#include "Server.h"
#include <iostream>
#include <sys/socket.h>
#include <cstdio>
#include <cstring>
#include <stdexcept>
#include <netinet/in.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <poll.h>
#include <time.h>
#include <signal.h>
#include "../stream/Stream.h"

using namespace std;

Server::Server(unsigned short port, unsigned short maxClients) : port(port), maxClients(maxClients) 
{
    try
    {
        // create socket for incoming connections
        listenerSocket = socket(AF_INET, SOCK_STREAM, 0);
        if(listenerSocket == -1)
        {
            throw runtime_error(string("cannot create socket: ") + strerror(errno));
        }

        // prevents clients from blocking the port if the server exits
        struct linger sl;
        sl.l_onoff = 1;
        sl.l_linger = 0;
        if(setsockopt(listenerSocket, SOL_SOCKET, SO_LINGER, &sl, sizeof(struct linger)) == -1)
        {
            throw runtime_error(string("cannot set non lingering: ") + strerror(errno));
        }

        // specifies data of the port ...
        struct sockaddr_in connectSocketData;
        memset(&connectSocketData, 0, sizeof(struct sockaddr_in));
        connectSocketData.sin_family = AF_INET;
        connectSocketData.sin_addr.s_addr = INADDR_ANY;
        connectSocketData.sin_port = htons(port);
        // ... and binds it
        if(bind(listenerSocket, (struct sockaddr*) &connectSocketData, sizeof(struct sockaddr_in)) == -1)
        {
            throw runtime_error(string("cannot bind socket: ") + strerror(errno));
        }

        // mark this socket as handler for connection requests
        if(listen(listenerSocket, 5) != 0)
        {
            throw runtime_error(string("cannot start listening: ") + strerror(errno));
        }
        
        // array for client connections, pointer to pointer to change placement
        clients = new ConnectedClient*[maxClients];
        for(int i = 0; i < maxClients; i++)
        {
            clients[i] = nullptr;
        }
    }
    catch(runtime_error& err)
    {
        clean();
        throw err; 
    }
}

Server::~Server()
{
    clean();
}

void Server::clean()
{
    if(listenerSocket != -1)
    {
        // ignore error
        close(listenerSocket);
    }
    if(clients != nullptr)
    {
        for(int i = 0; i < maxClients; i++)
        {
            if(clients[i] != nullptr)
            {
                if(clients[i]->socket != -1)
                {
                    close(clients[i]->socket);
                }
                delete clients[i];
            }
        }
        delete[] clients;
    }
}

void Server::start(IServerListener* listener)
{
    serverListener = listener;
    shouldRun = true;
    listenerThread = thread(&Server::listenForClients, this);
}

void Server::stop()
{
    shouldRun = false;
    
    listenerThread.join();
    for(int i = 0; i < maxClients; i++)
    {
        if(clients[i] != nullptr)
        {
            clients[i]->th.join();
        }
    }
}

void Server::listenForClients()
{
    while(shouldRun)
    {
        struct pollfd fds;
        fds.fd = listenerSocket;
        fds.events = POLLIN;
        fds.revents = 0;
        int pollData = poll(&fds, 1, 100);
        if(pollData > 0)
        {
            struct sockaddr_in clientSocketData;
            socklen_t addrlen = sizeof(struct sockaddr_in);
            int clientSocket = accept(listenerSocket, (struct sockaddr*) &clientSocketData, &addrlen);
            if(clientSocket >= 0)
            {
                //cout << "Client connected from " << inet_ntoa(clientSocketData.sin_addr) << ":" << (int) ntohs(clientSocketData.sin_port) << endl;
                
                clientMutex.lock();
                addClient(clientSocket);
                clientMutex.unlock();
            }
            else
            {
                break;
            }
        }
        else if(pollData == -1)
        {
            cerr << "poll error: " << strerror(errno) << endl;
        }
    }
}

void Server::addClient(int clientSocket)
{
    if(clientIndex >= maxClients)
    {
        serverListener->onFullServerClientConnect(clientSocket);
        close(clientSocket);
    }
    else
    {
        if(clients[clientIndex] == nullptr)
        {
            clients[clientIndex] = new ConnectedClient();
        }
        else
        {
            //ensure old thread has ended
            if(!clients[clientIndex]->th.joinable())
            {
                cerr << "cannot join thread of non used client connection" << endl;
                close(clientSocket);
                return;
            }
            clients[clientIndex]->th.join();
        }
        
        clients[clientIndex]->index = clientIndex;
        clients[clientIndex]->socket = clientSocket;
        clients[clientIndex]->th = thread(&Server::listenOnClient, this, clients[clientIndex]);

        clientIndex++;
    }
}

void Server::listenOnClient(ConnectedClient* cc)
{
    struct pollfd fds;
    fds.fd = cc->socket;
    fds.events = POLLIN;
    fds.revents = 0;
    
    serverListener->onClientConnect(cc->socket);
    
    Stream st;
    
    while(shouldRun)
    {
        int pollData = poll(&fds, 1, 100);
        if(pollData > 0)
        {
            st.readSocket(cc->socket);
            if(st.hasData())
            {
                serverListener->onClientPackage(cc->socket, st);
            }
            else
            {
                // client closed connection
                break;
            }
        }
        else if(pollData == -1)
        {
            cout << "poll error: " << strerror(errno) << endl;
        }
    }
    
    serverListener->onClientDisconnect(cc->socket);
    
    // do not swap on server shutdown
    if(!shouldRun)
    {
        return;
    }
    
    // remove client from list, move last client to empty slot
    clientMutex.lock();
    
    clientIndex--;
    if(cc->index != clientIndex) // client is not the last connected client
    {
        // move last element to empty slot
        ConnectedClient* tmp = clients[clientIndex];
        clients[clientIndex] = clients[cc->index];
        clients[cc->index] = tmp;
        // set indices
        int i = cc->index;
        clients[i]->index = i;
        clients[clientIndex]->index = clientIndex;
    }
    
    if(close(cc->socket) == -1)
    {
        cerr << "cannot close socket of client: " << strerror(errno) << endl;
    }
    cc->socket = -1;
    
    clientMutex.unlock();
}