#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#include <string>
#include <unistd.h>

using namespace std;

string replace_string(string str, const string from, const string to) {
    size_t start_pos = str.find(from);
    if(start_pos == string::npos)
        return str;
    str.replace(start_pos, from.length(), to);
    return str;
}

void sigchld_handler(int s)
{
    while(waitpid(-1, NULL, WNOHANG) > 0);
}
class Server
{
private:
    string PORT;
    int MAXDATASIZE;
public:
    Server()
    {
        PORT = "3490";
        MAXDATASIZE = 14096;
    
    }

  

    // get sockaddr, IPv4 or IPv6:
    void *get_in_addr(struct sockaddr *sa)
    {
        if (sa->sa_family == AF_INET) {
            return &(((struct sockaddr_in*)sa)->sin_addr);
        }

        return &(((struct sockaddr_in6*)sa)->sin6_addr);
    }

    int start_server()
    {

        // first, load up address structs with getaddrinfo():
        int socketfd, new_socketfd;
        struct addrinfo hints, *servinfo, *p;
        struct sockaddr_storage their_addr;
        socklen_t their_addr_size, addr_size;
        struct sigaction sa;
  
        char s[INET6_ADDRSTRLEN];

        int rv;
        int yes = 1;
        int BACKLOG = 10;
        int numbytes;
        unsigned char buf[MAXDATASIZE];
        
        memset(&hints, 0, sizeof hints); // Make sure it is cleared
        hints.ai_family = AF_UNSPEC;     // use IPv4 or IPv6, whichever
        hints.ai_socktype = SOCK_STREAM; // TCP socket
        hints.ai_flags = AI_PASSIVE;     // fill in my IP for me

        if ((rv = getaddrinfo(NULL, PORT.c_str(), &hints, &servinfo)) != 0) {
            cerr << "getaddrinfo: " << gai_strerror(rv) << endl;
            return -1;
        }
        
        // make a socket, bind it asap
        for(p = servinfo; p != NULL; p = p->ai_next)
        {
            if ((socketfd = socket(p->ai_family, p->ai_socktype,
                                   p->ai_protocol)) == -1) {
                //perror("server: socket");
                cerr << "ERROR: Server: socket" << endl;
                continue;
            }

            if (setsockopt(socketfd, SOL_SOCKET, SO_REUSEADDR, &yes,
                           sizeof(int)) == -1) {
                //perror("setsockopt");
                cerr << "ERROR: setsockopt" << endl;
                exit(1);
            }

            if (bind(socketfd, p->ai_addr, p->ai_addrlen) == -1) {
                close(socketfd);
                //perror("server: bind");
                cerr << "ERROR: server: bind" << endl;
                continue;
            }
            break;	
        }
        //If the binding failed
        if ( p == NULL)
        {
            cerr << "Server: failed to bind" << endl;
            return -1;
        }

        //Free space, we do not need it anymore.
        freeaddrinfo(servinfo);

        //Listen to the socket (port)
        if ( listen(socketfd, BACKLOG) == -1)
        {
            cerr << "ERROR: listen" << endl;
        }

        // killing zombie processs (all dead processes)
        sa.sa_handler = sigchld_handler; 
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = SA_RESTART;
        if (sigaction(SIGCHLD, &sa, NULL) == -1) {
            perror("sigaction");
            exit(1);
        }
        
        cout << "Server: waiting for connections ...\n"<<endl;
        
        //Main loop 
        for(;;)
        {  
            their_addr_size = sizeof their_addr;          
            //Create a new socket when we got a connection
            if ((new_socketfd = accept(socketfd, (struct sockaddr *)&their_addr, &their_addr_size))== -1) {
                continue;
            }
            if (!fork())
            {
                //Converts IP address to 127.0.0.1 (or IPv6 format..) format instead of binary 
                inet_ntop(their_addr.ss_family,get_in_addr((struct sockaddr *)&their_addr), s, sizeof s);

                if ((numbytes = recv(new_socketfd, buf, MAXDATASIZE-1, 0)) == -1) {
                    cerr << "ERROR: Failed to receive from user-agent" << endl;
                    exit(1);
                }
                else
                {
                    /*Parse the header and change some things.*/

                    string buffer_str(reinterpret_cast<char*>(buf), MAXDATASIZE);   // Convert to unsigned char array to make it easier to handle                              
                    buffer_str = replace_string(buffer_str, "Proxy-Connection: keep-alive","Connection: close"); // Make it connection Close instead of Keep-Alive
                    buffer_str = replace_string(buffer_str, "Connection: keep-alive","Connection: close"); // Make it connection Close instead of Keep-Alive
                    // removes host from GET, and saves it
                    int first = buffer_str.find_first_of("/");                      
                    int last =  buffer_str.find_first_of("/", first+2);
                    int size_of_buf=buffer_str.size();
                    unsigned char host_request[MAXDATASIZE];
                    for (int a=0;a<=size_of_buf;a++)
                        host_request[a]=buffer_str[a];
                    host_request[size_of_buf]='\0';
                    string host_name = "";
                    for(int i=first+2;i<last;++i) 
                        host_name += buffer_str[i];
                    buffer_str.erase(4, buffer_str.find_first_of("/", first+2)-4);
	  

	  
                    /*Set up the socket for the proxy-host */

                    int host_sockfd, host_numbytes;  
                    unsigned char host_buf[MAXDATASIZE];
                    struct addrinfo host_hints, *host_servinfo, *host_p;
                    int host_rv;
                    char host_s[INET6_ADDRSTRLEN];


                    memset(&host_hints, 0, sizeof(host_hints));
                    host_hints.ai_family = AF_UNSPEC;
                    host_hints.ai_socktype = SOCK_STREAM;


                    if ((rv = getaddrinfo(host_name.c_str(), "80", &host_hints, &host_servinfo)) != 0) {
                        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
                        cerr << "host: " << host_name << endl;
                        return 1;
                    }

                    // loop through all the results and connect to the first we can
                    for(host_p = host_servinfo; host_p != NULL; host_p = host_p->ai_next) {
                        if ((host_sockfd = socket(host_p->ai_family, host_p->ai_socktype,
                                                  host_p->ai_protocol)) == -1) {
                            perror("client: socket");
                            continue;
                        }

                        if (connect(host_sockfd, host_p->ai_addr, host_p->ai_addrlen) == -1) {
                            close(host_sockfd);
                            perror("client: connect");
                            continue;
                        }

                        break;
                    }

                    if (host_p == NULL) {
                        fprintf(stderr, "client: failed to connect\n");
                        return 2;
                    }

                    inet_ntop(host_p->ai_family, get_in_addr((struct sockaddr *)host_p->ai_addr),s, sizeof s); //Converts the IP address from binary to IPv4/6-format
                    //printf("client: connecting to %s\n", s);

                    freeaddrinfo(host_servinfo); // all done with this structure

                    /*Send the GET request to the server*/
                    send_message(host_sockfd, host_request, sizeof(host_request), "Webserver");
                
                    memset(&host_buf, 0, MAXDATASIZE);
                    
                    while (recv(host_sockfd, &host_buf, MAXDATASIZE, 0) > 0 ) {
                        int len;
                        len = sizeof(host_buf);
                        if ( send_message(new_socketfd, (unsigned char *)host_buf, MAXDATASIZE, "Browser") == -1) {
                            perror("sendall");
                            printf("We only sent %d bytes because of the error!\n", len);
                        } 
                        memset(&host_buf, 0, MAXDATASIZE);
                    }

                    
                    //close(host_sockfd);
                    exit(0);
                }
                close(new_socketfd);
                
            }
    
      
            //cout << "server: got connection from " << s << endl;
 
            close(new_socketfd);  // parent doesn't need this
          
        }

        return 1;
    }
    int send_message(int &socket,unsigned char msg[], int length, string too)
    {
        int total = 0;        // how many bytes we've sent
        int bytesleft = length; // how many we have left to send
        int data_sent;

        while(total < length) {
            if ((data_sent = (send(socket, msg+total, bytesleft, 0))) == -1)
            {
                cerr << "ERROR: sending to " << too << endl;
                cerr << "We will lose a packet due to" << endl;
                perror("send");
                cerr << "-------------------MEDDELANDE-------------------\n\n" << msg << endl << 
                    "--------------------------------------------------\n\n";
                cerr << "Closing the connection\n";
                return -1;
            }
            if (data_sent == -1) { break; }
            total += data_sent;
            bytesleft -= data_sent;
        }
        
        
        return total;
    }
};

int main()
{
    Server srv;
    srv.start_server();
}