PHP web crawler

[jotfish]

I have a basic PHP web crawler script and I need to expand its functionality, the problem is I'm a total noob at PHP and my knowledge is very basic so I'm coming here for some help.

My goal is to have a basic user input (text box) and when the user types in a phrase; let's say "Red Apples" and hits the enter button the script should start crawling the web for the phrase "Red Apples" and store the plain text results along with the URL they originated from in a database.

Here is what I've got so far:

error_reporting( E_ERROR );
 
define( "CRAWL_LIMIT_PER_DOMAIN", 50 );
 

$domains = array();

$urls = array();
 
function crawl( $url )
{
  global $domains, $urls;
 
  echo "Crawling $url... ";
 
  $parse = parse_url( $url );

  $domains[ $parse['host'] ]++;
  $urls[] = $url;
 
  $content = file_get_contents( $url );
  if ( $content === FALSE )
  {
    echo "Error.\n";
    return;
  }
 
 
  $content = stristr( $content, "body" );
  preg_match_all( '/http:\/\/[^ "\']+/', $content, $matches );
 
  echo 'Found ' . count( $matches[0] ) . " urls.\n";
 
  foreach( $matches[0] as $crawled_url )
  {
    $parse = parse_url( $crawled_url );
 
    if ( count( $domains[ $parse['host'] ] ) < CRAWL_LIMIT_PER_DOMAIN
        && !in_array( $crawled_url, $urls ) )
    {
      sleep( 1 );
      crawl( $crawled_url );
    }
  }
}

If anybody could point me in the right direction that would be awesome.