/*
 * Copyright (C) 2020-2023 CESNET, https://photonics.cesnet.cz/
 *
 * Written by Tomáš Pecka <tomas.pecka@fit.cvut.cz>
 *
 */

#include <regex>
#include <sysrepo-cpp/Connection.hpp>
#include "Sysrepo.h"
#include "utils/alarms.h"
#include "utils/log.h"
#include "utils/sysrepo.h"

namespace {

const auto ALARM_SENSOR_MISSING = "velia-alarms:sensor-missing-alarm";
const auto ALARM_THRESHOLD_CROSSING_LOW = "velia-alarms:sensor-low-value-alarm";
const auto ALARM_THRESHOLD_CROSSING_HIGH = "velia-alarms:sensor-high-value-alarm";

/** @brief Extracts component path prefix from an XPath under /ietf-hardware/component node
 *
 * Example input:  /ietf-hardware:hardware/component[name='ne:psu:child']/oper-state/disabled
 * Example output: /ietf-hardware:hardware/component[name='ne:psu:child']
 */
std::string extractComponentPrefix(const std::string& componentXPath)
{
    static const std::regex regex(R"((/ietf-hardware:hardware/component\[name=('|").*?(\2)\]).*)");
    std::smatch match;

    if (std::regex_match(componentXPath, match, regex)) {
        return match.str(1);
    }

    throw std::logic_error("Invalid xPath provided ('" + componentXPath + "')");
}
}

namespace velia::ietf_hardware::sysrepo {

/** @brief The constructor expects the HardwareState instance which will provide the actual hardware state data and the poll interval */
Sysrepo::Sysrepo(::sysrepo::Session session, std::shared_ptr<IETFHardware> hwState, std::chrono::microseconds pollInterval)
    : m_log(spdlog::get("hardware"))
    , m_pollInterval(std::move(pollInterval))
    , m_session(std::move(session))
    , m_hwState(std::move(hwState))
    , m_quit(false)
{
    for (const auto& sensorXPath : m_hwState->sensorsXPaths()) {
        auto componentXPath = extractComponentPrefix(sensorXPath);
        utils::addResourceToAlarmInventoryEntry(m_session, ALARM_THRESHOLD_CROSSING_LOW, std::nullopt, componentXPath);
        utils::addResourceToAlarmInventoryEntry(m_session, ALARM_THRESHOLD_CROSSING_HIGH, std::nullopt, componentXPath);
        utils::addResourceToAlarmInventoryEntry(m_session, ALARM_SENSOR_MISSING, std::nullopt, componentXPath);
    }

    m_pollThread = std::thread([&]() {
        auto conn = m_session.getConnection();

        DataTree prevValues;

        while (!m_quit) {
            m_log->trace("IetfHardware poll");

            auto [hwStateValues, thresholds] = m_hwState->process();
            std::set<std::string> deletedComponents;

            /* Some data readers can stop returning data in some cases (e.g. ejected PSU).
             * Prune tree components that were removed before updating to avoid having not current data from previous invocations.
             */
            for (const auto& [k, v] : prevValues) {
                if (!hwStateValues.contains(k)) {
                    deletedComponents.emplace(extractComponentPrefix(k));
                }
            }

            std::vector<std::string> discards;
            discards.reserve(deletedComponents.size());
            std::copy(deletedComponents.begin(), deletedComponents.end(), std::back_inserter(discards));

            utils::valuesPush(hwStateValues, {}, discards, m_session, ::sysrepo::Datastore::Operational);

            prevValues = std::move(hwStateValues);
            std::this_thread::sleep_for(m_pollInterval);
        }
    });
}

Sysrepo::~Sysrepo()
{
    m_log->trace("Requesting poll thread stop");
    m_quit = true;
    m_pollThread.join();
}
}