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//
 
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// Copyright (c) 2026 Michael Vandeberg
 
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//
 
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
 
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
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//
 
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// Official repository: https://github.com/cppalliance/corosio
 
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//
 
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#ifndef BOOST_COROSIO_LOCAL_STREAM_SOCKET_HPP
 
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#define BOOST_COROSIO_LOCAL_STREAM_SOCKET_HPP
 
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#include <boost/corosio/detail/config.hpp>
 
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#include <boost/corosio/detail/platform.hpp>
 
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#include <boost/corosio/detail/except.hpp>
 
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#include <boost/corosio/detail/native_handle.hpp>
 
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#include <boost/corosio/detail/op_base.hpp>
 
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#include <boost/corosio/io/io_stream.hpp>
 
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#include <boost/capy/io_result.hpp>
 
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#include <boost/corosio/detail/buffer_param.hpp>
 
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#include <boost/corosio/local_endpoint.hpp>
 
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#include <boost/corosio/local_stream.hpp>
 
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#include <boost/corosio/shutdown_type.hpp>
 
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#include <boost/capy/ex/executor_ref.hpp>
 
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#include <boost/capy/ex/execution_context.hpp>
 
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#include <boost/capy/ex/io_env.hpp>
 
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#include <boost/capy/concept/executor.hpp>
 
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#include <system_error>
 
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#include <concepts>
 
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#include <coroutine>
 
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#include <cstddef>
 
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#include <stop_token>
 
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#include <type_traits>
 
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namespace boost::corosio {
 
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/** An asynchronous Unix stream socket for coroutine I/O.
 
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    This class provides asynchronous Unix domain stream socket
 
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    operations that return awaitable types. Each operation
 
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    participates in the affine awaitable protocol, ensuring
 
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    coroutines resume on the correct executor.
 
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    The socket must be opened before performing I/O operations.
 
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    Operations support cancellation through std::stop_token via
 
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    the affine protocol, or explicitly through cancel().
 
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    Satisfies capy::Stream.
 
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    @par Thread Safety
 
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    Distinct objects: Safe.@n
 
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    Shared objects: Unsafe. A socket must not have concurrent
 
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    operations of the same type. One read and one write may be
 
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    in flight simultaneously.
 
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*/
 
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class BOOST_COROSIO_DECL local_stream_socket : public io_stream
 
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{
 
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public:
 
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    using shutdown_type = corosio::shutdown_type;
 
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    using enum corosio::shutdown_type;
 
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    /** Define backend hooks for local stream socket operations.
 
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        Platform backends (epoll, kqueue, select) derive from this
 
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        to implement socket I/O, connection, and option management.
 
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    */
 
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    struct implementation : io_stream::implementation
 
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    {
 
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        virtual std::coroutine_handle<> connect(
 
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            std::coroutine_handle<> h,
 
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            capy::executor_ref ex,
 
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            corosio::local_endpoint ep,
 
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            std::stop_token token,
 
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            std::error_code* ec) = 0;
 
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        virtual std::error_code shutdown(shutdown_type what) noexcept = 0;
 
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        virtual native_handle_type native_handle() const noexcept = 0;
 
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        virtual native_handle_type release_socket() noexcept = 0;
 
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        virtual void cancel() noexcept = 0;
 
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        virtual std::error_code set_option(
 
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            int level,
 
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            int optname,
 
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            void const* data,
 
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            std::size_t size) noexcept = 0;
 
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        virtual std::error_code
 
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        get_option(int level, int optname, void* data, std::size_t* size)
 
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            const noexcept = 0;
 
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        virtual corosio::local_endpoint local_endpoint() const noexcept = 0;
 
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        virtual corosio::local_endpoint remote_endpoint() const noexcept = 0;
 
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    };
 
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    /// Represent the awaitable returned by connect.
 
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    struct connect_awaitable
 
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        : detail::void_op_base<connect_awaitable>
 
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    {
 
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        local_stream_socket& s_;
 
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        corosio::local_endpoint endpoint_;
 
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        connect_awaitable(
 
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            local_stream_socket& s, corosio::local_endpoint ep) noexcept
 
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            : s_(s), endpoint_(ep) {}
 
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        std::coroutine_handle<> dispatch(
 
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            std::coroutine_handle<> h, capy::executor_ref ex) const
 
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        {
 
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            return s_.get().connect(h, ex, endpoint_, token_, &ec_);
 
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        }
 
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    };
 
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public:
 
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    ~local_stream_socket() override;
 
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    explicit local_stream_socket(capy::execution_context& ctx);
 
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    template<class Ex>
 
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        requires(!std::same_as<std::remove_cvref_t<Ex>, local_stream_socket>) &&
 
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        capy::Executor<Ex>
 
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    explicit local_stream_socket(Ex const& ex) : local_stream_socket(ex.context())
 
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    {
 
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    }
 
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    local_stream_socket(local_stream_socket&& other) noexcept
 
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        : io_object(std::move(other))
 
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    {
 
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    }
 
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    local_stream_socket& operator=(local_stream_socket&& other) noexcept
 
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    {
 
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        if (this != &other)
 
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        {
 
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            close();
 
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            io_object::operator=(std::move(other));
 
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        }
 
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        return *this;
 
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    }
 
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    local_stream_socket(local_stream_socket const&)            = delete;
 
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    local_stream_socket& operator=(local_stream_socket const&) = delete;
 
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    /** Open the socket.
 
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        Creates a Unix stream socket and associates it with
 
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        the platform reactor.
 
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        @param proto The protocol. Defaults to local_stream{}.
 
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        @throws std::system_error on failure.
 
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    */
 
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    void open(local_stream proto = {});
 
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    /// Close the socket.
 
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    void close();
 
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    /// Check if the socket is open.
 
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    bool is_open() const noexcept
 
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    {
 
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        return h_ && get().native_handle() >= 0;
 
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    }
 
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    /** Initiate an asynchronous connect operation.
 
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        If the socket is not already open, it is opened automatically.
 
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        @param ep The peer endpoint (path) to connect to.
 
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        @par Cancellation
 
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        Supports cancellation via the awaitable's stop_token or by
 
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        calling @ref cancel. On cancellation, yields
 
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        `errc::operation_canceled`.
 
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        @return An awaitable that completes with io_result<>.
 
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        @throws std::system_error if the socket needs to be opened
 
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            and the open fails.
 
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    */
 
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    auto connect(corosio::local_endpoint ep)
 
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    {
 
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        if (!is_open())
 
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            open();
 
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        return connect_awaitable(*this, ep);
 
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    }
 
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    void cancel();
 
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    native_handle_type native_handle() const noexcept;
 
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    /** Query the number of bytes available for reading.
 
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        @return The number of bytes that can be read without blocking.
 
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        @throws std::logic_error if the socket is not open.
 
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        @throws std::system_error on ioctl failure.
 
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    */
 
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    std::size_t available() const;
 
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    /** Release ownership of the native socket handle.
 
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        Deregisters the socket from the reactor and cancels pending
 
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        operations without closing the fd. The caller takes ownership
 
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        of the returned descriptor.
 
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        @return The native handle.
 
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        @throws std::logic_error if the socket is not open.
 
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    */
 
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    native_handle_type release();
 
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    /** Shut down part or all of the socket (best-effort).
 
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        Unix stream sockets are full-duplex: each direction (send and
 
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        receive) operates independently. This function allows you to
 
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        close one or both directions without destroying the socket.
 
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        @li @ref shutdown_send signals end-of-stream to the peer: their
 
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            subsequent reads will complete with `capy::cond::eof` after
 
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            they drain any data already in flight. You can still
 
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            receive data from the peer until they also close their
 
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            send direction. This is the cleanest way to end a session
 
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            — preferable to @ref close() because it gives the peer an
 
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            explicit EOF rather than tearing the socket down abruptly.
 
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        @li @ref shutdown_receive disables reading on the socket. The
 
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            peer is not informed and may continue sending; data
 
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            already buffered or arriving later is discarded.
 
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        @li @ref shutdown_both combines both effects.
 
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        When the peer shuts down their send direction, subsequent read
 
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        operations on this socket complete with `capy::cond::eof`. Use
 
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        the portable condition test rather than comparing error codes
 
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        directly:
 
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        @code
 
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        auto [ec, n] = co_await sock.read_some(buffer);
 
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        if (ec == capy::cond::eof)
 
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        {
 
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            // Peer closed their send direction
 
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        }
 
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        @endcode
 
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        Calls `::shutdown` on the underlying descriptor when open.
 
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        Errors from the syscall (such as `ENOTCONN` on a peer that
 
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        already closed) are swallowed because they are typically
 
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        unhelpful at this layer; if the socket is not open, the call
 
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        is a no-op. To observe errors, use the
 
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        @ref shutdown(shutdown_type,std::error_code&) overload.
 
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        @param what Which direction to shut down.
 
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    */
 
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    void shutdown(shutdown_type what);
 
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    /** Shut down part or all of the socket (non-throwing).
 
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        Same semantics as @ref shutdown(shutdown_type) but reports
 
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        syscall errors via @p ec instead of swallowing them.
 
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        @param what Which direction to shut down.
 
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        @param ec Set to the error code on failure.
 
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    */
 
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    void shutdown(shutdown_type what, std::error_code& ec) noexcept;
 
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    template<class Option>
 
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    void set_option(Option const& opt)
 
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    {
 
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        if (!is_open())
 
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            detail::throw_logic_error("set_option: socket not open");
 
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        std::error_code ec = get().set_option(
 
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            Option::level(), Option::name(), opt.data(), opt.size());
 
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        if (ec)
 
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            detail::throw_system_error(ec, "local_stream_socket::set_option");
 
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    }
 
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    template<class Option>
 
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    Option get_option() const
 
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    {
 
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        if (!is_open())
 
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            detail::throw_logic_error("get_option: socket not open");
 
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        Option opt{};
 
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        std::size_t sz = opt.size();
 
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        std::error_code ec =
 
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            get().get_option(Option::level(), Option::name(), opt.data(), &sz);
 
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        if (ec)
 
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            detail::throw_system_error(ec, "local_stream_socket::get_option");
 
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        opt.resize(sz);
 
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        return opt;
 
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    }
 
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    /** Assign an existing file descriptor to this socket.
 
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        The fd is adopted and registered with the platform reactor.
 
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        Used by @ref make_local_stream_pair to wrap `socketpair`
 
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        fds.
 
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        @param fd The file descriptor to adopt. Must be a valid,
 
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            open Unix domain stream socket.
 
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        @par Preconditions
 
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        The socket must not already be open.
 
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        @throws std::logic_error if the precondition is violated
 
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            (the socket is already open).
 
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        @throws std::system_error on any other failure (e.g. the
 
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            fd is not a Unix domain stream socket, or backend
 
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            configuration fails).
 
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    */
 
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    void assign(int fd);
 
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    corosio::local_endpoint local_endpoint() const noexcept;
 
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    corosio::local_endpoint remote_endpoint() const noexcept;
 
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protected:
 
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    local_stream_socket() noexcept = default;
 
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324 + 
    explicit local_stream_socket(handle h) noexcept : io_object(std::move(h)) {}
 
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326 + 
private:
 
327 + 
    friend class local_stream_acceptor;
 
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329 + 
    void open_for_family(int family, int type, int protocol);
 
330 +
 
331 + 
    inline implementation& get() const noexcept
 
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    {
 
333 + 
        return *static_cast<implementation*>(h_.get());
 
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    }
 
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};
 
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} // namespace boost::corosio
 
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#endif // BOOST_COROSIO_LOCAL_STREAM_SOCKET_HPP