<?php

/**
* Tools for validing a UTF-8 string is well formed.
* The Original Code is Mozilla Communicator client code.
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
* Ported to PHP by Henri Sivonen (http://hsivonen.iki.fi)
* Slight modifications to fit with phputf8 library by Harry Fuecks (hfuecks gmail com)
* @see http://lxr.mozilla.org/seamonkey/source/intl/uconv/src/nsUTF8ToUnicode.cpp
* @see http://lxr.mozilla.org/seamonkey/source/intl/uconv/src/nsUnicodeToUTF8.cpp
* @see http://hsivonen.iki.fi/php-utf8/
* @package utf8
*/

//--------------------------------------------------------------------
/**
* Tests a string as to whether it's valid UTF-8 and supported by the
* Unicode standard
* Note: this function has been modified to simple return true or false
* @author <hsivonen@iki.fi>
* @param string UTF-8 encoded string
* @return boolean true if valid
* @see http://hsivonen.iki.fi/php-utf8/
* @see utf8_compliant
* @package utf8
*/
function utf8_is_valid($str)
{
    $mState = 0;     // cached expected number of octets after the current octet
                     // until the beginning of the next UTF8 character sequence
    $mUcs4  = 0;     // cached Unicode character
    $mBytes = 1;     // cached expected number of octets in the current sequence

    $len = strlen($str);

    for ($i = 0; $i < $len; $i++) {
        /*
         * Joomla modification - As of PHP 7.4, curly brace access has been deprecated. As a result the line below has
         * been modified to use square brace syntax
         * See https://github.com/php/php-src/commit/d574df63dc375f5fc9202ce5afde23f866b6450a
         * for additional references
         */
        $in = ord($str[$i]);

        if ($mState == 0) {
            // When mState is zero we expect either a US-ASCII character or a
            // multi-octet sequence.
            if (0 == (0x80 & ($in))) {
                // US-ASCII, pass straight through.
                $mBytes = 1;
            } elseif (0xC0 == (0xE0 & ($in))) {
                // First octet of 2 octet sequence
                $mUcs4  = ($in);
                $mUcs4  = ($mUcs4 & 0x1F) << 6;
                $mState = 1;
                $mBytes = 2;
            } elseif (0xE0 == (0xF0 & ($in))) {
                // First octet of 3 octet sequence
                $mUcs4  = ($in);
                $mUcs4  = ($mUcs4 & 0x0F) << 12;
                $mState = 2;
                $mBytes = 3;
            } elseif (0xF0 == (0xF8 & ($in))) {
                // First octet of 4 octet sequence
                $mUcs4  = ($in);
                $mUcs4  = ($mUcs4 & 0x07) << 18;
                $mState = 3;
                $mBytes = 4;
            } elseif (0xF8 == (0xFC & ($in))) {
                /* First octet of 5 octet sequence.
                *
                * This is illegal because the encoded codepoint must be either
                * (a) not the shortest form or
                * (b) outside the Unicode range of 0-0x10FFFF.
                * Rather than trying to resynchronize, we will carry on until the end
                * of the sequence and let the later error handling code catch it.
                */
                $mUcs4  = ($in);
                $mUcs4  = ($mUcs4 & 0x03) << 24;
                $mState = 4;
                $mBytes = 5;
            } elseif (0xFC == (0xFE & ($in))) {
                // First octet of 6 octet sequence, see comments for 5 octet sequence.
                $mUcs4  = ($in);
                $mUcs4  = ($mUcs4 & 1) << 30;
                $mState = 5;
                $mBytes = 6;
            } else {
                /* Current octet is neither in the US-ASCII range nor a legal first
                 * octet of a multi-octet sequence.
                 */
                return false;
            }
        } else {
            // When mState is non-zero, we expect a continuation of the multi-octet
            // sequence
            if (0x80 == (0xC0 & ($in))) {
                // Legal continuation.
                $shift = ($mState - 1) * 6;
                $tmp   = $in;
                $tmp   = ($tmp & 0x0000003F) << $shift;
                $mUcs4 |= $tmp;

                /**
                * End of the multi-octet sequence. mUcs4 now contains the final
                * Unicode codepoint to be output
                */
                if (0 == --$mState) {
                    /*
                    * Check for illegal sequences and codepoints.
                    */
                    // From Unicode 3.1, non-shortest form is illegal
                    if (
                        ((2 == $mBytes) && ($mUcs4 < 0x0080)) ||
                        ((3 == $mBytes) && ($mUcs4 < 0x0800)) ||
                        ((4 == $mBytes) && ($mUcs4 < 0x10000)) ||
                        (4 < $mBytes) ||
                        // From Unicode 3.2, surrogate characters are illegal
                        (($mUcs4 & 0xFFFFF800) == 0xD800) ||
                        // Codepoints outside the Unicode range are illegal
                        ($mUcs4 > 0x10FFFF)
                    ) {
                        return false;
                    }

                    //initialize UTF8 cache
                    $mState = 0;
                    $mUcs4  = 0;
                    $mBytes = 1;
                }
            } else {
                /**
                *((0xC0 & (*in) != 0x80) && (mState != 0))
                * Incomplete multi-octet sequence.
                */

                return false;
            }
        }
    }
    return true;
}

//--------------------------------------------------------------------
/**
* Tests whether a string complies as UTF-8. This will be much
* faster than utf8_is_valid but will pass five and six octet
* UTF-8 sequences, which are not supported by Unicode and
* so cannot be displayed correctly in a browser. In other words
* it is not as strict as utf8_is_valid but it's faster. If you use
* is to validate user input, you place yourself at the risk that
* attackers will be able to inject 5 and 6 byte sequences (which
* may or may not be a significant risk, depending on what you are
* are doing)
* @see utf8_is_valid
* @see http://www.php.net/manual/en/reference.pcre.pattern.modifiers.php#54805
* @param string UTF-8 string to check
* @return boolean TRUE if string is valid UTF-8
* @package utf8
*/
function utf8_compliant($str)
{
    if (strlen($str) == 0) {
        return true;
    }
    // If even just the first character can be matched, when the /u
    // modifier is used, then it's valid UTF-8. If the UTF-8 is somehow
    // invalid, nothing at all will match, even if the string contains
    // some valid sequences
    return (preg_match('/^.{1}/us', $str, $ar) == 1);
}
