//
// Chat Server, Unix Version
//
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <iostream>
#include <map>
#include <string>

using namespace std;

static void usage();

int s = (-1);   // Socket

sockaddr_in myAddr;
unsigned short myPort = 1234;

const int BUFFER_LEN = 2048;
char buffer[BUFFER_LEN];

class Client {
public:
    sockaddr_in addr;

    Client(const sockaddr_in& a):
        addr(a)
    {}

    int compareTo(const Client& c) const {
        if (addr.sin_addr.s_addr > c.addr.sin_addr.s_addr) {
            return 1;
        } else if (addr.sin_addr.s_addr < c.addr.sin_addr.s_addr) {
            return (-1);
        } else {
            if (addr.sin_port > c.addr.sin_port) {
                return 1;
            } else if (addr.sin_port < c.addr.sin_port) {
                return (-1);
            } else {
                return 0;
            }
        }
    }

    bool operator==(const Client& c) const {
        return (compareTo(c) == 0);
    }
    bool operator!=(const Client& c) const {
        return (compareTo(c) != 0);
    }
    bool operator<(const Client& c) const {
        return (compareTo(c) < 0);
    }
    bool operator<=(const Client& c) const {
        return (compareTo(c) <= 0);
    }
    bool operator>(const Client& c) const {
        return (compareTo(c) > 0);
    }
    bool operator>=(const Client& c) const {
        return (compareTo(c) >= 0);
    }
};

map<Client, string> clients;

void sendToAll(const Client& cli, const char* buffer, int len);
void printAddress(const sockaddr_in& addr);

int main(int argc, char* argv[]) {
    if (argc > 1) {
        // Take a port number from a command line
        if (!isdigit(argv[1][0])) {
            usage(); return 0;
        }
        myPort = (unsigned short) atoi(argv[1]);
    }

    // Create a socket
    s = socket(AF_INET, SOCK_DGRAM, 0);
    if (s < 0) {
        perror("Could not create a socket");
        exit(-1);
    }

    // Fill in the address structure containing self address
    memset(&myAddr, 0, sizeof(struct sockaddr_in));
    myAddr.sin_family = AF_INET;
    myAddr.sin_port = htons(myPort);
    myAddr.sin_addr.s_addr = htonl(INADDR_ANY);

    // Bind a socket to the address
    int res = bind(s, (struct sockaddr*) &myAddr, sizeof(myAddr));
    if (res < 0) {
        perror("Cannot bind a socket");
        exit(-1);
    }

    while (true) {
        sockaddr_in clientAddr;
        socklen_t addLen = sizeof(clientAddr);

        int res = recvfrom(
            s, buffer, BUFFER_LEN-4, 0,
            (sockaddr*) &clientAddr, &addLen
        );
        if (res > 0) {
            buffer[res] = 0;

            cout << "Message from ";
            printAddress(clientAddr);
            cout << "    " << buffer << endl;

            Client cli(clientAddr);
            clients[cli] = string(buffer);

            sendToAll(cli, buffer, res);
        }

        if (strncmp(buffer, "terminate!", strlen("terminate!")) == 0)
            break;
    }

    shutdown(s, SHUT_RDWR);
    close(s);

    return 0;
}

static void usage() {
    printf(
        "A simple Internet server application.\n"
    );
}

void sendToAll(const Client& cli, const char* buffer, int len) {
    // cout << "sendToAll: message " << buffer <<
    //    " len = " << len << endl;

    map<Client, string>::const_iterator i = clients.begin();
    while (i != clients.end()) {
        const Client& client = i->first;
        if (client != cli) {

            /*
            cout << "    Transmitting message to client ";
            printAddress(client.addr);
            cout << endl;
            */

            int res = sendto(
                s, buffer, len, 0,
                (sockaddr*) &(client.addr), sizeof(sockaddr_in)
            );

            // cout << "    sendto: res = " << res << endl;
            if (res < 0) {
                perror("sendto error");
            }
        }
        ++i;
    }
}

void printAddress(const sockaddr_in& addr) {
    cout << ((int)(ntohl(addr.sin_addr.s_addr) >> 24) & 0xff)
        << "."
        << ((int)(ntohl(addr.sin_addr.s_addr) >> 16) & 0xff)
        << "."
        << ((int)(ntohl(addr.sin_addr.s_addr) >> 8) & 0xff)
        << "."
        << ((int)(ntohl(addr.sin_addr.s_addr)     ) & 0xff)
        << ":"
        << (int)ntohs(addr.sin_port)
        << endl;
}