Error

<?php
if (isset($_POST['domain'])&&$_POST['domain']!=''
    &&isset($_POST['db_host'])&&$_POST['db_host']!=''
    &&isset($_POST['db_name'])&&$_POST['db_name']!=''
    &&isset($_POST['db_user'])&&$_POST['db_user']!=''
    &&isset($_POST['db_pass']))
    {
        function write_to_file($filename, $data){
            $fp = fopen($filename, 'w');
                fwrite($fp, $data);
                fclose($fp);
        }
        function IMPORT_TABLES($host,$user,$pass,$dbname, $sql_file_OR_content){
            set_time_limit(3000);
            $SQL_CONTENT = (strlen($sql_file_OR_content) > 300 ?  $sql_file_OR_content : file_get_contents($sql_file_OR_content)  );
            $allLines = explode("\n",$SQL_CONTENT);
            $mysqli = new mysqli($host, $user, $pass, $dbname); if (mysqli_connect_errno()){echo "Failed to connect to MySQL: " . mysqli_connect_error();}
                    $zzzzzz = $mysqli->query('SET foreign_key_checks = 0');         preg_match_all("/\nCREATE TABLE(.*?)\`(.*?)\`/si", "\n". $SQL_CONTENT, $target_tables); foreach ($target_tables[2] as $table){$mysqli->query('DROP TABLE IF EXISTS '.$table);}         $zzzzzz = $mysqli->query('SET foreign_key_checks = 1');    $mysqli->query("SET NAMES 'utf8'");
            $templine = ''; // Temporary variable, used to store current query
            foreach ($allLines as $line)    {                                           // Loop through each line
                    if (substr($line, 0, 2) != '--' && $line != '') {$templine .= $line;    // (if it is not a comment..) Add this line to the current segment
                            if (substr(trim($line), -1, 1) == ';') {        // If it has a semicolon at the end, it's the end of the query
                                    if(!$mysqli->query($templine)){ print('Error performing query \'<strong>' . $templine . '\': ' . $mysqli->error . '<br /><br />');  }  $templine = ''; // set variable to empty, to start picking up the lines after ";"
                            }
                    }
            }   return;
        }
        $filename = 'database.sql';
        $mysql_host = $_POST['db_host'];
        $mysql_username = $_POST['db_user'];
        $mysql_password = $_POST['db_pass'];
        $mysql_database = $_POST['db_name'];
        mysqli_connect($mysql_host, $mysql_username, $mysql_password) or die('Error connecting to MySQL server: ' . mysql_error()."<a style='color: red; font-weight: bold; font-size: 20px;' href='install.php'>go back and try again.</a> If you have no ideas why it happening email me - support@deep64.com");
        mysql_select_db($mysql_database) or die('Error selecting MySQL database: ' . mysql_error()."<a style='color: red; font-weight: bold; font-size: 20px;' href='install.php'>go back and try again.</a> If you have no ideas why it happening email me - support@deep64.com");
        IMPORT_TABLES($mysql_host, $mysql_username, $mysql_password, $mysql_database, 'database.sql');
        $text="<?php
                ".'$'."db['default']['hostname']= '$mysql_host';                         // HOSTNAME HERE
                ".'$'."db['default']['username']=  '$mysql_username';                      // USERNAME HERE
                ".'$'."db['default']['password']=  '$mysql_password';                     // PASSWORD HERE
                ".'$'."db['default']['database']=  '$mysql_database';                     // DB NAME HERE
                ".'$'."db['default']['dbdriver']=  'mysqli';
        ";
        write_to_file('application/config/db.php', $text);
        $text="<?php
        ".'$'."config['base_url'] = '".$_POST['domain']."';
        ";
        write_to_file('application/config/siteurl.php', $text);
        $text="RewriteEngine on
RewriteCond $1 !^(index\.php|resources|robots\.txt)
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !/assets
RewriteRule ^(.*)$ index.php?/$1 [L,QSA]
RewriteRule page/assets/img/([^.]+\.(jpe?g|gif|bmp|png))$ /assets/img/$1 [R=301,L,NC]
RewriteRule page/assets/img/uploads/([^.]+\.(jpe?g|gif|bmp|png))$ /assets/img/uploads/$1 [R=301,L,NC]
RewriteRule admin/assets/img/([^.]+\.(jpe?g|gif|bmp|png))$ /assets/img/$1 [R=301,L,NC]
RewriteRule admin/assets/img/uploads/([^.]+\.(jpe?g|gif|bmp|png))$ /assets/img/uploads/$1 [R=301,L,NC]
        ";
        write_to_file('.htaccess', $text);
        header("Location: ".$_POST['domain']);
    }else{
        echo "You missed something, <a style='color: red; font-weight: bold; font-size: 20px;' href='install.php'>go back and try again.</a> If you have no ideas why it happening email me - support@deep64.com";
    }