<?php

/**
 * Matomo - free/libre analytics platform
 *
 * @link    https://matomo.org
 * @license https://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
 */

namespace Piwik;

use Exception;
use Piwik\Db\Schema;
use Piwik\DataAccess\ArchiveTableCreator;

/**
 * Contains database related helper functions.
 */
class DbHelper
{
    /**
     * Get list of tables installed
     *
     * @param bool $forceReload Invalidate cache
     * @return array  Tables installed
     */
    public static function getTablesInstalled($forceReload = true)
    {
        return Schema::getInstance()->getTablesInstalled($forceReload);
    }

    /**
     * Returns `true` if a table exists in the database, `false` if otherwise.
     *
     * @param string $tableName The name of the table to check for. Must be prefixed.
     *                          Avoid using user input, as the variable will be used in a query unescaped.
     * @return bool
     * @throws \Exception
     */
    public static function tableExists($tableName)
    {
        $tableName = str_replace(['%', '_', "'"], ['\%', '\_', '_'], $tableName);
        return Db::get()->query(sprintf("SHOW TABLES LIKE '%s'", $tableName))->rowCount() > 0;
    }

    /**
     * Get list of installed columns in a table
     *
     * @param  string $tableName The name of a table.
     *
     * @return array  Installed columns indexed by the column name.
     */
    public static function getTableColumns($tableName)
    {
        return Schema::getInstance()->getTableColumns($tableName);
    }

    /**
     * Creates a new table in the database.
     *
     * Example:
     * ```
     * $tableDefinition = "`age` INT(11) NOT NULL AUTO_INCREMENT,
     *                     `name` VARCHAR(255) NOT NULL";
     *
     * DbHelper::createTable('tablename', $tableDefinition);
     * ``
     *
     * @param string $nameWithoutPrefix   The name of the table without any piwik prefix.
     * @param string $createDefinition    The table create definition
     *
     * @api
     */
    public static function createTable($nameWithoutPrefix, $createDefinition)
    {
        Schema::getInstance()->createTable($nameWithoutPrefix, $createDefinition);
    }

    /**
     * Returns true if Piwik is installed
     *
     * @since 0.6.3
     *
     * @return bool  True if installed; false otherwise
     */
    public static function isInstalled()
    {
        try {
            return Schema::getInstance()->hasTables();
        } catch (Exception $e) {
            return false;
        }
    }

    /**
     * Truncate all tables
     */
    public static function truncateAllTables()
    {
        Schema::getInstance()->truncateAllTables();
    }

    /**
     * Creates an entry in the User table for the "anonymous" user.
     */
    public static function createAnonymousUser()
    {
        Schema::getInstance()->createAnonymousUser();
    }

    /**
     * Records the Matomo version a user used when installing this Matomo for the first time
     */
    public static function recordInstallVersion()
    {
        Schema::getInstance()->recordInstallVersion();
    }

    /**
     * Returns which Matomo version was used to install this Matomo for the first time.
     */
    public static function getInstallVersion(): string
    {
        return Schema::getInstance()->getInstallVersion() ?? '0';
        // need string as usage is usually
        // version_compare(DbHelper::getInstallVersion(),'4.0.0-b1', '<') or similar
        // and PHP 8.1 throws a deprecation warning otherwise
        // @see https://github.com/matomo-org/matomo/pull/17989#issuecomment-921298360
    }

    public static function wasMatomoInstalledBeforeVersion($version)
    {
        $installVersion = self::getInstallVersion();
        if (empty($installVersion)) {
            return true; // we assume yes it was installed
        }
        return true === version_compare($version, $installVersion, '>');
    }

    /**
     * Create all tables
     */
    public static function createTables()
    {
        Schema::getInstance()->createTables();
    }

    /**
     * Drop database, used in tests
     */
    public static function dropDatabase($dbName = null)
    {
        if (defined('PIWIK_TEST_MODE') && PIWIK_TEST_MODE) {
            Schema::getInstance()->dropDatabase($dbName);
        }
    }


    /**
     * Checks the database server version against the required minimum
     * version.
     *
     * @see config/global.ini.php
     * @since 0.4.4
     * @throws Exception if server version is less than the required version
     */
    public static function checkDatabaseVersion()
    {
        Schema::getInstance()->unsetSchema();
        Db::get()->checkServerVersion();
    }

    /**
     * Disconnect from database
     */
    public static function disconnectDatabase()
    {
        Db::get()->closeConnection();
    }

    /**
     * Create database
     *
     * @param string|null $dbName
     */
    public static function createDatabase($dbName = null)
    {
        Schema::getInstance()->createDatabase($dbName);
    }

    /**
     * Returns if the given table has an index with the given name
     *
     * @param string $table
     * @param string $indexName
     *
     * @return bool
     * @throws Exception
     */
    public static function tableHasIndex($table, $indexName)
    {
        $result = Db::get()->fetchOne('SHOW INDEX FROM `' . $table . '` WHERE Key_name = ?', [$indexName]);
        return !empty($result);
    }

    /**
     * Returns the default database charset to use
     *
     * Returns utf8mb4 if supported, with fallback to utf8
     *
     * @throws Tracker\Db\DbException
     */
    public static function getDefaultCharset(): string
    {
        $result = Db::get()->fetchRow("SHOW CHARACTER SET LIKE 'utf8mb4'");

        if (empty($result)) {
            return 'utf8'; // charset not available
        }

        $result = Db::get()->fetchRow("SHOW VARIABLES LIKE 'character_set_database'");

        if (!empty($result) && $result['Value'] === 'utf8mb4') {
            return 'utf8mb4'; // database has utf8mb4 charset, so assume it can be used
        }

        $result = Db::get()->fetchRow("SHOW VARIABLES LIKE 'innodb_file_per_table'");

        if (empty($result) || $result['Value'] !== 'ON') {
            return 'utf8'; // innodb_file_per_table is required for utf8mb4
        }

        return 'utf8mb4';
    }

    /**
     * Returns the default collation for a charset.
     *
     * @throws Exception
     */
    public static function getDefaultCollationForCharset(string $charset): string
    {
        return Schema::getInstance()->getDefaultCollationForCharset($charset);
    }

    /**
     * Returns sql queries to convert all installed tables to utf8mb4
     *
     * @return array
     */
    public static function getUtf8mb4ConversionQueries()
    {
        $allTables = DbHelper::getTablesInstalled();

        $queries   = [];

        foreach ($allTables as $table) {
            $queries[] = "ALTER TABLE `$table` CONVERT TO CHARACTER SET utf8mb4;";
        }

        return $queries;
    }

    /**
     * Get the SQL to create Piwik tables
     *
     * @return array  array of strings containing SQL
     */
    public static function getTablesCreateSql()
    {
        return Schema::getInstance()->getTablesCreateSql();
    }

    /**
     * Get the SQL to create a specific Piwik table
     *
     * @param string $tableName Unprefixed table name.
     * @return string  SQL
     */
    public static function getTableCreateSql($tableName)
    {
        return Schema::getInstance()->getTableCreateSql($tableName);
    }

    /**
     * Deletes archive tables. For use in tests.
     */
    public static function deleteArchiveTables()
    {
        foreach (ArchiveTableCreator::getTablesArchivesInstalled() as $table) {
            Log::debug("Dropping table $table");

            Db::query("DROP TABLE IF EXISTS `$table`");
        }

        ArchiveTableCreator::refreshTableList();
    }

    /**
     * Adds a MAX_EXECUTION_TIME hint into a SELECT query if $limit is bigger than 0
     *
     * @param string $sql  query to add hint to
     * @param float $limit  time limit in seconds
     */
    public static function addMaxExecutionTimeHintToQuery(string $sql, float $limit): string
    {
        return Schema::getInstance()->addMaxExecutionTimeHintToQuery($sql, $limit);
    }

    /**
     * Add an origin hint to the query to identify the main parameters and segment for debugging
     *
     * @param string        $sql        SQL query string
     * @param string        $origin     Origin string to describe the source of the query
     * @param Date|null     $dateStart  Start date used in the query, optional
     * @param Date|null     $dateEnd    End date used in the query, optional
     * @param array|null    $sites      Sites list used in the query, optional
     * @param Segment|null  $segment    Segment, the segment hash will be added if this is set
     *
     * @return string   Modified SQL query string with hint added
     */
    public static function addOriginHintToQuery(
        string $sql,
        string $origin,
        ?Date $dateStart = null,
        ?Date $dateEnd = null,
        ?array $sites = null,
        ?Segment $segment = null
    ): string {
        $select = 'SELECT';
        if ($origin && 0 === strpos(trim($sql), $select)) {
            $sql = trim($sql);
            $sql = 'SELECT /* ' . $origin . ' */' . substr($sql, strlen($select));
        }

        if ($dateStart !== null && $dateEnd !== null && 0 === strpos(trim($sql), $select)) {
            $sql = trim($sql);
            $sql = 'SELECT /* ' . $dateStart->toString() . ',' . $dateEnd->toString() . ' */' . substr($sql, strlen($select));
        }

        if ($sites && is_array($sites) && 0 === strpos(trim($sql), $select)) {
            $sql = trim($sql);
            $sql = 'SELECT /* ' . 'sites ' . implode(',', array_map('intval', $sites)) . ' */' . substr($sql, strlen($select));
        }

        if ($segment && !$segment->isEmpty() && 0 === strpos(trim($sql), $select)) {
            $sql = trim($sql);
            $sql = 'SELECT /* ' . 'segmenthash ' . $segment->getHash() . ' */' . substr($sql, strlen($select));
        }

        return $sql;
    }

    /**
     * Add an optimizer hint to the query to set the first table used by the MySQL join execution plan
     *
     * https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html#optimizer-hints-join-order
     *
     * @param string $sql       SQL query string
     * @param string $prefix    Table prefix to be used as the first table in the plan
     *
     * @return string           Modified query string with hint added
     */
    public static function addJoinPrefixHintToQuery(string $sql, string $prefix): string
    {
        return self::addOptimizerHintToQuery($sql, 'JOIN_PREFIX(' . $prefix . ')');
    }

    /**
     * Add an optimizer hint to the query.
     *
     * Creating and using a "add_x_HintToQuery" functions is preferred
     * over using this function directly, as some optimizer hints depend
     * on the database used.
     *
     * If an optimizer hint is already present (check is done by name only)
     * in the query the new value will be silently discarded.
     *
     * @param string $sql   SQL query string
     * @param string $hint  Hint to add
     *
     * @return string       Modified query string with hint added
     */
    public static function addOptimizerHintToQuery(string $sql, string $hint): string
    {
        $sql = trim($sql);

        // only apply hints to SELECT queries
        if (0 !== stripos($sql, 'SELECT')) {
            return $sql;
        }

        $pattern =
            '@^SELECT\s+' .
            // ignore non-hint comments ("/* ... */")
            '(?:|/\*[^+]*?\*/\s*)' .
            // capture hint comments ("/*+ ... */")
            '(/\*\+\s*(.*?)\s*\*/)' .
            '@is';

        preg_match($pattern, $sql, $matches);

        if (empty($matches)) {
            return 'SELECT /*+ ' . $hint . ' */' . substr($sql, strlen('SELECT'));
        }

        $originalComment = $matches[1];
        $hints = $matches[2];

        $newHintNameEnd = stripos($hint, '(') ?: strlen($hint);
        $newHintName = substr($hint, 0, $newHintNameEnd);

        // only add new hints
        if (preg_match('/(?:^|\s)' . preg_quote($newHintName) . '(?:\\(|\s|$)/i', $hints)) {
            return $sql;
        }

        $hints = trim($hint . ' ' . $hints);

        return substr_replace(
            $sql,
            '/*+ ' . $hints . ' */',
            strpos($sql, $originalComment),
            strlen($originalComment)
        );
    }

    /**
     * Extracts the "ORDER BY" clause from a query.
     *
     * Will return null if no clause found or the extraction failed,
     * e.g. parentheses in the extracted clause are not balanced.
     */
    public static function extractOrderByFromQuery(string $sql): ?string
    {
        $pattern = '/.*ORDER\s+BY\s+(.*?)(?:\s+LIMIT|\s*;|\s*$)/is';

        if (preg_match($pattern, $sql, $matches)) {
            $orderBy = $matches[1];
            $openParentheses = substr_count($orderBy, '(');
            $closeParentheses = substr_count($orderBy, ')');

            if ($openParentheses === $closeParentheses) {
                return trim($orderBy);
            }
        }

        return null;
    }

    /**
     * Returns true if the string is a valid database name for MySQL. MySQL allows + in the database names.
     * Database names that start with a-Z or 0-9 and contain a-Z, 0-9, underscore(_), dash(-), plus(+), and dot(.) will be accepted.
     * Database names beginning with anything but a-Z or 0-9 will be rejected.
     * Database names containing anything other than above mentioned will also be rejected (names with spaces won't be accepted).
     *
     * @param string $dbname
     * @return bool
     */
    public static function isValidDbname($dbname)
    {
        return (0 !== preg_match('/(^[a-zA-Z0-9]+([a-zA-Z0-9\_\.\-\+]*))$/D', $dbname));
    }
}
