#include <cerrno>
#include <condition_variable>
#include <cstddef>
#include <cinttypes>
#include <cstdint>
#include <cstdio>     // for fprintf()
#include <functional>
#include <iostream>
#include <queue>
#include <ratio>
#include <unistd.h>    // for close(), read()
#include <sys/epoll.h> // for epoll_create1(), epoll_ctl(), struct epoll_event
#include <cstring>    // for strncmp

//my addition to the online guide
#include <csignal>
#include <cstdlib>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <sys/socket.h>

#include <fcntl.h>
#include <utility>
#include <vector>
#include <chrono>
#include <fstream>

#include <thread>
#include <mutex>
#include <atomic>
#include <array>
#include <numeric>

#include "fragment_dataformat.h"
#include "full_event_format.h"
#include "TimeoutException.h"
#include "ControlledQueue.h"

#define MAX_EVENTS 1024
#define MAX_QUEUE_SIZE 1000000

#define READER_THREADS 6
// That's a buffer size of 64 kB, to maximize performance without it being too big, according to testing
#define BUFFER_SIZE_WORDS 16384

int min_fd = MAX_EVENTS + 1;
int max_fd = 0;
int exp_num = 0;

std::mutex conn_mutex;
std::condition_variable conn_cv;

int makeSocket() {
    int sockfd;
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }
    return sockfd;
}

void bindSocketPort(int server_fd, int port) {
    struct sockaddr_in localAddr;
    localAddr.sin_family = AF_INET;
    localAddr.sin_addr.s_addr = INADDR_ANY;
    localAddr.sin_port = htons(port);

    if (bind(server_fd, (struct sockaddr *)&localAddr, sizeof(localAddr)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }
    printf("FD %d bound to port %d\n", server_fd, port);
}

void startListening(int server_fd) {
    if (listen(server_fd, 20000) < 0) {
        perror("listen");
        exit(EXIT_FAILURE);
    }
    printf("FD %d listening to new connections\n", server_fd);
}

int acceptConnection(int server_fd) {
    int client_fd;
    struct sockaddr_in remoteAddr;

    size_t addrlen = sizeof(remoteAddr);
    if ((client_fd = accept(server_fd, (struct sockaddr *)&remoteAddr, (socklen_t *)&addrlen)) < 0) {
        perror("accept");
        exit(EXIT_FAILURE);
    } else {
        int flags = fcntl(client_fd, F_GETFL);
        fcntl(client_fd, F_SETFL, flags | O_NONBLOCK);
    }
    printf("Connection from host %s, port %d, FD %d\n", inet_ntoa(remoteAddr.sin_addr), ntohs(remoteAddr.sin_port), client_fd);
    return client_fd;
}

void acceptConnectionEpollStyle(int server_fd, int &efd) {
    struct sockaddr_in new_remoteAddr;
    int addrlen = sizeof(struct sockaddr_in);

    while (true) {
        int conn_sock = accept(server_fd, (struct sockaddr*)&new_remoteAddr, (socklen_t*)&addrlen);

        if (conn_sock == -1) {
            // All incoming connections have been processed
            if ((errno == EAGAIN) || (errno == EWOULDBLOCK)) {
                break;
            } else {
                perror("accept");
                break;
            }
        }

        // make new connection non-blocking
        int flags = fcntl(conn_sock, F_GETFL, 0);
        fcntl(conn_sock, F_SETFL, flags | O_NONBLOCK);

        // monitor new connection for read events, always in edge triggered
        struct epoll_event event;
        event.events = EPOLLIN | EPOLLEXCLUSIVE;//| EPOLLET;
        event.data.fd = conn_sock;

        // Allow epoll to monitor the new connection
        if (epoll_ctl(efd, EPOLL_CTL_ADD, conn_sock, &event) == -1) {
            perror("epoll_ctl: conn_sock");
            break;
        }
        printf("Accepted epoll style connection from %s:%d from fd: %d\n", inet_ntoa(new_remoteAddr.sin_addr), ntohs(new_remoteAddr.sin_port), conn_sock);
        if (max_fd < conn_sock) max_fd = conn_sock;
        if (min_fd > conn_sock) min_fd = conn_sock;

    }
}

void term_handler(int signal) {
    printf("Terminated, received SIGNAL %d", signal);
    exit(EXIT_SUCCESS);
}

std::array<std::mutex, MAX_EVENTS> queues_mutexes;

void thradizable(int &epoll_fd, int &master_socket, std::array<ControlledQueue, MAX_EVENTS>& queues_array, const int &th_flag, const int thread_index) {
    epoll_event events[MAX_EVENTS];

    while (true) {
        if (th_flag == 1) break;
        // Time measurements
        ///auto start = std::chrono::high_resolution_clock::now();

        // Returns only the sockets for which there are events
        //printf("Before wait\n");
        int nfds = epoll_wait(epoll_fd, events, MAX_EVENTS, -1);
        //printf("After wait\n");
        if (nfds == -1) {
            perror("epoll_wait");
            exit(EXIT_FAILURE);
        }

        // Iterate on the sockets having events
        for (int i = 0; i < nfds; i++) {
            //printf("Tot fds = %d reading from %d\n", nfds, i);
            int fd = events[i].data.fd;
            if (fd == master_socket) {
                // If the activity is on the master socket, than it's a new connection request
                std::unique_lock<std::mutex> conn_lk(conn_mutex);
                acceptConnectionEpollStyle(master_socket, epoll_fd);
                conn_lk.unlock();
                conn_cv.notify_all();
            } else if ((events[i].events & EPOLLERR) || (events[i].events & EPOLLHUP) || (!(events[i].events & EPOLLIN))) {
                // Than the client connection is closed, so I close it
                printf("Closing %d", fd);
                close(fd);
            } else {
                //printf("Ev trig th %d with tot b %lu\n", thread_index, part);
                // Than we received data from one of the monitored sockets
                uint32_t buffer[BUFFER_SIZE_WORDS];
                //while (valread != EAGAIN) {
                    std::unique_lock<std::mutex> lk(queues_mutexes[fd]);
                    ssize_t valread = recv(fd, reinterpret_cast<char*>(buffer), sizeof(buffer), 0);
                    if (valread > 0) {
                        //printf("[RICEVUTO]\t FROM %d\n", fd);
                        int opt_incr = (valread % 4) ? 1 : 0;
                        for (int q_i = 0; q_i < (valread/4) + opt_incr; q_i++) {
                            queues_array[fd].put(buffer[q_i]);
                        }

                        /*
                        bytes_read += valread;
                        int kilos = 0;
                        if ((kilos = bytes_read / 1024) > 0) {
                            kBytes_read += kilos;
                            bytes_read -= (kilos * 1024);
                            //printf("reade bites %lu", bytes_read);
                        }*/
                    }
                    lk.unlock();
                //}

            }
        }

        ///auto end = std::chrono::high_resolution_clock::now();
        ///double time_taken = std::chrono::duration_cast<std::chrono::nanoseconds>(end - start).count();
        //time taken in milliseconds
        ///
        /*time_taken *= 1e-6;
        total_time_taken += time_taken;

        if (total_time_taken > 3e4) {
            times.push_back(total_time_taken);
            tot_received_data.push_back(kBytes_read);
            break;
        }*/
        ///
    }

}

std::vector<double> times;
std::vector<double> timed_means;

double tot_time_taken = 0;
uint32_t tot_size_full_event = 0;
uint32_t num_events_stored = 0;
uint32_t fragments_lost = 0;
int fragments_per_event = max_fd - min_fd + 1;
void builder_thread (std::array<ControlledQueue, MAX_EVENTS> &queues_array, uint32_t &runNumber) {

    uint32_t counter = 0;
    while (1) {
        auto start = std::chrono::high_resolution_clock::now();
        if ( (max_fd < min_fd) || (exp_num <= 0) || ((max_fd - min_fd + 1) != exp_num)) {
            std::unique_lock<std::mutex> conn_lk(conn_mutex);
            while ( (max_fd < min_fd) || (exp_num <= 0) || ((max_fd - min_fd + 1) != exp_num)) {
                conn_cv.wait(conn_lk);
            }

            conn_lk.unlock();
        }
        //printf("sono fuori bro");

        FullEvent fullEvent;
        fullEvent.headerSize = 5;
        fullEvent.runNumber = runNumber;
        fullEvent.eventNumber = counter;

        fullEvent.fragmentsArray = new Fragment[max_fd - min_fd + 1];

        uint32_t fullEventPayloadSize = 0;

        double sumsize = 0;

        for (int i = min_fd; i <= max_fd; i++){
            //std::unique_lock<std::mutex> lk(queues_mutexes[i]);
            int inCurrentEventNumber = 0;
            while (inCurrentEventNumber != 1) {
                try {
                    uint32_t starter = queues_array[i].get();

                    if (starter == FRAGMENT_HEADER_MARKER) {
                        uint32_t headerSize = queues_array[i].get();
                        uint32_t fragmentSize = queues_array[i].get();
                        uint32_t* buffer = new uint32_t[fragmentSize];
                        buffer[0] = starter;
                        buffer[1] = headerSize;
                        buffer[2] = fragmentSize;


                        for (int j = 3; j < fragmentSize; j++) {
                            buffer[j] = queues_array[i].get();
                        }

                        if (getDetectorEventNumber(buffer) < fullEvent.eventNumber) {
                            continue;
                        } else if (getDetectorEventNumber(buffer) == fullEvent.eventNumber) {

                            Fragment& fragment = fullEvent.fragmentsArray[i - min_fd];
                            decode_fragment(buffer, fragment);
                            inCurrentEventNumber = 1;
                            
                            fullEventPayloadSize += fragment.header.fragmentSize;

                        } else {
                            printf("È successo un cazzo di casino");
                        }
                        delete [] buffer;
                    }
                } catch (const TimeoutException& ex) {
                    //printf("Ho catchato\n");
                    inCurrentEventNumber = 1;
                    Fragment& fragment = fullEvent.fragmentsArray[i - min_fd];
                    Header& header = fragment.header;
                    header.sourceIdentifier = i - min_fd;
                    header.runNumber = runNumber;
                    header.detectorEventNumber = counter;
                    header.numberOfStatusElements = 1;

                    uint32_t firstStatusElement = 0x0;
                    firstStatusElement  |= TIMEOUT_ERROR;

                    header.statusElementsArray = new uint32_t[header.numberOfStatusElements];
                    header.statusElementsArray[0] = firstStatusElement;

                    header.headerSize = 7 + header.numberOfStatusElements;
                    header.fragmentSize = header.headerSize;

                    //fragment.header = header;

                    //fullEvent.fragmentsArray[i - min_fd] = fragment;
                    fullEventPayloadSize += fragment.header.fragmentSize;

                    fragments_lost++;
                }
            }

            sumsize += queues_array[i].size();

            //lk.unlock();
        }

        double mean = sumsize / queues_array.size();
        //timed_means.push_back(mean);

        fullEvent.eventSize = fullEvent.headerSize + fullEventPayloadSize;
        //printFullEvent(fullEvent);
        num_events_stored = counter;
        counter++;

        auto end = std::chrono::high_resolution_clock::now();
        double time_taken = std::chrono::duration_cast<std::chrono::nanoseconds>(end - start).count();

        time_taken *= 1e-9;

        tot_time_taken += time_taken;
        //times.push_back(tot_time_taken);
        tot_size_full_event += fullEvent.eventSize;

        //printf("timee %f", tot_time_taken);

        if (tot_time_taken >= 30) break;
    }
}


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

    signal(SIGTERM, term_handler);


    if (argc != 5) {
        printf("Usage: %s portNumber runNumber numClients timeout_ms\n", argv[0]);
        exit(EXIT_FAILURE);
    }
    int port = atoi(argv[1]);
    uint32_t runNumber = atoi(argv[2]);
    exp_num = atoi(argv[3]);
    int timeout_ms = atoi(argv[4]);

    printf("You chose parameters: pnum %d runNum %d numClients %d timeout %d", port, runNumber, exp_num, timeout_ms);

    printf("Start socket port %d\n", port);
 
    int master_socket;
    const int opt = 1;


    master_socket = makeSocket();

    //set master socket to allow multiple connections , 
    //this is just a good habit, it will work without this 
    if( setsockopt(master_socket, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, 
          sizeof(opt)) < 0 )  
    {  
        perror("setsockopt");  
        exit(EXIT_FAILURE);  
    }

    if( setsockopt(master_socket, IPPROTO_TCP, TCP_NODELAY, (char *)&opt, 
          sizeof(opt)) < 0 )  
    {  
        perror("setsockopt");  
        exit(EXIT_FAILURE);  
    }

    bindSocketPort(master_socket, port);
    startListening(master_socket);

    int flags = fcntl(master_socket, F_GETFL, 0);
    fcntl(master_socket, F_SETFL, flags | O_NONBLOCK);

    epoll_event ev, events[MAX_EVENTS];
    std::array<uint64_t, MAX_EVENTS> kBytes_read_on_descr;

    //The atomic here is used as a flag to tell the thread to stop
    std::vector<std::thread> vThreads;

    //create the epoll instance
    int epoll_fd = epoll_create1(0);
    if (epoll_fd == -1) {
        printf("Failed to create epoll file descriptor\n");
        exit(EXIT_FAILURE);
    }

    ev.data.fd = master_socket;
    // Reading events with edge triggered mode
    ev.events = EPOLLIN | EPOLLEXCLUSIVE;//| EPOLLET;

    // Allowing epoll to monitor the master_socket
    if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, master_socket, &ev) == -1){
        perror("epoll_ctl");
        exit(EXIT_FAILURE);
    }
    
    std::array<std::thread, READER_THREADS> vT;
    std::array<int, READER_THREADS> thread_flags;

    // Creating the data structure and initialization with max size and timeout ez win
    std::array<ControlledQueue, MAX_EVENTS> queues_array;
    for (auto& queue : queues_array) {
        queue.init(MAX_QUEUE_SIZE, timeout_ms * 1000);
    }
    
    for (int t_i = 0; t_i < READER_THREADS; t_i++) {
        thread_flags[t_i] = 0;
        vT[t_i] = std::thread(thradizable, std::ref(epoll_fd), std::ref(master_socket), std::ref(queues_array), std::cref(thread_flags.at(t_i)), t_i);
        //vT[t_i].detach();
    }

    std::thread bdth(builder_thread, std::ref(queues_array), std::ref(runNumber));

    //ADD CONSUMER THREAD

    bdth.join();

    //for (double mean : timed_means) {
    //    printf("%.0f ", mean);
    //}
    //sleep(30);
    printf("fragments lost %d\n", fragments_lost);
    printf("tot ev %d\n", num_events_stored);
    std::ofstream outfile;

    //Test on queue size over time
    //outfile.open("queue_occup_1kmean_20ms_timeout50ms_500clients.csv");
    //outfile << "times;means;\n";

    //auto iter_times = times.begin();
    //auto iter_sizes = timed_means.begin();

    //for ( ; iter_times != times.end() && iter_sizes != timed_means.end(); (++iter_times, ++iter_sizes)) {
    //    outfile << *iter_times << ";" << *iter_sizes << ";\n";
    //}

    outfile.open("mean_4_std_0_meantime_0ms_stddevtime_0ms_NODELAY.csv", std::ios_base::app);
    outfile << timeout_ms << ";" << tot_time_taken << ";" << tot_size_full_event * 4 << ";" << fragments_lost/static_cast<double>(fragments_per_event * num_events_stored) << ";\n";

    if (close(epoll_fd)) {
        printf("Failed to close epoll file descriptor");
        exit(EXIT_FAILURE);
    }

    return 0;
}