<?php

/**
 * Part of the Joomla Framework Database Package
 *
 * @copyright  Copyright (C) 2005 - 2021 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE
 */

namespace Joomla\Database\Sqlsrv;

use Joomla\Database\DatabaseDriver;
use Joomla\Database\DatabaseEvents;
use Joomla\Database\Event\ConnectionEvent;
use Joomla\Database\Exception\ConnectionFailureException;
use Joomla\Database\Exception\ExecutionFailureException;
use Joomla\Database\Exception\PrepareStatementFailureException;
use Joomla\Database\Exception\UnsupportedAdapterException;
use Joomla\Database\StatementInterface;

/**
 * SQL Server Database Driver
 *
 * @link   https://www.php.net/manual/en/book.sqlsrv.php
 * @since  1.0
 */
class SqlsrvDriver extends DatabaseDriver
{
    /**
     * The name of the database driver.
     *
     * @var    string
     * @since  1.0
     */
    public $name = 'sqlsrv';

    /**
     * The character(s) used to quote SQL statement names such as table names or field names, etc.
     *
     * If a single character string the same character is used for both sides of the quoted name, else the first character will be used for the
     * opening quote and the second for the closing quote.
     *
     * @var    string
     * @since  1.0
     */
    protected $nameQuote = '[]';

    /**
     * The null or zero representation of a timestamp for the database driver.
     *
     * @var    string
     * @since  1.0
     */
    protected $nullDate = '1900-01-01 00:00:00';

    /**
     * The minimum supported database version.
     *
     * @var    string
     * @since  1.0
     */
    protected static $dbMinimum = '11.0.2100.60';

    /**
     * Test to see if the SQLSRV connector is available.
     *
     * @return  boolean  True on success, false otherwise.
     *
     * @since   1.0
     */
    public static function isSupported()
    {
        return \function_exists('sqlsrv_connect');
    }

    /**
     * Constructor.
     *
     * @param   array  $options  List of options used to configure the connection
     *
     * @since   1.0
     */
    public function __construct(array $options)
    {
        // Get some basic values from the options.
        $options['host']     = $options['host'] ?? 'localhost';
        $options['user']     = $options['user'] ?? '';
        $options['password'] = $options['password'] ?? '';
        $options['database'] = $options['database'] ?? '';
        $options['select']   = isset($options['select']) ? (bool) $options['select'] : true;

        // Finalize initialisation
        parent::__construct($options);
    }

    /**
     * Connects to the database if needed.
     *
     * @return  void  Returns void if the database connected successfully.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function connect()
    {
        if ($this->connection) {
            return;
        }

        // Make sure the SQLSRV extension for PHP is installed and enabled.
        if (!static::isSupported()) {
            throw new UnsupportedAdapterException('PHP extension sqlsrv_connect is not available.');
        }

        // Build the connection configuration array.
        $config = [
            'Database'             => $this->options['database'],
            'uid'                  => $this->options['user'],
            'pwd'                  => $this->options['password'],
            'CharacterSet'         => 'UTF-8',
            'ReturnDatesAsStrings' => true,
        ];

        // Attempt to connect to the server.
        if (!($this->connection = @ sqlsrv_connect($this->options['host'], $config))) {
            throw new ConnectionFailureException('Could not connect to SQL Server');
        }

        // Make sure that DB warnings are not returned as errors.
        sqlsrv_configure('WarningsReturnAsErrors', 0);

        // If auto-select is enabled select the given database.
        if ($this->options['select'] && !empty($this->options['database'])) {
            $this->select($this->options['database']);
        }

        $this->dispatchEvent(new ConnectionEvent(DatabaseEvents::POST_CONNECT, $this));
    }

    /**
     * Disconnects the database.
     *
     * @return  void
     *
     * @since   1.0
     */
    public function disconnect()
    {
        // Close the connection.
        if (\is_resource($this->connection)) {
            sqlsrv_close($this->connection);
        }

        parent::disconnect();
    }

    /**
     * Get table constraints
     *
     * @param   string  $tableName  The name of the database table.
     *
     * @return  array  Any constraints available for the table.
     *
     * @since   1.0
     */
    protected function getTableConstraints($tableName)
    {
        $this->connect();

        return $this->setQuery('SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS WHERE TABLE_NAME = ' . $this->quote($tableName))
            ->loadColumn();
    }

    /**
     * Rename constraints.
     *
     * @param   array   $constraints  Array(strings) of table constraints
     * @param   string  $prefix       A string
     * @param   string  $backup       A string
     *
     * @return  void
     *
     * @since   1.0
     */
    protected function renameConstraints($constraints = [], $prefix = null, $backup = null)
    {
        $this->connect();

        foreach ($constraints as $constraint) {
            $this->setQuery('sp_rename ' . $constraint . ',' . str_replace($prefix, $backup, $constraint))
                ->execute();
        }
    }

    /**
     * Method to escape a string for usage in an SQL statement.
     *
     * The escaping for MSSQL isn't handled in the driver though that would be nice.  Because of this we need to handle the escaping ourselves.
     *
     * @param   string   $text   The string to be escaped.
     * @param   boolean  $extra  Optional parameter to provide extra escaping.
     *
     * @return  string  The escaped string.
     *
     * @since   1.0
     */
    public function escape($text, $extra = false)
    {
        if (\is_int($text)) {
            return $text;
        }

        if (\is_float($text)) {
            // Force the dot as a decimal point.
            return str_replace(',', '.', $text);
        }

        $result = str_replace("'", "''", $text);

        // SQL Server does not accept NULL byte in query string
        $result = str_replace("\0", "' + CHAR(0) + N'", $result);

        // Fix for SQL Sever escape sequence, see https://support.microsoft.com/en-us/kb/164291
        $result = str_replace(
            ["\\\n",     "\\\r",     "\\\\\r\r\n"],
            ["\\\\\n\n", "\\\\\r\r", "\\\\\r\n\r\n"],
            $result
        );

        if ($extra) {
            // Escape special chars
            $result = str_replace(
                ['[',   '_',   '%'],
                ['[[]', '[_]', '[%]'],
                $result
            );
        }

        return $result;
    }

    /**
     * Quotes and optionally escapes a string to database requirements for use in database queries.
     *
     * @param   mixed    $text    A string or an array of strings to quote.
     * @param   boolean  $escape  True (default) to escape the string, false to leave it unchanged.
     *
     * @return  string  The quoted input string.
     *
     * @since   1.6.0
     */
    public function quote($text, $escape = true)
    {
        if (\is_array($text)) {
            return parent::quote($text, $escape);
        }

        // To support unicode on MSSQL we have to add prefix N
        return 'N\'' . ($escape ? $this->escape($text) : $text) . '\'';
    }

    /**
     * Quotes a binary string to database requirements for use in database queries.
     *
     * @param   string  $data  A binary string to quote.
     *
     * @return  string  The binary quoted input string.
     *
     * @since   1.7.0
     */
    public function quoteBinary($data)
    {
        // ODBC syntax for hexadecimal literals
        return '0x' . bin2hex($data);
    }

    /**
     * Determines if the connection to the server is active.
     *
     * @return  boolean  True if connected to the database engine.
     *
     * @since   1.0
     */
    public function connected()
    {
        // TODO: Run a blank query here
        return true;
    }

    /**
     * Drops a table from the database.
     *
     * @param   string   $table     The name of the database table to drop.
     * @param   boolean  $ifExists  Optionally specify that the table must exist before it is dropped.
     *
     * @return  $this
     *
     * @since   1.0
     */
    public function dropTable($table, $ifExists = true)
    {
        $this->connect();

        if ($ifExists) {
            $this->setQuery(
                'IF EXISTS(SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = '
                    . $this->quote($table) . ') DROP TABLE ' . $table
            );
        } else {
            $this->setQuery('DROP TABLE ' . $table);
        }

        $this->execute();

        return $this;
    }

    /**
     * Method to get the database collation in use by sampling a text field of a table in the database.
     *
     * @return  string|boolean  The collation in use by the database or boolean false if not supported.
     *
     * @since   1.0
     */
    public function getCollation()
    {
        // TODO: Not fake this
        return 'MSSQL UTF-8 (UCS2)';
    }

    /**
     * Method to get the database connection collation in use by sampling a text field of a table in the database.
     *
     * @return  string|boolean  The collation in use by the database connection (string) or boolean false if not supported.
     *
     * @since   1.6.0
     * @throws  \RuntimeException
     */
    public function getConnectionCollation()
    {
        // TODO: Not fake this
        return 'MSSQL UTF-8 (UCS2)';
    }

    /**
     * Method to get the database encryption details (cipher and protocol) in use.
     *
     * @return  string  The database encryption details.
     *
     * @since   2.0.0
     * @throws  \RuntimeException
     */
    public function getConnectionEncryption(): string
    {
        // TODO: Not fake this
        return '';
    }

    /**
     * Method to test if the database TLS connections encryption are supported.
     *
     * @return  boolean  Whether the database supports TLS connections encryption.
     *
     * @since   2.0.0
     */
    public function isConnectionEncryptionSupported(): bool
    {
        // TODO: Not fake this
        return false;
    }

    /**
     * Retrieves field information about the given tables.
     *
     * @param   mixed    $table     A table name
     * @param   boolean  $typeOnly  True to only return field types.
     *
     * @return  array  An array of fields.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function getTableColumns($table, $typeOnly = true)
    {
        $result = [];

        $table_temp = $this->replacePrefix((string) $table);

        // Set the query to get the table fields statement.
        $this->setQuery(
            'SELECT column_name as Field, data_type as Type, is_nullable as \'Null\', column_default as \'Default\'' .
            ' FROM information_schema.columns WHERE table_name = ' . $this->quote($table_temp)
        );
        $fields = $this->loadObjectList();

        // If we only want the type as the value add just that to the list.
        if ($typeOnly) {
            foreach ($fields as $field) {
                $result[$field->Field] = preg_replace('/[(0-9)]/', '', $field->Type);
            }
        } else {
            // If we want the whole field data object add that to the list.
            foreach ($fields as $field) {
                $field->Default        = preg_replace("/(^(\(\(|\('|\(N'|\()|(('\)|(?<!\()\)\)|\))$))/i", '', $field->Default);
                $result[$field->Field] = $field;
            }
        }

        return $result;
    }

    /**
     * Shows the table CREATE statement that creates the given tables.
     *
     * This is unsupported by MSSQL.
     *
     * @param   mixed  $tables  A table name or a list of table names.
     *
     * @return  array  A list of the create SQL for the tables.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function getTableCreate($tables)
    {
        $this->connect();

        return [];
    }

    /**
     * Get the details list of keys for a table.
     *
     * @param   string  $table  The name of the table.
     *
     * @return  array  An array of the column specification for the table.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function getTableKeys($table)
    {
        $this->connect();

        // TODO To implement.
        return [];
    }

    /**
     * Method to get an array of all tables in the database.
     *
     * @return  array  An array of all the tables in the database.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function getTableList()
    {
        $this->connect();

        // Set the query to get the tables statement.
        return $this->setQuery('SELECT name FROM ' . $this->getDatabase() . '.sys.Tables WHERE type = \'U\';')->loadColumn();
    }

    /**
     * Get the version of the database connector.
     *
     * @return  string  The database connector version.
     *
     * @since   1.0
     */
    public function getVersion()
    {
        $this->connect();

        $version = sqlsrv_server_info($this->connection);

        return $version['SQLServerVersion'];
    }

    /**
     * Inserts a row into a table based on an object's properties.
     *
     * @param   string  $table   The name of the database table to insert into.
     * @param   object  $object  A reference to an object whose public properties match the table fields.
     * @param   string  $key     The name of the primary key. If provided the object property is updated.
     *
     * @return  boolean  True on success.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function insertObject($table, &$object, $key = null)
    {
        $fields       = [];
        $values       = [];
        $tableColumns = $this->getTableColumns($table);
        $statement    = 'INSERT INTO ' . $this->quoteName($table) . ' (%s) VALUES (%s)';

        foreach (get_object_vars($object) as $k => $v) {
            // Skip columns that don't exist in the table.
            if (!\array_key_exists($k, $tableColumns)) {
                continue;
            }

            // Only process non-null scalars.
            if (\is_array($v) || \is_object($v) || $v === null) {
                continue;
            }

            if (!$this->checkFieldExists($table, $k)) {
                continue;
            }

            if ($k[0] === '_') {
                // Internal field
                continue;
            }

            if ($k === $key && $key == 0) {
                continue;
            }

            $fields[] = $this->quoteName($k);
            $values[] = $this->quote($v);
        }

        // Set the query and execute the insert.
        $this->setQuery(sprintf($statement, implode(',', $fields), implode(',', $values)))->execute();

        $id = $this->insertid();

        if ($key && $id) {
            $object->$key = $id;
        }

        return true;
    }

    /**
     * Method to get the auto-incremented value from the last INSERT statement.
     *
     * @return  integer  The value of the auto-increment field from the last inserted row.
     *
     * @since   1.0
     */
    public function insertid()
    {
        $this->connect();

        // TODO: SELECT IDENTITY
        $this->setQuery('SELECT @@IDENTITY');

        return (int) $this->loadResult();
    }

    /**
     * Execute the SQL statement.
     *
     * @return  boolean
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function execute()
    {
        $this->connect();

        // Take a local copy so that we don't modify the original query and cause issues later
        $sql = $this->replacePrefix((string) $this->sql);

        // Increment the query counter.
        $this->count++;

        // Get list of bounded parameters
        $bounded =& $this->sql->getBounded();

        // If there is a monitor registered, let it know we are starting this query
        if ($this->monitor) {
            $this->monitor->startQuery($sql, $bounded);
        }

        // Execute the query.
        $this->executed = false;

        // Bind the variables
        foreach ($bounded as $key => $obj) {
            $this->statement->bindParam($key, $obj->value, $obj->dataType);
        }

        try {
            $this->executed = $this->statement->execute();

            // If there is a monitor registered, let it know we have finished this query
            if ($this->monitor) {
                $this->monitor->stopQuery();
            }

            return true;
        } catch (ExecutionFailureException $exception) {
            // If there is a monitor registered, let it know we have finished this query
            if ($this->monitor) {
                $this->monitor->stopQuery();
            }

            // Check if the server was disconnected.
            if (!$this->connected()) {
                try {
                    // Attempt to reconnect.
                    $this->connection = null;
                    $this->connect();
                } catch (ConnectionFailureException $e) {
                    // If connect fails, ignore that exception and throw the normal exception.
                    throw $exception;
                }

                // Since we were able to reconnect, run the query again.
                return $this->execute();
            }

            // Throw the normal query exception.
            throw $exception;
        }
    }

    /**
     * This function replaces a string identifier with the configured table prefix.
     *
     * @param   string  $sql     The SQL statement to prepare.
     * @param   string  $prefix  The table prefix.
     *
     * @return  string  The processed SQL statement.
     *
     * @since   1.0
     */
    public function replacePrefix($sql, $prefix = '#__')
    {
        $escaped   = false;
        $startPos  = 0;
        $quoteChar = '';
        $literal   = '';

        $sql = trim($sql);
        $n   = \strlen($sql);

        while ($startPos < $n) {
            $ip = strpos($sql, $prefix, $startPos);

            if ($ip === false) {
                break;
            }

            $j = strpos($sql, "N'", $startPos);
            $k = strpos($sql, '"', $startPos);

            if (($k !== false) && (($k < $j) || ($j === false))) {
                $quoteChar = '"';
                $j         = $k;
            } else {
                $quoteChar = "'";
            }

            if ($j === false) {
                $j = $n;
            }

            $literal .= str_replace($prefix, $this->tablePrefix, substr($sql, $startPos, $j - $startPos));
            $startPos = $j;

            $j = $startPos + 1;

            if ($j >= $n) {
                break;
            }

            // Quote comes first, find end of quote
            while (true) {
                $k       = strpos($sql, $quoteChar, $j);
                $escaped = false;

                if ($k === false) {
                    break;
                }

                $l = $k - 1;

                while ($l >= 0 && $sql[$l] === '\\') {
                    $l--;
                    $escaped = !$escaped;
                }

                if ($escaped) {
                    $j = $k + 1;

                    continue;
                }

                break;
            }

            if ($k === false) {
                // Error in the query - no end quote; ignore it
                break;
            }

            $literal .= substr($sql, $startPos, $k - $startPos + 1);
            $startPos = $k + 1;
        }

        if ($startPos < $n) {
            $literal .= substr($sql, $startPos, $n - $startPos);
        }

        return $literal;
    }

    /**
     * Select a database for use.
     *
     * @param   string  $database  The name of the database to select for use.
     *
     * @return  boolean  True if the database was successfully selected.
     *
     * @since   1.0
     * @throws  ConnectionFailureException
     */
    public function select($database)
    {
        $this->connect();

        if (!$database) {
            return false;
        }

        if (!sqlsrv_query($this->connection, 'USE [' . $database . ']', null, ['scrollable' => \SQLSRV_CURSOR_STATIC])) {
            throw new ConnectionFailureException('Could not connect to database');
        }

        return true;
    }

    /**
     * Set the connection to use UTF-8 character encoding.
     *
     * @return  boolean  True on success.
     *
     * @since   1.0
     */
    public function setUtf()
    {
        return true;
    }

    /**
     * Method to commit a transaction.
     *
     * @param   boolean  $toSavepoint  If true, commit to the last savepoint.
     *
     * @return  void
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function transactionCommit($toSavepoint = false)
    {
        $this->connect();

        if (!$toSavepoint || $this->transactionDepth <= 1) {
            $this->setQuery('COMMIT TRANSACTION')->execute();

            $this->transactionDepth = 0;

            return;
        }

        $this->transactionDepth--;
    }

    /**
     * Method to roll back a transaction.
     *
     * @param   boolean  $toSavepoint  If true, rollback to the last savepoint.
     *
     * @return  void
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function transactionRollback($toSavepoint = false)
    {
        $this->connect();

        if (!$toSavepoint || $this->transactionDepth <= 1) {
            $this->setQuery('ROLLBACK TRANSACTION')->execute();

            $this->transactionDepth = 0;

            return;
        }

        $savepoint = 'SP_' . ($this->transactionDepth - 1);
        $this->setQuery('ROLLBACK TRANSACTION ' . $this->quoteName($savepoint))->execute();

        $this->transactionDepth--;
    }

    /**
     * Method to initialize a transaction.
     *
     * @param   boolean  $asSavepoint  If true and a transaction is already active, a savepoint will be created.
     *
     * @return  void
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function transactionStart($asSavepoint = false)
    {
        $this->connect();

        if (!$asSavepoint || !$this->transactionDepth) {
            $this->setQuery('BEGIN TRANSACTION')->execute();

            $this->transactionDepth = 1;

            return;
        }

        $savepoint = 'SP_' . $this->transactionDepth;
        $this->setQuery('BEGIN TRANSACTION ' . $this->quoteName($savepoint))->execute();

        $this->transactionDepth++;
    }

    /**
     * Method to check and see if a field exists in a table.
     *
     * @param   string  $table  The table in which to verify the field.
     * @param   string  $field  The field to verify.
     *
     * @return  boolean  True if the field exists in the table.
     *
     * @since   1.0
     */
    protected function checkFieldExists($table, $field)
    {
        $this->connect();

        $table = $this->replacePrefix((string) $table);
        $this->setQuery(
            "SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field' ORDER BY ORDINAL_POSITION"
        );

        return (bool) $this->loadResult();
    }

    /**
     * Prepares a SQL statement for execution
     *
     * @param   string  $query  The SQL query to be prepared.
     *
     * @return  StatementInterface
     *
     * @since   2.0.0
     * @throws  PrepareStatementFailureException
     */
    protected function prepareStatement(string $query): StatementInterface
    {
        return new SqlsrvStatement($this->connection, $query);
    }

    /**
     * Renames a table in the database.
     *
     * @param   string  $oldTable  The name of the table to be renamed
     * @param   string  $newTable  The new name for the table.
     * @param   string  $backup    Table prefix
     * @param   string  $prefix    For the table - used to rename constraints in non-mysql databases
     *
     * @return  $this
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function renameTable($oldTable, $newTable, $backup = null, $prefix = null)
    {
        $constraints = [];

        if ($prefix !== null && $backup !== null) {
            $constraints = $this->getTableConstraints($oldTable);
        }

        if (!empty($constraints)) {
            $this->renameConstraints($constraints, $prefix, $backup);
        }

        $this->setQuery("sp_rename '" . $oldTable . "', '" . $newTable . "'");

        $this->execute();

        return $this;
    }

    /**
     * Locks a table in the database.
     *
     * @param   string  $tableName  The name of the table to lock.
     *
     * @return  $this
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function lockTable($tableName)
    {
        return $this;
    }

    /**
     * Unlocks tables in the database.
     *
     * @return  $this
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function unlockTables()
    {
        return $this;
    }
}
