/*=========================================================================

  Program:   Visualization Toolkit

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
#include "vtkShaderProgram.h"
#include "vtkObjectFactory.h"

#include "vtk_glew.h"
#include "vtkShader.h"
#include "vtkMatrix3x3.h"
#include "vtkMatrix4x4.h"
#include "vtkOpenGLRenderWindow.h"
#include "vtkOpenGLShaderCache.h"
#include "vtkTypeTraits.h"

# include <sstream>

namespace {

inline GLenum convertTypeToGL(int type)
{
  switch (type)
    {
    case VTK_CHAR:
      return GL_BYTE;
    case VTK_UNSIGNED_CHAR:
      return GL_UNSIGNED_BYTE;
    case VTK_SHORT:
      return GL_SHORT;
    case VTK_UNSIGNED_SHORT:
      return GL_UNSIGNED_SHORT;
    case VTK_INT:
      return GL_INT;
    case VTK_UNSIGNED_INT:
      return GL_UNSIGNED_INT;
    case VTK_FLOAT:
      return GL_FLOAT;
    case VTK_DOUBLE:
#ifdef GL_DOUBLE
      return GL_DOUBLE;
#else
      vtkGenericWarningMacro(<< "Attempt to use GL_DOUBLE when not supported");
      return 0;
#endif
    default:
      return 0;
    }
}

} // end anon namespace

vtkStandardNewMacro(vtkShaderProgram)

vtkCxxSetObjectMacro(vtkShaderProgram,VertexShader,vtkShader)
vtkCxxSetObjectMacro(vtkShaderProgram,FragmentShader,vtkShader)
vtkCxxSetObjectMacro(vtkShaderProgram,GeometryShader,vtkShader)

vtkShaderProgram::vtkShaderProgram()
{
  this->VertexShader = vtkShader::New();
  this->VertexShader->SetType(vtkShader::Vertex);
  this->FragmentShader = vtkShader::New();
  this->FragmentShader->SetType(vtkShader::Fragment);
  this->GeometryShader = vtkShader::New();
  this->GeometryShader->SetType(vtkShader::Geometry);

  this->Compiled = false;
  this->NumberOfOutputs = 0;
  this->Handle = 0;
  this->VertexShaderHandle = 0;
  this->FragmentShaderHandle = 0;
  this->GeometryShaderHandle = 0;
  this->Linked = false;
  this->Bound = false;
}

vtkShaderProgram::~vtkShaderProgram()
{
  if (this->VertexShader)
    {
    this->VertexShader->Delete();
    this->VertexShader = NULL;
    }
  if (this->FragmentShader)
    {
    this->FragmentShader->Delete();
    this->FragmentShader = NULL;
    }
  if (this->GeometryShader)
    {
    this->GeometryShader->Delete();
    this->GeometryShader = NULL;
    }
}

// Process the string, and return a version with replacements.
bool vtkShaderProgram::Substitute(std::string &source, const std::string &search,
             const std::string replace, bool all)
{
  std::string::size_type pos = 0;
  bool replaced = false;
  while ((pos = source.find(search, 0)) != std::string::npos)
    {
    source.replace(pos, search.length(), replace);
    if (!all)
      {
      return true;
      }
    pos += search.length();
    replaced = true;
    }
  return replaced;
}



template <class T> bool vtkShaderProgram::SetAttributeArray(const char *name,
                                                const T &array, int tupleSize,
                                                NormalizeOption normalize)
{
  if (array.empty())
    {
    this->Error = "Refusing to upload empty array for attribute " + std::string(name) + ".";
    return false;
    }
  int type = vtkTypeTraits<typename T::value_type>::VTKTypeID();
  return this->SetAttributeArrayInternal(name, &array[0], type, tupleSize,
                                         normalize);
}

bool vtkShaderProgram::AttachShader(const vtkShader *shader)
{
  if (shader->GetHandle() == 0)
    {
    this->Error = "Shader object was not initialized, cannot attach it.";
    return false;
    }
  if (shader->GetType() == vtkShader::Unknown)
    {
    this->Error = "Shader object is of type Unknown and cannot be used.";
    return false;
    }

  if (this->Handle == 0)
    {
    GLuint handle_ = glCreateProgram();
    if (handle_ == 0)
      {
      this->Error = "Could not create shader program.";
      return false;
      }
    this->Handle = static_cast<int>(handle_);
    this->Linked = false;
    }

  if (shader->GetType() == vtkShader::Vertex)
    {
    if (this->VertexShaderHandle != 0)
      {
      glDetachShader(static_cast<GLuint>(this->Handle),
                     static_cast<GLuint>(this->VertexShaderHandle));
      }
    this->VertexShaderHandle = shader->GetHandle();
    }
  else if (shader->GetType() == vtkShader::Fragment)
    {
    if (this->FragmentShaderHandle != 0)
      {
      glDetachShader(static_cast<GLuint>(this->Handle),
                     static_cast<GLuint>(this->FragmentShaderHandle));
      }
    this->FragmentShaderHandle = shader->GetHandle();
    }
  else if (shader->GetType() == vtkShader::Geometry)
    {
    if (this->GeometryShaderHandle != 0)
      {
      glDetachShader(static_cast<GLuint>(this->Handle),
                     static_cast<GLuint>(this->GeometryShaderHandle));
      }
// only use GS if supported
#ifdef GL_GEOMETRY_SHADER
    this->GeometryShaderHandle = shader->GetHandle();
#endif
    }
  else
    {
    this->Error = "Unknown shader type encountered - this should not happen.";
    return false;
  }

  glAttachShader(static_cast<GLuint>(this->Handle),
                 static_cast<GLuint>(shader->GetHandle()));
  this->Linked = false;
  return true;
}

bool vtkShaderProgram::DetachShader(const vtkShader *shader)
{
  if (shader->GetHandle() == 0)
    {
    this->Error = "Shader object was not initialized, cannot attach it.";
    return false;
    }
  if (shader->GetType() == vtkShader::Unknown)
    {
    this->Error = "Shader object is of type Unknown and cannot be used.";
    return false;
    }
  if (this->Handle == 0)
    {
    this->Error = "This shader prorgram has not been initialized yet.";
    }

  switch (shader->GetType())
    {
    case vtkShader::Vertex:
      if (this->VertexShaderHandle != shader->GetHandle())
        {
        Error = "The supplied shader was not attached to this program.";
        return false;
        }
      else
        {
        glDetachShader(static_cast<GLuint>(this->Handle),
                       static_cast<GLuint>(shader->GetHandle()));
        this->VertexShaderHandle = 0;
        this->Linked = false;
        return true;
        }
    case vtkShader::Fragment:
      if (this->FragmentShaderHandle != shader->GetHandle())
        {
        this->Error = "The supplied shader was not attached to this program.";
        return false;
        }
      else
        {
        glDetachShader(static_cast<GLuint>(this->Handle),
                       static_cast<GLuint>(shader->GetHandle()));
        this->FragmentShaderHandle = 0;
        this->Linked = false;
        return true;
        }
#ifdef GL_GEOMETRY_SHADER
    case vtkShader::Geometry:
      if (this->GeometryShaderHandle != shader->GetHandle())
        {
        this->Error = "The supplied shader was not attached to this program.";
        return false;
        }
      else
        {
        glDetachShader(static_cast<GLuint>(this->Handle),
                       static_cast<GLuint>(shader->GetHandle()));
        this->GeometryShaderHandle = 0;
        this->Linked = false;
        return true;
        }
#endif
    default:
      return false;
    }
}

bool vtkShaderProgram::Link()
{
  if (this->Linked)
    {
    return true;
    }

  if (this->Handle == 0)
    {
    this->Error = "Program has not been initialized, and/or does not have shaders.";
    return false;
    }

#if GL_ES_VERSION_2_0 != 1
  // bind the outputs if specified
  if (this->NumberOfOutputs)
    {
    for (unsigned int i = 0; i < this->NumberOfOutputs; i++)
      {
      // this naming has to match the bindings
      // in vtkOpenGLShaderCache.cxx
      std::ostringstream dst;
      dst << "fragOutput" << i;
      glBindFragDataLocation(static_cast<GLuint>(this->Handle), i,
        dst.str().c_str());
      }
    }
#endif

  GLint isCompiled;
  glLinkProgram(static_cast<GLuint>(this->Handle));
  glGetProgramiv(static_cast<GLuint>(this->Handle), GL_LINK_STATUS, &isCompiled);
  if (isCompiled == 0)
    {
    GLint length(0);
    glGetProgramiv(static_cast<GLuint>(this->Handle), GL_INFO_LOG_LENGTH, &length);
    if (length > 1)
      {
      char *logMessage = new char[length];
      glGetProgramInfoLog(static_cast<GLuint>(this->Handle), length, NULL, logMessage);
      this->Error = logMessage;
      delete[] logMessage;
      }
    return false;
    }
  this->Linked = true;
  this->Attributes.clear();
  return true;
}

bool vtkShaderProgram::Bind()
{
  if (!this->Linked && !this->Link())
    {
    return false;
    }

  glUseProgram(static_cast<GLuint>(this->Handle));
  this->Bound = true;
  return true;
}

// return 0 if there is an issue
int vtkShaderProgram::CompileShader()
{
  if (!this->GetVertexShader()->Compile())
    {
    int lineNum = 1;
    std::istringstream stream(this->GetVertexShader()->GetSource());
    std::stringstream sstm;
    std::string aline;
    while (std::getline(stream, aline))
      {
      sstm << lineNum << ": " << aline << "\n";
      lineNum++;
      }
    vtkErrorMacro(<< sstm.str());
    vtkErrorMacro(<< this->GetVertexShader()->GetError());
    return 0;
    }
  if (!this->GetFragmentShader()->Compile())
    {
    int lineNum = 1;
    std::istringstream stream(this->GetFragmentShader()->GetSource());
    std::stringstream sstm;
    std::string aline;
    while (std::getline(stream, aline))
      {
      sstm << lineNum << ": " << aline << "\n";
      lineNum++;
      }
    vtkErrorMacro(<< sstm.str());
    vtkErrorMacro(<< this->GetFragmentShader()->GetError());
    return 0;
    }
#ifdef GL_GEOMETRY_SHADER
  if (this->GetGeometryShader()->GetSource().size() > 0 &&
      !this->GetGeometryShader()->Compile())
    {
    int lineNum = 1;
    std::istringstream stream(this->GetGeometryShader()->GetSource());
    std::stringstream sstm;
    std::string aline;
    while (std::getline(stream, aline))
      {
      sstm << lineNum << ": " << aline << "\n";
      lineNum++;
      }
    vtkErrorMacro(<< sstm.str());
    vtkErrorMacro(<< this->GetGeometryShader()->GetError());
    return 0;
    }
  if (this->GetGeometryShader()->GetSource().size() > 0 &&
      !this->AttachShader(this->GetGeometryShader()))
    {
    vtkErrorMacro(<< this->GetError());
    return 0;
    }
#endif
  if (!this->AttachShader(this->GetVertexShader()))
    {
    vtkErrorMacro(<< this->GetError());
    return 0;
    }
  if (!this->AttachShader(this->GetFragmentShader()))
    {
    vtkErrorMacro(<< this->GetError());
    return 0;
    }
  if (!this->Link())
    {
    vtkErrorMacro(<< "Links failed: " << this->GetError());
    return 0;
    }

  this->Compiled = true;
  return 1;
}

void vtkShaderProgram::Release()
{
  glUseProgram(0);
  this->Bound = false;
}

void vtkShaderProgram::ReleaseGraphicsResources(vtkWindow *win)
{
  this->Release();

  if (this->Compiled)
    {
    this->DetachShader(this->VertexShader);
    this->DetachShader(this->FragmentShader);
    this->DetachShader(this->GeometryShader);
    this->VertexShader->Cleanup();
    this->FragmentShader->Cleanup();
    this->GeometryShader->Cleanup();
    this->Compiled = false;
    }

  vtkOpenGLRenderWindow *renWin = vtkOpenGLRenderWindow::SafeDownCast(win);
  if (renWin->GetShaderCache()->GetLastShaderBound() == this)
    {
    renWin->GetShaderCache()->ClearLastShaderBound();
    }

  if (this->Handle != 0)
    {
    glDeleteProgram(this->Handle);
    this->Handle = 0;
    this->Linked = false;
    }

}

bool vtkShaderProgram::EnableAttributeArray(const char *name)
{
  GLint location = static_cast<GLint>(this->FindAttributeArray(name));
  if (location == -1)
    {
    this->Error = "Could not enable attribute " + std::string(name) + ". No such attribute.";
    return false;
    }
  glEnableVertexAttribArray(location);
  return true;
}

bool vtkShaderProgram::DisableAttributeArray(const char *name)
{
  GLint location = static_cast<GLint>(this->FindAttributeArray(name));
  if (location == -1)
    {
    this->Error = "Could not disable attribute " + std::string(name) + ". No such attribute.";
    return false;
    }
  glDisableVertexAttribArray(location);
  return true;
}

#define BUFFER_OFFSET(i) ((char *)NULL + (i))

bool vtkShaderProgram::UseAttributeArray(const char *name, int offset,
                                      size_t stride, int elementType,
                                      int elementTupleSize,
                                      NormalizeOption normalize)
{
  GLint location = static_cast<GLint>(this->FindAttributeArray(name));
  if (location == -1)
    {
    this->Error = "Could not use attribute " + std::string(name) + ". No such attribute.";
    return false;
    }
  glVertexAttribPointer(location, elementTupleSize, convertTypeToGL(elementType),
                        normalize == Normalize ? GL_TRUE : GL_FALSE,
                        static_cast<GLsizei>(stride), BUFFER_OFFSET(offset));
  return true;
}

bool vtkShaderProgram::SetUniformi(const char *name, int i)
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform1i(location, static_cast<GLint>(i));
  return true;
}

bool vtkShaderProgram::SetUniformf(const char *name, float f)
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform1f(location, static_cast<GLfloat>(f));
  return true;
}

bool vtkShaderProgram::SetUniformMatrix(const char *name,
                                    vtkMatrix4x4 *matrix)
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  float data[16];
  for (int i = 0; i < 16; ++i)
    {
    data[i] = matrix->Element[i / 4][i % 4];
    }
  glUniformMatrix4fv(location, 1, GL_FALSE, data);
  return true;
}

bool vtkShaderProgram::SetUniformMatrix3x3(const char *name,
                                           float *matrix)
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniformMatrix3fv(location, 1, GL_FALSE, matrix);
  return true;
}

bool vtkShaderProgram::SetUniformMatrix4x4(const char *name,
                                           float *matrix)
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniformMatrix4fv(location, 1, GL_FALSE, matrix);
  return true;
}

bool vtkShaderProgram::SetUniformMatrix(const char *name,
                                    vtkMatrix3x3 *matrix)
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  float data[9];
  for (int i = 0; i < 9; ++i)
    {
    data[i] = matrix->GetElement(i / 3, i % 3);
    }
  glUniformMatrix3fv(location, 1, GL_FALSE, data);
  return true;
}

bool vtkShaderProgram::SetUniform1fv(const char *name, const int count,
                                    const float *v)
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform1fv(location, count, static_cast<const GLfloat *>(v));
  return true;
}

bool vtkShaderProgram::SetUniform1iv(const char *name, const int count,
                                    const int *v)
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform1iv(location, count, static_cast<const GLint *>(v));
  return true;
}

bool vtkShaderProgram::SetUniform3fv(const char *name, const int count,
                                    const float (*v)[3])
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform3fv(location, count, (const GLfloat *)v);
  return true;
}

bool vtkShaderProgram::SetUniform4fv(const char *name, const int count,
                                    const float (*v)[4])
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform4fv(location, count, (const GLfloat *)v);
  return true;
}

bool vtkShaderProgram::SetUniform2f(const char *name, const float v[2])
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform2fv(location, 1, v);
  return true;
}

bool vtkShaderProgram::SetUniform2fv(const char *name, const int count,
                                    const float (*f)[2])
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform2fv(location, count, (const GLfloat *)f);
  return true;
}

bool vtkShaderProgram::SetUniform3f(const char *name, const float v[3])
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform3fv(location, 1, v);
  return true;
}

bool vtkShaderProgram::SetUniform4f(const char *name, const float v[4])
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform4fv(location, 1, v);
  return true;
}

bool vtkShaderProgram::SetUniform2i(const char *name, const int v[2])
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  glUniform2iv(location, 1, v);
  return true;
}

bool vtkShaderProgram::SetUniform3uc(const char *name,
                                    const unsigned char v[3])
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  float colorf[3] = {v[0] / 255.0f, v[1] / 255.0f, v[2] / 255.0f};
  glUniform3fv(location, 1, colorf);
  return true;
}

bool vtkShaderProgram::SetUniform4uc(const char *name,
                                    const unsigned char v[4])
{
  GLint location = static_cast<GLint>(this->FindUniform(name));
  if (location == -1)
    {
    this->Error = "Could not set uniform " + std::string(name) + ". No such uniform.";
    return false;
    }
  float colorf[4] = {v[0] / 255.0f, v[1] / 255.0f, v[2] / 255.0f, v[3] / 255.0f};
  glUniform4fv(location, 1, colorf);
  return true;
}

bool vtkShaderProgram::SetAttributeArrayInternal(
    const char *name, void *buffer, int type, int tupleSize,
    vtkShaderProgram::NormalizeOption normalize)
{
  if (type == -1)
    {
    this->Error = "Unrecognized data type for attribute " + std::string(name) + ".";
    return false;
    }
  GLint location = static_cast<GLint>(this->FindAttributeArray(name));
  if (location == -1)
    {
    this->Error = "Could not set attribute " + std::string(name) + ". No such attribute.";
    return false;
    }
  const GLvoid *data = static_cast<const GLvoid *>(buffer);
  glVertexAttribPointer(location, tupleSize, convertTypeToGL(type),
                        normalize == Normalize ? GL_TRUE : GL_FALSE, 0, data);
  return true;
}

inline int vtkShaderProgram::FindAttributeArray(const char *name)
{
  if (name == NULL || !this->Linked)
    {
    return -1;
    }
  GLint location =
      static_cast<int>(glGetAttribLocation(static_cast<GLuint>(Handle),
                                           (const GLchar *)name));
  if (location == -1)
    {
    this->Error = "Specified attribute not found in current shader program: ";
    this->Error += name;
    }

  return location;
}

inline int vtkShaderProgram::FindUniform(const char *name)
{
  if (name == NULL || !this->Linked)
    {
    return -1;
    }
  GLint location =
      static_cast<int>(glGetUniformLocation(static_cast<GLuint>(Handle),
                                            (const GLchar *)name));
  if (location == -1)
    {
    this->Error = "Uniform " + std::string(name) + " not found in current shader program.";
    }

  return location;
}

// ----------------------------------------------------------------------------
void vtkShaderProgram::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os,indent);
}
