Web crawler in PHP

<?php 
$start = "http://localhost/se_india/test.html";
$pdo = new PDO('mysql:host=127.0.0.1;dbname=seindia','root','');
$already_crawled = array();
$crawling = array();
function get_details($url){
    $options = array('http'=>array('method'=>"GET",'headers'=>"User-Agent: Botman/0.1\n"));
    $context = stream_context_create($options);
    $doc =  new DOMDocument();
    @$doc ->loadHTML(@file_get_contents($url,false,$context));
    $title = $doc->getElementsByTagName("title");
    $title = $title ->item(0)->nodeValue;
    $description ="";
    $keywords="";
    $metas = $doc ->getElementsByTagName("meta");
    for ($i = 0; $i<$metas->length;$i++){
        $meta =$metas->item($i);
        if(strtolower($meta->getAttribute("name"))=="description")
            $description = $meta->getAttribute("content");
        if(strtolower($meta->getAttribute("name"))=="keywords")
            $keywords = $meta->getAttribute("content");
    }
    return '{ " Title " : " ' .str_replace( " \n " , "" , $title ).' "," Description " : " ' .str_replace( " \n " , "" , $description ).' "," Keywords " : " ' .str_replace( " \n " , "" , $keywords ).' ","URL":" ' .$url. ' "}';
}
function  follow_links($url){
    global $already_crawled;
    global $crawling;
    $options = array('http'=>array('method'=>"GET",'headers'=>"User-Agent: Botman/0.1\n"));
    $context = stream_context_create($options);
    $doc =  new DOMDocument();
    @$doc ->loadHTML(@file_get_contents($url,false,$context));
    $linklist = $doc->getElementsByTagName("a");
    foreach ($linklist as $link){
        $l =  $link->getAttribute("href");
        if (substr($l,0,1)=="/"&&substr($i,0,2)=="//"){
                $l = parse_url($url)["scheme"]. " :// ". parse_url($url)["host"].$l;
        }else if(substr($l,0,2) == "//"){
                $l = parse_url($url)["scheme"].":".$l;
        }else if(substr($l,0,2)=="./"){
                $l = parse_url($url)["scheme"]."://".parse_url($url)["host"].dirname(parse_url($url)["path"]).substr($l,1);
        }else if (substr($l,0,1)=="#"){
                $l = parse_url($url)["scheme"]."://".parse_url($url)["host"].parse_url($url)["path"].$l;
        }else if(substr($l,0,3)=="../"){
                $l = parse_url($url)["scheme"]."://".parse_url($url)["host"]."/".$l;
        }else if (substr($l,0,11)=="javascript:"){
            continue;
        }else if (substr($l,0,1)=="https" && substr($l,0,1)=="http"){
            $l = parse_url($url)["scheme"]."://".parse_url($url)["host"]."/".$l;
        }
        if(!in_array($l,$already_crawled)){
            $already_crawled[] = $l;
            $crawling[]=$l;
            $details = json_decode(get_details($l));
            print_r($details)."\n";
            // echo get_details($l)."\n";
        }
    }
    array_shift($crawling);
    foreach($crawling as $site){
        follow_links($site);
    }
}
follow_links($start);
?>