#pragma once

#include <arpa/inet.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <unistd.h>
#include <fcntl.h>

#include <variant>

#include "poller.hpp"
#include "corochain.hpp"

namespace NNet
{

class TAddress
{
public:
    TAddress(const std::string& addr, int port);
    TAddress(sockaddr_in addr);
    TAddress(sockaddr_in6 addr);
    TAddress(sockaddr* addr, socklen_t len);
    TAddress() = default;

    const std::variant<sockaddr_in, sockaddr_in6>& Addr() const;
    std::pair<const sockaddr*, int> RawAddr() const;
    bool operator==(const TAddress& other) const;
    int Domain() const;
    TAddress WithPort(int port) const;

    std::string ToString() const;

private:
    std::variant<sockaddr_in, sockaddr_in6> Addr_ = {};
};

class TSocketOps
{
public:
    TSocketOps(TPollerBase& poller, int domain, int type);
    TSocketOps(int fd, TPollerBase& poller);
    TSocketOps() = default;

    TPollerBase* Poller()
    {
        return Poller_;
    }

protected:
    int Create(int domain, int type);
    int Setup(int s);

    TPollerBase* Poller_ = nullptr;
    int Fd_ = -1;
};

template <typename TSockOps>
class TSocketBase : public TSocketOps
{
public:
    TSocketBase(TPollerBase& poller, int domain, int type) : TSocketOps(poller, domain, type)
    {
    }

    TSocketBase(int fd, TPollerBase& poller) : TSocketOps(fd, poller)
    {
    }

    TSocketBase() = default;

    auto ReadSome(void* buf, size_t size)
    {
        struct TAwaitableRead : public TAwaitable<TAwaitableRead>
        {
            void run()
            {
                this->ret = static_cast<int>(TSockOps::read(this->fd, this->b, this->s));
            }

            void await_suspend(std::coroutine_handle<> h)
            {
                this->poller->AddRead(this->fd, h);
            }
        };
        return TAwaitableRead{Poller_, Fd_, buf, size, 0, false};
    }

    // force read on next loop iteration
    auto ReadSomeYield(void* buf, size_t size)
    {
        struct TAwaitableRead : public TAwaitable<TAwaitableRead>
        {
            bool await_ready()
            {
                return (this->ready = false);
            }

            void run()
            {
                this->ret = TSockOps::read(this->fd, this->b, this->s);
            }

            void await_suspend(std::coroutine_handle<> h)
            {
                this->poller->AddRead(this->fd, h);
            }
        };
        return TAwaitableRead{Poller_, Fd_, buf, size, 0, false};
    }

    auto WriteSome(const void* buf, size_t size)
    {
        struct TAwaitableWrite : public TAwaitable<TAwaitableWrite>
        {
            void run()
            {
                this->ret = static_cast<int>(TSockOps::write(this->fd, this->b, this->s));
            }

            void await_suspend(std::coroutine_handle<> h)
            {
                this->poller->AddWrite(this->fd, h);
            }
        };
        return TAwaitableWrite{Poller_, Fd_, const_cast<void*>(buf), size, 0, false};
    }

    auto WriteSomeYield(const void* buf, size_t size)
    {
        struct TAwaitableWrite : public TAwaitable<TAwaitableWrite>
        {
            bool await_ready()
            {
                return (this->ready = false);
            }

            void run()
            {
                this->ret = TSockOps::write(this->fd, this->b, this->s);
            }

            void await_suspend(std::coroutine_handle<> h)
            {
                this->poller->AddWrite(this->fd, h);
            }
        };
        return TAwaitableWrite{Poller_, Fd_, const_cast<void*>(buf), size, 0, false};
    }

protected:
    template <typename T>
    struct TAwaitable
    {
        bool await_ready()
        {
            SafeRun();
            return (ready = (ret >= 0));
        }

        int await_resume()
        {
            if (!ready)
            {
                SafeRun();
            }
            return ret;
        }

        void SafeRun()
        {
            ((T*)this)->run();
            if (ret < 0 && !(errno == EINTR || errno == EAGAIN || errno == EINPROGRESS))
            {
                throw std::system_error(errno, std::generic_category());
            }
        }

        TPollerBase* poller;
        int fd;
        void* b;
        size_t s;
        int ret;
        bool ready;
    };
};

class TFileOps
{
public:
    static auto read(int fd, void* buf, size_t count)
    {
        return ::read(fd, buf, count);
    }

    static auto write(int fd, const void* buf, size_t count)
    {
        return ::write(fd, buf, count);
    }
};

class TFileHandle : public TSocketBase<TFileOps>
{
public:
    TFileHandle(int fd, TPollerBase& poller) : TSocketBase(fd, poller)
    {
    }

    TFileHandle() = default;
};

class TSockOps
{
public:
    static auto read(int fd, void* buf, size_t count)
    {
        return ::recv(fd, buf, count, 0);
    }

    static auto write(int fd, const void* buf, size_t count)
    {
        return ::send(fd, buf, count, 0);
    }
};

class TSocket : public TSocketBase<TSockOps>
{
public:
    using TPoller = TPollerBase;

    TSocket(TAddress&& addr, TPollerBase& poller, int type = SOCK_STREAM);
    TSocket(const TAddress& addr, int fd, TPollerBase& poller);
    TSocket(const TAddress& addr, TPollerBase& poller, int type = SOCK_STREAM);
    TSocket(TSocket&& other);
    ~TSocket();

    TSocket() = default;
    TSocket(const TSocket& other) = delete;
    TSocket& operator=(TSocket& other) const = delete;

    TSocket& operator=(TSocket&& other);

    TValueTask<void> Close();

    auto Connect(TTime deadline = TTime::max())
    {
        struct TAwaitable
        {
            bool await_ready()
            {
                int ret = connect(fd, addr.first, addr.second);
                if (ret < 0 && !(errno == EINTR || errno == EAGAIN || errno == EINPROGRESS))
                {
                    throw std::system_error(errno, std::generic_category(), "connect");
                }
                return ret >= 0;
            }

            void await_suspend(std::coroutine_handle<> h)
            {
                poller->AddWrite(fd, h);
                if (deadline != TTime::max())
                {
                    poller->AddTimer(fd, deadline, h);
                }
            }

            void await_resume()
            {
                if (deadline != TTime::max() && poller->RemoveTimer(fd, deadline))
                {
                    throw std::system_error(std::make_error_code(std::errc::timed_out));
                }
            }

            TPollerBase* poller;
            int fd;
            std::pair<const sockaddr*, int> addr;
            TTime deadline;
        };
        return TAwaitable{Poller_, Fd_, Addr_.RawAddr(), deadline};
    }

    auto Accept()
    {
        struct TAwaitable
        {
            bool await_ready() const
            {
                return false;
            }
            void await_suspend(std::coroutine_handle<> h)
            {
                poller->AddRead(fd, h);
            }
            TSocket await_resume()
            {
                char clientaddr[sizeof(sockaddr_in6)];
                socklen_t len = sizeof(sockaddr_in6);

                int clientfd = accept(fd, reinterpret_cast<sockaddr*>(&clientaddr[0]), &len);
                if (clientfd < 0)
                {
                    throw std::system_error(errno, std::generic_category(), "accept");
                }

                return TSocket{
                    TAddress{reinterpret_cast<sockaddr*>(&clientaddr[0]), len}, clientfd, *poller};
            }

            TPollerBase* poller;
            int fd;
        };

        return TAwaitable{Poller_, Fd_};
    }

    void Bind();
    void Listen(int backlog = 128);
    const TAddress& Addr() const;
    int Fd() const;

protected:
    TAddress Addr_;
};

} // namespace NNet