//
// impl/buffered_read_stream.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef BOOST_ASIO_IMPL_BUFFERED_READ_STREAM_HPP
#define BOOST_ASIO_IMPL_BUFFERED_READ_STREAM_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include <boost/asio/associator.hpp>
#include <boost/asio/detail/handler_cont_helpers.hpp>
#include <boost/asio/detail/handler_type_requirements.hpp>
#include <boost/asio/detail/non_const_lvalue.hpp>
#include <boost/asio/detail/type_traits.hpp>

#include <boost/asio/detail/push_options.hpp>

namespace boost {
namespace asio {

template <typename Stream>
std::size_t buffered_read_stream<Stream>::fill()
{
  detail::buffer_resize_guard<detail::buffered_stream_storage>
    resize_guard(storage_);
  std::size_t previous_size = storage_.size();
  storage_.resize(storage_.capacity());
  storage_.resize(previous_size + next_layer_.read_some(buffer(
          storage_.data() + previous_size,
          storage_.size() - previous_size)));
  resize_guard.commit();
  return storage_.size() - previous_size;
}

template <typename Stream>
std::size_t buffered_read_stream<Stream>::fill(boost::system::error_code& ec)
{
  detail::buffer_resize_guard<detail::buffered_stream_storage>
    resize_guard(storage_);
  std::size_t previous_size = storage_.size();
  storage_.resize(storage_.capacity());
  storage_.resize(previous_size + next_layer_.read_some(buffer(
          storage_.data() + previous_size,
          storage_.size() - previous_size),
        ec));
  resize_guard.commit();
  return storage_.size() - previous_size;
}

namespace detail
{
  template <typename ReadHandler>
  class buffered_fill_handler
  {
  public:
    buffered_fill_handler(detail::buffered_stream_storage& storage,
        std::size_t previous_size, ReadHandler& handler)
      : storage_(storage),
        previous_size_(previous_size),
        handler_(static_cast<ReadHandler&&>(handler))
    {
    }

    buffered_fill_handler(const buffered_fill_handler& other)
      : storage_(other.storage_),
        previous_size_(other.previous_size_),
        handler_(other.handler_)
    {
    }

    buffered_fill_handler(buffered_fill_handler&& other)
      : storage_(other.storage_),
        previous_size_(other.previous_size_),
        handler_(static_cast<ReadHandler&&>(other.handler_))
    {
    }

    void operator()(const boost::system::error_code& ec,
        const std::size_t bytes_transferred)
    {
      storage_.resize(previous_size_ + bytes_transferred);
      static_cast<ReadHandler&&>(handler_)(ec, bytes_transferred);
    }

  //private:
    detail::buffered_stream_storage& storage_;
    std::size_t previous_size_;
    ReadHandler handler_;
  };

  template <typename ReadHandler>
  inline bool asio_handler_is_continuation(
      buffered_fill_handler<ReadHandler>* this_handler)
  {
    return boost_asio_handler_cont_helpers::is_continuation(
          this_handler->handler_);
  }

  template <typename Stream>
  class initiate_async_buffered_fill
  {
  public:
    typedef typename remove_reference_t<
      Stream>::lowest_layer_type::executor_type executor_type;

    explicit initiate_async_buffered_fill(
        remove_reference_t<Stream>& next_layer)
      : next_layer_(next_layer)
    {
    }

    executor_type get_executor() const noexcept
    {
      return next_layer_.lowest_layer().get_executor();
    }

    template <typename ReadHandler>
    void operator()(ReadHandler&& handler,
        buffered_stream_storage* storage) const
    {
      // If you get an error on the following line it means that your handler
      // does not meet the documented type requirements for a ReadHandler.
      BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;

      non_const_lvalue<ReadHandler> handler2(handler);
      std::size_t previous_size = storage->size();
      storage->resize(storage->capacity());
      next_layer_.async_read_some(
          buffer(
            storage->data() + previous_size,
            storage->size() - previous_size),
          buffered_fill_handler<decay_t<ReadHandler>>(
            *storage, previous_size, handler2.value));
    }

  private:
    remove_reference_t<Stream>& next_layer_;
  };
} // namespace detail

#if !defined(GENERATING_DOCUMENTATION)

template <template <typename, typename> class Associator,
    typename ReadHandler, typename DefaultCandidate>
struct associator<Associator,
    detail::buffered_fill_handler<ReadHandler>,
    DefaultCandidate>
  : Associator<ReadHandler, DefaultCandidate>
{
  static typename Associator<ReadHandler, DefaultCandidate>::type get(
      const detail::buffered_fill_handler<ReadHandler>& h) noexcept
  {
    return Associator<ReadHandler, DefaultCandidate>::get(h.handler_);
  }

  static auto get(const detail::buffered_fill_handler<ReadHandler>& h,
      const DefaultCandidate& c) noexcept
    -> decltype(Associator<ReadHandler, DefaultCandidate>::get(h.handler_, c))
  {
    return Associator<ReadHandler, DefaultCandidate>::get(h.handler_, c);
  }
};

#endif // !defined(GENERATING_DOCUMENTATION)

template <typename Stream>
template <
    BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
      std::size_t)) ReadHandler>
inline auto buffered_read_stream<Stream>::async_fill(ReadHandler&& handler)
  -> decltype(
    async_initiate<ReadHandler,
      void (boost::system::error_code, std::size_t)>(
        declval<detail::initiate_async_buffered_fill<Stream>>(),
        handler, declval<detail::buffered_stream_storage*>()))
{
  return async_initiate<ReadHandler,
    void (boost::system::error_code, std::size_t)>(
      detail::initiate_async_buffered_fill<Stream>(next_layer_),
      handler, &storage_);
}

template <typename Stream>
template <typename MutableBufferSequence>
std::size_t buffered_read_stream<Stream>::read_some(
    const MutableBufferSequence& buffers)
{
  using boost::asio::buffer_size;
  if (buffer_size(buffers) == 0)
    return 0;

  if (storage_.empty())
    this->fill();

  return this->copy(buffers);
}

template <typename Stream>
template <typename MutableBufferSequence>
std::size_t buffered_read_stream<Stream>::read_some(
    const MutableBufferSequence& buffers, boost::system::error_code& ec)
{
  ec = boost::system::error_code();

  using boost::asio::buffer_size;
  if (buffer_size(buffers) == 0)
    return 0;

  if (storage_.empty() && !this->fill(ec))
    return 0;

  return this->copy(buffers);
}

namespace detail
{
  template <typename MutableBufferSequence, typename ReadHandler>
  class buffered_read_some_handler
  {
  public:
    buffered_read_some_handler(detail::buffered_stream_storage& storage,
        const MutableBufferSequence& buffers, ReadHandler& handler)
      : storage_(storage),
        buffers_(buffers),
        handler_(static_cast<ReadHandler&&>(handler))
    {
    }

    buffered_read_some_handler(const buffered_read_some_handler& other)
      : storage_(other.storage_),
        buffers_(other.buffers_),
        handler_(other.handler_)
    {
    }

    buffered_read_some_handler(buffered_read_some_handler&& other)
      : storage_(other.storage_),
        buffers_(other.buffers_),
        handler_(static_cast<ReadHandler&&>(other.handler_))
    {
    }

    void operator()(const boost::system::error_code& ec, std::size_t)
    {
      if (ec || storage_.empty())
      {
        const std::size_t length = 0;
        static_cast<ReadHandler&&>(handler_)(ec, length);
      }
      else
      {
        const std::size_t bytes_copied = boost::asio::buffer_copy(
            buffers_, storage_.data(), storage_.size());
        storage_.consume(bytes_copied);
        static_cast<ReadHandler&&>(handler_)(ec, bytes_copied);
      }
    }

  //private:
    detail::buffered_stream_storage& storage_;
    MutableBufferSequence buffers_;
    ReadHandler handler_;
  };

  template <typename MutableBufferSequence, typename ReadHandler>
  inline bool asio_handler_is_continuation(
      buffered_read_some_handler<
        MutableBufferSequence, ReadHandler>* this_handler)
  {
    return boost_asio_handler_cont_helpers::is_continuation(
          this_handler->handler_);
  }

  template <typename Stream>
  class initiate_async_buffered_read_some
  {
  public:
    typedef typename remove_reference_t<
      Stream>::lowest_layer_type::executor_type executor_type;

    explicit initiate_async_buffered_read_some(
        remove_reference_t<Stream>& next_layer)
      : next_layer_(next_layer)
    {
    }

    executor_type get_executor() const noexcept
    {
      return next_layer_.lowest_layer().get_executor();
    }

    template <typename ReadHandler, typename MutableBufferSequence>
    void operator()(ReadHandler&& handler,
        buffered_stream_storage* storage,
        const MutableBufferSequence& buffers) const
    {
      // If you get an error on the following line it means that your handler
      // does not meet the documented type requirements for a ReadHandler.
      BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;

      using boost::asio::buffer_size;
      non_const_lvalue<ReadHandler> handler2(handler);
      if (buffer_size(buffers) == 0 || !storage->empty())
      {
        next_layer_.async_read_some(mutable_buffer(0, 0),
            buffered_read_some_handler<MutableBufferSequence,
              decay_t<ReadHandler>>(
                *storage, buffers, handler2.value));
      }
      else
      {
        initiate_async_buffered_fill<Stream>(this->next_layer_)(
            buffered_read_some_handler<MutableBufferSequence,
              decay_t<ReadHandler>>(
                *storage, buffers, handler2.value),
            storage);
      }
    }

  private:
    remove_reference_t<Stream>& next_layer_;
  };
} // namespace detail

#if !defined(GENERATING_DOCUMENTATION)

template <template <typename, typename> class Associator,
    typename MutableBufferSequence, typename ReadHandler,
    typename DefaultCandidate>
struct associator<Associator,
    detail::buffered_read_some_handler<MutableBufferSequence, ReadHandler>,
    DefaultCandidate>
  : Associator<ReadHandler, DefaultCandidate>
{
  static typename Associator<ReadHandler, DefaultCandidate>::type get(
      const detail::buffered_read_some_handler<
        MutableBufferSequence, ReadHandler>& h) noexcept
  {
    return Associator<ReadHandler, DefaultCandidate>::get(h.handler_);
  }

  static auto get(
      const detail::buffered_read_some_handler<
        MutableBufferSequence, ReadHandler>& h,
      const DefaultCandidate& c) noexcept
    -> decltype(Associator<ReadHandler, DefaultCandidate>::get(h.handler_, c))
  {
    return Associator<ReadHandler, DefaultCandidate>::get(h.handler_, c);
  }
};

#endif // !defined(GENERATING_DOCUMENTATION)

template <typename Stream>
template <typename MutableBufferSequence,
    BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
      std::size_t)) ReadHandler>
inline auto buffered_read_stream<Stream>::async_read_some(
    const MutableBufferSequence& buffers, ReadHandler&& handler)
  -> decltype(
    async_initiate<ReadHandler,
      void (boost::system::error_code, std::size_t)>(
        declval<detail::initiate_async_buffered_read_some<Stream>>(),
        handler, declval<detail::buffered_stream_storage*>(), buffers))
{
  return async_initiate<ReadHandler,
    void (boost::system::error_code, std::size_t)>(
      detail::initiate_async_buffered_read_some<Stream>(next_layer_),
      handler, &storage_, buffers);
}

template <typename Stream>
template <typename MutableBufferSequence>
std::size_t buffered_read_stream<Stream>::peek(
    const MutableBufferSequence& buffers)
{
  if (storage_.empty())
    this->fill();
  return this->peek_copy(buffers);
}

template <typename Stream>
template <typename MutableBufferSequence>
std::size_t buffered_read_stream<Stream>::peek(
    const MutableBufferSequence& buffers, boost::system::error_code& ec)
{
  ec = boost::system::error_code();
  if (storage_.empty() && !this->fill(ec))
    return 0;
  return this->peek_copy(buffers);
}

} // namespace asio
} // namespace boost

#include <boost/asio/detail/pop_options.hpp>

#endif // BOOST_ASIO_IMPL_BUFFERED_READ_STREAM_HPP
