/*
 * Shader.cpp
 *
 * Copyright (C) 2009 Matthias Schiffer <matthias@gamezock.de>
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include "Shader.h"

#include <iostream>
#include <fstream>
#include <vector>
#include <boost/scoped_array.hpp>

namespace Zoom {

boost::shared_ptr<Shader> Shader::load(const std::string &vertexShader, const std::string &fragmentShader) {
  GLhandleARB program, vs = 0, fs = 0;
  bool ok = false;

  if(!vertexShader.empty())
    vs = loadShader(vertexShader, GL_VERTEX_SHADER_ARB);

  if(!fragmentShader.empty())
    fs = loadShader(fragmentShader, GL_FRAGMENT_SHADER_ARB);

  program = glCreateProgramObjectARB();

  if(program) {
    if(vs)
      glAttachObjectARB(program, vs);

    if(fs)
      glAttachObjectARB(program, fs);

    glLinkProgramARB(program);
    if(glGetError()) {
      printInfoLog(program);
    }
    else {
      ok = true;
    }

    if(vs) {
      glDeleteObjectARB(vs);
    }

    if(fs) {
      glDeleteObjectARB(fs);
    }
  }

  if(ok)
    return boost::shared_ptr<Shader>(new Shader(program));
  else
    return boost::shared_ptr<Shader>();
}

GLhandleARB Shader::loadShader(const std::string &name, GLenum type) {
  std::vector<std::string> lines;
  std::ifstream file(("shader/" + name).c_str(), std::ios_base::in);
  if(!file.good())
    return 0;

  while(file.good() && !file.eof()) {
    std::string line;
    std::getline(file, line);

    if(!line.empty())
      lines.push_back(line);
  }

  boost::scoped_array<const char *> strings(new const char*[lines.size()]);
  for(std::size_t i = 0; i < lines.size(); ++i) {
    strings[i] = lines[i].c_str();
  }

  bool ok = false;
  GLhandleARB shader = glCreateShaderObjectARB(type);

  if(shader) {
    glShaderSourceARB(shader, lines.size(), strings.get(), 0);
    glCompileShaderARB(shader);
    if(glGetError()) {
      printInfoLog(shader);

      glDeleteObjectARB(shader);
    }
    else {
      ok = true;
    }
  }

  if(ok)
    return shader;
  else
    return 0;
}

void Shader::printInfoLog(GLhandleARB obj) {
  int length = 0;

  glGetObjectParameterivARB(obj, GL_OBJECT_INFO_LOG_LENGTH_ARB, &length);

  if(length > 0) {
    boost::scoped_array<char> log(new char[length]);

    int foo;
    glGetInfoLogARB(obj, length, &foo, log.get());
    std::cerr << log.get() << std::endl;
  }
}


}