#pragma once
// Copyright (c) 2018-present, Facebook, Inc.
//
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.

#include "../piping.h"
#include "extension_operators.h"

namespace pushmi {

namespace detail {

struct switch_on_error_fn {
private:
  template <class ErrorSelector>
  struct on_error_impl {
    ErrorSelector es_;
    PUSHMI_TEMPLATE (class Out, class E)
      (requires Receiver<Out> && Invocable<const ErrorSelector&, E> && SenderTo<pushmi::invoke_result_t<ErrorSelector&, E>, Out>)
    void operator()(Out& out, E&& e) const noexcept {
      static_assert(::pushmi::NothrowInvocable<const ErrorSelector&, E>,
        "switch_on_error - error selector function must be noexcept");
      auto next = es_((E&&) e);
      ::pushmi::submit(next, out);
    }
  };
  template <class In, class ErrorSelector>
  struct out_impl {
    ErrorSelector es_;
    PUSHMI_TEMPLATE (class Out)
      (requires Receiver<Out>)
    auto operator()(Out out) const {
      return ::pushmi::detail::receiver_from_fn<In>()(
        std::move(out),
        // copy 'es' to allow multiple calls to submit
        ::pushmi::on_error(on_error_impl<ErrorSelector>{es_})
      );
    }
  };
  template <class ErrorSelector>
  struct in_impl {
    ErrorSelector es_;
    PUSHMI_TEMPLATE (class In)
      (requires Sender<In>)
    auto operator()(In in) const {
      return ::pushmi::detail::sender_from(
        std::move(in),
        ::pushmi::detail::submit_transform_out<In>(
          out_impl<In, ErrorSelector>{es_}
        )
      );
    }
  };
public:
  PUSHMI_TEMPLATE(class ErrorSelector)
    (requires SemiMovable<ErrorSelector>)
  auto operator()(ErrorSelector es) const {
    return in_impl<ErrorSelector>{std::move(es)};
  }
};

} // namespace detail

namespace operators {
PUSHMI_INLINE_VAR constexpr detail::switch_on_error_fn switch_on_error{};
} // namespace operators

} // namespace pushmi
