<?php
//function to locate expiry date in P tag
function filterObsolete($str) {
        date_default_timezone_set('Asia/Calcutta');
        $today = date("d-M-Y");

        //trim string
        $str = trim(preg_replace('/\s+/', ' ', $str));
	$attr = 'expDate="';
	$i = 0;
	$j = 0;
	$k = 0;
	$slen = 0;
	$oTAG = '';
	$cTAG = '';
	$summary = '';

        //check existance of expDate
        while (($i = @strpos($str, $attr, $k)) !== false) {
                //find value of expDate
                $expDateValue = substr($str, $i + strlen($attr), 11);

                //if value of expDate is found in string, locate opening/closing TAGs
		//check value of expDate against system date
                if ($expDateValue && ($expDateValue < $today)) {
                        //find position of opening TAG
                        $j = $i;
                        while ($str[$j] != '<') {
                                $j--;
                        }

			//find opening TAG name
			$oTAG = substr($str, $j, strpos($str, ' ', $j) - $j);

			//find closing TAG name
			$cTAG = str_replace('<', '</', $oTAG) .'>';

                        //find position of closing TAG
			$k = strpos($str, $cTAG, $i) + strlen($cTAG);

                        //number of obsolete characters
			$slen = $k - $j;
                        
			//mark obsolescence and filter from content
                        $obsolete = substr($str, $j, $slen);
                        $str = str_replace($obsolete, '', $str);
                        $summary .= "$slen Obsolete characters filtered (".htmlspecialchars($oTAG).">) $j-$k<br>";
                        $k = $j;
                }
                $k = $k + strlen($attr);
                if ($i >= strlen($str)) break;
        }
        //return filtered content
        $str .=  '<hr>' .$summary;
        return $str;
}

//function to locate expiry date in P tag
function filterExpiry($str) {
        date_default_timezone_set('Asia/Calcutta');
        $today = date("d-M-Y");
        //trim string
        $str = trim(preg_replace('/\s+/', ' ', $str));

        //check existance of expDate
        while (($i = @strpos($str, "expDate", $k)) !== false) {
		//find value of expDate
                $expDateValue = substr($str, $i+9, 11);

                //if value of expDate is found in string, locate opening TAG
                if ($expDateValue && ($expDateValue < $today)) {
			$j = $i;
                        //find position of opening TAG
		        while ($j >= 0 && $str[$j] != '<') {
                		$j--;
        		}
                        
			//$j = tagStart($str, $i);

                        $k = $j;
			//find position of closing TAG
        		$slen = strlen($str);
        		while ($k < $slen) {
				if ($str[$k] == '<' && $str[$k+1] == '/') {
					$k = $k+4;
					break;
                		}
                		$k++;
        		}
			//$k = tagEnd($str, $i) + 1;
			
			$slen = $k-$j;
	                //check value of expDate against system date
        		$obsolete = substr($str, $j, $slen);
			$summary .= "\n$slen Obsolete characters\n<br>";
			$str = str_replace($obsolete, '', $str);
			$k = $j;
        	}
		$k = $k + 8;
		if ($i >= strlen($str)) break;
        }
	//return filtered content
	$str .=  '<hr>' .$summary;
        return $str;
}


//function to locate expiry date in P tag
function checkExpiry($str) {
	date_default_timezone_set('Asia/Calcutta');
        $today = date("d-M-Y"); 
	//trim string
	$str = trim($str);
	
	//get length of string
	$slen = strlen($str);

	//check existance of expDate
	if (substr_count($str, "expDate")) {
		//find position of expDate in string
		$i = strpos($str, "expDate");
		
		//find value of expDate
		$expDateValue = substr($str, $i+9, 11);
		
		//if value of expDate is found in string, locate opening TAG
		if ($expDateValue) {
			//find position of opening TAG
			$j = tagStart($str, $i);
			
			//find position of closing TAG
			$k = tagEnd($str, $i);
			
			//if closing TAG could not be found
			if (!$k) {
				//mark end of string with unpaired TAG
				$k = $slen-1;
				$pair = FALSE;
			} else {
				//mark end of string with paired TAG
				$pair = TRUE;
			}
		} else {
			//mark end of string with unpaired TAG
			$j = $i+1;
			$pair = FALSE;
		}

		//check value of expDate against system date
		if ($expDateValue < $today) {
			//chop first part of string with unexpired content
			$str1 = substr($str, 0, $j);

			//chop second part of string with probable expired content
			$str2 = substr($str, $k+1);
			
			if ($str2) {
				//few content is expired
				//check probable expired content in second part
				$str = $str1. checkExpiry($str2);
			} else {
				//no expired content
				$str = $str1;
			}
		} else {
			//chop first part of string with unexpired content
			$str1 = substr($str, 0, $k);

			//chop second part of string with probable expired content
			$str2 = substr($str, $k+1);
			
			//check for next expired content
			$str = $str1. checkExpiry($str2);
		}
	}
	//return filtered content
	return $str;
}

//function to locate HTML tag opening
function tagStart($str, $j) {
        while ($j >= 0 && $str[$j] != '<'){
                $j--;
        }
        return $j;
}

//function to locate HTML tag closing
function tagEnd($str, $k) {
        $open = 1;
        $close = 0;
        $slen = strlen($str);
        while ($k < $slen) {
                if ($str[$k] == '<') {
                        //$check = 0;
                        while ($k < $slen && $str[$k] != '>') {
                                if ($str[$k] == '<' && $str[$k+1] == '/') {
                                    	return $k+4;
					//$check = 1;
                                }
                                $k++;
                        }
                        //if ($check) {
                        //        $close++;
                        //} else {
                        //        $open++;
                        //}
                        //if ($open == $close) {
                        //        return ($k+1);
                        //}
                }
                $k++;
        }
}

/*
function tagFilter1($str) {
        $i = 0;
        while($i < $httplen) {
                if($httpbuffer[i] == $str[0]) {
                        $j = i;
                        $k = 0;
                        $check = 0;
                        while($j < $httplen && $str[$k] != '\0') {
                                if($str[$k] != $httpbuffer[$j]) {
                                        $check = 1;
                                        break;
                                }
                                $j++;
                                $k++;
                        }
                        if(!$check) {
                                $ax=0;
                                $date[8]='';

                                $ax = $j + 2;

                                //Assuming date format as exp="dd/mm/yyyy"
                                $date[0] = $httpbuffer[$ax] - 48;
                                $date[1] = $httpbuffer[$ax+1] - 48;
                                $date[2] = $httpbuffer[$ax+3] - 48;
                                $date[3] = $httpbuffer[$ax+4] - 48;
                                $date[4] = $httpbuffer[$ax+6] - 48;
                                $date[5] = $httpbuffer[$ax+7] - 48;
                                $date[6] = $httpbuffer[$ax+8] - 48;
                                $date[7] = $httpbuffer[$ax+9] - 48;

                                //Catched_date contains the date extracted from the HTML.
                                $catched_date = (struct tm *)malloc(sizeof(struct tm));
                                $catched_date -> tm_mday = (date[0] * 10) + date[1];
                                $catched_date -> tm_mon = (date[2] * 10) + date[3];
                                $catched_date -> tm_year = (date[4] * 1000) + (date[5] * 100) + (date[6] * 10) + date[7];
                                if(dateisexpired($catched_date)) {
                                    $start = tagStart($i);
                                    $end = tagEnd($j);
                                    tagDelete($start,$end);
                                }
                        }
                }  
                $i++;
        }
}
*/

?>