/*
Copyright (c) 2020 Intel Corporation

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#pragma once
#include "dbus_log_watcher.hpp"
#include "dbus_singleton.hpp"
#include "dbus_utility.hpp"
#include "error_messages.hpp"
#include "event_log.hpp"
#include "event_matches_filter.hpp"
#include "event_service_store.hpp"
#include "filesystem_log_watcher.hpp"
#include "metric_report.hpp"
#include "ossl_random.hpp"
#include "persistent_data.hpp"
#include "subscription.hpp"
#include "utility.hpp"
#include "utils/dbus_event_log_entry.hpp"
#include "utils/json_utils.hpp"
#include "utils/time_utils.hpp"

#include <boost/asio/io_context.hpp>
#include <boost/asio/steady_timer.hpp>
#include <boost/circular_buffer.hpp>
#include <boost/container/flat_map.hpp>
#include <boost/url/format.hpp>
#include <boost/url/url_view_base.hpp>

#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <format>
#include <fstream>
#include <memory>
#include <string>
#include <string_view>
#include <utility>
#include <variant>

namespace redfish
{

static constexpr const char* eventFormatType = "Event";
static constexpr const char* metricReportFormatType = "MetricReport";

static constexpr const char* eventServiceFile =
    "/var/lib/bmcweb/eventservice_config.json";

class EventServiceManager
{
  private:
    bool serviceEnabled = false;
    uint32_t retryAttempts = 0;
    uint32_t retryTimeoutInterval = 0;

    size_t noOfEventLogSubscribers{0};
    size_t noOfMetricReportSubscribers{0};
    std::optional<DbusEventLogMonitor> dbusEventLogMonitor;
    std::optional<DbusTelemetryMonitor> matchTelemetryMonitor;
    std::optional<FilesystemLogWatcher> filesystemLogMonitor;
    boost::container::flat_map<std::string, std::shared_ptr<Subscription>>
        subscriptionsMap;

    uint64_t eventId{1};

    struct Event
    {
        std::string id;
        nlohmann::json message;
    };

    constexpr static size_t maxMessages = 200;
    boost::circular_buffer<Event> messages{maxMessages};

    boost::asio::io_context& ioc;

  public:
    EventServiceManager(const EventServiceManager&) = delete;
    EventServiceManager& operator=(const EventServiceManager&) = delete;
    EventServiceManager(EventServiceManager&&) = delete;
    EventServiceManager& operator=(EventServiceManager&&) = delete;
    ~EventServiceManager() = default;

    explicit EventServiceManager(boost::asio::io_context& iocIn) : ioc(iocIn)
    {
        // Load config from persist store.
        initConfig();
    }

    static EventServiceManager&
        getInstance(boost::asio::io_context* ioc = nullptr)
    {
        static EventServiceManager handler(*ioc);
        return handler;
    }

    void initConfig()
    {
        loadOldBehavior();

        persistent_data::EventServiceConfig eventServiceConfig =
            persistent_data::EventServiceStore::getInstance()
                .getEventServiceConfig();

        serviceEnabled = eventServiceConfig.enabled;
        retryAttempts = eventServiceConfig.retryAttempts;
        retryTimeoutInterval = eventServiceConfig.retryTimeoutInterval;

        for (const auto& it : persistent_data::EventServiceStore::getInstance()
                                  .subscriptionsConfigMap)
        {
            std::shared_ptr<persistent_data::UserSubscription> newSub =
                it.second;

            boost::system::result<boost::urls::url> url =
                boost::urls::parse_absolute_uri(newSub->destinationUrl);

            if (!url)
            {
                BMCWEB_LOG_ERROR(
                    "Failed to validate and split destination url");
                continue;
            }
            std::shared_ptr<Subscription> subValue =
                std::make_shared<Subscription>(newSub, *url, ioc);
            std::string id = subValue->userSub->id;
            subValue->deleter = [id]() {
                EventServiceManager::getInstance().deleteSubscription(id);
            };

            subscriptionsMap.emplace(id, subValue);

            updateNoOfSubscribersCount();

            // Update retry configuration.
            subValue->updateRetryConfig(retryAttempts, retryTimeoutInterval);

            // schedule a heartbeat if sendHeartbeat was set to true
            if (subValue->userSub->sendHeartbeat)
            {
                subValue->scheduleNextHeartbeatEvent();
            }
        }
    }

    static void loadOldBehavior()
    {
        std::ifstream eventConfigFile(eventServiceFile);
        if (!eventConfigFile.good())
        {
            BMCWEB_LOG_DEBUG("Old eventService config not exist");
            return;
        }
        auto jsonData = nlohmann::json::parse(eventConfigFile, nullptr, false);
        if (jsonData.is_discarded())
        {
            BMCWEB_LOG_ERROR("Old eventService config parse error.");
            return;
        }

        const nlohmann::json::object_t* obj =
            jsonData.get_ptr<const nlohmann::json::object_t*>();
        for (const auto& item : *obj)
        {
            if (item.first == "Configuration")
            {
                persistent_data::EventServiceStore::getInstance()
                    .getEventServiceConfig()
                    .fromJson(item.second);
            }
            else if (item.first == "Subscriptions")
            {
                for (const auto& elem : item.second)
                {
                    std::optional<persistent_data::UserSubscription>
                        newSubscription =
                            persistent_data::UserSubscription::fromJson(elem,
                                                                        true);
                    if (!newSubscription)
                    {
                        BMCWEB_LOG_ERROR("Problem reading subscription "
                                         "from old persistent store");
                        continue;
                    }
                    persistent_data::UserSubscription& newSub =
                        *newSubscription;

                    std::uniform_int_distribution<uint32_t> dist(0);
                    bmcweb::OpenSSLGenerator gen;

                    std::string id;

                    int retry = 3;
                    while (retry != 0)
                    {
                        id = std::to_string(dist(gen));
                        if (gen.error())
                        {
                            retry = 0;
                            break;
                        }
                        newSub.id = id;
                        auto inserted =
                            persistent_data::EventServiceStore::getInstance()
                                .subscriptionsConfigMap.insert(std::pair(
                                    id, std::make_shared<
                                            persistent_data::UserSubscription>(
                                            newSub)));
                        if (inserted.second)
                        {
                            break;
                        }
                        --retry;
                    }

                    if (retry <= 0)
                    {
                        BMCWEB_LOG_ERROR(
                            "Failed to generate random number from old "
                            "persistent store");
                        continue;
                    }
                }
            }

            persistent_data::getConfig().writeData();
            std::error_code ec;
            std::filesystem::remove(eventServiceFile, ec);
            if (ec)
            {
                BMCWEB_LOG_DEBUG(
                    "Failed to remove old event service file.  Ignoring");
            }
            else
            {
                BMCWEB_LOG_DEBUG("Remove old eventservice config");
            }
        }
    }

    void updateSubscriptionData() const
    {
        persistent_data::EventServiceStore::getInstance()
            .eventServiceConfig.enabled = serviceEnabled;
        persistent_data::EventServiceStore::getInstance()
            .eventServiceConfig.retryAttempts = retryAttempts;
        persistent_data::EventServiceStore::getInstance()
            .eventServiceConfig.retryTimeoutInterval = retryTimeoutInterval;

        persistent_data::getConfig().writeData();
    }

    void setEventServiceConfig(const persistent_data::EventServiceConfig& cfg)
    {
        bool updateConfig = false;
        bool updateRetryCfg = false;

        if (serviceEnabled)
        {
            if (noOfEventLogSubscribers > 0U)
            {
                if constexpr (BMCWEB_REDFISH_DBUS_LOG)
                {
                    if (!dbusEventLogMonitor)
                    {
                        if constexpr (
                            BMCWEB_EXPERIMENTAL_REDFISH_DBUS_LOG_SUBSCRIPTION)
                        {
                            dbusEventLogMonitor.emplace();
                        }
                    }
                }
                else
                {
                    if (!filesystemLogMonitor)
                    {
                        filesystemLogMonitor.emplace(ioc);
                    }
                }
            }
            else
            {
                dbusEventLogMonitor.reset();
                filesystemLogMonitor.reset();
            }

            if (noOfMetricReportSubscribers > 0U)
            {
                if (!matchTelemetryMonitor)
                {
                    matchTelemetryMonitor.emplace();
                }
            }
            else
            {
                matchTelemetryMonitor.reset();
            }
        }
        else
        {
            matchTelemetryMonitor.reset();
            dbusEventLogMonitor.reset();
            filesystemLogMonitor.reset();
        }

        if (serviceEnabled != cfg.enabled)
        {
            serviceEnabled = cfg.enabled;
            updateConfig = true;
        }

        if (retryAttempts != cfg.retryAttempts)
        {
            retryAttempts = cfg.retryAttempts;
            updateConfig = true;
            updateRetryCfg = true;
        }

        if (retryTimeoutInterval != cfg.retryTimeoutInterval)
        {
            retryTimeoutInterval = cfg.retryTimeoutInterval;
            updateConfig = true;
            updateRetryCfg = true;
        }

        if (updateConfig)
        {
            updateSubscriptionData();
        }

        if (updateRetryCfg)
        {
            // Update the changed retry config to all subscriptions
            for (const auto& it :
                 EventServiceManager::getInstance().subscriptionsMap)
            {
                Subscription& entry = *it.second;
                entry.updateRetryConfig(retryAttempts, retryTimeoutInterval);
            }
        }
    }

    void updateNoOfSubscribersCount()
    {
        size_t eventLogSubCount = 0;
        size_t metricReportSubCount = 0;
        for (const auto& it : subscriptionsMap)
        {
            std::shared_ptr<Subscription> entry = it.second;
            if (entry->userSub->eventFormatType == eventFormatType)
            {
                eventLogSubCount++;
            }
            else if (entry->userSub->eventFormatType == metricReportFormatType)
            {
                metricReportSubCount++;
            }
        }
        noOfEventLogSubscribers = eventLogSubCount;
        if (eventLogSubCount > 0U)
        {
            if constexpr (BMCWEB_REDFISH_DBUS_LOG)
            {
                if (!dbusEventLogMonitor &&
                    BMCWEB_EXPERIMENTAL_REDFISH_DBUS_LOG_SUBSCRIPTION)
                {
                    dbusEventLogMonitor.emplace();
                }
            }
            else
            {
                if (!filesystemLogMonitor)
                {
                    filesystemLogMonitor.emplace(ioc);
                }
            }
        }
        else
        {
            dbusEventLogMonitor.reset();
            filesystemLogMonitor.reset();
        }

        noOfMetricReportSubscribers = metricReportSubCount;
        if (metricReportSubCount > 0U)
        {
            if (!matchTelemetryMonitor)
            {
                matchTelemetryMonitor.emplace();
            }
        }
        else
        {
            matchTelemetryMonitor.reset();
        }
    }

    std::shared_ptr<Subscription> getSubscription(const std::string& id)
    {
        auto obj = subscriptionsMap.find(id);
        if (obj == subscriptionsMap.end())
        {
            BMCWEB_LOG_ERROR("No subscription exist with ID:{}", id);
            return nullptr;
        }
        std::shared_ptr<Subscription> subValue = obj->second;
        return subValue;
    }

    std::string
        addSubscriptionInternal(const std::shared_ptr<Subscription>& subValue)
    {
        std::uniform_int_distribution<uint32_t> dist(0);
        bmcweb::OpenSSLGenerator gen;

        std::string id;

        int retry = 3;
        while (retry != 0)
        {
            id = std::to_string(dist(gen));
            if (gen.error())
            {
                retry = 0;
                break;
            }
            auto inserted = subscriptionsMap.insert(std::pair(id, subValue));
            if (inserted.second)
            {
                break;
            }
            --retry;
        }

        if (retry <= 0)
        {
            BMCWEB_LOG_ERROR("Failed to generate random number");
            return "";
        }

        // Set Subscription ID for back trace
        subValue->userSub->id = id;

        persistent_data::EventServiceStore::getInstance()
            .subscriptionsConfigMap.emplace(id, subValue->userSub);

        updateNoOfSubscribersCount();

        // Update retry configuration.
        subValue->updateRetryConfig(retryAttempts, retryTimeoutInterval);

        return id;
    }

    std::string
        addSSESubscription(const std::shared_ptr<Subscription>& subValue,
                           std::string_view lastEventId)
    {
        std::string id = addSubscriptionInternal(subValue);

        if (!lastEventId.empty())
        {
            BMCWEB_LOG_INFO("Attempting to find message for last id {}",
                            lastEventId);
            boost::circular_buffer<Event>::iterator lastEvent =
                std::find_if(messages.begin(), messages.end(),
                             [&lastEventId](const Event& event) {
                                 return event.id == lastEventId;
                             });
            // Can't find a matching ID
            if (lastEvent == messages.end())
            {
                nlohmann::json msg = messages::eventBufferExceeded();
                // If the buffer overloaded, send all messages.
                subValue->sendEventToSubscriber(msg);
                lastEvent = messages.begin();
            }
            else
            {
                // Skip the last event the user already has
                lastEvent++;
            }

            for (boost::circular_buffer<Event>::const_iterator event =
                     lastEvent;
                 lastEvent != messages.end(); lastEvent++)
            {
                subValue->sendEventToSubscriber(event->message);
            }
        }
        return id;
    }

    std::string
        addPushSubscription(const std::shared_ptr<Subscription>& subValue)
    {
        std::string id = addSubscriptionInternal(subValue);
        subValue->deleter = [id]() {
            EventServiceManager::getInstance().deleteSubscription(id);
        };
        updateSubscriptionData();
        return id;
    }

    bool isSubscriptionExist(const std::string& id)
    {
        auto obj = subscriptionsMap.find(id);
        return obj != subscriptionsMap.end();
    }

    bool deleteSubscription(const std::string& id)
    {
        auto obj = subscriptionsMap.find(id);
        if (obj == subscriptionsMap.end())
        {
            BMCWEB_LOG_WARNING("Could not find subscription with id {}", id);
            return false;
        }
        subscriptionsMap.erase(obj);
        auto& event = persistent_data::EventServiceStore::getInstance();
        auto persistentObj = event.subscriptionsConfigMap.find(id);
        if (persistentObj == event.subscriptionsConfigMap.end())
        {
            BMCWEB_LOG_ERROR("Subscription wasn't in persistent data");
            return true;
        }
        persistent_data::EventServiceStore::getInstance()
            .subscriptionsConfigMap.erase(persistentObj);
        updateNoOfSubscribersCount();
        updateSubscriptionData();

        return true;
    }

    void deleteSseSubscription(const crow::sse_socket::Connection& thisConn)
    {
        for (auto it = subscriptionsMap.begin(); it != subscriptionsMap.end();)
        {
            std::shared_ptr<Subscription> entry = it->second;
            bool entryIsThisConn = entry->matchSseId(thisConn);
            if (entryIsThisConn)
            {
                persistent_data::EventServiceStore::getInstance()
                    .subscriptionsConfigMap.erase(entry->userSub->id);
                it = subscriptionsMap.erase(it);
                return;
            }
            it++;
        }
    }

    size_t getNumberOfSubscriptions() const
    {
        return subscriptionsMap.size();
    }

    size_t getNumberOfSSESubscriptions() const
    {
        auto size = std::ranges::count_if(
            subscriptionsMap,
            [](const std::pair<std::string, std::shared_ptr<Subscription>>&
                   entry) {
                return (entry.second->userSub->subscriptionType ==
                        subscriptionTypeSSE);
            });
        return static_cast<size_t>(size);
    }

    std::vector<std::string> getAllIDs()
    {
        std::vector<std::string> idList;
        for (const auto& it : subscriptionsMap)
        {
            idList.emplace_back(it.first);
        }
        return idList;
    }

    bool sendTestEventLog()
    {
        for (const auto& it : subscriptionsMap)
        {
            std::shared_ptr<Subscription> entry = it.second;
            if (!entry->sendTestEventLog())
            {
                return false;
            }
        }
        return true;
    }

    static void
        sendEventsToSubs(const std::vector<EventLogObjectsType>& eventRecords)
    {
        for (const auto& it :
             EventServiceManager::getInstance().subscriptionsMap)
        {
            Subscription& entry = *it.second;
            entry.filterAndSendEventLogs(eventRecords);
        }
    }

    static void sendTelemetryReportToSubs(
        const std::string& reportId, const telemetry::TimestampReadings& var)
    {
        for (const auto& it :
             EventServiceManager::getInstance().subscriptionsMap)
        {
            Subscription& entry = *it.second;
            entry.filterAndSendReports(reportId, var);
        }
    }

    void sendEvent(nlohmann::json::object_t eventMessage,
                   std::string_view origin, std::string_view resourceType)
    {
        eventMessage["EventId"] = eventId;

        eventMessage["EventTimestamp"] =
            redfish::time_utils::getDateTimeOffsetNow().first;
        eventMessage["OriginOfCondition"] = origin;

        // MemberId is 0 : since we are sending one event record.
        eventMessage["MemberId"] = "0";

        messages.push_back(Event(std::to_string(eventId), eventMessage));

        for (auto& it : subscriptionsMap)
        {
            std::shared_ptr<Subscription>& entry = it.second;
            if (!eventMatchesFilter(*entry->userSub, eventMessage,
                                    resourceType))
            {
                BMCWEB_LOG_DEBUG("Filter didn't match");
                continue;
            }

            nlohmann::json::array_t eventRecord;
            eventRecord.emplace_back(eventMessage);

            nlohmann::json msgJson;

            msgJson["@odata.type"] = "#Event.v1_4_0.Event";
            msgJson["Name"] = "Event Log";
            msgJson["Id"] = eventId;
            msgJson["Events"] = std::move(eventRecord);

            std::string strMsg = msgJson.dump(
                2, ' ', true, nlohmann::json::error_handler_t::replace);
            entry->sendEventToSubscriber(std::move(strMsg));
        }
        eventId++; // increment the eventId
    }
};

} // namespace redfish