#include <iostream>
#include <unistd.h>
#include <cstdio>
#include <string>
#include <cstring>
#include <cstdlib>
#include <sys/types.h>
#include <sys/wait.h>

#define N 2
#define NUM 1024

using namespace std;

//子进程
void Writer(int wfd)
{
    string str = "hello, I am a child";
    pid_t slef = getpid();
    int number = 0;

    char buffer[NUM];
    while(true)
    {
        //3.写端每隔1秒写一次，读端读5秒关闭
        sleep(1);//1.慢慢写，读端一直读，看看情况如何
        //构建发送字符串
        buffer[0] = 0;//字符串清空，只是为了提醒阅读代码的人，我们把这个数组当作字符串了
        snprintf(buffer, sizeof(buffer), "%s-%d-%d", str.c_str(), slef, number++);
        //cout << buffer << endl;
        //发送\写入给父进程
        write(wfd, buffer, strlen(buffer));//写入字符串内容即可，不用写入 \0（只是C语言字符串结束标志，文件可以控制字节数）
        // write(wfd, "c", 1);
        // cout << number << endl;//写满为65536个字节，64KB
        //每隔一秒写入
        // sleep(1);
        //2.写端关闭，读端的情况如何？
        // if(number >= 5) break;
    }

}
//父进程
void Reader(int rfd)
{
    char buffer[NUM];
    int cnt = 0;
    while(true)
    {
        // sleep(1);
        ssize_t n = read(rfd, buffer, sizeof(buffer) - 1);//留一个位置给\0
        if(n > 0)
        {
            buffer[n] = 0;//手动添加 \0
            cout << "father[" << getpid() << "]get a message: " << buffer << endl; 
        }
        else if(n == 0)
        {
            cout << "father read the end of the file!" << endl;
             break;//读到了文件结尾就不用读了
        }
        else break;//读取出错
        //3.读端读5秒后关闭，写端一直写
        if(++cnt > 5) break;
        cout << "cnt: " << cnt << endl;
        // cout << "n: " << n << endl;
    }
}


int main()
{
    //创建管道
    int pipeid[N] = {0};
    int n = pipe(pipeid);
    if(n <  0) return 1;
    // cout << "pipeid[0]: "  << pipeid[0] << ", pipeid[1: " << pipeid[1] << endl;
    //创建子进程
    //子进程写入(关闭读)，父进程读取（关闭写）
    pid_t id = fork();
    if(id < 0) return 2;
    else if(id == 0)
    {
        //子进程
        close(pipeid[0]);
        //通信代码
        Writer(pipeid[1]);

        close(pipeid[1]);//可以不关，后续由操作系统回收
        exit(0);
    }
    //父进程
    close(pipeid[1]);
    //通信代码
    Reader(pipeid[0]);//3.读端读5秒后关闭，写端一直写
    close(pipeid[0]);//可以不关，后续后操作系统回收
    std::cout << "father close read fd: " << pipeid[0] << endl;
    sleep(5);//观察僵尸状态

    //等待子进程
    int status = 0;
    pid_t ret = waitpid(id, &status, 0);
    if(ret < 0) return 3;

    cout << "wait child success: "<< ret << "exit code:  " << WEXITSTATUS(status) << "exit signal: " << WTERMSIG(status) << endl;

    sleep(5);//观察回收过程
    cout << "father quit" << endl;
    return 0; 
}