// Copyright 2019 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include "Common/Matrix.h"

#include <algorithm>
#include <cmath>

namespace
{
void MatrixMul(int n, const float* a, const float* b, float* result)
{
  for (int i = 0; i < n; ++i)
  {
    for (int j = 0; j < n; ++j)
    {
      float temp = 0;
      for (int k = 0; k < n; ++k)
      {
        temp += a[i * n + k] * b[k * n + j];
      }
      result[i * n + j] = temp;
    }
  }
}
}  // namespace

namespace Common
{
Matrix33 Matrix33::Identity()
{
  Matrix33 mtx = {};
  mtx.data[0] = 1.0f;
  mtx.data[4] = 1.0f;
  mtx.data[8] = 1.0f;
  return mtx;
}

Matrix33 Matrix33::RotateX(float rad)
{
  const float s = sin(rad);
  const float c = cos(rad);
  Matrix33 mtx = {};
  mtx.data[0] = 1;
  mtx.data[4] = c;
  mtx.data[5] = -s;
  mtx.data[7] = s;
  mtx.data[8] = c;
  return mtx;
}

Matrix33 Matrix33::RotateY(float rad)
{
  const float s = sin(rad);
  const float c = cos(rad);
  Matrix33 mtx = {};
  mtx.data[0] = c;
  mtx.data[2] = s;
  mtx.data[4] = 1;
  mtx.data[6] = -s;
  mtx.data[8] = c;
  return mtx;
}

Matrix33 Matrix33::RotateZ(float rad)
{
  const float s = sin(rad);
  const float c = cos(rad);
  Matrix33 mtx = {};
  mtx.data[0] = c;
  mtx.data[1] = -s;
  mtx.data[3] = s;
  mtx.data[4] = c;
  mtx.data[8] = 1;
  return mtx;
}

Matrix33 Matrix33::Scale(const Vec3& vec)
{
  Matrix33 mtx = {};
  mtx.data[0] = vec.x;
  mtx.data[4] = vec.y;
  mtx.data[8] = vec.z;
  return mtx;
}

void Matrix33::Multiply(const Matrix33& a, const Matrix33& b, Matrix33* result)
{
  MatrixMul(3, a.data.data(), b.data.data(), result->data.data());
}

void Matrix33::Multiply(const Matrix33& a, const Vec3& vec, Vec3* result)
{
  for (int i = 0; i < 3; ++i)
  {
    result->data[i] = 0;

    for (int k = 0; k < 3; ++k)
    {
      result->data[i] += a.data[i * 3 + k] * vec.data[k];
    }
  }
}

Matrix44 Matrix44::Identity()
{
  Matrix44 mtx = {};
  mtx.data[0] = 1.0f;
  mtx.data[5] = 1.0f;
  mtx.data[10] = 1.0f;
  mtx.data[15] = 1.0f;
  return mtx;
}

Matrix44 Matrix44::FromMatrix33(const Matrix33& m33)
{
  Matrix44 mtx;
  for (int i = 0; i < 3; ++i)
  {
    for (int j = 0; j < 3; ++j)
    {
      mtx.data[i * 4 + j] = m33.data[i * 3 + j];
    }
  }

  for (int i = 0; i < 3; ++i)
  {
    mtx.data[i * 4 + 3] = 0;
    mtx.data[i + 12] = 0;
  }
  mtx.data[15] = 1.0f;
  return mtx;
}

Matrix44 Matrix44::FromArray(const std::array<float, 16>& arr)
{
  Matrix44 mtx;
  mtx.data = arr;
  return mtx;
}

Matrix44 Matrix44::Translate(const Vec3& vec)
{
  Matrix44 mtx = Matrix44::Identity();
  mtx.data[3] = vec.x;
  mtx.data[7] = vec.y;
  mtx.data[11] = vec.z;
  return mtx;
}

Matrix44 Matrix44::Shear(const float a, const float b)
{
  Matrix44 mtx = Matrix44::Identity();
  mtx.data[2] = a;
  mtx.data[6] = b;
  return mtx;
}

void Matrix44::Multiply(const Matrix44& a, const Matrix44& b, Matrix44* result)
{
  MatrixMul(4, a.data.data(), b.data.data(), result->data.data());
}
}  // namespace Common