#include <iterator>
#include <map>
#include <string>
#if 0
#include <iostream>
#include <cstring>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <unistd.h>
 
int main() {
    char hostname[256];
    char ip[INET_ADDRSTRLEN];
    struct hostent *host;
 
    // 获取主机名
    if (gethostname(hostname, sizeof(hostname)) == -1) {
        perror("获取主机名失败");
        return 1;
    }

  printf("hostname: %s\n", hostname);
 
    // 根据主机名获取IP地址
    if ((host = gethostbyname(hostname)) == NULL) {
        perror("获取IP地址失败");
        return 1;
    }
 
    // 遍历IP地址列表
    for (int i = 0; host->h_addr_list[i] != NULL; i++) {
        strcpy(ip, inet_ntoa(*(struct in_addr*)host->h_addr_list[i]));
        std::cout << "IP地址: " << ip << std::endl;
    }
 
    return 0;
}
#endif
#include <iostream> 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <ifaddrs.h>
 


int get_ips(std::map<std::string, std::string>& ips)
{
  struct ifaddrs *ifaddr, *ifa;
  int family;
  char host[NI_MAXHOST];

  if (getifaddrs(&ifaddr) == -1) {
    perror("getifaddrs");
    exit(EXIT_FAILURE);
  }

  int num = 0;
  for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
    if (ifa->ifa_addr == NULL)
      continue;
    
    if (strcmp(ifa->ifa_name, "lo") == 0) {
      continue;
    }

    family = ifa->ifa_addr->sa_family;
    printf("family: %d\n", family);
    printf("name: %s\n", ifa->ifa_name);

    if (family == AF_INET) {
      int s = getnameinfo(ifa->ifa_addr, sizeof(struct sockaddr_in), host, NI_MAXHOST, NULL, 0, NI_NUMERICHOST);
      printf("getnameinfo n = %d\n", s);
      if (s != 0) {
        printf("getnameinfo() failed: %s\n", gai_strerror(s));
        exit(EXIT_FAILURE);
      }
      printf("%s\n", host);
      ips.insert(std::pair<std::string, std::string>(ifa->ifa_name, host));
      num++;
    }
  }

  freeifaddrs(ifaddr);
  return num;
}

std::string get_one(int n)
{
  std::map<std::string, std::string> ips; 
  int s = get_ips(ips);
  if (n > s) {
    return "0.0.0.0";
  }

  std::map<std::string, std::string>::iterator iter;
  for (iter = ips.begin(); iter != ips.end(); iter++) {
    // std::cout << "Net name: " << iter->first << ", ip: " << iter->second << std::endl;
  }
  std::map<std::string, std::string>::iterator it = ips.begin();
  it = std::next(it, n);
  if (it != ips.end()) {
    return (*it).second;
  }

  return "0.0.0.0";
}

std::string get_one(const std::string name)
{
  std::map<std::string, std::string> ips; 
  int s = get_ips(ips);

  std::map<std::string, std::string>::iterator it;

  it = ips.find(name);
  if (it != ips.end()) {
    return it->second;
  }

  return "0.0.0.0";
}



int main (int argc, char *argv[]) 
{

  std::string ip0 = get_one(0);
  std::cout << "IP0: " << ip0 << std::endl;


  std::string ip1 = get_one(1);
  std::cout << "IP1: " << ip1 << std::endl;


  std::string ip2 = get_one(2);
  std::cout << "IP2: " << ip2 << std::endl;


  std::string ip6 = get_one(6);
  std::cout << "IP6: " << ip6 << std::endl;

  std::string ip00 = get_one("enp3s0");
  std::cout << "enp3s0 IP: " << ip00 << std::endl;

  std::string ip01 = get_one("wlo1");
  std::cout << "wlo1 IP: " << ip01 << std::endl;

  std::string ip02 = get_one("wlo1x");
  std::cout << "wlo1x IP: " << ip02 << std::endl;



  #if 0
  int n = get_ips(ips);
  printf("get_ips count: %d\n", n);
  std::map<std::string, std::string>::iterator iter;
  for (iter = ips.begin(); iter != ips.end(); iter++) {
    std::cout << "Net name: " << iter->first << ", ip: " << iter->second << std::endl;
  }

  std::map<std::string, std::string>::iterator iter1= ips.begin();
  // iter1 = iter1 + 1;
  iter1 = std::next(iter1, 3);
  if (iter1 != ips.end()) {
    std::cout << "Net[0] name: " << iter1->first << ", ip: " << (*iter1).second << std::endl;
  }
  else {
    std::cout << "std::map iterator end()" << std::endl;
  }
  #endif

  return 0;
}