// Copyright (C) 2013-2020 Bayerische Motoren Werke Aktiengesellschaft (BMW AG)
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifdef _WIN32
#include <WinSock2.h>
#include <ws2tcpip.h>
#else
#include <poll.h>
#include <unistd.h>
#include <sys/eventfd.h>
#endif

#include <fcntl.h>
#include <cstdio>

#include <chrono>

#include <CommonAPI/DBus/DBusMainLoopContext.hpp>
#include <CommonAPI/DBus/DBusConnection.hpp>

namespace CommonAPI {
namespace DBus {

DBusDispatchSource::DBusDispatchSource(std::weak_ptr<DBusConnection> dbusConnection):
    dbusConnection_(dbusConnection) {
}

DBusDispatchSource::~DBusDispatchSource() {
}

bool DBusDispatchSource::prepare(int64_t &_timeout) {
    _timeout = -1;
    if(auto itsConnection = dbusConnection_.lock()) {
        return itsConnection->isDispatchReady();
    }
    return false;
}

bool DBusDispatchSource::check() {
    if(auto itsConnection = dbusConnection_.lock()) {
        return itsConnection->isDispatchReady();
    }
    return false;
}

bool DBusDispatchSource::dispatch() {
    if(auto itsConnection = dbusConnection_.lock()) {
        return itsConnection->singleDispatch();
    }
    return false;
}

DBusQueueDispatchSource::DBusQueueDispatchSource(DBusQueueWatch* watch) :
    watch_(watch) {
    watch_->addDependentDispatchSource(this);
}

DBusQueueDispatchSource::~DBusQueueDispatchSource() {
    watch_->removeDependentDispatchSource(this);
}

bool DBusQueueDispatchSource::prepare(int64_t& timeout) {
    timeout = -1;
    return !watch_->emptyQueue();
}

bool DBusQueueDispatchSource::check() {
    return !watch_->emptyQueue();
}

bool DBusQueueDispatchSource::dispatch() {
    if (auto queueEntry = watch_->frontQueue()) {
        watch_->popQueue();
        watch_->processQueueEntry(queueEntry);
    }

    return !watch_->emptyQueue();
}

DBusWatch::DBusWatch(::DBusWatch* libdbusWatch, std::weak_ptr<MainLoopContext>& mainLoopContext,
                     std::weak_ptr<DBusConnection>& dbusConnection):
                libdbusWatch_(libdbusWatch),
                mainLoopContext_(mainLoopContext),
                dbusConnection_(dbusConnection) {
    if (NULL == libdbusWatch_) {
        COMMONAPI_ERROR(std::string(__FUNCTION__) + " libdbusWatch_ == NULL");
    }
}

bool DBusWatch::isReadyToBeWatched() {
    return 0 != dbus_watch_get_enabled(libdbusWatch_);
}

void DBusWatch::startWatching() {
    if(!dbus_watch_get_enabled(libdbusWatch_)) stopWatching();

    unsigned int channelFlags_ = dbus_watch_get_flags(libdbusWatch_);
    short int pollFlags = 0;

    if(channelFlags_ & DBUS_WATCH_READABLE) {
        pollFlags |= POLLIN;
    }
    if(channelFlags_ & DBUS_WATCH_WRITABLE) {
        pollFlags |= POLLOUT;
    }

#ifdef _WIN32
    pollFileDescriptor_.fd = dbus_watch_get_socket(libdbusWatch_);
    wsaEvent_ = WSACreateEvent();
    WSAEventSelect(pollFileDescriptor_.fd, wsaEvent_, FD_READ);
#else
    pollFileDescriptor_.fd = dbus_watch_get_unix_fd(libdbusWatch_);
#endif

    pollFileDescriptor_.events = pollFlags;
    pollFileDescriptor_.revents = 0;

    auto lockedContext = mainLoopContext_.lock();
    if (NULL == lockedContext) {
        COMMONAPI_ERROR(std::string(__FUNCTION__) + " lockedContext == NULL");
    } else {
        lockedContext->registerWatch(this);
    }
}

void DBusWatch::stopWatching() {
    auto lockedContext = mainLoopContext_.lock();
    if (lockedContext) {
        lockedContext->deregisterWatch(this);
    }
}

const pollfd& DBusWatch::getAssociatedFileDescriptor() {
    return pollFileDescriptor_;
}

#ifdef _WIN32
const HANDLE& DBusWatch::getAssociatedEvent() {
    return wsaEvent_;
}
#endif

void DBusWatch::dispatch(unsigned int eventFlags) {
#ifdef _WIN32
    unsigned int dbusWatchFlags = 0;

    if (eventFlags & (POLLRDBAND | POLLRDNORM)) {
        dbusWatchFlags |= DBUS_WATCH_READABLE;
    }
    if (eventFlags & POLLWRNORM) {
        dbusWatchFlags |= DBUS_WATCH_WRITABLE;
    }
    if (eventFlags & (POLLERR | POLLNVAL)) {
        dbusWatchFlags |= DBUS_WATCH_ERROR;
    }
    if (eventFlags & POLLHUP) {
        dbusWatchFlags |= DBUS_WATCH_HANGUP;
    }
#else
    // Pollflags do not correspond directly to DBus watch flags
    unsigned int dbusWatchFlags = (eventFlags & POLLIN) |
                            ((eventFlags & POLLOUT) >> 1) |
                            ((eventFlags & POLLERR) >> 1) |
                            ((eventFlags & POLLHUP) >> 1);
#endif
    std::shared_ptr<DBusConnection> itsConnection = dbusConnection_.lock();
    if(itsConnection) {
        if(itsConnection->setDispatching(true)) {
            dbus_bool_t response = dbus_watch_handle(libdbusWatch_, dbusWatchFlags);
            if (!response) {
                printf("dbus_watch_handle returned FALSE!");
            }
            itsConnection->setDispatching(false);
        }
    }
}

const std::vector<DispatchSource*>& DBusWatch::getDependentDispatchSources() {
    std::lock_guard<std::mutex> itsLock(dependentDispatchSourcesMutex_);
    return dependentDispatchSources_;
}

void DBusWatch::addDependentDispatchSource(DispatchSource* dispatchSource) {
    std::lock_guard<std::mutex> itsLock(dependentDispatchSourcesMutex_);
    dependentDispatchSources_.push_back(dispatchSource);
}

DBusQueueWatch::DBusQueueWatch(std::shared_ptr<DBusConnection> _connection) :
#ifdef _WIN32
        pipeValue_(4)
#else
        eventFd_(0),
        eventFdValue_(1)
#endif
{
#ifdef _WIN32
    WSADATA wsaData;
    int iResult;

    SOCKET ListenSocket = INVALID_SOCKET;

    struct addrinfo *result = NULL;
    struct addrinfo hints;

    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed with error: %d\n", iResult);
    }

    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    hints.ai_flags = AI_PASSIVE;

    // Resolve the server address and port
    iResult = getaddrinfo(NULL, "0", &hints, &result);
    if (iResult != 0) {
        printf("getaddrinfo failed with error: %d\n", iResult);
        WSACleanup();
    }

    // Create a SOCKET for connecting to server
    ListenSocket = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
    if (ListenSocket == INVALID_SOCKET) {
        printf("socket failed with error: %ld\n", WSAGetLastError());
        freeaddrinfo(result);
        WSACleanup();
    }

    // Setup the TCP listening socket
    iResult = bind(ListenSocket, result->ai_addr, (int)result->ai_addrlen);
    if (iResult == SOCKET_ERROR) {
        printf("bind failed with error: %d\n", WSAGetLastError());
        freeaddrinfo(result);
        closesocket(ListenSocket);
        WSACleanup();
    }

    sockaddr* connected_addr = new sockaddr();
    USHORT port = 0;
    int namelength = sizeof(sockaddr);
    iResult = getsockname(ListenSocket, connected_addr, &namelength);
    if (iResult == SOCKET_ERROR) {
        printf("getsockname failed with error: %d\n", WSAGetLastError());
    } else if (connected_addr->sa_family == AF_INET) {
        port = ((struct sockaddr_in*)connected_addr)->sin_port;
    }
    delete connected_addr;

    freeaddrinfo(result);

    iResult = listen(ListenSocket, SOMAXCONN);
    if (iResult == SOCKET_ERROR) {
        printf("listen failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
    }

    wsaData;
    pipeFileDescriptors_[0] = INVALID_SOCKET;
    struct addrinfo *ptr = NULL;

    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed with error: %d\n", iResult);
    }

    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    // Resolve the server address and port
    iResult = getaddrinfo("127.0.0.1", std::to_string(ntohs(port)).c_str(), &hints, &result);
    if (iResult != 0) {
        printf("getaddrinfo failed with error: %d\n", iResult);
        WSACleanup();
    }

    // Attempt to connect to an address until one succeeds
    for (ptr = result; ptr != NULL; ptr = ptr->ai_next) {

        // Create a SOCKET for connecting to server
        pipeFileDescriptors_[0] = socket(ptr->ai_family, ptr->ai_socktype,
            ptr->ai_protocol);
        if (pipeFileDescriptors_[0] == INVALID_SOCKET) {
            printf("socket failed with error: %ld\n", WSAGetLastError());
            WSACleanup();
        }

        // Connect to server.
        iResult = connect(pipeFileDescriptors_[0], ptr->ai_addr, (int)ptr->ai_addrlen);
        if (iResult == SOCKET_ERROR) {
            printf("connect failed with error: %ld\n", WSAGetLastError());
            closesocket(pipeFileDescriptors_[0]);
            pipeFileDescriptors_[0] = INVALID_SOCKET;
            continue;
        }
        break;
    }

    freeaddrinfo(result);

    if (pipeFileDescriptors_[0] == INVALID_SOCKET) {
        printf("Unable to connect to server!\n");
        WSACleanup();
    }

    // Accept a client socket
    pipeFileDescriptors_[1] = accept(ListenSocket, NULL, NULL);
    if (pipeFileDescriptors_[1] == INVALID_SOCKET) {
        printf("accept failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
    }
    pollFileDescriptor_.fd = pipeFileDescriptors_[0];
#else
    eventFd_ = eventfd(0, EFD_NONBLOCK | EFD_SEMAPHORE);
    if (eventFd_ == -1) {
        std::perror(__func__);
    }
    pollFileDescriptor_.fd = eventFd_;
#endif
    pollFileDescriptor_.events = POLLIN;

    connection_ = _connection;
}

DBusQueueWatch::~DBusQueueWatch() {
#ifdef _WIN32
    // shutdown the connection since no more data will be sent
    int iResult = shutdown(pipeFileDescriptors_[0], SD_SEND);
    if (iResult == SOCKET_ERROR) {
        printf("shutdown failed with error: %d\n", WSAGetLastError());
        closesocket(pipeFileDescriptors_[0]);
        WSACleanup();
    }

    // cleanup
    closesocket(pipeFileDescriptors_[0]);
    WSACleanup();
#else
    close(eventFd_);
#endif

    std::unique_lock<std::mutex> itsLock(queueMutex_);
    while(!queue_.empty()) {
        auto queueEntry = queue_.front();
        queue_.pop();
        queueEntry->clear();
    }
}

void DBusQueueWatch::dispatch(unsigned int) {
}

const pollfd& DBusQueueWatch::getAssociatedFileDescriptor() {
    return pollFileDescriptor_;
}

#ifdef _WIN32
const HANDLE& DBusQueueWatch::getAssociatedEvent() {
    return wsaEvent_;
}
#endif

const std::vector<DispatchSource*>& DBusQueueWatch::getDependentDispatchSources() {
    std::lock_guard<std::mutex> itsLock(dependentDispatchSourcesMutex_);
    return dependentDispatchSources_;
}

void DBusQueueWatch::addDependentDispatchSource(CommonAPI::DispatchSource* _dispatchSource) {
    std::lock_guard<std::mutex> itsLock(dependentDispatchSourcesMutex_);
    dependentDispatchSources_.push_back(_dispatchSource);
}

void DBusQueueWatch::removeDependentDispatchSource(CommonAPI::DispatchSource* _dispatchSource) {
    std::lock_guard<std::mutex> itsLock(dependentDispatchSourcesMutex_);
    std::vector<CommonAPI::DispatchSource*>::iterator it;

    for (it = dependentDispatchSources_.begin(); it != dependentDispatchSources_.end(); it++) {
        if ( (*it) == _dispatchSource ) {
            dependentDispatchSources_.erase(it);
            break;
        }
    }
}

void DBusQueueWatch::pushQueue(std::shared_ptr<QueueEntry> _queueEntry) {
    {
        std::unique_lock<std::mutex> itsLock(queueMutex_);
        queue_.push(_queueEntry);
    }

#ifdef _WIN32
    // Send an initial buffer
    char *sendbuf = "1";

    int iResult = send(pipeFileDescriptors_[1], sendbuf, (int)strlen(sendbuf), 0);
    if (iResult == SOCKET_ERROR) {
        int error = WSAGetLastError();

        if (error != WSANOTINITIALISED) {
            printf("send failed with error: %d\n", error);
        }
    }
#else
    while (write(eventFd_, &eventFdValue_, sizeof(eventFdValue_)) == -1) {
        if (errno != EAGAIN && errno != EINTR) {
            std::perror(__func__);
            break;
        }
        std::this_thread::yield();
    }
#endif
}

void DBusQueueWatch::popQueue() {
#ifdef _WIN32
    // Receive until the peer closes the connection
    int iResult;
    char recvbuf[1];
    int recvbuflen = 1;

    iResult = recv(pipeFileDescriptors_[0], recvbuf, recvbuflen, 0);
    if (iResult > 0) {
        //printf("Bytes received from %d: %d\n", wakeFd_.fd, iResult);
    }
    else if (iResult == 0) {
        printf("Connection closed\n");
    }
    else {
        printf("recv failed with error: %d\n", WSAGetLastError());
    }
#else
    std::uint64_t readValue(0);
    while (read(eventFd_, &readValue, sizeof(readValue)) == -1) {
        if (errno != EAGAIN && errno != EINTR) {
            std::perror(__func__);
            break;
        }
        std::this_thread::yield();
    }
#endif
    {
        std::unique_lock<std::mutex> itsLock(queueMutex_);
        queue_.pop();
    }
}

std::shared_ptr<QueueEntry> DBusQueueWatch::frontQueue() {
    std::unique_lock<std::mutex> itsLock(queueMutex_);

    if(queue_.empty()) {
        return NULL;
    } else {
        return queue_.front();
    }
}

bool DBusQueueWatch::emptyQueue() {
    std::unique_lock<std::mutex> itsLock(queueMutex_);

    return queue_.empty();
}

void DBusQueueWatch::processQueueEntry(std::shared_ptr<QueueEntry> _queueEntry) {
    std::shared_ptr<DBusConnection> itsConnection = connection_.lock();
    if(itsConnection) {
        _queueEntry->process(itsConnection);
    }
}

} // namespace DBus
} // namespace CommonAPI