/*
// 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_utility.hpp"
#include "error_messages.hpp"
#include "event_service_store.hpp"
#include "filter_expr_executor.hpp"
#include "generated/enums/event.hpp"
#include "generated/enums/log_entry.hpp"
#include "http_client.hpp"
#include "metric_report.hpp"
#include "ossl_random.hpp"
#include "persistent_data.hpp"
#include "registries.hpp"
#include "registries_selector.hpp"
#include "str_utility.hpp"
#include "utility.hpp"
#include "utils/json_utils.hpp"
#include "utils/time_utils.hpp"

#include <sys/inotify.h>

#include <boost/asio/io_context.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 <sdbusplus/bus/match.hpp>

#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <fstream>
#include <memory>
#include <ranges>
#include <span>

namespace redfish
{

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

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

static constexpr const uint8_t maxNoOfSubscriptions = 20;
static constexpr const uint8_t maxNoOfSSESubscriptions = 10;

// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
static std::optional<boost::asio::posix::stream_descriptor> inotifyConn;
static constexpr const char* redfishEventLogDir = "/var/log";
static constexpr const char* redfishEventLogFile = "/var/log/redfish";
static constexpr const size_t iEventSize = sizeof(inotify_event);

// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
static int inotifyFd = -1;
// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
static int dirWatchDesc = -1;
// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
static int fileWatchDesc = -1;
struct EventLogObjectsType
{
    std::string id;
    std::string timestamp;
    std::string messageId;
    std::vector<std::string> messageArgs;
};

namespace registries
{
static const Message*
    getMsgFromRegistry(const std::string& messageKey,
                       const std::span<const MessageEntry>& registry)
{
    std::span<const MessageEntry>::iterator messageIt = std::ranges::find_if(
        registry, [&messageKey](const MessageEntry& messageEntry) {
            return messageKey == messageEntry.first;
        });
    if (messageIt != registry.end())
    {
        return &messageIt->second;
    }

    return nullptr;
}

static const Message* formatMessage(std::string_view messageID)
{
    // Redfish MessageIds are in the form
    // RegistryName.MajorVersion.MinorVersion.MessageKey, so parse it to find
    // the right Message
    std::vector<std::string> fields;
    fields.reserve(4);

    bmcweb::split(fields, messageID, '.');
    if (fields.size() != 4)
    {
        return nullptr;
    }
    const std::string& registryName = fields[0];
    const std::string& messageKey = fields[3];

    // Find the right registry and check it for the MessageKey
    return getMsgFromRegistry(messageKey, getRegistryFromPrefix(registryName));
}
} // namespace registries

namespace event_log
{
inline bool getUniqueEntryID(const std::string& logEntry, std::string& entryID)
{
    static time_t prevTs = 0;
    static int index = 0;

    // Get the entry timestamp
    std::time_t curTs = 0;
    std::tm timeStruct = {};
    std::istringstream entryStream(logEntry);
    if (entryStream >> std::get_time(&timeStruct, "%Y-%m-%dT%H:%M:%S"))
    {
        curTs = std::mktime(&timeStruct);
        if (curTs == -1)
        {
            return false;
        }
    }
    // If the timestamp isn't unique, increment the index
    index = (curTs == prevTs) ? index + 1 : 0;

    // Save the timestamp
    prevTs = curTs;

    entryID = std::to_string(curTs);
    if (index > 0)
    {
        entryID += "_" + std::to_string(index);
    }
    return true;
}

inline int getEventLogParams(const std::string& logEntry,
                             std::string& timestamp, std::string& messageID,
                             std::vector<std::string>& messageArgs)
{
    // The redfish log format is "<Timestamp> <MessageId>,<MessageArgs>"
    // First get the Timestamp
    size_t space = logEntry.find_first_of(' ');
    if (space == std::string::npos)
    {
        return -EINVAL;
    }
    timestamp = logEntry.substr(0, space);
    // Then get the log contents
    size_t entryStart = logEntry.find_first_not_of(' ', space);
    if (entryStart == std::string::npos)
    {
        return -EINVAL;
    }
    std::string_view entry(logEntry);
    entry.remove_prefix(entryStart);
    // Use split to separate the entry into its fields
    std::vector<std::string> logEntryFields;
    bmcweb::split(logEntryFields, entry, ',');
    // We need at least a MessageId to be valid
    if (logEntryFields.empty())
    {
        return -EINVAL;
    }
    messageID = logEntryFields[0];

    // Get the MessageArgs from the log if there are any
    if (logEntryFields.size() > 1)
    {
        const std::string& messageArgsStart = logEntryFields[1];
        // If the first string is empty, assume there are no MessageArgs
        if (!messageArgsStart.empty())
        {
            messageArgs.assign(logEntryFields.begin() + 1,
                               logEntryFields.end());
        }
    }

    return 0;
}

inline void getRegistryAndMessageKey(const std::string& messageID,
                                     std::string& registryName,
                                     std::string& messageKey)
{
    // Redfish MessageIds are in the form
    // RegistryName.MajorVersion.MinorVersion.MessageKey, so parse it to find
    // the right Message
    std::vector<std::string> fields;
    fields.reserve(4);
    bmcweb::split(fields, messageID, '.');
    if (fields.size() == 4)
    {
        registryName = fields[0];
        messageKey = fields[3];
    }
}

inline int formatEventLogEntry(
    const std::string& logEntryID, const std::string& messageID,
    const std::span<std::string_view> messageArgs, std::string timestamp,
    const std::string& customText, nlohmann::json::object_t& logEntryJson)
{
    // Get the Message from the MessageRegistry
    const registries::Message* message = registries::formatMessage(messageID);

    if (message == nullptr)
    {
        return -1;
    }

    std::string msg =
        redfish::registries::fillMessageArgs(messageArgs, message->message);
    if (msg.empty())
    {
        return -1;
    }

    // Get the Created time from the timestamp. The log timestamp is in
    // RFC3339 format which matches the Redfish format except for the
    // fractional seconds between the '.' and the '+', so just remove them.
    std::size_t dot = timestamp.find_first_of('.');
    std::size_t plus = timestamp.find_first_of('+', dot);
    if (dot != std::string::npos && plus != std::string::npos)
    {
        timestamp.erase(dot, plus - dot);
    }

    // Fill in the log entry with the gathered data
    logEntryJson["EventId"] = logEntryID;

    logEntryJson["Severity"] = message->messageSeverity;
    logEntryJson["Message"] = std::move(msg);
    logEntryJson["MessageId"] = messageID;
    logEntryJson["MessageArgs"] = messageArgs;
    logEntryJson["EventTimestamp"] = std::move(timestamp);
    logEntryJson["Context"] = customText;
    return 0;
}

} // namespace event_log

class Subscription : public persistent_data::UserSubscription
{
  public:
    Subscription(const Subscription&) = delete;
    Subscription& operator=(const Subscription&) = delete;
    Subscription(Subscription&&) = delete;
    Subscription& operator=(Subscription&&) = delete;

    Subscription(const boost::urls::url_view_base& url,
                 boost::asio::io_context& ioc) :
        policy(std::make_shared<crow::ConnectionPolicy>())
    {
        destinationUrl = url;
        client.emplace(ioc, policy);
        // Subscription constructor
        policy->invalidResp = retryRespHandler;
    }

    explicit Subscription(crow::sse_socket::Connection& connIn) :
        sseConn(&connIn)
    {}

    ~Subscription() = default;

    bool sendEvent(std::string&& msg)
    {
        persistent_data::EventServiceConfig eventServiceConfig =
            persistent_data::EventServiceStore::getInstance()
                .getEventServiceConfig();
        if (!eventServiceConfig.enabled)
        {
            return false;
        }

        if (client)
        {
            client->sendData(
                std::move(msg), destinationUrl,
                static_cast<ensuressl::VerifyCertificate>(verifyCertificate),
                httpHeaders, boost::beast::http::verb::post);
            return true;
        }

        if (sseConn != nullptr)
        {
            eventSeqNum++;
            sseConn->sendEvent(std::to_string(eventSeqNum), msg);
        }
        return true;
    }

    bool eventMatchesFilter(const nlohmann::json::object_t& eventMessage,
                            std::string_view resType)
    {
        // If resourceTypes list is empty, assume all
        if (!resourceTypes.empty())
        {
            // Search the resourceTypes list for the subscription.
            auto resourceTypeIndex = std::ranges::find_if(
                resourceTypes, [resType](const std::string& rtEntry) {
                    return rtEntry == resType;
                });
            if (resourceTypeIndex == resourceTypes.end())
            {
                BMCWEB_LOG_DEBUG("Not subscribed to this resource");
                return false;
            }
            BMCWEB_LOG_DEBUG("ResourceType {} found in the subscribed list",
                             resType);
        }

        // If registryMsgIds list is empty, assume all
        if (!registryMsgIds.empty())
        {
            auto eventJson = eventMessage.find("MessageId");
            if (eventJson == eventMessage.end())
            {
                return false;
            }

            const std::string* messageId =
                eventJson->second.get_ptr<const std::string*>();
            if (messageId == nullptr)
            {
                BMCWEB_LOG_ERROR("EventType wasn't a string???");
                return false;
            }

            std::string registry;
            std::string messageKey;
            event_log::getRegistryAndMessageKey(*messageId, registry,
                                                messageKey);

            auto obj = std::ranges::find(registryMsgIds, registry);
            if (obj == registryMsgIds.end())
            {
                return false;
            }
        }

        if (filter)
        {
            if (!memberMatches(eventMessage, *filter))
            {
                BMCWEB_LOG_DEBUG("Filter didn't match");
                return false;
            }
        }

        return true;
    }

    bool sendTestEventLog()
    {
        nlohmann::json::array_t logEntryArray;
        nlohmann::json& logEntryJson = logEntryArray.emplace_back();

        logEntryJson["EventId"] = "TestID";
        logEntryJson["Severity"] = log_entry::EventSeverity::OK;
        logEntryJson["Message"] = "Generated test event";
        logEntryJson["MessageId"] = "OpenBMC.0.2.TestEventLog";
        // MemberId is 0 : since we are sending one event record.
        logEntryJson["MemberId"] = 0;
        logEntryJson["MessageArgs"] = nlohmann::json::array();
        logEntryJson["EventTimestamp"] =
            redfish::time_utils::getDateTimeOffsetNow().first;
        logEntryJson["Context"] = customText;

        nlohmann::json msg;
        msg["@odata.type"] = "#Event.v1_4_0.Event";
        msg["Id"] = std::to_string(eventSeqNum);
        msg["Name"] = "Event Log";
        msg["Events"] = logEntryArray;

        std::string strMsg =
            msg.dump(2, ' ', true, nlohmann::json::error_handler_t::replace);
        return sendEvent(std::move(strMsg));
    }

    void filterAndSendEventLogs(
        const std::vector<EventLogObjectsType>& eventRecords)
    {
        nlohmann::json::array_t logEntryArray;
        for (const EventLogObjectsType& logEntry : eventRecords)
        {
            std::vector<std::string_view> messageArgsView(
                logEntry.messageArgs.begin(), logEntry.messageArgs.end());

            nlohmann::json::object_t bmcLogEntry;
            if (event_log::formatEventLogEntry(
                    logEntry.id, logEntry.messageId, messageArgsView,
                    logEntry.timestamp, customText, bmcLogEntry) != 0)
            {
                BMCWEB_LOG_DEBUG("Read eventLog entry failed");
                continue;
            }

            if (!eventMatchesFilter(bmcLogEntry, ""))
            {
                continue;
            }

            logEntryArray.emplace_back(std::move(bmcLogEntry));
        }

        if (logEntryArray.empty())
        {
            BMCWEB_LOG_DEBUG("No log entries available to be transferred.");
            return;
        }

        nlohmann::json msg;
        msg["@odata.type"] = "#Event.v1_4_0.Event";
        msg["Id"] = std::to_string(eventSeqNum);
        msg["Name"] = "Event Log";
        msg["Events"] = std::move(logEntryArray);
        std::string strMsg =
            msg.dump(2, ' ', true, nlohmann::json::error_handler_t::replace);
        sendEvent(std::move(strMsg));
        eventSeqNum++;
    }

    void filterAndSendReports(const std::string& reportId,
                              const telemetry::TimestampReadings& var)
    {
        boost::urls::url mrdUri = boost::urls::format(
            "/redfish/v1/TelemetryService/MetricReportDefinitions/{}",
            reportId);

        // Empty list means no filter. Send everything.
        if (!metricReportDefinitions.empty())
        {
            if (std::ranges::find(metricReportDefinitions, mrdUri.buffer()) ==
                metricReportDefinitions.end())
            {
                return;
            }
        }

        nlohmann::json msg;
        if (!telemetry::fillReport(msg, reportId, var))
        {
            BMCWEB_LOG_ERROR("Failed to fill the MetricReport for DBus "
                             "Report with id {}",
                             reportId);
            return;
        }

        // Context is set by user during Event subscription and it must be
        // set for MetricReport response.
        if (!customText.empty())
        {
            msg["Context"] = customText;
        }

        std::string strMsg =
            msg.dump(2, ' ', true, nlohmann::json::error_handler_t::replace);
        sendEvent(std::move(strMsg));
    }

    void updateRetryConfig(uint32_t retryAttempts,
                           uint32_t retryTimeoutInterval)
    {
        if (policy == nullptr)
        {
            BMCWEB_LOG_DEBUG("Retry policy was nullptr, ignoring set");
            return;
        }
        policy->maxRetryAttempts = retryAttempts;
        policy->retryIntervalSecs = std::chrono::seconds(retryTimeoutInterval);
    }

    uint64_t getEventSeqNum() const
    {
        return eventSeqNum;
    }

    void setSubscriptionId(const std::string& id2)
    {
        BMCWEB_LOG_DEBUG("Subscription ID: {}", id2);
        subId = id2;
    }

    std::string getSubscriptionId()
    {
        return subId;
    }

    bool matchSseId(const crow::sse_socket::Connection& thisConn)
    {
        return &thisConn == sseConn;
    }

    // Check used to indicate what response codes are valid as part of our retry
    // policy.  2XX is considered acceptable
    static boost::system::error_code retryRespHandler(unsigned int respCode)
    {
        BMCWEB_LOG_DEBUG(
            "Checking response code validity for SubscriptionEvent");
        if ((respCode < 200) || (respCode >= 300))
        {
            return boost::system::errc::make_error_code(
                boost::system::errc::result_out_of_range);
        }

        // Return 0 if the response code is valid
        return boost::system::errc::make_error_code(
            boost::system::errc::success);
    }

  private:
    std::string subId;
    uint64_t eventSeqNum = 1;
    boost::urls::url host;
    std::shared_ptr<crow::ConnectionPolicy> policy;
    crow::sse_socket::Connection* sseConn = nullptr;

    std::optional<crow::HttpClient> client;

  public:
    std::optional<filter_ast::LogicalAnd> filter;
};

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

    std::streampos redfishLogFilePosition{0};
    size_t noOfEventLogSubscribers{0};
    size_t noOfMetricReportSubscribers{0};
    std::shared_ptr<sdbusplus::bus::match_t> matchTelemetryMonitor;
    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>(*url, ioc);

            subValue->id = newSub->id;
            subValue->destinationUrl = newSub->destinationUrl;
            subValue->protocol = newSub->protocol;
            subValue->verifyCertificate = newSub->verifyCertificate;
            subValue->retryPolicy = newSub->retryPolicy;
            subValue->customText = newSub->customText;
            subValue->eventFormatType = newSub->eventFormatType;
            subValue->subscriptionType = newSub->subscriptionType;
            subValue->registryMsgIds = newSub->registryMsgIds;
            subValue->registryPrefixes = newSub->registryPrefixes;
            subValue->resourceTypes = newSub->resourceTypes;
            subValue->httpHeaders = newSub->httpHeaders;
            subValue->metricReportDefinitions = newSub->metricReportDefinitions;

            if (subValue->id.empty())
            {
                BMCWEB_LOG_ERROR("Failed to add subscription");
            }
            subscriptionsMap.insert(std::pair(subValue->id, subValue));

            updateNoOfSubscribersCount();

            if constexpr (!BMCWEB_REDFISH_DBUS_LOG)
            {
                cacheRedfishLogFile();
            }

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

    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::shared_ptr<persistent_data::UserSubscription>
                        newSubscription =
                            persistent_data::UserSubscription::fromJson(elem,
                                                                        true);
                    if (newSubscription == nullptr)
                    {
                        BMCWEB_LOG_ERROR("Problem reading subscription "
                                         "from old persistent store");
                        continue;
                    }

                    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;
                        }
                        newSubscription->id = id;
                        auto inserted =
                            persistent_data::EventServiceStore::getInstance()
                                .subscriptionsConfigMap.insert(
                                    std::pair(id, newSubscription));
                        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 != cfg.enabled)
        {
            serviceEnabled = cfg.enabled;
            if (serviceEnabled && noOfMetricReportSubscribers != 0U)
            {
                registerMetricReportSignal();
            }
            else
            {
                unregisterMetricReportSignal();
            }
            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->eventFormatType == eventFormatType)
            {
                eventLogSubCount++;
            }
            else if (entry->eventFormatType == metricReportFormatType)
            {
                metricReportSubCount++;
            }
        }

        noOfEventLogSubscribers = eventLogSubCount;
        if (noOfMetricReportSubscribers != metricReportSubCount)
        {
            noOfMetricReportSubscribers = metricReportSubCount;
            if (noOfMetricReportSubscribers != 0U)
            {
                registerMetricReportSignal();
            }
            else
            {
                unregisterMetricReportSignal();
            }
        }
    }

    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 "";
        }

        std::shared_ptr<persistent_data::UserSubscription> newSub =
            std::make_shared<persistent_data::UserSubscription>();
        newSub->id = id;
        newSub->destinationUrl = subValue->destinationUrl;
        newSub->protocol = subValue->protocol;
        newSub->retryPolicy = subValue->retryPolicy;
        newSub->customText = subValue->customText;
        newSub->eventFormatType = subValue->eventFormatType;
        newSub->subscriptionType = subValue->subscriptionType;
        newSub->registryMsgIds = subValue->registryMsgIds;
        newSub->registryPrefixes = subValue->registryPrefixes;
        newSub->resourceTypes = subValue->resourceTypes;
        newSub->httpHeaders = subValue->httpHeaders;
        newSub->metricReportDefinitions = subValue->metricReportDefinitions;
        persistent_data::EventServiceStore::getInstance()
            .subscriptionsConfigMap.emplace(newSub->id, newSub);

        updateNoOfSubscribersCount();

        if constexpr (!BMCWEB_REDFISH_DBUS_LOG)
        {
            if (redfishLogFilePosition != 0)
            {
                cacheRedfishLogFile();
            }
        }
        // Update retry configuration.
        subValue->updateRetryConfig(retryAttempts, retryTimeoutInterval);

        // Set Subscription ID for back trace
        subValue->setSubscriptionId(id);

        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->sendEvent(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->sendEvent(event->message);
            }
        }
        return id;
    }

    std::string
        addPushSubscription(const std::shared_ptr<Subscription>& subValue)
    {
        std::string id = addSubscriptionInternal(subValue);

        updateSubscriptionData();
        return id;
    }

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

    void deleteSubscription(const std::string& id)
    {
        auto obj = subscriptionsMap.find(id);
        if (obj != subscriptionsMap.end())
        {
            subscriptionsMap.erase(obj);
            auto obj2 = persistent_data::EventServiceStore::getInstance()
                            .subscriptionsConfigMap.find(id);
            persistent_data::EventServiceStore::getInstance()
                .subscriptionsConfigMap.erase(obj2);
            updateNoOfSubscribersCount();
            updateSubscriptionData();
        }
    }

    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(
                        it->second->getSubscriptionId());
                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->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;
    }

    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 (!entry->eventMatchesFilter(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->sendEvent(std::move(strMsg));
            eventId++; // increment the eventId
        }
    }

    void resetRedfishFilePosition()
    {
        // Control would be here when Redfish file is created.
        // Reset File Position as new file is created
        redfishLogFilePosition = 0;
    }

    void cacheRedfishLogFile()
    {
        // Open the redfish file and read till the last record.

        std::ifstream logStream(redfishEventLogFile);
        if (!logStream.good())
        {
            BMCWEB_LOG_ERROR(" Redfish log file open failed ");
            return;
        }
        std::string logEntry;
        while (std::getline(logStream, logEntry))
        {
            redfishLogFilePosition = logStream.tellg();
        }
    }

    void readEventLogsFromFile()
    {
        std::ifstream logStream(redfishEventLogFile);
        if (!logStream.good())
        {
            BMCWEB_LOG_ERROR(" Redfish log file open failed");
            return;
        }

        std::vector<EventLogObjectsType> eventRecords;

        std::string logEntry;

        // Get the read pointer to the next log to be read.
        logStream.seekg(redfishLogFilePosition);

        while (std::getline(logStream, logEntry))
        {
            // Update Pointer position
            redfishLogFilePosition = logStream.tellg();

            std::string idStr;
            if (!event_log::getUniqueEntryID(logEntry, idStr))
            {
                continue;
            }

            if (!serviceEnabled || noOfEventLogSubscribers == 0)
            {
                // If Service is not enabled, no need to compute
                // the remaining items below.
                // But, Loop must continue to keep track of Timestamp
                continue;
            }

            std::string timestamp;
            std::string messageID;
            std::vector<std::string> messageArgs;
            if (event_log::getEventLogParams(logEntry, timestamp, messageID,
                                             messageArgs) != 0)
            {
                BMCWEB_LOG_DEBUG("Read eventLog entry params failed");
                continue;
            }

            eventRecords.emplace_back(idStr, timestamp, messageID, messageArgs);
        }

        if (!serviceEnabled || noOfEventLogSubscribers == 0)
        {
            BMCWEB_LOG_DEBUG("EventService disabled or no Subscriptions.");
            return;
        }

        if (eventRecords.empty())
        {
            // No Records to send
            BMCWEB_LOG_DEBUG("No log entries available to be transferred.");
            return;
        }

        for (const auto& it : subscriptionsMap)
        {
            std::shared_ptr<Subscription> entry = it.second;
            if (entry->eventFormatType == "Event")
            {
                entry->filterAndSendEventLogs(eventRecords);
            }
        }
    }

    static void watchRedfishEventLogFile()
    {
        if (!inotifyConn)
        {
            return;
        }

        static std::array<char, 1024> readBuffer;

        inotifyConn->async_read_some(
            boost::asio::buffer(readBuffer),
            [&](const boost::system::error_code& ec,
                const std::size_t& bytesTransferred) {
                if (ec == boost::asio::error::operation_aborted)
                {
                    BMCWEB_LOG_DEBUG("Inotify was canceled (shutdown?)");
                    return;
                }
                if (ec)
                {
                    BMCWEB_LOG_ERROR("Callback Error: {}", ec.message());
                    return;
                }
                std::size_t index = 0;
                while ((index + iEventSize) <= bytesTransferred)
                {
                    struct inotify_event event
                    {};
                    std::memcpy(&event, &readBuffer[index], iEventSize);
                    if (event.wd == dirWatchDesc)
                    {
                        if ((event.len == 0) ||
                            (index + iEventSize + event.len > bytesTransferred))
                        {
                            index += (iEventSize + event.len);
                            continue;
                        }

                        std::string fileName(&readBuffer[index + iEventSize]);
                        if (fileName != "redfish")
                        {
                            index += (iEventSize + event.len);
                            continue;
                        }

                        BMCWEB_LOG_DEBUG(
                            "Redfish log file created/deleted. event.name: {}",
                            fileName);
                        if (event.mask == IN_CREATE)
                        {
                            if (fileWatchDesc != -1)
                            {
                                BMCWEB_LOG_DEBUG(
                                    "Remove and Add inotify watcher on "
                                    "redfish event log file");
                                // Remove existing inotify watcher and add
                                // with new redfish event log file.
                                inotify_rm_watch(inotifyFd, fileWatchDesc);
                                fileWatchDesc = -1;
                            }

                            fileWatchDesc = inotify_add_watch(
                                inotifyFd, redfishEventLogFile, IN_MODIFY);
                            if (fileWatchDesc == -1)
                            {
                                BMCWEB_LOG_ERROR("inotify_add_watch failed for "
                                                 "redfish log file.");
                                return;
                            }

                            EventServiceManager::getInstance()
                                .resetRedfishFilePosition();
                            EventServiceManager::getInstance()
                                .readEventLogsFromFile();
                        }
                        else if ((event.mask == IN_DELETE) ||
                                 (event.mask == IN_MOVED_TO))
                        {
                            if (fileWatchDesc != -1)
                            {
                                inotify_rm_watch(inotifyFd, fileWatchDesc);
                                fileWatchDesc = -1;
                            }
                        }
                    }
                    else if (event.wd == fileWatchDesc)
                    {
                        if (event.mask == IN_MODIFY)
                        {
                            EventServiceManager::getInstance()
                                .readEventLogsFromFile();
                        }
                    }
                    index += (iEventSize + event.len);
                }

                watchRedfishEventLogFile();
            });
    }

    static int startEventLogMonitor(boost::asio::io_context& ioc)
    {
        inotifyConn.emplace(ioc);
        inotifyFd = inotify_init1(IN_NONBLOCK);
        if (inotifyFd == -1)
        {
            BMCWEB_LOG_ERROR("inotify_init1 failed.");
            return -1;
        }

        // Add watch on directory to handle redfish event log file
        // create/delete.
        dirWatchDesc = inotify_add_watch(inotifyFd, redfishEventLogDir,
                                         IN_CREATE | IN_MOVED_TO | IN_DELETE);
        if (dirWatchDesc == -1)
        {
            BMCWEB_LOG_ERROR(
                "inotify_add_watch failed for event log directory.");
            return -1;
        }

        // Watch redfish event log file for modifications.
        fileWatchDesc =
            inotify_add_watch(inotifyFd, redfishEventLogFile, IN_MODIFY);
        if (fileWatchDesc == -1)
        {
            BMCWEB_LOG_ERROR("inotify_add_watch failed for redfish log file.");
            // Don't return error if file not exist.
            // Watch on directory will handle create/delete of file.
        }

        // monitor redfish event log file
        inotifyConn->assign(inotifyFd);
        watchRedfishEventLogFile();

        return 0;
    }

    static void stopEventLogMonitor()
    {
        inotifyConn.reset();
    }

    static void getReadingsForReport(sdbusplus::message_t& msg)
    {
        if (msg.is_method_error())
        {
            BMCWEB_LOG_ERROR("TelemetryMonitor Signal error");
            return;
        }

        sdbusplus::message::object_path path(msg.get_path());
        std::string id = path.filename();
        if (id.empty())
        {
            BMCWEB_LOG_ERROR("Failed to get Id from path");
            return;
        }

        std::string interface;
        dbus::utility::DBusPropertiesMap props;
        std::vector<std::string> invalidProps;
        msg.read(interface, props, invalidProps);

        auto found = std::ranges::find_if(props, [](const auto& x) {
            return x.first == "Readings";
        });
        if (found == props.end())
        {
            BMCWEB_LOG_INFO("Failed to get Readings from Report properties");
            return;
        }

        const telemetry::TimestampReadings* readings =
            std::get_if<telemetry::TimestampReadings>(&found->second);
        if (readings == nullptr)
        {
            BMCWEB_LOG_INFO("Failed to get Readings from Report properties");
            return;
        }

        for (const auto& it :
             EventServiceManager::getInstance().subscriptionsMap)
        {
            Subscription& entry = *it.second;
            if (entry.eventFormatType == metricReportFormatType)
            {
                entry.filterAndSendReports(id, *readings);
            }
        }
    }

    void unregisterMetricReportSignal()
    {
        if (matchTelemetryMonitor)
        {
            BMCWEB_LOG_DEBUG("Metrics report signal - Unregister");
            matchTelemetryMonitor.reset();
            matchTelemetryMonitor = nullptr;
        }
    }

    void registerMetricReportSignal()
    {
        if (!serviceEnabled || matchTelemetryMonitor)
        {
            BMCWEB_LOG_DEBUG("Not registering metric report signal.");
            return;
        }

        BMCWEB_LOG_DEBUG("Metrics report signal - Register");
        std::string matchStr = "type='signal',member='PropertiesChanged',"
                               "interface='org.freedesktop.DBus.Properties',"
                               "arg0=xyz.openbmc_project.Telemetry.Report";

        matchTelemetryMonitor = std::make_shared<sdbusplus::bus::match_t>(
            *crow::connections::systemBus, matchStr, getReadingsForReport);
    }
};

} // namespace redfish