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#pragma once

#include "hytlass/detail/dependent_false.hpp"
#include "hytlass/epilogue/fusion/operations.hpp"

/////////////////////////////////////////////////////////////////////////////////////////////////

namespace hytlass::epilogue::fusion {

/////////////////////////////////////////////////////////////////////////////////////////////////

// Dispatch interface for epilogue fusion callbacks
// For visitor fusions, this is just a convenience wrapper to provide metadata and non-nested args.
// It is also valid to just pass visitor callbacks directly to the collective
// provided the collective supports a visitor callbacks interface. This is useful for implementing custom fusions.
template <
  class DispatchPolicy,  // specialize on collective's dispatch policy since callbacks API will depend on collective's algorithm
  class Operation,       // the fusion operation being performed, e.g. fusion::LinearCombination
  class CtaTile_MNK,     // computed tile per CTA
  class EpilogueTile_MN, // epilogue subtile size
  class... Args          // callbacks implementation dependent args (e.g. copy atoms, smem layouts)
>
struct FusionCallbacks {
  static_assert(hytlass::detail::dependent_false<DispatchPolicy, Operation>, "Could not find a callbacks specialization.");
};

// Metadata helper to handle custom EVTs or other non-FusionCallbacks types
template <class T>
struct FusionCallbacksTraits {
  using DispatchPolicy = void;
  using Operation = T;
  using CtaTile_MNK = void;
  using EpilogueTile_MN = void;
  using ElementCompute = void;
};

template <
  class DispatchPolicy_,
  class Operation_,
  class CtaTile_MNK_,
  class EpilogueTile_MN_,
  class... Args
>
struct FusionCallbacksTraits<
  FusionCallbacks<DispatchPolicy_, Operation_, CtaTile_MNK_, EpilogueTile_MN_, Args...>
> {
  using DispatchPolicy = DispatchPolicy_;
  using Operation = Operation_;
  using CtaTile_MNK = CtaTile_MNK_;
  using EpilogueTile_MN = EpilogueTile_MN_;
  using ElementCompute = typename Operation::ElementCompute;
};

/////////////////////////////////////////////////////////////////////////////////////////////////

} // namespace hytlass::epilogue::fusion

/////////////////////////////////////////////////////////////////////////////////////////////////
