<?php
/*
 * SnmpQueryMock.php
 *
 * Load data from snmprec files
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @package    LibreNMS
 * @link       http://librenms.org
 * @copyright  2021 Tony Murray
 * @author     Tony Murray <murraytony@gmail.com>
 */

namespace LibreNMS\Tests\Mocks;

use App\Models\Device;
use DeviceCache;
use Exception;
use Illuminate\Support\Arr;
use Illuminate\Support\Str;
use LibreNMS\Data\Source\NetSnmpQuery;
use LibreNMS\Data\Source\SnmpQueryInterface;
use LibreNMS\Data\Source\SnmpResponse;
use LibreNMS\Device\YamlDiscovery;
use Log;

class SnmpQueryMock implements SnmpQueryInterface
{
    /**
     * @var array
     */
    private static $cache;

    /**
     * @var Device
     */
    private $device;
    /**
     * @var string
     */
    private $context;
    /**
     * @var string|null
     */
    private $mibDir;
    /**
     * @var bool
     */
    private $numeric = false;
    /**
     * @var bool
     */
    private $hideMib = false;
    /**
     * @var array|mixed
     */
    private $options = [];
    /**
     * @var bool
     */
    private $abort = false;

    public static function make(): SnmpQueryInterface
    {
        $new = new static;
        $new->device = DeviceCache::getPrimary();

        return $new;
    }

    public function device(Device $device): SnmpQueryInterface
    {
        $this->device = $device;

        return $this;
    }

    public function deviceArray(array $device): SnmpQueryInterface
    {
        $this->device = new Device($device);

        return $this;
    }

    public function context(string $context): SnmpQueryInterface
    {
        $this->context = $context;

        return $this;
    }

    public function translate(string $oid, ?string $mib = null): SnmpResponse
    {
        // call real snmptranslate
        $options = $this->options;
        if ($this->numeric) {
            $options[] = '-On';
        }
        if ($this->hideMib) {
            $options[] = '-Os';
        }

        return NetSnmpQuery::make()
            ->mibDir($this->mibDir)
            ->options($options)
            ->translate($oid, $mib);
    }

    public function abortOnFailure(): SnmpQueryInterface
    {
        $this->abort = true;

        return $this;
    }

    public function allowUnordered(): SnmpQueryInterface
    {
        return $this;
    }

    public function numeric(bool $numeric = true): SnmpQueryInterface
    {
        $this->numeric = $numeric;

        return $this;
    }

    public function hideMib(): SnmpQueryInterface
    {
        $this->hideMib = true;

        return $this;
    }

    public function enumStrings(): SnmpQueryInterface
    {
        // TODO: Implement enumStrings() method, no idea how
        Log::error('enumStrings not implemented in SnmpQueryMock');

        return $this;
    }

    public function options($options = []): SnmpQueryInterface
    {
        $this->options = $options === null ? [] : Arr::wrap($options);

        return $this;
    }

    public function mibDir(?string $dir): SnmpQueryInterface
    {
        $this->mibDir = $dir;

        return $this;
    }

    public function get($oid): SnmpResponse
    {
        $community = $this->community();
        $num_oid = $this->translateNumber($oid);
        $data = $this->getSnmprec($community)[$num_oid] ?? [0, ''];

        Log::debug("[SNMP] snmpget $community $num_oid: ");

        return new SnmpResponse($this->outputLine($oid, $num_oid, $data[0], $data[1]));
    }

    /**
     * @param  array|string  $oids
     * @return \LibreNMS\Data\Source\SnmpResponse
     *
     * @throws \Exception
     */
    public function walk($oids): SnmpResponse
    {
        $community = $this->community();
        $dev = $this->getSnmprec($community);
        $response = new SnmpResponse('');

        foreach (Arr::wrap($oids) as $oid) {
            $num_oid = $this->translateNumber($oid);

            $output = '';
            foreach ($dev as $key => $data) {
                if (Str::startsWith($key, $num_oid)) {
                    $output .= $this->outputLine($oid, $num_oid, $data[0], $data[1]);
                }
            }

            $response = $response->append(new SnmpResponse($output));

            if ($this->abort && ! $response->isValid()) {
                return $response;
            }

            Log::debug("[SNMP] snmpwalk $community $num_oid");
        }

        return $response;
    }

    public function next($oid): SnmpResponse
    {
        $community = $this->community();
        $num_oid = $this->translateNumber($oid);
        $dev = $this->getSnmprec($community);

        Log::debug("[SNMP] snmpnext $community $num_oid: ");
        while (Str::contains($num_oid, '.')) {
            foreach ($dev as $key => $data) {
                if (Str::startsWith($key, $num_oid)) {
                    return new SnmpResponse($this->outputLine($oid, $num_oid, $data[0], $data[1]));
                }
            }

            $num_oid = substr($num_oid, 0, strrpos($num_oid, '.'));
        }

        return new SnmpResponse('');
    }

    private function cacheSnmprec(string $file): void
    {
        if (isset(self::$cache[$file])) {
            return;
        }
        self::$cache[$file] = [];

        $data = file_get_contents(base_path("/tests/snmpsim/$file.snmprec"));
        $line = strtok($data, "\r\n");
        while ($line !== false) {
            [$oid, $type, $data] = explode('|', $line, 3);
            if ($type == '4') {
                $data = trim($data);
            } elseif ($type == '6') {
                $data = trim($data, '.');
            } elseif ($type == '4x') {
                // MacAddress type is stored as hex string, but we don't understand mibs
                if (Str::startsWith($oid, [
                    '1.3.6.1.2.1.2.2.1.6', // IF-MIB::ifPhysAddress
                    '1.3.6.1.2.1.17.1.1.0', // BRIDGE-MIB::dot1dBaseBridgeAddress.0
                    '1.3.6.1.4.1.890.1.5.13.13.8.1.1.20', // IES5206-MIB::slotModuleMacAddress
                ])) {
                    $data = \LibreNMS\Util\Rewrite::readableMac($data);
                } else {
                    $data = hex2str($data);
                }
            }

            self::$cache[$file][$oid] = [$type, $data];
            $line = strtok("\r\n");
        }
    }

    /**
     * Get all data of the specified $community from the snmprec cache
     *
     * @param  string  $community  snmp community to return
     * @return array array of the data containing: [$oid][$type, $data]
     *
     * @throws Exception this $community is not cached
     */
    private function getSnmprec(string $community): array
    {
        if (! isset(self::$cache[$community])) {
            $this->cacheSnmprec($community);
        }

        if (isset(self::$cache[$community])) {
            return self::$cache[$community];
        }

        throw new Exception("SNMPREC: community $community not cached");
    }

    private function outputLine(string $oid, string $num_oid, string $type, string $data): string
    {
        if ($type == 6) {
            $data = $this->numeric ? ".$data" : $this->translate($data, $this->extractMib($oid))->value();
        }

        if ($this->numeric) {
            return "$num_oid = $data";
        }

        if (! empty($oid) && YamlDiscovery::oidIsNumeric($oid)) {
            $oid = $this->translate($oid)->value();
        }

        return "$oid = $data";
    }

    /**
     * Get the numeric oid of an oid
     * The leading dot is ommited by default to be compatible with snmpsim
     *
     * @param  string  $oid  the oid to tranlslate
     * @param  string  $mib  mib to use
     * @return string the oid in numeric format (1.3.4.5)
     *
     * @throws Exception Could not translate the oid
     */
    private function translateNumber($oid, $mib = null)
    {
        // optimizations (35s -> 1.6s on my laptop)
        switch ($oid) {
            case 'SNMPv2-MIB::sysDescr.0':
                return '1.3.6.1.2.1.1.1.0';
            case 'SNMPv2-MIB::sysObjectID.0':
                return '1.3.6.1.2.1.1.2.0';
            case 'ENTITY-MIB::entPhysicalDescr.1':
                return '1.3.6.1.2.1.47.1.1.1.1.2.1';
            case 'SML-MIB::product-Name.0':
                return '1.3.6.1.4.1.2.6.182.3.3.1.0';
            case 'ENTITY-MIB::entPhysicalMfgName.1':
                return '1.3.6.1.2.1.47.1.1.1.1.12.1';
            case 'GAMATRONIC-MIB::psUnitManufacture.0':
                return '1.3.6.1.4.1.6050.1.1.2.0';
            case 'SYNOLOGY-SYSTEM-MIB::systemStatus.0':
                return '1.3.6.1.4.1.6574.1.1.0';
        }

        if (YamlDiscovery::oidIsNumeric($oid)) {
            return ltrim($oid, '.');
        }

        $options = ['-IR'];
        if ($mib) {
            $options[] = "-m $mib";
        }

        $number = NetSnmpQuery::make()->mibDir($this->mibDir)
            ->options(array_merge($options, $this->options))->numeric()->translate($oid)->value();

        if (empty($number)) {
            throw new Exception('Could not translate oid: ' . $oid . PHP_EOL);
        }

        return ltrim($number, '.');
    }

    private function community(): string
    {
        $community = $this->device->community;

        if (! empty($this->context)) {
            $community .= '_' . $this->context;
        }

        return $community;
    }

    private function extractMib(string $oid): ?string
    {
        if (Str::contains($oid, '::')) {
            return explode('::', $oid, 2)[0];
        }

        return null;
    }
}