// * This file is part of the COLOBOT source code
// * Copyright (C) 2012, Polish Portal of Colobot (PPC)
// *
// * 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 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 General Public License for more details.
// *
// * You should have received a copy of the GNU General Public License
// * along with this program. If not, see  http://www.gnu.org/licenses/.

// math/matrix.h

/* Matrix struct and functions */

#pragma once

#include "const.h"

#include <cmath>

// Math module namespace
namespace Math
{

/** 4x4 matrix

  Represents an universal 4x4 matrix that can be used in OpenGL and DirectX engines.
  Contains the required methods for operating on matrices (inverting, multiplying, etc.).

  All methods are made inline to maximize optimization.

 **/
struct Matrix
{
  //! Matrix values in row-major format
  float m[16];

  //! Creates the indentity matrix
  inline Matrix()
  {
    LoadIdentity();
  }

  //! Creates the matrix from given values
  /** \a m  values in row-major format */
  inline Matrix(float m[16])
  {
    this->m = m;
  }

  //! Loads the zero matrix
  inline void LoadZero()
  {
    for (int i = 0; i < 16; ++i)
      m[i] = 0.0f;
  }

  //! Loads the identity matrix
  inline void LoadIdentity()
  {
    LoadZero();
    m[0] = m[5] = m[10] = m[15] = 1.0f;
  }

  //! Calculates the determinant of the matrix
  /** \returns the determinant */
  float Det() const
  {
    float result = 0.0f;
    for (int i = 0; i < 4; ++i)
    {
      result += m[0][i] * Cofactor(0, i);
    }
    return result;
  }

  //! Transposes the matrix
  void Transpose()
  {
    Matrix temp = *this;
    for (int r = 0; r < 4; ++r)
    {
      for (int c = 0; c < 4; ++c)
      {
        m[4*r+c] = temp.m[4*c+r];
      }
    }
  }

  //! Calculates the cofactor of the matrix
  /** \a r row (0 to 3)
      \a c column (0 to 3)
      \returns the cofactor or 0.0f if invalid r, c given*/
  float Cofactor(int r, int c) const
  {
    if ((r < 0) || (r > 3) || (c < 0) || (c > 3))
      return 0.0f;

    float tab[3][3];
    int tabR = 0;
    for (int r = 0; r < 4; ++r)
    {
      if (r == i) continue;
      int tabC = 0;
      for (int c = 0; c < 4; ++c)
      {
        if (c == j) continue;
        tab[tabR][tabC] = m[4*r + c];
        ++tabC;
      }
      ++tabR;
    }

    float result =   tab[0][0] * (tab[1][1] * tab[2][2] - tab[1][2] * tab[2][1])
                   - tab[0][1] * (tab[1][0] * tab[2][2] - tab[1][2] * tab[2][0])
                   + tab[0][2] * (tab[1][0] * tab[2][1] - tab[1][1] * tab[2][0]);

    if ((i + j) % 2 == 0)
      result = -result;

    return result;
  }

  //! Inverts the matrix
  inline void Invert()
  {
    float d = Det();
    if (fabs(d) <= Math::TOLERANCE)
      return;

    Matrix temp = *this;
    for (int r = 0; r < 4; ++r)
    {
      for (int c = 0; c < 4; ++c)
      {
        m[r][c] = (1.0f / d) * temp.Cofactor(r, c);
      }
    }

    Tranpose();
  }

  //! Multiplies the matrix with the given matrix
  /** \a right right-hand matrix */
  inline void Multiply(const Matrix &right)
  {
    Matrix left = *this;
    for (int r = 0; r < 4; ++r)
    {
      for (int c = 0; c < 4; ++c)
      {
        m[r][c] = 0.0;
        for (int i = 0; i < 4; ++i)
        {
          m[4*r+c] += left.m[4*r+i] * right.m[4*i+c];
        }
      }
    }
  }

  inline void LoadViewMatrix(const Vector &from, const Vector &at, const Vector &up)
  {
    // TODO
  }

  inline void LoadProjectionMatrix(float fov = 1.570795f, float aspect = 1.0f,
                           float nearPlane = 1.0f, float farPlane = 1000.0f)
  {
    // TODO
  }

  inline void LoadTranslateMatrix(const Vector &trans)
  {
    // TODO
  }

  inline void LoadScaleMatrix(const Vector &scale)
  {
    // TODO
  }

  inline void LoadRotateXMatrix(float angle)
  {
    // TODO
  }

  inline void LoadRotateYMatrix(float angle)
  {
    // TODO
  }

  inline void LoadRotateZMatrix(float angle)
  {
    // TODO
  }

  inline void LoadRotationMatrix(const Vector &dir, float angle)
  {
    // TODO
  }

  //! Calculates the matrix to make three rotations in the order X, Z and Y
  inline void RotateXZY(const Vector &angle)
  {
    Matrix temp;
    temp.SetRotateXMatrix(angle.x);
    this->SetRotateZMatrix(angle.z);
    this->Multiply(temp);
    temp.SetRotateYMatrix(angle.y);
    this->Multiply(temp);
  }

  //! Calculates the matrix to make three rotations in the order Z, X and Y
  inline void MatRotateZXY(const Vector &angle)
  {
    Matrix temp;
    temp.SetRotateZMatrix(angle.z);
    this->SetRotateXMatrix(angle.x);
    this->Multiply(temp);
    temp.SetRotateYMatrix(angle.y);
    this->Multiply(temp);
  }
};

//! Convenience function for inverting a matrix
/** \a m input matrix
    \a result result -- inverted matrix */
void InvertMatrix(const Matrix &m, Matrix &result)
{
  result = m;
  result.Invert();
}

//! Convenience function for multiplying a matrix
/** \a left left-hand matrix
    \a right right-hand matrix
    \a result result -- multiplied matrices */*
void MultiplyMatrices(const Matrix &left, const Matrix &right, Matrix &result)
{
  result = left;
  result.Multiply(right);
}

}; // namespace Math