int fcntl(int fd, int cmd, ... /* arg */ );

void SetNonBlock(int fd)
{
    int fl = fcntl(fd, F_GETFL);
    if (fl < 0)
    {
        perror("fcntl");
        return;
    }
    fcntl(fd, F_SETFL, fl | O_NONBLOCK);
    cout << " set " << fd << " nonblock done" << endl;
}

int main()
{
    char buffer[1024];
    SetNonBlock(0);
    sleep(1);
    while (true)
    {
        // printf("Please Enter# ");
        // fflush(stdout);

        ssize_t n = read(0, buffer, sizeof(buffer) - 1);
        if (n > 0)
        {
            buffer[n - 1] = 0;
            cout << "echo : " << buffer << endl;
        }
        else if (n == 0)
        {
            cout << "read done" << endl;
            break;
        }
        else
        {
            // 1. 設(shè)置成為非阻塞，如果底層fd數(shù)據(jù)沒(méi)有就緒，recv/read/write/send, 返回值會(huì)以出錯(cuò)的形式返回
            // 2. a. 真的出錯(cuò) b. 底層沒(méi)有就緒
            // 3. 我怎么區(qū)分呢？通過(guò)errno區(qū)分！?。?
            if (errno == EWOULDBLOCK)
            {
                cout << "0 fd data not ready, try again!" << endl;
                // do_other_thing();
                sleep(1);
            }
            else
            {
                cerr << "read error, n = " << n << "errno code: "
                     << errno << ", error str: " << strerror(errno) << endl;
            }
            // TODO 信號(hào)中斷IO？
        }
    }

    return 0;
}

int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout); 

void FD_CLR(int fd, fd_set *set); // 用來(lái)清除描述詞組set中相關(guān)fd的位
int FD_ISSET(int fd, fd_set *set); // 用來(lái)測(cè)試描述詞組set中相關(guān)fd的位是否為真
void FD_SET(int fd, fd_set *set); // 用來(lái)設(shè)置描述詞組set中相關(guān)fd的位
void FD_ZERO(fd_set *set); // 用來(lái)清除描述詞組set的全部位

#pragma once

#include <iostream>
#include <string>
#include <unistd.h>
#include <cstring>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include "Log.hpp"

enum
{
    SocketErr = 2,
    BindErr,
    ListenErr,
};

// TODO
const int backlog = 10;

class Sock
{
public:
    Sock()
    {
    }
    ~Sock()
    {
    }

public:
    void Socket()
    {
        sockfd_ = socket(AF_INET, SOCK_STREAM, 0);
        if (sockfd_ < 0)
        {
            lg(Fatal, "socker error, %s: %d", strerror(errno), errno);
            exit(SocketErr);
        }
        int opt = 1;
        setsockopt(sockfd_, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt));
    }
    void Bind(uint16_t port)
    {
        struct sockaddr_in local;
        memset(&local, 0, sizeof(local));
        local.sin_family = AF_INET;
        local.sin_port = htons(port);
        local.sin_addr.s_addr = INADDR_ANY;

        if (bind(sockfd_, (struct sockaddr *)&local, sizeof(local)) < 0)
        {
            lg(Fatal, "bind error, %s: %d", strerror(errno), errno);
            exit(BindErr);
        }
    }
    void Listen()
    {
        if (listen(sockfd_, backlog) < 0)
        {
            lg(Fatal, "listen error, %s: %d", strerror(errno), errno);
            exit(ListenErr);
        }
    }
    int Accept(std::string *clientip, uint16_t *clientport)
    {
        struct sockaddr_in peer;
        socklen_t len = sizeof(peer);
        int newfd = accept(sockfd_, (struct sockaddr*)&peer, &len);
        if(newfd < 0)
        {
            lg(Warning, "accept error, %s: %d", strerror(errno), errno);
            return -1;
        }
        char ipstr[64];
        inet_ntop(AF_INET, &peer.sin_addr, ipstr, sizeof(ipstr));
        *clientip = ipstr;
        *clientport = ntohs(peer.sin_port);

        return newfd;
    }
    bool Connect(const std::string &ip, const uint16_t &port)
    {
        struct sockaddr_in peer;
        memset(&peer, 0, sizeof(peer));
        peer.sin_family = AF_INET;
        peer.sin_port = htons(port);
        inet_pton(AF_INET, ip.c_str(), &(peer.sin_addr));

        int n = connect(sockfd_, (struct sockaddr*)&peer, sizeof(peer));
        if(n == -1) 
        {
            std::cerr << "connect to " << ip << ":" << port << " error" << std::endl;
            return false;
        }
        return true;
    }
    void Close()
    {
        close(sockfd_);
    }
    int Fd()
    {
        return sockfd_;
    }

private:
    int sockfd_;
};

#pragma once

#include <iostream>
#include <time.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>

#define SIZE 1024

#define Info 0
#define Debug 1
#define Warning 2
#define Error 3
#define Fatal 4

#define Screen 1
#define Onefile 2
#define Classfile 3

#define LogFile "log.txt"

class Log
{
public:
    Log()
    {
        printMethod = Screen;
        path = "./log/";
    }
    void Enable(int method)
    {
        printMethod = method;
    }
    std::string levelToString(int level)
    {
        switch (level)
        {
        case Info:
            return "Info";
        case Debug:
            return "Debug";
        case Warning:
            return "Warning";
        case Error:
            return "Error";
        case Fatal:
            return "Fatal";
        default:
            return "None";
        }
    }

    // void logmessage(int level, const char *format, ...)
    // {
    //     time_t t = time(nullptr);
    //     struct tm *ctime = localtime(&t);
    //     char leftbuffer[SIZE];
    //     snprintf(leftbuffer, sizeof(leftbuffer), "[%s][%d-%d-%d %d:%d:%d]", levelToString(level).c_str(),
    //              ctime->tm_year + 1900, ctime->tm_mon + 1, ctime->tm_mday,
    //              ctime->tm_hour, ctime->tm_min, ctime->tm_sec);

    //     // va_list s;
    //     // va_start(s, format);
    //     char rightbuffer[SIZE];
    //     vsnprintf(rightbuffer, sizeof(rightbuffer), format, s);
    //     // va_end(s);

    //     // 格式：默認(rèn)部分+自定義部分
    //     char logtxt[SIZE * 2];
    //     snprintf(logtxt, sizeof(logtxt), "%s %s\n", leftbuffer, rightbuffer);

    //     // printf("%s", logtxt); // 暫時(shí)打印
    //     printLog(level, logtxt);
    // }
    void printLog(int level, const std::string &logtxt)
    {
        switch (printMethod)
        {
        case Screen:
            std::cout << logtxt << std::endl;
            break;
        case Onefile:
            printOneFile(LogFile, logtxt);
            break;
        case Classfile:
            printClassFile(level, logtxt);
            break;
        default:
            break;
        }
    }
    void printOneFile(const std::string &logname, const std::string &logtxt)
    {
        std::string _logname = path + logname;
        int fd = open(_logname.c_str(), O_WRONLY | O_CREAT | O_APPEND, 0666); // "log.txt"
        if (fd < 0)
            return;
        write(fd, logtxt.c_str(), logtxt.size());
        close(fd);
    }
    void printClassFile(int level, const std::string &logtxt)
    {
        std::string filename = LogFile;
        filename += ".";
        filename += levelToString(level); // "log.txt.Debug/Warning/Fatal"
        printOneFile(filename, logtxt);
    }

    ~Log()
    {
    }
    void operator()(int level, const char *format, ...)
    {
        time_t t = time(nullptr);
        struct tm *ctime = localtime(&t);
        char leftbuffer[SIZE];
        snprintf(leftbuffer, sizeof(leftbuffer), "[%s][%d-%d-%d %d:%d:%d]", levelToString(level).c_str(),
                 ctime->tm_year + 1900, ctime->tm_mon + 1, ctime->tm_mday,
                 ctime->tm_hour, ctime->tm_min, ctime->tm_sec);

        va_list s;
        va_start(s, format);
        char rightbuffer[SIZE];
        vsnprintf(rightbuffer, sizeof(rightbuffer), format, s);
        va_end(s);

        // 格式：默認(rèn)部分+自定義部分
        char logtxt[SIZE * 2];
        snprintf(logtxt, sizeof(logtxt), "%s %s", leftbuffer, rightbuffer);

        // printf("%s", logtxt); // 暫時(shí)打印
        printLog(level, logtxt);
    }

private:
    int printMethod;
    std::string path;
};

Log lg;

// int sum(int n, ...)
// {
//     va_list s; // char*
//     va_start(s, n);

//     int sum = 0;
//     while(n)
//     {
//         sum += va_arg(s, int); // printf("hello %d, hello %s, hello %c, hello %d,", 1, "hello", 'c', 123);
//         n--;
//     }

//     va_end(s); //s = NULL
//     return sum;
// }

select_server:Main.cc
	g++ -o $@ $^ -std=c++11
.PHONY:clean
clean:
	rm -f select_server

#pragma once

#include <iostream>
#include <sys/select.h>
#include <sys/time.h>
#include "Socket.hpp"

using namespace std;

static const uint16_t defaultport = 8888;
static const int fd_num_max = (sizeof(fd_set) * 8);
int defaultfd = -1;

class SelectServer
{
public:
    SelectServer(uint16_t port = defaultport) : _port(port)
    {
        for (int i = 0; i < fd_num_max; i++)
        {
            fd_array[i] = defaultfd;
            // std::cout << "fd_array[" << i << "]" << " : " << fd_array[i] << std::endl;
        }
    }
    bool Init()
    {
        _listensock.Socket();
        _listensock.Bind(_port);
        _listensock.Listen();

        return true;
    }
    void Accepter()
    {
        // 我們的連接事件就緒了
        std::string clientip;
        uint16_t clientport = 0;
        int sock = _listensock.Accept(&clientip, &clientport); // 會(huì)不會(huì)阻塞在這里？不會(huì)
        if (sock < 0) return;
        lg(Info, "accept success, %s: %d, sock fd: %d", clientip.c_str(), clientport, sock);

        // sock -> fd_array[]
        int pos = 1;
        for (; pos < fd_num_max; pos++) // 第二個(gè)循環(huán)
        {
            if (fd_array[pos] != defaultfd)
                continue;
            else
                break;
        }
        if (pos == fd_num_max)
        {
            lg(Warning, "server is full, close %d now!", sock);
            close(sock);
        }
        else
        {
            fd_array[pos] = sock;
            PrintFd();
            // TODO
        }
    }
    void Recver(int fd, int pos)
    {
        // demo
        char buffer[1024];
        ssize_t n = read(fd, buffer, sizeof(buffer) - 1); // bug?
        if (n > 0)
        {
            buffer[n] = 0;
            cout << "get a messge: " << buffer << endl;
        }
        else if (n == 0)
        {
            lg(Info, "client quit, me too, close fd is : %d", fd);
            close(fd);
            fd_array[pos] = defaultfd; // 這里本質(zhì)是從select中移除
        }
        else
        {
            lg(Warning, "recv error: fd is : %d", fd);
            close(fd);
            fd_array[pos] = defaultfd; // 這里本質(zhì)是從select中移除
        }
    }
    void Dispatcher(fd_set &rfds)
    {
        for (int i = 0; i < fd_num_max; i++) // 這是第三個(gè)循環(huán)
        {
            int fd = fd_array[i];
            if (fd == defaultfd)
                continue;

            if (FD_ISSET(fd, &rfds))
            {
                if (fd == _listensock.Fd())
                {
                    Accepter(); // 連接管理器
                }
                else // non listenfd
                {
                    Recver(fd, i);
                }
            }
        }
    }
    void Start()
    {
        int listensock = _listensock.Fd();
        fd_array[0] = listensock;
        for (;;)
        {
            fd_set rfds;
            FD_ZERO(&rfds);

            int maxfd = fd_array[0];
            for (int i = 0; i < fd_num_max; i++) // 第一次循環(huán)
            {
                if (fd_array[i] == defaultfd)
                    continue;
                FD_SET(fd_array[i], &rfds);
                if (maxfd < fd_array[i])
                {
                    maxfd = fd_array[i];
                    lg(Info, "max fd update, max fd is: %d", maxfd);
                }
            }

            // accept?不能直接accept！檢測(cè)并獲取listensock上面的事件，新連接到來(lái)，等價(jià)于讀事件就緒

            // struct timeval timeout = {1, 0}; // 輸入輸出，可能要進(jìn)行周期的重復(fù)設(shè)置
            struct timeval timeout = {0, 0}; // 輸入輸出，可能要進(jìn)行周期的重復(fù)設(shè)置
            // 如果事件就緒，上層不處理，select會(huì)一直通知你！
            // select告訴你就緒了，接下來(lái)的一次讀取，我們讀取fd的時(shí)候，不會(huì)被阻塞
            // rfds: 輸入輸出型參數(shù)。 1111 1111 -> 0000 0000
            int n = select(maxfd + 1, &rfds, nullptr, nullptr, /*&timeout*/ nullptr);
            switch (n)
            {
            case 0:
                cout << "time out, timeout: " << timeout.tv_sec << "." << timeout.tv_usec << endl;
                break;
            case -1:
                cerr << "select error" << endl;
                break;
            default:
                // 有事件就緒了，TODO
                cout << "get a new link!!!!!" << endl;
                Dispatcher(rfds); // 就緒的事件和fd你怎么知道只有一個(gè)呢？？？
                break;
            }
        }
    }
    void PrintFd()
    {
        cout << "online fd list: ";
        for (int i = 0; i < fd_num_max; i++)
        {
            if (fd_array[i] == defaultfd)
                continue;
            cout << fd_array[i] << " ";
        }
        cout << endl;
    }
    ~SelectServer()
    {
        _listensock.Close();
    }

private:
    Sock _listensock;
    uint16_t _port;
    int fd_array[fd_num_max];   // 數(shù)組, 用戶維護(hù)的！
    // int wfd_array[fd_num_max];
};

#include "SelectServer.hpp"
#include <memory>

int main()
{
    // std::cout <<"fd_set bits num : " << sizeof(fd_set) * 8 << std::endl;

    std::unique_ptr<SelectServer> svr(new SelectServer());
    svr->Init();
    svr->Start();

    return 0;
}