/*
 * Copyright (c) 2016 MariaDB Corporation Ab
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
 *
 * Change Date: 2022-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2 or later of the General
 * Public License.
 */

#define MXS_MODULE_NAME "csmon"

#include "csmon.hh"

#include <regex>
#include <vector>
#include <string>

#include <maxscale/modinfo.h>
#include <maxscale/mysql_utils.h>

namespace
{

constexpr const char* alive_query = "SELECT mcsSystemReady() = 1 && mcsSystemReadOnly() <> 2";
constexpr const char* role_query = "SELECT mcsSystemPrimary()";

// Helper for extracting string results from queries
static std::string do_query(MXS_MONITORED_SERVER* srv, const char* query)
{
    std::string rval;
    MYSQL_RES* result;

    if (mxs_mysql_query(srv->con, query) == 0 && (result = mysql_store_result(srv->con)))
    {
        MYSQL_ROW row = mysql_fetch_row(result);

        if (row && row[0])
        {
            rval = row[0];
        }

        mysql_free_result(result);
    }
    else
    {
        mon_report_query_error(srv);
    }

    return rval;
}

// Returns a numeric version similar to mysql_get_server_version
int get_cs_version(MXS_MONITORED_SERVER* srv)
{
    int rval = -1;
    std::string prefix = "Columnstore ";
    std::string result = do_query(srv, "SELECT @@version_comment");
    auto pos = result.find(prefix);

    if (pos != std::string::npos)
    {
        std::istringstream os(result.substr(pos + prefix.length()));
        int major = 0, minor = 0, patch = 0;
        char dot;
        os >> major;
        os >> dot;
        os >> minor;
        os >> dot;
        os >> patch;
        rval = major * 10000 + minor * 100 + patch;
    }

    return rval;
}
}

CsMonitor::CsMonitor(MXS_MONITOR* monitor)
    : maxscale::MonitorInstanceSimple(monitor)
    , m_primary(config_get_server(monitor->parameters, "primary"))
{
}

CsMonitor::~CsMonitor()
{
}

// static
CsMonitor* CsMonitor::create(MXS_MONITOR* monitor)
{
    return new CsMonitor(monitor);
}

bool CsMonitor::has_sufficient_permissions() const
{
    return check_monitor_permissions(m_monitor, alive_query);
}

void CsMonitor::update_server_status(MXS_MONITORED_SERVER* srv)
{
    monitor_clear_pending_status(srv, SERVER_MASTER | SERVER_SLAVE | SERVER_RUNNING);
    int status = 0;

    if (do_query(srv, alive_query) == "1")
    {
        auto version = get_cs_version(srv);

        if (version >= 0)
        {
            status |= SERVER_RUNNING;

            if (version >= 10200)
            {
                // 1.2 supports the mcsSystemPrimary function
                status |= do_query(srv, role_query) == "1" ? SERVER_MASTER : SERVER_SLAVE;
            }
            else
            {
                status |= srv->server == m_primary ? SERVER_MASTER : SERVER_SLAVE;
            }
        }
    }

    monitor_set_pending_status(srv, status);
}

extern "C" MXS_MODULE* MXS_CREATE_MODULE()
{
    static MXS_MODULE info =
    {
        MXS_MODULE_API_MONITOR,
        MXS_MODULE_BETA_RELEASE,
        MXS_MONITOR_VERSION,
        "MariaDB ColumnStore monitor",
        "V1.0.0",
        MXS_NO_MODULE_CAPABILITIES,
        &maxscale::MonitorApi<CsMonitor>::s_api,
        NULL,   /* Process init. */
        NULL,   /* Process finish. */
        NULL,   /* Thread init. */
        NULL,   /* Thread finish. */
        {
            {"primary", MXS_MODULE_PARAM_SERVER},
            {MXS_END_MODULE_PARAMS}
        }
    };

    return &info;
}