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/* ----------------------------------------------------------------------- *
 * This file is part of GEL, http://www.imm.dtu.dk/GEL
 * Copyright (C) the authors and DTU Informatics
 * For license and list of authors, see ../../doc/intro.pdf
 * ----------------------------------------------------------------------- */

#include <iostream>
#include <fstream>
#include <string>
#include "../GL/glew.h"
using namespace std;

namespace GLGraphics
{
  void print_glsl_program_log(GLuint program)
  {
    GLint infoLog_length = 0;
    glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLog_length);

    // Some drivers return 1 as infoLog_length when the infoLog is an empty string
    if(infoLog_length > 1) 
    {
      char* infoLog = new char[infoLog_length];
      glGetProgramInfoLog(program, infoLog_length, 0, infoLog);
      cerr << "InfoLog:" << endl << infoLog << endl << endl;
      delete [] infoLog;
    }
  }

  void print_glsl_shader_log(GLuint shader)
  {
    GLint infoLog_length = 0;
    glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLog_length);

    // Some drivers return 1 as infoLog_length when the infoLog is an empty string
    if(infoLog_length > 1)
    {
      char* infoLog = new char[infoLog_length];
      glGetShaderInfoLog(shader, infoLog_length, 0, infoLog);
      cerr << "InfoLog:" << endl << infoLog << endl << endl;
      delete [] infoLog;
    }
  }

  bool check_glsl_shader(GLuint shader)
  {
    GLint status;
    glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
    return status == GL_TRUE;
  }

  const std::string read_glsl_source(const std::string& path, const std::string& file)
  {
    string fullpath = path + "/" + file;
    ifstream is(fullpath.c_str(), ios::binary);
    string str, contents;
    while(getline(is,str)) 
    {
      contents += str;
      contents += "\n";
    }
    return contents;
  }

  GLuint create_glsl_shader(GLuint stype, const std::string& src, bool print_log)
  {
    GLuint S = glCreateShader(stype);
    const GLchar* src_cstr = src.c_str();
    glShaderSource(S, 1, &src_cstr, 0);
    glCompileShader(S);
    
    if(print_log && !check_glsl_shader(S))
    {
      print_glsl_shader_log(S);
      glDeleteShader(S);
      return 0;
    }
    return S;
  }

  GLuint create_glsl_shader(GLuint stype, const std::string& path, const std::string& file)
  {
    string str = read_glsl_source(path, file);
    if(!str.empty())
    {
      GLuint shader = create_glsl_shader(stype, str, false);
      if(!check_glsl_shader(shader))
      {
        cerr << path << file << endl;
        print_glsl_shader_log(shader);
        glDeleteShader(shader);
        return 0;
      }
      return shader;
    }
    return 0;
  }
}