#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#include <string>
#include <iostream>

using namespace std;

// ------------------------------------------------------
const short SOCKET_ERROR = -1;

const short RECV_BUFFER_SIZE = 20;
const short REQUEST_BUFFER_SIZE = 255;

int sock;
char recv_buf [RECV_BUFFER_SIZE + 1];
char req_buf [REQUEST_BUFFER_SIZE + 1];

const static char REQUEST_TEMPLATE [] = 
{
    "GET %s HTTP/1.1\r\n"
    "Host: xxx.xxx.xxx\r\n" // should be replaced with a really host
    "Connection: Keep-Alive\r\n"
    "\r\n"
};

// ------------------------------------------------------
void create_socket ();
void download (const string& path, string& response);

// ------------------------------------------------------

int main (void)
{
    string first_addr = "/~pdu/index.html"; // should be replaced with a really URL
    string second_addr = "/~pdu/a.html"; // should be replaced with a really URL
    string response;

    create_socket ();
    download (first_addr, response);
    cout << response << endl << endl;
    response = "";
    download (second_addr, response);
    if (response.size() > 0)
    {
        cout << response << endl;
    }
    else
    {
        cout << "### The 2nd recv() failed to receive any bytes from the socket!" << endl << endl;
    }
    
    close (sock);

    return 0;
}

void create_socket ()
{
    struct sockaddr_in addr;

    // ------------------------------------------------------
    sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if(sock == SOCKET_ERROR)
    {
        perror ("Could not make a socket.\n");
        exit (-1);
    }

    cout << ">>> Socket created!" << endl;

    // ------------------------------------------------------
    struct hostent* host_info = gethostbyname("cse.unl.edu");    
    
    cout << ">>> DNS done!" << endl;

    long host_addr;

    /* copy address into long */
    memcpy(&host_addr, host_info->h_addr,
        host_info->h_length);

    /* fill address struct */
    addr.sin_addr.s_addr = host_addr;
    addr.sin_port = htons(80);
    addr.sin_family = AF_INET;

    // ------------------------------------------------------
    if( connect(sock, (struct sockaddr*)(&addr),
        sizeof(addr)) == SOCKET_ERROR )
    {
        perror("Could not connect to HTTP server.\n");
        exit (-1);
    }

    cout << ">>> Connection established!" << endl;
}

void download (const string& path, string& response) 
{
    size_t nBytes = snprintf(
        req_buf, 
        REQUEST_BUFFER_SIZE, 
        REQUEST_TEMPLATE, 
        path.c_str());

    if (nBytes >= REQUEST_BUFFER_SIZE)
    {
        cerr << "Buffer is too small for making a request message" << endl;
        exit (-1);
    }

    if (send(sock, req_buf, nBytes, 0) != nBytes)
    {
        perror("Could not send request to the HTTP server.\n");
        exit (-1);
    }
    cout << ">>> Request sent! -> " << path << endl << req_buf << endl;
    
    ssize_t size = 0;
    
    while ((size = recv(sock, recv_buf, 
        RECV_BUFFER_SIZE, 0)) > 0) 
    {
        recv_buf[size] = '\0';
        response.append(recv_buf);
    }

    cout << ">>> Response received!" << endl;
}