<?php
/**
* Mirasvit
*
* This source file is subject to the Mirasvit Software License, which is available at https://mirasvit.com/license/.
* Do not edit or add to this file if you wish to upgrade the to newer versions in the future.
* If you wish to customize this module for your needs.
* Please refer to http://www.magentocommerce.com for more information.
*
* @category Mirasvit
* @package mirasvit/module-misspell
* @version 1.0.38
* @copyright Copyright (C) 2020 Mirasvit (https://mirasvit.com/)
*/



namespace Mirasvit\Misspell\Provider;

use Magento\Framework\App\ResourceConnection;
use Mirasvit\Misspell\Helper\Text as TextHelper;

class Indexer
{
/**
* @var array
*/
private $allowedTables
= [
'catalogsearch_fulltext',
'mst_searchindex_',
'catalog_product_entity_text',
'catalog_product_entity_varchar',
'catalog_category_entity_text',
'catalog_category_entity_varchar',
];

/**
* @var array
*/
private $disallowedTables
= [
'mst_searchindex_mage_catalogsearch_query',
];

/**
* @var \Magento\Framework\App\ResourceConnection
*/
private $resource;

/**
* @var \Magento\Framework\DB\Adapter\AdapterInterface
*/
private $connection;

/**
* @var \Mirasvit\Misspell\Helper\Text
*/
private $text;

/**
* Indexer constructor.
*
* @param ResourceConnection $resource
* @param TextHelper $textHelper
*/
public function __construct(
ResourceConnection $resource,
TextHelper $textHelper
) {
$this->resource = $resource;
$this->connection = $this->resource->getConnection();
$this->text = $textHelper;
}

/**
* @return void
*/
public function reindex()
{
$indexTable = $this->resource->getTableName('mst_misspell_index');
$this->connection->delete($indexTable);

foreach ($this->getTables() as $table => $columns) {
$results = [];

if (!count($columns)) {
continue;
}

foreach ($columns as $idx => $col) {
$columns[$idx] = '`' . $col . '`';
}

$select = $this->connection->select();
$fromColumns = new \Zend_Db_Expr("CONCAT_WS(' '," . implode(',', $columns) . ") as data_index");
$select->from($table, $fromColumns);
$results = $this->getTablesData($select);
$rows = [];
foreach ($results as $word => $freq) {
$localFrequency = $freq / count($results);
$rows[] = [
'keyword' => $word,
'trigram' => $this->text->getTrigram($word),
'frequency' => $localFrequency,
];

if (count($rows) > 1000) {
$this->connection->insertArray($indexTable, ['keyword', 'trigram', 'frequency'], $rows);
$rows = [];
}
}

if (count($rows) > 0) {
$this->connection->insertArray($indexTable, ['keyword', 'trigram', 'frequency'], $rows);
}
}

$this->connection->delete($this->resource->getTableName('mst_misspell_suggest'));
}

/**
* @param \Magento\Framework\DB\Select $select
* @param array $results
* @param int $offset
*
* @return array
* @throws \Zend_Db_Statement_Exception
*/
private function getTablesData($select, $results = [], $offset = 0)
{
while (true) {
$select->limit('10000', $offset);
$result = $this->connection->query($select);
$rows = $result->fetchAll();
if (!$rows) {
return $results;
}

foreach ($rows as $row) {
$data = $row['data_index'];
if (!empty($data)) {
$this->split($data, $results);
}
}

$offset += 10000;
}

return $results;
}

/**
* Split string to words
*
* @param string $string
* @param array $results
* @param int $increment
*
* @return void
*/
protected function split($string, &$results, $increment = 1)
{
$string = $this->text->cleanString($string);
$words = $this->text->splitWords($string);

foreach ($words as $word) {
if ($this->text->strlen($word) >= $this->text->getGram()
&& !is_numeric($word)
) {
$word = $this->text->strtolower($word);
if (!isset($results[$word])) {
$results[$word] = $increment;
} else {
$results[$word] += $increment;
}
}
}
}

/**
* List of tables that follow allowedTables, disallowedTables conditions
* @return array
*/
protected function getTables()
{
$result = [];
$tables = $this->connection->getTables();

foreach ($tables as $table) {
$isAllowed = false;

foreach ($this->allowedTables as $allowedTable) {
if (mb_strpos($table, $allowedTable) !== false) {
$isAllowed = true;
}
}

foreach ($this->disallowedTables as $disallowedTable) {
if (mb_strpos($table, $disallowedTable) !== false) {
$isAllowed = false;
}
}

if (!$isAllowed) {
continue;
}

$result[$table] = $this->getTextColumns($table);
}

return $result;
}

/**
* Text columns
*
* @param string $table Database table name
*
* @return array list of columns with text type
*/
protected function getTextColumns($table)
{
$result = [];
$allowedTypes = ['text', 'varchar', 'mediumtext', 'longtext'];
$columns = $this->connection->describeTable($table);

foreach ($columns as $column => $info) {
if (in_array($info['DATA_TYPE'], $allowedTypes)) {
$result[] = $column;
}
}

return $result;
}
}