<?php

/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package	CodeIgniter
 * @author	EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	https://codeigniter.com
 * @since	Version 1.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * Common Functions
 *
 * Loads the base classes and executes the request.
 *
 * @package		CodeIgniter
 * @subpackage	CodeIgniter
 * @category	Common Functions
 * @author		EllisLab Dev Team
 * @link		https://codeigniter.com/user_guide/
 */
// ------------------------------------------------------------------------

if (!function_exists('is_php')) {

    /**
     * Determines if the current version of PHP is equal to or greater than the supplied value
     *
     * @param	string
     * @return	bool	TRUE if the current version is $version or higher
     */
    function is_php($version) {
        static $_is_php;
        $version = (string) $version;

        if (!isset($_is_php[$version])) {
            $_is_php[$version] = version_compare(PHP_VERSION, $version, '>=');
        }

        return $_is_php[$version];
    }

}

// ------------------------------------------------------------------------

if (!function_exists('is_really_writable')) {

    /**
     * Tests for file writability
     *
     * is_writable() returns TRUE on Windows servers when you really can't write to
     * the file, based on the read-only attribute. is_writable() is also unreliable
     * on Unix servers if safe_mode is on.
     *
     * @link	https://bugs.php.net/bug.php?id=54709
     * @param	string
     * @return	bool
     */
    function is_really_writable($file) {
        // If we're on a Unix server with safe_mode off we call is_writable
        if (DIRECTORY_SEPARATOR === '/' && (is_php('5.4') OR ! ini_get('safe_mode'))) {
            return is_writable($file);
        }

        /* For Windows servers and safe_mode "on" installations we'll actually
         * write a file then read it. Bah...
         */
        if (is_dir($file)) {
            $file = rtrim($file, '/') . '/' . md5(mt_rand());
            if (($fp = @fopen($file, 'ab')) === FALSE) {
                return FALSE;
            }

            fclose($fp);
            @chmod($file, 0777);
            @unlink($file);
            return TRUE;
        } elseif (!is_file($file) OR ( $fp = @fopen($file, 'ab')) === FALSE) {
            return FALSE;
        }

        fclose($fp);
        return TRUE;
    }

}

// ------------------------------------------------------------------------

if (!function_exists('load_class')) {

    /**
     * Class registry
     *
     * This function acts as a singleton. If the requested class does not
     * exist it is instantiated and set to a static variable. If it has
     * previously been instantiated the variable is returned.
     *
     * @param	string	the class name being requested
     * @param	string	the directory where the class should be found
     * @param	string	an optional argument to pass to the class constructor
     * @return	object
     */
    function &load_class($class, $directory = 'libraries', $param = NULL) {
        static $_classes = array();

        // Does the class exist? If so, we're done...
        if (isset($_classes[$class])) {
            return $_classes[$class];
        }

        $name = FALSE;

        // Look for the class first in the local application/libraries folder
        // then in the native system/libraries folder
        foreach (array(APPPATH, BASEPATH) as $path) {
            if (file_exists($path . $directory . '/' . $class . '.php')) {
                $name = 'CI_' . $class;

                if (class_exists($name, FALSE) === FALSE) {
                    require_once($path . $directory . '/' . $class . '.php');
                }

                break;
            }
        }

        // Is the request a class extension? If so we load it too
        if (file_exists(APPPATH . $directory . '/' . config_item('subclass_prefix') . $class . '.php')) {
            $name = config_item('subclass_prefix') . $class;

            if (class_exists($name, FALSE) === FALSE) {
                require_once(APPPATH . $directory . '/' . $name . '.php');
            }
        }

        // Did we find the class?
        if ($name === FALSE) {
            // Note: We use exit() rather than show_error() in order to avoid a
            // self-referencing loop with the Exceptions class
            set_status_header(503);
            echo 'Unable to locate the specified class: ' . $class . '.php';
            exit(5); // EXIT_UNK_CLASS
        }

        // Keep track of what we just loaded
        is_loaded($class);

        $_classes[$class] = isset($param) ? new $name($param) : new $name();
        return $_classes[$class];
    }

}

// --------------------------------------------------------------------

if (!function_exists('is_loaded')) {

    /**
     * Keeps track of which libraries have been loaded. This function is
     * called by the load_class() function above
     *
     * @param	string
     * @return	array
     */
    function &is_loaded($class = '') {
        static $_is_loaded = array();

        if ($class !== '') {
            $_is_loaded[strtolower($class)] = $class;
        }

        return $_is_loaded;
    }

}

// ------------------------------------------------------------------------

if (!function_exists('get_config')) {

    /**
     * Loads the main config.php file
     *
     * This function lets us grab the config file even if the Config class
     * hasn't been instantiated yet
     *
     * @param	array
     * @return	array
     */
    function &get_config(Array $replace = array()) {
        static $config;

        if (empty($config)) {
            $file_path = APPPATH . 'config/config.php';
            $found = FALSE;
            if (file_exists($file_path)) {
                $found = TRUE;
                require($file_path);
            }

            // Is the config file in the environment folder?
            if (file_exists($file_path = APPPATH . 'config/' . ENVIRONMENT . '/config.php')) {
                require($file_path);
            } elseif (!$found) {
                set_status_header(503);
                echo 'The configuration file does not exist.';
                exit(3); // EXIT_CONFIG
            }

            // Does the $config array exist in the file?
            if (!isset($config) OR ! is_array($config)) {
                set_status_header(503);
                echo 'Your config file does not appear to be formatted correctly.';
                exit(3); // EXIT_CONFIG
            }
        }

        // Are any values being dynamically added or replaced?
        foreach ($replace as $key => $val) {
            $config[$key] = $val;
        }

        return $config;
    }

}

// ------------------------------------------------------------------------

if (!function_exists('config_item')) {

    /**
     * Returns the specified config item
     *
     * @param	string
     * @return	mixed
     */
    function config_item($item) {
        static $_config;

        if (empty($_config)) {
            // references cannot be directly assigned to static variables, so we use an array
            $_config[0] = & get_config();
        }

        return isset($_config[0][$item]) ? $_config[0][$item] : NULL;
    }

}

// ------------------------------------------------------------------------

if (!function_exists('get_mimes')) {

    /**
     * Returns the MIME types array from config/mimes.php
     *
     * @return	array
     */
    function &get_mimes() {
        static $_mimes;

        if (empty($_mimes)) {
            $_mimes = file_exists(APPPATH . 'config/mimes.php') ? include(APPPATH . 'config/mimes.php') : array();

            if (file_exists(APPPATH . 'config/' . ENVIRONMENT . '/mimes.php')) {
                $_mimes = array_merge($_mimes, include(APPPATH . 'config/' . ENVIRONMENT . '/mimes.php'));
            }
        }

        return $_mimes;
    }

}

// ------------------------------------------------------------------------

if (!function_exists('is_https')) {

    /**
     * Is HTTPS?
     *
     * Determines if the application is accessed via an encrypted
     * (HTTPS) connection.
     *
     * @return	bool
     */
    function is_https() {
        if (!empty($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) !== 'off') {
            return TRUE;
        } elseif (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && strtolower($_SERVER['HTTP_X_FORWARDED_PROTO']) === 'https') {
            return TRUE;
        } elseif (!empty($_SERVER['HTTP_FRONT_END_HTTPS']) && strtolower($_SERVER['HTTP_FRONT_END_HTTPS']) !== 'off') {
            return TRUE;
        }

        return FALSE;
    }

}

// ------------------------------------------------------------------------

if (!function_exists('is_cli')) {

    /**
     * Is CLI?
     *
     * Test to see if a request was made from the command line.
     *
     * @return 	bool
     */
    function is_cli() {
        return (PHP_SAPI === 'cli' OR defined('STDIN'));
    }

}

// ------------------------------------------------------------------------

if (!function_exists('show_error')) {

    /**
     * Error Handler
     *
     * This function lets us invoke the exception class and
     * display errors using the standard error template located
     * in application/views/errors/error_general.php
     * This function will send the error page directly to the
     * browser and exit.
     *
     * @param	string
     * @param	int
     * @param	string
     * @return	void
     */
    function show_error($message, $status_code = 500, $heading = 'An Error Was Encountered') {
        $status_code = abs($status_code);
        if ($status_code < 100) {
            $exit_status = $status_code + 9; // 9 is EXIT__AUTO_MIN
            $status_code = 500;
        } else {
            $exit_status = 1; // EXIT_ERROR
        }

        $_error = & load_class('Exceptions', 'core');
        echo $_error->show_error($heading, $message, 'error_general', $status_code);
        exit($exit_status);
    }

}

// ------------------------------------------------------------------------

if (!function_exists('show_404')) {

    /**
     * 404 Page Handler
     *
     * This function is similar to the show_error() function above
     * However, instead of the standard error template it displays
     * 404 errors.
     *
     * @param	string
     * @param	bool
     * @return	void
     */
    function show_404($page = '', $log_error = TRUE) {
        $_error = & load_class('Exceptions', 'core');
        $_error->show_404($page, $log_error);
        exit(4); // EXIT_UNKNOWN_FILE
    }

}

// ------------------------------------------------------------------------

if (!function_exists('log_message')) {

    /**
     * Error Logging Interface
     *
     * We use this as a simple mechanism to access the logging
     * class and send messages to be logged.
     *
     * @param	string	the error level: 'error', 'debug' or 'info'
     * @param	string	the error message
     * @return	void
     */
    function log_message($level, $message) {
        static $_log;

        if ($_log === NULL) {
            // references cannot be directly assigned to static variables, so we use an array
            $_log[0] = & load_class('Log', 'core');
        }

        $_log[0]->write_log($level, $message);
    }

}

// ------------------------------------------------------------------------

if (!function_exists('set_status_header')) {

    /**
     * Set HTTP Status Header
     *
     * @param	int	the status code
     * @param	string
     * @return	void
     */
    function set_status_header($code = 200, $text = '') {
        if (is_cli()) {
            return;
        }

        if (empty($code) OR ! is_numeric($code)) {
            show_error('Status codes must be numeric', 500);
        }

        if (empty($text)) {
            is_int($code) OR $code = (int) $code;
            $stati = array(
                100 => 'Continue',
                101 => 'Switching Protocols',
                200 => 'OK',
                201 => 'Created',
                202 => 'Accepted',
                203 => 'Non-Authoritative Information',
                204 => 'No Content',
                205 => 'Reset Content',
                206 => 'Partial Content',
                300 => 'Multiple Choices',
                301 => 'Moved Permanently',
                302 => 'Found',
                303 => 'See Other',
                304 => 'Not Modified',
                305 => 'Use Proxy',
                307 => 'Temporary Redirect',
                400 => 'Bad Request',
                401 => 'Unauthorized',
                402 => 'Payment Required',
                403 => 'Forbidden',
                404 => 'Not Found',
                405 => 'Method Not Allowed',
                406 => 'Not Acceptable',
                407 => 'Proxy Authentication Required',
                408 => 'Request Timeout',
                409 => 'Conflict',
                410 => 'Gone',
                411 => 'Length Required',
                412 => 'Precondition Failed',
                413 => 'Request Entity Too Large',
                414 => 'Request-URI Too Long',
                415 => 'Unsupported Media Type',
                416 => 'Requested Range Not Satisfiable',
                417 => 'Expectation Failed',
                422 => 'Unprocessable Entity',
                426 => 'Upgrade Required',
                428 => 'Precondition Required',
                429 => 'Too Many Requests',
                431 => 'Request Header Fields Too Large',
                500 => 'Internal Server Error',
                501 => 'Not Implemented',
                502 => 'Bad Gateway',
                503 => 'Service Unavailable',
                504 => 'Gateway Timeout',
                505 => 'HTTP Version Not Supported',
                511 => 'Network Authentication Required',
            );

            if (isset($stati[$code])) {
                $text = $stati[$code];
            } else {
                show_error('No status text available. Please check your status code number or supply your own message text.', 500);
            }
        }

        if (strpos(PHP_SAPI, 'cgi') === 0) {
            header('Status: ' . $code . ' ' . $text, TRUE);
            return;
        }

        $server_protocol = (isset($_SERVER['SERVER_PROTOCOL']) && in_array($_SERVER['SERVER_PROTOCOL'], array('HTTP/1.0', 'HTTP/1.1', 'HTTP/2'), TRUE)) ? $_SERVER['SERVER_PROTOCOL'] : 'HTTP/1.1';
        header($server_protocol . ' ' . $code . ' ' . $text, TRUE, $code);
    }

}

// --------------------------------------------------------------------

if (!function_exists('_error_handler')) {

    /**
     * Error Handler
     *
     * This is the custom error handler that is declared at the (relative)
     * top of CodeIgniter.php. The main reason we use this is to permit
     * PHP errors to be logged in our own log files since the user may
     * not have access to server logs. Since this function effectively
     * intercepts PHP errors, however, we also need to display errors
     * based on the current error_reporting level.
     * We do that with the use of a PHP error template.
     *
     * @param	int	$severity
     * @param	string	$message
     * @param	string	$filepath
     * @param	int	$line
     * @return	void
     */
    function _error_handler($severity, $message, $filepath, $line) {
        $is_error = (((E_ERROR | E_PARSE | E_COMPILE_ERROR | E_CORE_ERROR | E_USER_ERROR) & $severity) === $severity);

        // When an error occurred, set the status header to '500 Internal Server Error'
        // to indicate to the client something went wrong.
        // This can't be done within the $_error->show_php_error method because
        // it is only called when the display_errors flag is set (which isn't usually
        // the case in a production environment) or when errors are ignored because
        // they are above the error_reporting threshold.
        if ($is_error) {
            set_status_header(500);
        }

        // Should we ignore the error? We'll get the current error_reporting
        // level and add its bits with the severity bits to find out.
        if (($severity & error_reporting()) !== $severity) {
            return;
        }

        $_error = & load_class('Exceptions', 'core');
        $_error->log_exception($severity, $message, $filepath, $line);

        // Should we display the error?
        if (str_ireplace(array('off', 'none', 'no', 'false', 'null'), '', ini_get('display_errors'))) {
            $_error->show_php_error($severity, $message, $filepath, $line);
        }

        // If the error is fatal, the execution of the script should be stopped because
        // errors can't be recovered from. Halting the script conforms with PHP's
        // default error handling. See http://www.php.net/manual/en/errorfunc.constants.php
        if ($is_error) {
            exit(1); // EXIT_ERROR
        }
    }

}

// ------------------------------------------------------------------------

if (!function_exists('_exception_handler')) {

    /**
     * Exception Handler
     *
     * Sends uncaught exceptions to the logger and displays them
     * only if display_errors is On so that they don't show up in
     * production environments.
     *
     * @param	Exception	$exception
     * @return	void
     */
    function _exception_handler($exception) {
        $_error = & load_class('Exceptions', 'core');
        $_error->log_exception('error', 'Exception: ' . $exception->getMessage(), $exception->getFile(), $exception->getLine());

        is_cli() OR set_status_header(500);
        // Should we display the error?
        if (str_ireplace(array('off', 'none', 'no', 'false', 'null'), '', ini_get('display_errors'))) {
            $_error->show_exception($exception);
        }

        exit(1); // EXIT_ERROR
    }

}

// ------------------------------------------------------------------------

if (!function_exists('_shutdown_handler')) {

    /**
     * Shutdown Handler
     *
     * This is the shutdown handler that is declared at the top
     * of CodeIgniter.php. The main reason we use this is to simulate
     * a complete custom exception handler.
     *
     * E_STRICT is purposively neglected because such events may have
     * been caught. Duplication or none? None is preferred for now.
     *
     * @link	http://insomanic.me.uk/post/229851073/php-trick-catching-fatal-errors-e-error-with-a
     * @return	void
     */
    function _shutdown_handler() {
        $last_error = error_get_last();
        if (isset($last_error) &&
                ($last_error['type'] & (E_ERROR | E_PARSE | E_CORE_ERROR | E_CORE_WARNING | E_COMPILE_ERROR | E_COMPILE_WARNING))) {
            _error_handler($last_error['type'], $last_error['message'], $last_error['file'], $last_error['line']);
        }
    }

}

// --------------------------------------------------------------------

if (!function_exists('remove_invisible_characters')) {

    /**
     * Remove Invisible Characters
     *
     * This prevents sandwiching null characters
     * between ascii characters, like Java\0script.
     *
     * @param	string
     * @param	bool
     * @return	string
     */
    function remove_invisible_characters($str, $url_encoded = TRUE) {
        $non_displayables = array();

        // every control character except newline (dec 10),
        // carriage return (dec 13) and horizontal tab (dec 09)
        if ($url_encoded) {
            $non_displayables[] = '/%0[0-8bcef]/i'; // url encoded 00-08, 11, 12, 14, 15
            $non_displayables[] = '/%1[0-9a-f]/i'; // url encoded 16-31
            $non_displayables[] = '/%7f/i'; // url encoded 127
        }

        $non_displayables[] = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S'; // 00-08, 11, 12, 14-31, 127

        do {
            $str = preg_replace($non_displayables, '', $str, -1, $count);
        } while ($count);

        return $str;
    }

}

// ------------------------------------------------------------------------

if (!function_exists('html_escape')) {

    /**
     * Returns HTML escaped variable.
     *
     * @param	mixed	$var		The input string or array of strings to be escaped.
     * @param	bool	$double_encode	$double_encode set to FALSE prevents escaping twice.
     * @return	mixed			The escaped string or array of strings as a result.
     */
    function html_escape($var, $double_encode = TRUE) {
        if (empty($var)) {
            return $var;
        }

        if (is_array($var)) {
            foreach (array_keys($var) as $key) {
                $var[$key] = html_escape($var[$key], $double_encode);
            }

            return $var;
        }

        return htmlspecialchars($var, ENT_QUOTES, config_item('charset'), $double_encode);
    }

}

// ------------------------------------------------------------------------

if (!function_exists('_stringify_attributes')) {

    /**
     * Stringify attributes for use in HTML tags.
     *
     * Helper function used to convert a string, array, or object
     * of attributes to a string.
     *
     * @param	mixed	string, array, object
     * @param	bool
     * @return	string
     */
    function _stringify_attributes($attributes, $js = FALSE) {
        $atts = NULL;

        if (empty($attributes)) {
            return $atts;
        }

        if (is_string($attributes)) {
            return ' ' . $attributes;
        }

        $attributes = (array) $attributes;

        foreach ($attributes as $key => $val) {
            $atts .= ($js) ? $key . '=' . $val . ',' : ' ' . $key . '="' . $val . '"';
        }

        return rtrim($atts, ',');
    }

}

// ------------------------------------------------------------------------

if (!function_exists('function_usable')) {

    /**
     * Function usable
     *
     * Executes a function_exists() check, and if the Suhosin PHP
     * extension is loaded - checks whether the function that is
     * checked might be disabled in there as well.
     *
     * This is useful as function_exists() will return FALSE for
     * functions disabled via the *disable_functions* php.ini
     * setting, but not for *suhosin.executor.func.blacklist* and
     * *suhosin.executor.disable_eval*. These settings will just
     * terminate script execution if a disabled function is executed.
     *
     * The above described behavior turned out to be a bug in Suhosin,
     * but even though a fix was committed for 0.9.34 on 2012-02-12,
     * that version is yet to be released. This function will therefore
     * be just temporary, but would probably be kept for a few years.
     *
     * @link	http://www.hardened-php.net/suhosin/
     * @param	string	$function_name	Function to check for
     * @return	bool	TRUE if the function exists and is safe to call,
     * 			FALSE otherwise.
     */
    function function_usable($function_name) {
        static $_suhosin_func_blacklist;

        if (function_exists($function_name)) {
            if (!isset($_suhosin_func_blacklist)) {
                $_suhosin_func_blacklist = extension_loaded('suhosin') ? explode(',', trim(ini_get('suhosin.executor.func.blacklist'))) : array();
            }

            return !in_array($function_name, $_suhosin_func_blacklist, TRUE);
        }

        return FALSE;
    }

}
