xbot/irc_coroutine.hpp

#pragma once

#include "connection.hpp"

#include <coroutine>
#include <vector>

struct irc_promise;

struct irc_coroutine : std::coroutine_handle<irc_promise> {
    using promise_type = irc_promise;

    auto start(Connection &connection) -> void;
    auto is_running() -> bool;
    auto exception() -> std::exception_ptr;
};

struct irc_promise
{
    // Pointer to the connection while running. Cleared on termination.
    std::shared_ptr<Connection> connection_;

    // Pointer to exception that terminated this coroutine if there is one.
    std::exception_ptr exception_;

    irc_coroutine get_return_object()
    {
        return {irc_coroutine::from_promise(*this)};
    }

    // Suspend waiting for start() to initialize connection_
    std::suspend_always initial_suspend() noexcept { return {}; }

    // Suspend so that is_running() and exception() work
    std::suspend_always final_suspend() noexcept { return {}; }

    // Normal termination
    void return_void() {
        connection_.reset();
    }

    // Abnormal termination - remember the exception
    void unhandled_exception() {
        connection_.reset();
        exception_ = std::current_exception();
    }
};

/*
struct wait_ircmsg {
    using result_type = std::pair<IrcCommand, const IrcMsg &>
    std::vector<IrcCommand> want_cmds_;
};

struct wait_timeout {
    struct result_type {};
    std::vector<IrcCommand> want_cmds_;
};

*/

class wait_command {
    std::vector<IrcCommand> want_cmds_;

    IrcCommand resultCmd;
    const IrcMsg *resultMsg;

    boost::signals2::scoped_connection ircmsg_connection_;
    boost::signals2::scoped_connection disconnect_connection_;

    void unsubscribe() {
        ircmsg_connection_.disconnect();
        disconnect_connection_.disconnect();
    }

public:
    wait_command(std::initializer_list<IrcCommand> want_cmds)
        : want_cmds_(want_cmds)
        , resultMsg{}
        {}

    /// The coroutine always needs to wait for a message. It will never
    /// be ready immediately.
    bool await_ready() noexcept { return false; }

    /// Install event handles in the connection that will resume this coroutine.
    void await_suspend(std::coroutine_handle<irc_promise> handle);

    auto await_resume() -> std::pair<IrcCommand, const IrcMsg &> {
        if (resultMsg) {
            return std::make_pair(resultCmd, std::cref(*resultMsg));
        } else {
            throw std::runtime_error{"connection terminated"};
        }
    }
};