url_fns.php

<?php
require_once('db_fns.php');

function get_user_urls($username)
{
  //extract from the database all the URLs this user has stored
  $conn = db_connect();
  $result = $conn->query( "select bm_URL
                          from bookmark
                          where username = '$username'");
  if (!$result)
    return false; 

  //create an array of the URLs 
  $url_array = array();
  for ($count = 1; $row = $result->fetch_row(); ++$count) 
  {
    $url_array[$count] = $row[0];
  }  
  return $url_array;
}
  
function add_bm($new_url)
{
  // Add new bookmark to the database

  echo "Attempting to add ".htmlspecialchars($new_url).'<br />';
  $valid_user = $_SESSION['valid_user'];
  
  $conn = db_connect();

  // check not a repeat bookmark
  $result = $conn->query("select * from bookmark
                         where username='$valid_user' 
                         and bm_URL='$new_url'");
  if ($result && ($result->num_rows>0))
    throw new Exception('Bookmark already exists.');

  // insert the new bookmark
  if (!$conn->query( "insert into bookmark values
                          ('$valid_user', '$new_url')"))
    throw new Exception('Bookmark could not be inserted.'); 

  return true;
} 

function delete_bm($user, $url)
{
  // delete one URL from the database
  $conn = db_connect();
  // delete the bookmark
  if (!$conn->query( "delete from bookmark 
                       where username='$user' and bm_url='$url'"))
    throw new Exception('Bookmark could not be deleted');
  return true;  
}


/*function recommend_urls($valid_user, $popularity = 1)*/
function recommend_urls()
{
  // We will provide semi intelligent recomendations to people
  // If they have an URL in common with other users, they may like
  // other URLs that these people like 
  $conn = db_connect();

  // find other matching users
  // with an url the same as you
  // as a simple way of excluding people's private pages, and 
  // increasing the chance of recommending appealing URLs, we
  // specify a minimum popularity level
  // if $popularity = 1, then more than one person must have 
  // an URL before we will recomend it
 $query="
select x.bm_URL from (
select count(a.bm_URL) counth, c.bm_url
from bookmark a, user b,bookmark c where a.username=b.username and a.username=c.username
group by c.bm_url
ORDER by counth desc limit 4) x";
	
	
	
	/*$query = "select max(count(bm_URL))
	    from bookmark
	    where username in
	   	 (select distinct(b2.username)
                  from bookmark b1, bookmark b2
		  where b1.username='$valid_user'
                  and b1.username != b2.username
                  and b1.bm_URL = b2.bm_URL)
	    and bm_URL not in
 				  (select bm_URL
				   from bookmark
				   where username='$valid_user')
            group by bm_url
            having count(bm_url)>$popularity";*/
 
  if (!($result = $conn->query($query)))
     throw new Exception('Could not find any bookmarks to recommend.');
  if ($result->num_rows==0)
     throw new Exception('Could not find any bookmarks to recommend.');
 
  $urls = array();
  // build an array of the relevant urls
  for ($count=0; $row = $result->fetch_object(); $count++)
  {
     $urls[$count] = $row->bm_URL; 
  }
                              
  return $urls; 
}
?>