// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause

/**
 * @class   vtkTuple
 * @brief   templated base type for containers of constant size.
 *
 *
 * This class is a templated data type for storing and manipulating tuples.
 */

#ifndef vtkTuple_h
#define vtkTuple_h

#include "vtkIOStream.h" // For streaming operators
#include "vtkSystemIncludes.h"

#include <algorithm> // for std::copy
#include <array>     // for std::array
#include <cassert>   // For inline assert for bounds checked methods.
#include <cmath>     // for std::abs() with float overloads
#include <cstdlib>   // for std::abs() with int overloads

VTK_ABI_NAMESPACE_BEGIN
template <typename T, int Size>
class vtkTuple
{
public:
  /**
   * The default constructor does not initialize values. If initializtion is
   * desired, this should be done explicitly using the constructors for scalar
   * initialization, or other suitable constructors taking arguments.
   */
  vtkTuple() = default;

  /**
   * Initialize all of the tuple's elements with the supplied scalar.
   */
  explicit vtkTuple(const T& scalar)
  {
    for (int i = 0; i < Size; ++i)
    {
      this->Data[i] = scalar;
    }
  }

  /**
   * Initialize the tuple's elements with the elements of the supplied array.
   * Note that the supplied pointer must contain at least as many elements as
   * the tuple, or it will result in access to out of bounds memory.
   */
  explicit vtkTuple(const T* init)
  {
    for (int i = 0; i < Size; ++i)
    {
      this->Data[i] = init[i];
    }
  }

  /**
   * Initialize the tuple's elements using a `std::array` for matching type and
   * size. Example usage: `vtkTuple<double, 2 >({0.1, 0.2})`.
   */
  explicit vtkTuple(const std::array<T, Size>& values)
  {
    std::copy(values.begin(), values.end(), this->Data);
  }

  /**
   * Get the size of the tuple.
   */
  int GetSize() const { return Size; }

  /**
   * Get a pointer to the underlying data of the tuple.
   */
  T* GetData() { return this->Data; }
  const T* GetData() const { return this->Data; }

  /**
   * Get a reference to the underlying data element of the tuple.
   * This works similarly to the way C++ STL containers work.  No
   * bounds checking is performed.
   */
  T& operator[](int i) { return this->Data[i]; }
  const T& operator[](int i) const { return this->Data[i]; }

  ///@{
  /**
   * Get the value of the tuple at the index specified. Does bounds
   * checking, similar to the at(i) method of C++ STL containers, but
   * only when the code is compiled in debug mode.
   */
  T operator()(int i) const
  {
    assert("pre: index_in_bounds" && i >= 0 && i < Size);
    return this->Data[i];
  }
  ///@}

  ///@{
  /**
   * Equality operator with a tolerance to allow fuzzy comparisons.
   */
  bool Compare(const vtkTuple<T, Size>& other, const T& tol) const
  {
    if (Size != other.GetSize())
    {
      return false;
    }
    for (int i = 0; i < Size; ++i)
    {
      if (std::abs(this->Data[i] - other.Data[i]) >= tol)
      {
        return false;
      }
    }
    return true;
  }
  ///@}

  ///@{
  /**
   * Cast the tuple to the specified type, returning the result.
   */
  template <typename TR>
  vtkTuple<TR, Size> Cast() const
  {
    vtkTuple<TR, Size> result;
    for (int i = 0; i < Size; ++i)
    {
      result[i] = static_cast<TR>(this->Data[i]);
    }
    return result;
  }
  ///@}

protected:
  ///@{
  /**
   * The only thing stored in memory!
   */
  T Data[Size];
  ///@}
};

///@{
/**
 * Output the contents of a tuple, mainly useful for debugging.
 */
template <typename A, int Size>
ostream& operator<<(ostream& out, const vtkTuple<A, Size>& t)
{
  out << "(";
  bool first = true;
  for (int i = 0; i < Size; ++i)
  {
    if (first)
    {
      first = false;
    }
    else
    {
      out << ", ";
    }
    out << t[i];
  }
  out << ")";
  return out;
}
// Specialize for unsigned char so that we can see the numbers!
template <int Size>
ostream& operator<<(ostream& out, const vtkTuple<unsigned char, Size>& t)
{
  out << "(";
  bool first = true;
  for (int i = 0; i < Size; ++i)
  {
    if (first)
    {
      first = false;
    }
    else
    {
      out << ", ";
    }
    out << static_cast<int>(t[i]);
  }
  out << ")";
  return out;
}
///@}

///@{
/**
 * Equality operator performs an equality check on each component.
 */
template <typename A, int Size>
bool operator==(const vtkTuple<A, Size>& t1, const vtkTuple<A, Size>& t2)
{
  for (int i = 0; i < Size; ++i)
  {
    if (t1[i] != t2[i])
    {
      return false;
    }
  }
  return true;
}
///@}

/**
 * Inequality for vector type.
 */
template <typename A, int Size>
bool operator!=(const vtkTuple<A, Size>& t1, const vtkTuple<A, Size>& t2)
{
  return !(t1 == t2);
}

VTK_ABI_NAMESPACE_END
#endif // vtkTuple_h
// VTK-HeaderTest-Exclude: vtkTuple.h
