#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <pthread.h>

#define BUF_SIZE 1024

void* request_handler(void* arg);// 用于处理请求，发送dmidecode的数据
void error_handler(char* message);// 处理错误

int main(int argc, int *argv[]) {
    // 返回一个AF_INET(ip4)，SOCK_STREAM(字节流套接字),IPPROTO_TCP(TCP传输协议)的socket描述符
    // 这是一个监听套接字描述符
    int server_sock = socket(AF_INET, SOCK_STREAM, 0);
    if(server_sock == -1) {
        error_handler("no more socket!!!");
        exit(-1);
    }
    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));// 这句话是干嘛的？
    server_addr.sin_family = AF_INET;// 设置协议族为ipv4
    server_addr.sin_port = htons(3527);// 设置监听端口,将host unigned short字节序转换为 net 字节序
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);// 监听任意网卡的报文数据，0.0.0.0表示来自任意网卡的包都要发给server
    
    // 绑定监听端口与套接字, 不过bind后面两个参数不太明确
    if(bind(server_sock,(struct sockaddr*)&server_addr, sizeof(server_addr)) == -1) {
        error_handler("bind() error");
        exit(-1);
    }
    // 监听
    if(listen(server_sock, 20) == -1) {
        error_handler("listen() error");
        exit(-1);
    }

    // 并发处理http request
    pthread_t t_id;
    while(1) {
        // accept返回真正与client交互的socket描述符
        struct sockaddr_in client_addr;
        int client_addr_len = sizeof(client_addr); // accept的第三个参数需要地址😓
        int client_sock = accept(server_sock, (struct sockaddr*)&client_addr,&(client_addr_len));
        if(client_sock == -1) {
            error_handler("accept() error");
            exit(-1);
        }
        
        if(pthread_create(&t_id, NULL, request_handler, &client_sock) == -1) {
            error_handler("pthread error");
            exit(-1);
        }
        pthread_detach(t_id);// 主线程与子线程分离，两者相互不干涉，子线程结束同时子线程的资源自动回收。
    }

    exit(0);
}


void *request_handler(void *arg) {
    int client_sock = *((int*)arg);
    int p[2];
    pipe(p);

    char status[] = "HTTP/1.1 200 OK\n\n";
    char header[] = "Content-Type: text/html;charset=utf-8\n\n";
    char body[BUF_SIZE];
    // write(client_sock, status, sizeof(status));
    // write(client_sock, header, sizeof(header));
    // cout<<sizeof(status)<<" "<<sizeof(header)<<endl;
    printf("%lu %lu\n", sizeof(status), sizeof(header));
    write(client_sock, "HTTP/1.1 200 OK\n\n", 15);// 为什么这里的长度明明是18，但是要设置成15
    write(client_sock, "Content-Type: text/html; charset=UTF-8\n\n", 40);
    // write(client_sock, "hello", 6);// 为什么body中有值，就是下载鸭？？？
    // write(client_sock, body, sizeof(body));
    if(fork() == 0) {
        close(p[0]);
        close(STDOUT_FILENO); // 将子进程标准输出重定向到管道end of write
        
        dup(p[1]);// dup用来复制参数oldfd所指的文件描述符。当复制成功时，返回最小的尚未被使用过的文件描述符
        execlp("dmidecode", "dmidecode",  NULL);
    }
    close(p[1]);// 关闭父进程end of write
    int len;
    while((len = read(p[0],body, BUF_SIZE)) != 0) {
        write(client_sock, body, len);
    }
    shutdown(client_sock, SHUT_RDWR);

} 
void error_handler(char *message) {
    fputs(message, stderr);
    fputs("\n", stderr);
    exit(1);
}