def real_get_page(url):
    import urllib
    try:
        return urllib.urlopen(url).read()
    except:
        return ""

cache = {
   'http://udacity.com/cs101x/urank/index.html': """<html>
<body>
<h1>Dave's Cooking Algorithms</h1>
<p>
Here are my favorite recipies:
<ul>
<li> <a href="http://udacity.com/cs101x/urank/hummus.html">Hummus Recipe</a>
<li> <a href="http://udacity.com/cs101x/urank/arsenic.html">World's Best Hummus</a>
<li> <a href="http://udacity.com/cs101x/urank/kathleen.html">Kathleen's Hummus Recipe</a>
</ul>

For more expert opinions, check out the 
<a href="http://udacity.com/cs101x/urank/nickel.html">Nickel Chef</a> 
and <a href="http://udacity.com/cs101x/urank/zinc.html">Zinc Chef</a>.
</body>
</html>






""", 
   'http://udacity.com/cs101x/urank/zinc.html': """<html>
<body>
<h1>The Zinc Chef</h1>
<p>
I learned everything I know from 
<a href="http://udacity.com/cs101x/urank/nickel.html">the Nickel Chef</a>.
</p>
<p>
For great hummus, try 
<a href="http://udacity.com/cs101x/urank/arsenic.html">this recipe</a>.

</body>
</html>






""", 
   'http://udacity.com/cs101x/urank/nickel.html': """<html>
<body>
<h1>The Nickel Chef</h1>
<p>
This is the
<a href="http://udacity.com/cs101x/urank/kathleen.html">
best Hummus recipe!
</a>

</body>
</html>






""", 
   'http://udacity.com/cs101x/urank/kathleen.html': """<html>
<body>
<h1>
Kathleen's Hummus Recipe
</h1>
<p>

<ol>
<li> Open a can of garbonzo beans.
<li> Crush them in a blender.
<li> Add 3 tablesppons of tahini sauce.
<li> Squeeze in one lemon.
<li> Add salt, pepper, and buttercream frosting to taste.
</ol>

</body>
</html>

""", 
   'http://udacity.com/cs101x/urank/arsenic.html': """<html>
<body>
<h1>
The Arsenic Chef's World Famous Hummus Recipe
</h1>
<p>

<ol>
<li> Kidnap the <a href="http://udacity.com/cs101x/urank/nickel.html">Nickel Chef</a>.
<li> Force her to make hummus for you.
</ol>

</body>
</html>

""", 
   'http://udacity.com/cs101x/urank/hummus.html': """<html>
<body>
<h1>
Hummus Recipe
</h1>
<p>

<ol>
<li> Go to the store and buy a container of hummus.
<li> Open it.
</ol>

</body>
</html>




""", 
}

def get_page(url):
#    return real_get_page(url)
    if url in cache:
        return cache[url]
    else:
        print "Page not in cache: " + url
        return None
    
def make_cache(seed):
    tocrawl = [seed]
    crawled = []
    graph = {seed: []}
    index = {}
    print "cache = {"
    while tocrawl: 
        page = tocrawl.pop()
        if page not in crawled:
            ## print "Crawing: " + page
            content = real_get_page(page)
            print "   '" + page + "'" + ': """' + content + '""", '
            add_page_to_index(index, page, content)
            outlinks = get_all_links(content)
            for link in outlinks:
                if link in graph: # already found one link to it
                    graph[link].append(page)
                else:
                    graph[link] = [page]
            union(tocrawl, outlinks)
            crawled.append(page)
    print "}"


    
