/***************************************************************************************************
 * Copyright (c) 2023 - 2023 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 **************************************************************************************************/
#pragma once

#include <cute/config.hpp>

#include <cute/underscore.hpp>
#include <cute/int_tuple.hpp>
#include <cute/stride.hpp>
#include <cute/numeric/arithmetic_tuple.hpp>

namespace cute
{

// Aliases

template <class... Shapes>
using Shape = IntTuple<Shapes...>;

template <class... Strides>
using Stride = IntTuple<Strides...>;

template <class... Strides>
using Step = IntTuple<Strides...>;

template <class... Coords>
using Coord = IntTuple<Coords...>;

template <class... Ts>
CUTE_HOST_DEVICE constexpr
Shape<Ts...>
make_shape(Ts const&... t) {
  return {t...};
}
template <class... Ts>
CUTE_HOST_DEVICE constexpr
Stride<Ts...>
make_stride(Ts const&... t) {
  return {t...};
}
template <class... Ts>
CUTE_HOST_DEVICE constexpr
Step<Ts...>
make_step(Ts const&... t) {
  return {t...};
}
template <class... Ts>
CUTE_HOST_DEVICE constexpr
Coord<Ts...>
make_coord(Ts const&... t) {
  return {t...};
}


template <class Shape, class Stride = LayoutLeft::Apply<Shape> >
struct Layout
    : private cute::tuple<Shape, Stride>   // EBO for static layouts
{
  // Expensive in compilation time...
  //static_assert(is_congruent<Shape, Stride>::value, "Shape and Stride must be congruent");

  // NOTE: This defaults static Shapes/Strides correctly, but not dynamic
  CUTE_HOST_DEVICE constexpr
  Layout(Shape  const& shape  = {}, Stride const& stride = {})
      : cute::tuple<Shape, Stride>(shape, stride)
  {}

  //
  // Accessors
  //

  static constexpr int rank  = rank_v<Shape>;

  CUTE_HOST_DEVICE constexpr
  decltype(auto)
  layout() {
    return *this;
  }

  CUTE_HOST_DEVICE constexpr
  decltype(auto)
  layout() const {
    return *this;
  }

  template <int... I>
  CUTE_HOST_DEVICE constexpr
  decltype(auto)
  shape() {
    return get<0,I...>(static_cast<cute::tuple<Shape, Stride>&>(*this));
  }

  template <int... I>
  CUTE_HOST_DEVICE constexpr
  decltype(auto)
  shape() const {
    return get<0,I...>(static_cast<cute::tuple<Shape, Stride> const&>(*this));
  }

  template <int... I>
  CUTE_HOST_DEVICE constexpr
  decltype(auto)
  stride() {
    return get<1,I...>(static_cast<cute::tuple<Shape, Stride>&>(*this));
  }

  template <int... I>
  CUTE_HOST_DEVICE constexpr
  decltype(auto)
  stride() const {
    return get<1,I...>(static_cast<cute::tuple<Shape, Stride> const&>(*this));
  }

  //
  // Mappings
  //

  // Map a logical coordinate to a linear index (Coord has no Underscore slice operators)
  // OR
  // Slice the layout and return the sublayout (Coord has an Underscore slice op)
  template <class Coord>
  CUTE_HOST_DEVICE constexpr
  auto
  operator()(Coord const& coord) const {
    if constexpr (has_underscore<Coord>::value) {
      return slice(coord, *this);
    } else {
      return crd2idx(coord, shape(), stride());
    }

    CUTE_GCC_UNREACHABLE;
  }

  // Convenience function for multi-dimensional coordinates
  template <class Coord0, class Coord1, class... Coords>
  CUTE_HOST_DEVICE constexpr
  auto
  operator()(Coord0 const& c0, Coord1 const& c1, Coords const&... cs) const {
    return operator()(make_coord(c0,c1,cs...));
  }

  // Map a linear index to a hier ND logical coordinate
  // NOTE: Dangerous and error-prone
  template <class Int>
  CUTE_HOST_DEVICE constexpr
  auto
  operator[](Int const& linear_idx) const {
    static_assert(is_integral<Int>::value);
    return get_hier_coord(linear_idx);
  }

  //
  // Compose
  //

  template <class OtherLayout>
  CUTE_HOST_DEVICE constexpr
  auto
  compose(OtherLayout const& other) const {
    return composition(*this, other);
  }

  template <class... Layouts>
  CUTE_HOST_DEVICE constexpr
  auto
  compose(Layouts const&... layouts) const {
    return composition(*this, make_tile(layouts...));
  }

  template <class OtherShape>
  CUTE_HOST_DEVICE constexpr
  auto
  with_shape(OtherShape const& shape) const {
    return composition(*this, make_layout(shape));
  }

  template <class... Shapes>
  CUTE_HOST_DEVICE constexpr
  auto
  with_shape(Shapes const&... shapes) const {
    return composition(*this, make_layout(make_shape(shapes...)));
  }

  //
  // Tile
  //

  template <class OtherLayout>
  CUTE_HOST_DEVICE constexpr
  auto
  tile(OtherLayout const& other) const {
    return tiled_divide(*this, other);
  }

  template <class... Layouts>
  CUTE_HOST_DEVICE constexpr
  auto
  tile(Layouts const&... layouts) const {
    return tiled_divide(*this, make_tile(layouts...));
  }

  //
  // Utility
  //

  //
  // Index to Coordinate
  //

  // NOTE: Only valid for compact layouts

  // Return the (hierarchical) ND logical coordinate corresponding to the linear index
  // @post crd2idx(@a result, shape(), stride()) == idx
  // @post congruent(@a result, shape())
  template <class IInt,
            __CUTE_REQUIRES(is_integral<IInt>::value)>
  CUTE_HOST_DEVICE constexpr
  auto
  get_hier_coord(IInt const& idx) const {
    return cute::idx2crd(idx, shape(), stride());
  }

  // Return the (flat) ND logical coordinate corresponding to the linear index
  // @post crd2idx(@a result, shape(), stride()) == idx
  // @post rank(@a result) == rank(shape()) && depth(@a result) == 1
  template <class IInt,
            __CUTE_REQUIRES(is_integral<IInt>::value)>
  CUTE_HOST_DEVICE constexpr
  auto
  get_flat_coord(IInt const& idx) const {
    return cute::crd2crd(this->get_hier_coord(idx), shape(), repeat<rank>(Int<1>{}));
  }

  // Return the generalized column-major 1D logical coordinate corresponding to the linear index
  // @post crd2idx(@a result, shape(), stride()) == idx
  // @post is_integral<decltype(@a result)>::value
  template <class IInt,
            __CUTE_REQUIRES(is_integral<IInt>::value)>
  CUTE_HOST_DEVICE constexpr
  auto
  get_1d_coord(IInt const& idx) const {
    return cute::crd2idx(this->get_hier_coord(idx), shape());
  }

  //
  // Coordinate to Coordinate
  //

#if 0
  // Return the (hierarchical) ND logical coordinate corresponding to the linear index
  // @post congruent(@a result, shape())
  template <class Coord>
  CUTE_HOST_DEVICE constexpr
  auto
  crd_2_hier_coord(Coord const& crd) const {
    return cute::crd2crd(crd, shape(), shape());
  }

  // Return the (flat) ND logical coordinate corresponding to the linear index
  // @post rank(@a result) == rank(shape()) && depth(@a result) == 1
  template <class Coord>
  CUTE_HOST_DEVICE constexpr
  auto
  crd_2_flat_coord(Coord const& crd) const {
    return cute::crd2crd(crd, shape(), product_each(shape()));
  }

  // Return the generalized column-major 1D logical coordinate corresponding to the linear index
  // @post is_integral<decltype(@a result)>::value
  template <class Coord>
  CUTE_HOST_DEVICE constexpr
  auto
  crd_2_1d_coord(Coord const& crd) const {
    //return cute::crd2crd(crd, shape(), product(shape()));
    return cute::crd2idx(crd, shape());
  }
#endif
};

template <class Layout>
struct is_layout : false_type {};
template <class Shape, class Stride>
struct is_layout<Layout<Shape,Stride>> : true_type {};


template <class Shape, class Stride,
          __CUTE_REQUIRES((is_tuple<Shape >::value || is_integral<Shape >::value) &&
                          (is_tuple<Stride>::value || is_integral<Stride>::value))>
CUTE_HOST_DEVICE constexpr
auto
make_layout(Shape const& shape, Stride const& stride)
{
  return Layout<Shape,Stride>(shape, stride);
}

template <class Shape,
          __CUTE_REQUIRES(is_tuple<Shape>::value || is_integral<Shape>::value)>
CUTE_HOST_DEVICE constexpr
auto
make_layout(Shape const& shape)
{
  return make_layout(shape, compact_col_major(shape));
}

// Construct a layout from multiple layouts by
//   concatenating each layout as an independent mode
template <class... Shapes, class... Strides>
CUTE_HOST_DEVICE constexpr
auto
make_layout(Layout<Shapes,Strides> const&... layouts)
{
  return make_layout(make_shape (layouts.shape()...),
                     make_stride(layouts.stride()...));
}

//
// Convenience tags for common layouts
//

template <class Shape>
CUTE_HOST_DEVICE constexpr
auto
make_layout(Shape const& shape, GenColMajor)
{
  return make_layout(shape, compact_col_major(shape));
}

template <class Shape>
CUTE_HOST_DEVICE constexpr
auto
make_layout(Shape const& shape, GenRowMajor)
{
  return make_layout(shape, compact_row_major(shape));
}

// Follow the same ordering induced by the strides, but make the layout compact
template <class Shape, class Order>
CUTE_HOST_DEVICE constexpr
auto
make_ordered_layout(Shape const& shape, Order const& order)
{
  static_assert(is_static<Shape>::value && is_static<Order>::value);
  return make_layout(shape, compact_order(shape, order));
}

template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
make_ordered_layout(Layout<Shape,Stride> const& layout)
{
  return make_ordered_layout(layout.shape(), layout.stride());
}

// Make a layout of the same shape that is either ordered or colmajor depending on staticness
template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
make_layout_like(Layout<Shape,Stride> const& layout)
{
  auto any_zero = any_of(layout.stride(), [](auto d) { return is_constant<0, decltype(d)>{}; });
  if constexpr (any_zero) {
    // If there are static-0 strides, then make a col-major layout that keeps those 0s
    return make_layout(layout.shape(),
                       compact_col_major(filter_zeros(layout.stride(), layout.shape())));
  } else
  if constexpr (is_static<Shape>::value && is_static<Stride>::value) {
    // If the layout is fully static, then make a layout that follows the same order as the strides
    // Assumes the strides are unique
    return make_ordered_layout(layout.shape(), layout.stride());
  } else {
    return make_layout(layout.shape());
  }

  CUTE_GCC_UNREACHABLE;
}

//
// Make a layout of the same shape,
//   with mode-0 being colmajor then following the mode order in layout
//
template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
make_fragment_like(Layout<Shape,Stride> const& layout)
{
  constexpr int R = Layout<Shape,Stride>::rank;
  if constexpr (R > 1 && is_static<Shape>::value && is_static<Stride>::value) {
    return tiled_product(make_layout(shape<0>(layout)), make_ordered_layout(take<1,R>(layout)));
  } else {
    return make_layout(layout.shape());
  }

  CUTE_GCC_UNREACHABLE;
}

template <class Shape,
          __CUTE_REQUIRES(is_tuple<Shape>::value || is_integral<Shape>::value)>
CUTE_HOST_DEVICE constexpr
auto
make_fragment_like(Shape const& shape)
{
  return make_layout(shape);
}

//
// Make an identity layout that maps a coordinate to itself
//

template <class Shape>
CUTE_HOST_DEVICE constexpr
auto
make_identity_layout(Shape const& shape)
{
  return make_layout(shape, make_basis_like(shape));
}

//
// Operations to manipulate Layouts like a tuple of pairs
//

template <size_t... Is, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
get(Layout<Shape,Stride> const& layout)
{
  // Let the static_asserts in get<I>(shape|stride) catch problems
  return make_layout(get<Is...>(layout.shape()), get<Is...>(layout.stride()));
}

template <int B, int E, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
take(Layout<Shape,Stride> const& layout)
{
  // Let the static_asserts in take<B,E>(shape|stride) catch problems
  return make_layout(take<B,E>(layout.shape()), take<B,E>(layout.stride()));
}

template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
flatten(Layout<Shape,Stride> const& layout)
{
  return make_layout(flatten(layout.shape()), flatten(layout.stride()));
}

//
// Utilities
//

// Return the layout of a mode
template <int... Is, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
decltype(auto)
layout(Layout<Shape,Stride> const& layout)
{
  if constexpr (sizeof...(Is) == 0) {
    return layout;
  } else {
    return get<Is...>(layout);
  }

  CUTE_GCC_UNREACHABLE;
}

// Return the shape of a mode
template <int... Is, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
decltype(auto)
shape(Layout<Shape,Stride>& layout)
{
  return layout.template shape<Is...>();
}

template <int... Is, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
decltype(auto)
shape(Layout<Shape,Stride> const& layout)
{
  return layout.template shape<Is...>();
}

// Return the stride of a mode
template <int... Is, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
decltype(auto)
stride(Layout<Shape,Stride>& layout)
{
  return layout.template stride<Is...>();
}

template <int... Is, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
decltype(auto)
stride(Layout<Shape,Stride> const& layout)
{
  return layout.template stride<Is...>();
}

// Return the number of elements in a mode
template <int... Is, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
size(Layout<Shape,Stride> const& layout)
{
  return size(shape<Is...>(layout));
}

// Return the number of modes
template <int... Is, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
rank(Layout<Shape,Stride> const& layout)
{
  return rank(shape<Is...>(layout));
}

// Return the depth of the layout
template <int... Is, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
depth(Layout<Shape,Stride> const& layout)
{
  return depth(shape<Is...>(layout));
}

// Return the codomain size of a mode
// @return M smallest integer such that @a sub_layout(c) < M for all c < size(@a sub_layout)
//           where sub_layout = get<Is...>(layout).
template <int... Is, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
cosize(Layout<Shape,Stride> const& layout)
{
  // Protect against negative strides
  auto abs_sub_layout = make_layout(shape<Is...>(layout),
                                    transform_leaf(stride<Is...>(layout), abs_fn{}));
  return abs_sub_layout(size(abs_sub_layout) - Int<1>{}) + Int<1>{};
}

template <class Layout>
using cosize_t = decltype(cosize(declval<Layout>()));

template <class Layout>
static constexpr int cosize_v = cosize_t<Layout>::value;

// Equality
// Return a static or dynamic boolean
template <class ShapeA, class StrideA,
          class ShapeB, class StrideB>
CUTE_HOST_DEVICE constexpr
auto
operator==(Layout<ShapeA,StrideA> const& layoutA, Layout<ShapeB,StrideB> const& layoutB)
{
  return layoutA.shape() == layoutB.shape() && layoutA.stride() == layoutB.stride();
}

// With crd2idx(coord, shape), makes sense to have crd2idx(coord, Layout) as well
template <class Coord, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
crd2idx(Coord const& c, Layout<Shape,Stride> const& layout)
{
  return crd2idx(c, layout.shape(), layout.stride());
}

//
// Slice and Dice a layout
//

template <class Coord, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
slice(Coord const& c, Layout<Shape,Stride> const& layout)
{
  return make_layout(slice(c, layout.shape()),
                     slice(c, layout.stride()));
}

template <class Coord, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
slice_and_offset(Coord const& c, Layout<Shape,Stride> const& layout)
{
  return cute::make_tuple(slice(c, layout), crd2idx(c, layout));
}

template <class Coord, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
dice(Coord const& c, Layout<Shape,Stride> const& layout)
{
  return make_layout(dice(c, layout.shape()),
                     dice(c, layout.stride()));
}

//
// Transform the modes of a layout
//

namespace detail {

template <class Tuple, class F, int... I>
CUTE_HOST_DEVICE constexpr
auto
transform_layout(Tuple const& t, F&& f, seq<I...>)
{
  return make_layout(f(get<I>(t))...);
}

template <class Tuple0, class Tuple1, class F, int... I, int... I0, int... I1>
CUTE_HOST_DEVICE constexpr
auto
transform_layout(Tuple0 const& t0, Tuple1 const& t1, F&& f, seq<I...>, seq<I0...>, seq<I1...>)
{
  return make_layout(f(get<I>(t0),get<I>(t1))..., get<I0>(t0)..., get<I1>(t1)...);
}

} // end namespace detail

template <class Tuple, class F>
CUTE_HOST_DEVICE constexpr
auto
transform_layout(Tuple const& t, F&& f)
{
  return detail::transform_layout(t, f, make_seq<decltype(rank(t))::value>{});
}

template <class Tuple0, class Tuple1, class F>
CUTE_HOST_DEVICE constexpr
auto
transform_layout(Tuple0 const& t0, Tuple1 const& t1, F&& f)
{
  constexpr int R0 = decltype(rank(t0))::value;
  constexpr int R1 = decltype(rank(t1))::value;
  constexpr int R  = (R0 < R1) ? R0 : R1;
  return detail::transform_layout(t0, t1, f, make_seq<R>{}, make_range<R,R0>{}, make_range<R,R1>{});
}

//
// Coalesce and Filter
//

namespace detail {

// Look at each element and the front of the stack (in order of priority)
// front(NewLayout)  get<I>(Layout)
//      s0:d0           _1:d1     =>  continue
//      _1:d0           s1:d1     =>  replace_front    s1:d1
//      s0:s1*d1        s1:d1     =>  replace_front s0*s1:d1
//      s0:d0           s1:d1     =>  prepend          s1:d1
//
// @pre OldShape and OldStride are flat
template <int I, class OldShape, class OldStride, class NewShape, class NewStride>
CUTE_HOST_DEVICE constexpr
auto
bw_coalesce(OldShape const& old_shape, OldStride const& old_stride,
            NewShape const& new_shape, NewStride const& new_stride)
{
  if constexpr (I == -1) {
    // Base case, we're done
    if constexpr (is_constant<1, NewShape>::value) {
      return Layout<_1,_0>{};
    } else {
      return Layout<NewShape,NewStride>{new_shape,new_stride};
    }
  } else if constexpr (is_constant<1, decltype(get<I>(old_shape))>::value) {
    // shape<I>(layout) == _1, skip it and continue
    return bw_coalesce<I-1>(old_shape, old_stride, new_shape, new_stride);
  } else if constexpr (is_constant<1, NewShape>::value) {
    // Replace our shape-1 with anything (Can only happen on input new_shape/new_stride)
    return bw_coalesce<I-1>(old_shape, old_stride, get<I>(old_shape), get<I>(old_stride));
  } else if constexpr (is_constant<true, decltype(get<I>(old_shape) * get<I>(old_stride) == get<0>(new_stride))>::value) {
    // Merge modes because the shapes and strides match
    return bw_coalesce<I-1>(old_shape, old_stride,
                            replace_front(new_shape,  get<I>(old_shape) * get<0>(new_shape)),
                            replace_front(new_stride, get<I>(old_stride)));
  } else {
    // Can't replace or merge, so prepend a new mode
    return bw_coalesce<I-1>(old_shape, old_stride,
                            prepend(new_shape,  get<I>(old_shape)),
                            prepend(new_stride, get<I>(old_stride)));
  }

  CUTE_GCC_UNREACHABLE;
}

} // end namespace detail

// Combine all the modes that are possible to combine
// Does not respect the profile of the layout, but does preserve total size
template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
coalesce(Layout<Shape,Stride> const& layout)
{
  auto flat_shape  = flatten(layout.shape());
  auto flat_stride = flatten(layout.stride());

  constexpr int R = decltype(rank(flat_shape))::value;
  return detail::bw_coalesce<R-2>(flat_shape, flat_stride, get<R-1>(flat_shape), get<R-1>(flat_stride));
}

// Apply coalesce at the terminals of trg_profile
template <class Shape, class Stride, class IntTuple>
CUTE_HOST_DEVICE constexpr
auto
coalesce(Layout<Shape,Stride> const& layout, IntTuple const& trg_profile)
{
  if constexpr (is_tuple<IntTuple>::value) {
    static_assert(tuple_size<IntTuple>::value <= Layout<Shape,Stride>::rank);
    return transform_layout(layout, trg_profile, [](auto const& l, auto const& t) { return coalesce(l,t); });
  } else {
    return coalesce(layout);
  }

  CUTE_GCC_UNREACHABLE;
}

// Replace the modes in layout that have a 0-stride with a 1-size
template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
filter_zeros(Layout<Shape,Stride> const& layout)
{
  return make_layout(filter_zeros(layout.stride(), layout.shape()), layout.stride());
}

// Remove all of the 0-strides and 1-sizes
// Return 1-shape if empty
template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
filter(Layout<Shape,Stride> const& layout)
{
  return coalesce(filter_zeros(layout));
}

// Apply filter at the terminals of trg_profile
template <class Shape, class Stride, class IntTuple>
CUTE_HOST_DEVICE constexpr
auto
filter(Layout<Shape,Stride> const& layout, IntTuple const& trg_profile)
{
  if constexpr (is_tuple<IntTuple>::value) {
    static_assert(tuple_size<IntTuple>::value <= Layout<Shape,Stride>::rank);
    return transform_layout(layout, trg_profile, [](auto const& l, auto const& t) { return filter(l,t); });
  } else {
    return filter(layout);
  }

  CUTE_GCC_UNREACHABLE;
}

//
// Append, Prepend, Replace
//

template <int N, class ShapeA, class StrideA, class ShapeX = _1, class StrideX = _0>
CUTE_HOST_DEVICE constexpr
auto
append(Layout<ShapeA,StrideA> const& layout,
       Layout<ShapeX,StrideX> const& x = {})
{
  return make_layout(append<N>(layout.shape(),  x.shape()),
                     append<N>(layout.stride(), x.stride()));
}

template <int N, class ShapeA, class StrideA, class ShapeX = _1, class StrideX = _0>
CUTE_HOST_DEVICE constexpr
auto
prepend(Layout<ShapeA,StrideA> const& layout,
        Layout<ShapeX,StrideX> const& x = {})
{
  return make_layout(prepend<N>(layout.shape(),  x.shape()),
                     prepend<N>(layout.stride(), x.stride()));
}

template <int N, class ShapeA, class StrideA, class ShapeX, class StrideX>
CUTE_HOST_DEVICE constexpr
auto
replace(Layout<ShapeA,StrideA> const& layout,
        Layout<ShapeX,StrideX> const& x)
{
  return make_layout(replace<N>(layout.shape(),  x.shape()),
                     replace<N>(layout.stride(), x.stride()));
}

template <int B, int E, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
group(Layout<Shape,Stride> const& layout)
{
  return make_layout(group<B,E>(layout.shape()),
                     group<B,E>(layout.stride()));
}

//
// Composition of two layouts: lhs o rhs
// @post compatible(rhs, result)
// @post result(c) = lhs(rhs(c))
//         for all c in the domain of result
//

namespace detail {

template <class LShape, class LStride,
          class RShape, class RStride>
CUTE_HOST_DEVICE constexpr
auto
composition(Layout<LShape,LStride> const& lhs,
            RShape const& rhs_shape, RStride const& rhs_stride)
{
  if constexpr (is_tuple<RShape>::value) {
    // Apply the right-distributivity of Layout composition
    return transform_layout(rhs_shape, rhs_stride, [&](auto const& s, auto const& d) { return composition(lhs, s, d); });
  } else
  if constexpr (is_scaled_basis<RStride>::value) {
    // Special case for a ScaledBasis stride
    return composition(get<rhs_stride.mode()>(lhs), rhs_shape, rhs_stride.value());
  } else
  if constexpr (is_integral<RStride>::value) {
    // Integral Rstride (and RShape)

    // NOTE: Should only flatten once for efficiency
    auto flat_shape  = flatten(lhs.shape());
    [[maybe_unused]] auto flat_stride = flatten(lhs.stride());
    [[maybe_unused]] constexpr int R  = rank(flat_shape);

    if constexpr (is_constant<0, RStride>::value) {
      // Special case shortcut for any static stride-0
      return Layout<RShape, RStride>{rhs_shape, rhs_stride};
    } else
    if constexpr (is_integral<decltype(flat_shape)>::value) {
      // Special case shortcut for any integral LShape
      auto result_stride = rhs_stride * flat_stride;
      return Layout<RShape, decltype(result_stride)>{rhs_shape, result_stride};
    } else
    if constexpr (is_constant<1, RStride>::value) {
      // Special case shortcut for any static stride-1
      auto result_shape_0  = take<0,R-1>(flat_shape);

      // Mod out the rhs_shape from the lhs.shape()
      auto const [result_shape_1, rest_shape]  = fold(result_shape_0, cute::make_tuple(cute::make_tuple(), rhs_shape),
        [] (auto const& init, auto const& si) {
          return cute::make_tuple(append(get<0>(init), cute::min(abs(si), get<1>(init))), shape_div(get<1>(init), abs(si)));
        });

      // Jump into coalesce and append (rest_shape, get<R-1>(lhs.stride())
      return detail::bw_coalesce<R-2>(result_shape_1, flat_stride, rest_shape, get<R-1>(flat_stride));
    } else
    {
      // General case
      auto result_shape_0  = take<0,R-1>(flat_shape);
      auto result_stride_0 = take<0,R-1>(flat_stride);

      // Divide out the rhs_stride from the lhs.shape()
      auto const [result_shape_1, rest_stride] = fold(result_shape_0, cute::make_tuple(cute::make_tuple(), rhs_stride),
        [] (auto const& init, auto const& di) {
          return cute::make_tuple(append(get<0>(init), shape_div(di, get<1>(init))), shape_div(get<1>(init), di));
        });

      // Apply any lhs.shape() changes to the stride
      auto result_stride_1 = elem_scale(result_stride_0, shape_div(result_shape_0, result_shape_1));

      // Mod out the rhs_shape from the lhs.shape()
      auto const [result_shape_2, rest_shape]  = fold(result_shape_1, cute::make_tuple(cute::make_tuple(), rhs_shape),
        [] (auto const& init, auto const& si) {
          return cute::make_tuple(append(get<0>(init), cute::min(abs(si), get<1>(init))), shape_div(get<1>(init), abs(si)));
        });

      // Jump into coalesce and append (rest_shape, rest_stride * get<R-1>(lhs.stride())
      return detail::bw_coalesce<R-2>(result_shape_2, result_stride_1, rest_shape, rest_stride * get<R-1>(flat_stride));
    }
  }

  CUTE_GCC_UNREACHABLE;
}

} // end namespace detail

template <class LShape, class LStride,
          class RShape, class RStride>
CUTE_HOST_DEVICE constexpr
auto
composition(Layout<LShape,LStride> const& lhs,
            Layout<RShape,RStride> const& rhs)
{
  //return detail::composition(flatten(lhs), rhs.shape(), rhs.stride());
  return detail::composition(lhs, rhs.shape(), rhs.stride());
}

template <class LShape, class LStride, class IntTuple>
CUTE_HOST_DEVICE constexpr
auto
composition(Layout<LShape,LStride> const& lhs,
            IntTuple               const& rhs)
{
  if constexpr (is_tuple<IntTuple>::value) {
    static_assert(tuple_size<IntTuple>::value <= Layout<LShape,LStride>::rank);
    // Drop any modes of lhs that aren't hit by rhs
    return detail::transform_layout(lhs, rhs, [](auto const& l, auto const& r) { return composition(l,r); }, make_seq<tuple_size<IntTuple>::value>{}, seq<>{}, seq<>{});
  } else if constexpr (is_underscore<IntTuple>::value) {
    return lhs;
  } else {
    return composition(lhs, make_layout(rhs));
  }

  CUTE_GCC_UNREACHABLE;
}

//
// Complement
//
// Build the complement of a layout.
// @post size(@a result) >= @a cosize_hi / size(filter(@a layout)));
// @post For all i in [1,size(@a result)),
//           @a result(i) < @a result(i-1)
//           For all j in [0, size(@a layout)),
//               @a result(i) != @a layout(j)
//

namespace detail {

// @pre @a layout has been filtered (flattened and no stride-0 or size-1 modes).
template <class Shape, class Stride, class CoSizeHi>
CUTE_HOST_DEVICE constexpr
auto
complement(Shape const& shape, Stride const& stride, CoSizeHi const& cosize_hi)
{
  if constexpr (is_constant<0, Stride>::value) {
    // Special case for irreducible rank-1 stride-0 layout
    return make_layout(cosize_hi);
  } else {
    // General case
    constexpr int R = rank_v<Shape>;
    static_assert(R == 1 || is_static<Stride>::value,
                  "Dynamic-stride complement only for rank-1 layouts");

    // Should just be a sort and a fold...
    // Then we could even handle dynamic strides (but they would destroy all static strides)
    auto result = fold(make_seq<R-1>{},
                       cute::make_tuple(shape,
                                  stride,
                                  cute::make_tuple(),
                                  cute::make_tuple(Int<1>{})),
      [](auto const& init, auto i)
      {
        auto curr_stride = cute::min(get<1>(init));
        auto curr_idx    = find(get<1>(init), curr_stride);
        auto curr_shape  = get<curr_idx>(get<0>(init));

        return cute::make_tuple(remove<curr_idx>(get<0>(init)),                     // Remove the curr shape
                          remove<curr_idx>(get<1>(init)),                     // Remove the curr stride
                          append(get<2>(init), curr_stride / get<3,i>(init)), // new shape  = curr_stride / last_stride
                          append(get<3>(init), curr_shape  * curr_stride));   // new stride = curr_shape  * curr_stride
      });

    // Append the last shape mode
    auto result_stride = get<3>(result);
    auto result_shape  = append(get<2>(result), get<1,0>(result) / back(result_stride)); // new shape  = curr_stride / last_stride

    // Compute the rest_stride
    auto rest_stride = get<0,0>(result) * get<1,0>(result);
    //return make_layout(append(result_shape,  ceil_div(cosize_hi, rest_stride)), append(result_stride, rest_stride));
    // Jump into coalesce and append (ceil_div(cosize_hi, rest_stride), rest_stride)
    return detail::bw_coalesce<R-1>(result_shape, result_stride, ceil_div(cosize_hi, rest_stride), rest_stride);
  }

  CUTE_GCC_UNREACHABLE;
}

} // end namespace detail

template <class Shape, class Stride, class CoSizeHi>
CUTE_HOST_DEVICE constexpr
auto
complement(Layout<Shape,Stride> const& layout, CoSizeHi const& cosize_hi)
{
  static_assert(cute::is_integral<CoSizeHi>::value, "Expected integral codomain size in complement.");
  auto filter_layout = filter(layout);
  return detail::complement(filter_layout.shape(), filter_layout.stride(), cosize_hi);
}

template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
complement(Layout<Shape,Stride> const& layout)
{
  auto filter_layout = filter(layout);
  return detail::complement(filter_layout.shape(), filter_layout.stride(), cosize(filter_layout));
}

//
// Right-Inverse and Left-Inverse
//

namespace detail {

template <int I, class Shape, class Stride, int... Is>
CUTE_HOST_DEVICE constexpr
auto
inverse_seq(Shape const& shape, Stride const& stride, seq<Is...>)
{
  if constexpr (I == decltype(rank(stride))::value) {
    return seq<Is...>{};
  } else {
    //auto next_stride = get<I>(shape) * get<I>(stride);
    using next_stride = decltype(get<I>(shape) * get<I>(stride));  // NOTE: WAR for g++-7

    if constexpr (is_static<next_stride>::value) {
      auto next_idx  = find_if(stride, [](auto a) { return is_constant<next_stride::value, decltype(a)>{}; });
      return inverse_seq<next_idx>(shape, stride, seq<Is..., I>{});
    } else {
      return seq<Is..., I>{};
    }
  }

  CUTE_GCC_UNREACHABLE;
}

} // end namespace detail

//
// Build the right-inverse of a layout
// @pre is_static<Layout>
// @result A layout @a result such that
//    @a layout(@a result(i)) == i for all i < size(@a result)
// @result A layout @a result such that
//    composition(@a layout, @a result) is identical to make_layout(shape(result))
//

template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
right_inverse(Layout<Shape,Stride> const& layout)
{
  auto flat_layout = coalesce(layout);
  auto astride = transform_leaf(flat_layout.stride(), abs_fn{});

  // Find Int<1>{}, the starting idx, and follow the strides to gen inverse_seq
  auto next_I  = find_if(astride, [](auto a) { return is_constant<1, decltype(a)>{}; });
  [[maybe_unused]] auto iseq    = detail::inverse_seq<next_I>(flat_layout.shape(), astride, seq<>{});

  if constexpr (tuple_size<decltype(iseq)>::value == 0) {
    return Layout<_1,_0>{};     // Empty case, nothing found
  } else {
    // Generate the corresponding new strides and construct
    auto rstride = compact_col_major(flat_layout.shape());
    return make_layout(unwrap(transform(iseq, [&](auto i) { return shape<i>(flat_layout); })),
                       unwrap(transform(iseq, [&](auto i) { return signum(stride<i>(flat_layout)) * get<i>(rstride); })));
  }

  CUTE_GCC_UNREACHABLE;
}

CUTE_HOST_DEVICE constexpr
auto
right_inverse(Underscore const& _)
{
  return _;
}

//
// Build the left-inverse of a layout
// @pre is_static<Layout>
// @pre @a layout is an injective function
// @result A layout @a result such that
//    @a result(@a layout(i)) == i for all i < size(@a layout)
// @result A layout @a result such that
//    composition(@a result, @a layout) is identical to make_layout(shape(layout))
//

template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
left_inverse(Layout<Shape,Stride> const& layout)
{
  return right_inverse(make_layout(layout, complement(layout)));
}

CUTE_HOST_DEVICE constexpr
auto
left_inverse(Underscore const& _)
{
  return _;
}

//
// Max Common Layout
//

/* Return a layout that points to the maximum number of contiguous elements
 * that logically correspond in the layouts of @a a and @a b. This is,
 * the elements that could reasonably be "vectorized" in the layouts.
 *
 * @returns Layout R
 * @post For all 0 <= i < size(R), a(R(i)) == i && b(R(i)) == i
 */
template <class ShapeA, class StrideA,
          class ShapeB, class StrideB>
CUTE_HOST_DEVICE constexpr
auto
max_common_layout(Layout<ShapeA,StrideA> const& a,
                  Layout<ShapeB,StrideB> const& b)
{
  if constexpr (is_static<ShapeA>::value && is_static<StrideA>::value &&
                is_static<ShapeB>::value && is_static<StrideB>::value)
  {
    Layout inv_b  = right_inverse(b);
    Layout common = coalesce(composition(a, inv_b));

    if constexpr (is_constant<1, decltype(stride<0>(common))>::value) {
      // Truncate to the size of the contiguous vector (static stride-1 mode)
      return composition(inv_b, layout<0>(common));
    } else {
      return Layout<_1,_0>{};
    }
  } else {
    // CASE: One of the layouts is dynamic, can't prove alignment+vectorization is valid
    // NOTE: Could weaken if we assume dynamic shapes/strides obey alignment requirements
    //         (i.e. are large and multiples of the vector)
    return Layout<_1,_0>{};
  }

  CUTE_GCC_UNREACHABLE;
}

/* Return Int<N> such that N is the maximum number of contiguous elements
 * that logically correspond in the layouts of @a a and @a b. This is,
 * the number of elements that could reasonably be "vectorized" in the layouts.
 *
 * @returns Int<N> with N >= 1
 * @post For all 0 <= n < N, a(b[n]) == n  (NOTE: Problems with negative strides/coords in this post-condition)
 */
template <class ShapeA, class StrideA,
          class ShapeB, class StrideB>
CUTE_HOST_DEVICE constexpr
auto
max_common_vector(Layout<ShapeA,StrideA> const& a,
                  Layout<ShapeB,StrideB> const& b)
{
  return size(max_common_layout(a, b));
}

//
// Zip
//

template <class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
zip(Layout<Shape,Stride> const& layout)
{
  return make_layout(zip(layout.shape()),
                     zip(layout.stride()));
}

template <class TShape, class TStride,
          class UShape, class UStride>
CUTE_HOST_DEVICE constexpr
auto
zip(Layout<TShape,TStride> const& layoutA,
    Layout<UShape,UStride> const& layoutB)
{
  return make_layout(zip(layoutA.shape(),  layoutB.shape()),
                     zip(layoutA.stride(), layoutB.stride()));
}

//
// Tile unzip
//   Logical product and logical divide (on layouts) produce rank-2 results by design.
//   Follow the profile of @a tile and zip the rank-2 modes located at the terminals into
//   their own mode.
//

template <class LShape, class LStride, class IntTuple>
CUTE_HOST_DEVICE constexpr
auto
tile_unzip(Layout<LShape,LStride> const& layout,
           IntTuple               const& tile)
{
  return make_layout(zip2_by(layout.shape(),  tile),
                     zip2_by(layout.stride(), tile));
}

//
// Logical divide
//

template <class LShape, class LStride,
          class TShape, class TStride>
CUTE_HOST_DEVICE constexpr
auto
logical_divide(Layout<LShape,LStride> const& layout,
               Layout<TShape,TStride> const& tile)
{
  //CUTE_STATIC_ASSERT_V(size(layout) % size(tile) == Int<0>{},
  //                     "Tiling does not evenly divide the block");
  // NOTE: With tiles that have stride-0, this doesn't have to be true

  return composition(layout, make_layout(tile, complement(tile, size(layout))));
}

template <class LShape, class LStride, class IntTuple>
CUTE_HOST_DEVICE constexpr
auto
logical_divide(Layout<LShape,LStride> const& layout,
               IntTuple               const& tile)
{
  if constexpr (is_tuple<IntTuple>::value) {
    static_assert(tuple_size<IntTuple>::value <= Layout<LShape,LStride>::rank, "logical_divide: Too many modes in tile.");
    return transform_layout(layout, tile, [](auto const& l, auto const& t) { return logical_divide(l,t); });
  } else if constexpr (is_underscore<IntTuple>::value) {
    return layout;
  } else if constexpr (is_integral<IntTuple>::value) {
    return logical_divide(layout, make_layout(tile));
  }

  CUTE_GCC_UNREACHABLE;
}

//
// Convenience operator
//   that produces layouts like ((BLK_A,BLK_B,...),(a,b,...,x,y))
//   by gathering the tile modes and residuals into a rank-2 result.
//

template <class LShape, class LStride,
          class Tile>
CUTE_HOST_DEVICE constexpr
auto
zipped_divide(Layout<LShape,LStride> const& layout,
              Tile                   const& tile)
{
  return tile_unzip(logical_divide(layout, tile), tile);
}

// Same as zipped_divide, but unpacks the second mode: ((BLK_A,BLK_B,...),a,b,...,x,y)
template <class LShape, class LStride,
          class Tile>
CUTE_HOST_DEVICE constexpr
auto
tiled_divide(Layout<LShape,LStride> const& layout,
             Tile                   const& tile)
{
  auto div = zipped_divide(layout, tile);

  auto R = rank<1>(div);
  return div(_, repeat<R>(_));
}

//
// Logical product
//

template <class LShape, class LStride,
          class TShape, class TStride>
CUTE_HOST_DEVICE constexpr
auto
logical_product(Layout<LShape,LStride> const& layout,
                Layout<TShape,TStride> const& tile)
{
  return make_layout(layout, composition(complement(layout, size(layout)*cosize(tile)), tile));
}

template <class LShape, class LStride, class IntTuple>
CUTE_HOST_DEVICE constexpr
auto
logical_product(Layout<LShape,LStride> const& layout,
                IntTuple               const& tile)
{
  if constexpr (is_tuple<IntTuple>::value) {
    static_assert(tuple_size<IntTuple>::value <= Layout<LShape,LStride>::rank);
    return transform_layout(layout, tile, [](auto const& l, auto const& t) { return logical_product(l,t); });
  } else if constexpr (is_underscore<IntTuple>::value) {
    return layout;
  } else if constexpr (is_integral<IntTuple>::value) {
    return logical_product(layout, make_layout(tile));
  }

  CUTE_GCC_UNREACHABLE;
}

//
// Convenience operator
//   that produces layouts like ((BLK_A,BLK_B,...),(a,b,...,x,y))
//   by gathering the block modes and products into a rank-2 result.
//

template <class LShape, class LStride,
          class Tile>
CUTE_HOST_DEVICE constexpr
auto
zipped_product(Layout<LShape,LStride> const& layout,
               Tile                   const& tile)
{
  return tile_unzip(logical_product(layout, tile), tile);
}

// Same as zipped_product, but unpacks the second mode: ((BLK_A,BLK_B,...),a,b,...,x,y)
template <class LShape, class LStride,
          class Tile>
CUTE_HOST_DEVICE constexpr
auto
tiled_product(Layout<LShape,LStride> const& layout,
              Tile                   const& tile)
{
  auto div = zipped_product(layout, tile);

  auto R = rank(tile);
  return div(_, repeat<R>(_));
}

// Attempts to reproduce layout "block" over layout "layout"
// That is, think of every element of "layout" as a "block"
//   and return the layout of the resulting structure
template <class TShape, class TStride,
          class UShape, class UStride>
CUTE_HOST_DEVICE constexpr
auto
blocked_product(Layout<TShape,TStride> const& block,
                Layout<UShape,UStride> const& layout)
{
  constexpr int R = cute::max(rank_v<TShape>, rank_v<UShape>);
  auto padded_block  = append<R>(block);
  auto padded_layout = append<R>(layout);

  auto result = logical_product(padded_block, padded_layout);

  return coalesce(zip(get<0>(result), get<1>(result)), repeat<R>(Int<1>{}));
}

template <class TShape, class TStride,
          class UShape, class UStride>
CUTE_HOST_DEVICE constexpr
auto
raked_product(Layout<TShape,TStride> const& block,
              Layout<UShape,UStride> const& layout)
{
  constexpr int R = cute::max(rank_v<TShape>, rank_v<UShape>);
  auto padded_block  = append<R>(block);
  auto padded_layout = append<R>(layout);

  auto result = logical_product(padded_block, padded_layout);

  return coalesce(zip(get<1>(result), get<0>(result)), repeat<R>(Int<1>{}));
}

template <class Shape, class Stride,
          class TrgShape, class ModeOrder = GenColMajor>
CUTE_HOST_DEVICE constexpr
auto
tile_to_shape(Layout<Shape,Stride> const& layout,
              TrgShape             const& trg_shape,
              ModeOrder            const& ord_shape = {})
{
  CUTE_STATIC_ASSERT_V(rank(layout) <= rank(trg_shape), "Rank of layout must be <= rank of target shape.");
  constexpr int R = rank_v<TrgShape>;

  auto padded_layout = append<R>(layout);

  auto layout_shape = product_each(padded_layout.shape());
  auto target_shape = product_each(trg_shape);

  // Assert proper division
  CUTE_STATIC_ASSERT_V(sum(transform(target_shape, layout_shape, modulus{})) == Int<0>{},
                       "Layout shape does not divide the target shape.");

  auto product_shape = shape_div(target_shape, layout_shape);

  return coalesce(blocked_product(padded_layout, make_ordered_layout(product_shape, ord_shape)), product_shape);
}

//
// Upcast
//   For stride-1 mode, divide size by N. Divide all other strides by N.
//

template <int N, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
upcast(Shape const& shape, Stride const& stride)
{
  if constexpr (is_tuple<Shape>::value) {                  // tuple stride
    return transform_layout(shape, stride, [](auto const& s, auto const& d) { return upcast<N>(s,d); });
  } else if constexpr (is_constant<0, Stride>::value) {    // static-0 stride
    return Layout<Shape,Stride>{shape,stride};
  } else if constexpr (is_static<Stride>::value) {         // static stride
    return make_layout(shape_div(shape,  shape_div(Int<N>{}, abs(stride))),
                       shape_div(stride, Int<N>{}));
  } else {                                                 // dynamic stride
    // assume dynamic strides are larger than N and divisible
    // assert(stride % N == 0);
    return make_layout(shape, safe_div(stride, Int<N>{}));
  }

  CUTE_GCC_UNREACHABLE;
}

template <int N, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
upcast(Layout<Shape,Stride> const& layout)
{
  return upcast<N>(layout.shape(), layout.stride());
}

//
// Downcast
//   For stride-1 mode, multiply size by N. Multiply all other strides by N.
//

template <int N, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
downcast(Shape const& shape, Stride const& stride)
{
  if constexpr (is_tuple<Shape>::value) {
    return transform_layout(shape, stride, [](auto const& s, auto const& d) { return downcast<N>(s,d); });
  } else if constexpr (is_constant<1, Stride>::value || is_constant<-1, Stride>::value) {
    return make_layout(shape * Int<N>{}, stride);
  } else {
    return make_layout(shape, stride * Int<N>{});
  }

  CUTE_GCC_UNREACHABLE;
}

template <int N, class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
downcast(Layout<Shape,Stride> const& layout)
{
  CUTE_STATIC_ASSERT(has_int1<Stride>::value, "Downcast requires adjacent elements");
  return downcast<N>(layout.shape(), layout.stride());
}

//
// Recast
//

template <class OldType, class NewType,
          class Shape, class Stride>
CUTE_HOST_DEVICE constexpr
auto
recast(Layout<Shape,Stride> const& layout)
{
  if constexpr (sizeof(NewType) == sizeof(OldType)) {
    return layout;
  } else if constexpr (sizeof(NewType) > sizeof(OldType)) {
    static_assert(sizeof(NewType) % sizeof(OldType) == 0, "NewType must be a multiple of OldType");
    return upcast<sizeof(NewType)/sizeof(OldType)>(layout);
  } else if constexpr (sizeof(NewType) < sizeof(OldType)) {
    static_assert(sizeof(OldType) % sizeof(NewType) == 0, "NewType must be a divisor of OldType");
    return downcast<sizeof(OldType)/sizeof(NewType)>(layout);
  }

  CUTE_GCC_UNREACHABLE;
}

//
// Display utilities
//

template <class Shape, class Stride>
CUTE_HOST_DEVICE void print(Layout<Shape,Stride> const& layout)
{
  print(layout.shape()); print(":"); print(layout.stride());
}

#if !defined(__CUDACC_RTC__)
template <class Shape, class Stride>
CUTE_HOST std::ostream& operator<<(std::ostream& os, Layout<Shape,Stride> const& layout)
{
  return os << shape(layout) << ":" << stride(layout);
}
#endif

// Generic 2D Layout to console table
template <class Layout>
CUTE_HOST_DEVICE
void
print_layout(Layout const& layout)  // (m,n) -> idx
{
  CUTE_STATIC_ASSERT_V(rank(layout) == Int<2>{});

  int idx_width = num_digits(cosize(layout)) + 2;
  const char* delim = "+-----------------------";

  print(layout); print("\n");

  // Column indices
  print("    ");
  for (int n = 0; n < size<1>(layout); ++n) { printf("  %*d ", idx_width-2, n); }
  printf("\n");

  // Print out A m-by-n
  for (int m = 0; m < size<0>(layout); ++m) {
    // Header
    print("    ");
    for (int n = 0; n < size<1>(layout); ++n) { printf("%.*s", idx_width+1, delim); }
    printf("+\n");
    // Values
    printf("%2d  ", m);  // Row indices
    for (int n = 0; n < size<1>(layout); ++n) { printf("| %*d ", idx_width-2, int(layout(m,n))); }
    printf("|\n");
  }
  // Footer
  print("    ");
  for (int n = 0; n < size<1>(layout); ++n) { printf("%.*s", idx_width+1, delim); }
  printf("+\n");
}

// Generic ThrVal 2D Layout to console table
template <class Layout, class ThrID>
CUTE_HOST_DEVICE
void
print_layout(Layout const& layout, ThrID const& thrid)  // (m,n) -> (tid,vid)  and  tid -> thr_idx
{
  CUTE_STATIC_ASSERT_V(rank(layout) == Int<2>{});

  print(layout); print("\n");
  print(thrid);  print("\n");

  // Print out m-by-n
  for (int m = 0; m < size<0>(layout); ++m) {
    // Header
    for (int n = 0; n < size<1>(layout); ++n) printf("+------");
    printf("+\n");
    // Values
    for (int n = 0; n < size<1>(layout); ++n) printf("|%03d-%02d", int(thrid(layout(m,n) % size(thrid))), int(layout(m,n) / size(thrid)));
    printf("|\n");
  }
  // Footer
  for (int n = 0; n < size<1>(layout); ++n) printf("+------");
  printf("+\n");
}

// Generic 2D Layout to Latex printer -- B&W 8-value color coding
template <class Layout>
CUTE_HOST_DEVICE
void
print_latex(Layout const& layout)  // (m,n) -> idx
{
  CUTE_STATIC_ASSERT_V(rank(layout) == Int<2>{});

  char const* latex_header =
      "\\documentclass[convert]{standalone}\n"
      "\\usepackage{tikz}\n\n"
      "\\begin{document}\n"
      "\\begin{tikzpicture}[x={(0cm,-1cm)},y={(1cm,0cm)},box/.style={rectangle,draw=black,thick,minimum size=1cm,anchor=center,font=\\Large}]\n\n";
  char const* latex_footer =
      "\\end{tikzpicture}\n"
      "\\end{document}\n";

  char const* color_map[8] = {"black!00",
                              "black!40",
                              "black!20",
                              "black!60",
                              "black!10",
                              "black!50",
                              "black!30",
                              "black!70"};

  // Header
  printf("%% Layout: "); print(layout); printf("\n");

  printf(latex_header);

  // Layout
  for (int i = 0; i < size<0>(layout); ++i) {
    for (int j = 0; j < size<1>(layout); ++j) {
      int idx = layout(i,j);

      printf("\\node[box,fill=%s] at (%d,%d) {%d};\n",
             color_map[idx % 8],
             i, j,
             idx);
    }
  }

  // Labels
  for (int i = 0, j = -1; i < size<0>(layout); ++i) {
    printf("\\node at (%d,%d) {\\Large{\\texttt{%d}}};\n", i, j, i);
  }
  for (int j = 0, i = -1; j < size<1>(layout); ++j) {
    printf("\\node at (%d,%d) {\\Large{\\texttt{%d}}};\n", i, j, j);
  }

  // Footer
  printf(latex_footer);
}

// Generic ThrVal 2D Layout to Latex TIKZ -- 8-value color coded by thread
template <class Layout, class ThrID>
CUTE_HOST_DEVICE
void
print_latex(Layout const& layout, ThrID const& thr)  // (m,n) -> (tid,vid)  and  tid -> thr_idx
{
  CUTE_STATIC_ASSERT_V(rank(layout) == Int<2>{});

  char const* latex_header =
      "\\documentclass[convert]{standalone}\n"
      "\\usepackage{tikz}\n\n"
      "\\begin{document}\n"
      "\\begin{tikzpicture}[x={(0cm,-1cm)},y={(1cm,0cm)},box/.style={rectangle,draw=black,thick,minimum size=1cm,anchor=center}]\n\n";
  char const* latex_footer =
      "\\end{tikzpicture}\n"
      "\\end{document}\n";

  char const* color_map[8] = {"{rgb,255:red,175;green,175;blue,255}",
                              "{rgb,255:red,175;green,255;blue,175}",
                              "{rgb,255:red,255;green,255;blue,175}",
                              "{rgb,255:red,255;green,175;blue,175}",
                              "{rgb,255:red,210;green,210;blue,255}",
                              "{rgb,255:red,210;green,255;blue,210}",
                              "{rgb,255:red,255;green,255;blue,210}",
                              "{rgb,255:red,255;green,210;blue,210}"};

  // Header
  printf("%% layout: "); print(layout); printf("\n");
  printf("%% thrid:  "); print(thr);    printf("\n\n");

  printf(latex_header);

  // Layout
  for (int i = 0; i < size<0>(layout); ++i) {
    for (int j = 0; j < size<1>(layout); ++j) {
      int thrid   = layout(i,j) % size(thr);
      int val_idx = layout(i,j) / size(thr);
      int thr_idx = thr(thrid);

      printf("\\node[box,fill=%s] at (%d,%d) {\\shortstack{T%d \\\\ V%d}};\n",
             color_map[thr_idx % 8],
             i, j,
             thr_idx, val_idx);
    }
  }

  // Labels
  for (int i = 0, j = -1; i < size<0>(layout); ++i) {
    printf("\\node at (%d,%d) {\\Large{\\texttt{%d}}};\n", i, j, i);
  }
  for (int j = 0, i = -1; j < size<1>(layout); ++j) {
    printf("\\node at (%d,%d) {\\Large{\\texttt{%d}}};\n", i, j, j);
  }

  // Footer
  printf(latex_footer);
}

} // end namespace cute

//
// Extended Layouts
//

#include <cute/swizzle_layout.hpp>
