this->fragmentShader);
    this->fragmentShader = 0;
  }
  else
    return;
}


void ShaderData::printError(GLhandleARB program)
{
  if (program == 0)
    return;

  int infologLength = 0;
  int charsWritten  = 0;
  char *infoLog;

  glGetObjectParameterivARB(program, GL_OBJECT_INFO_LOG_LENGTH_ARB,
                            &infologLength);

  if (infologLength > 0)
  {
    infoLog = new char[infologLength+1];
    glGetInfoLogARB(program, infologLength, &charsWritten, infoLog);
    printf("%s\n", infoLog);
    delete[] infoLog;
  }
}

void ShaderData::debug() const
{
  PRINT(3)("ShaderData 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));*/
  }
}