from urllib.request import urlopen

from bs4 import BeautifulSoup

import re

import datetime

import random

pages = set()

random.seed(datetime.datetime.now())

#Retrieves a list of all Internal links found on a page

def getInternalLinks(bsObj, includeUrl):

internalLinks = []

#Finds all links that begin with a "/"

for link in bsObj.findAll("a", href=re.compile("^(/|.*"+includeUrl+")")):

if link.attrs['href'] is not None:

if link.attrs['href'] not in internalLinks:

internalLinks.append(link.attrs['href'])

return internalLinks

#Retrieves a list of all external links found on a page

def getExternalLinks(bsObj, excludeUrl):

externalLinks = []

#Finds all links that start with "http" or "www" that do

#not contain the current URL

for link in bsObj.findAll("a", href=re.compile("^(http|www)((?!"+excludeUrl+").)*$")):

if link.attrs['href'] is not None:

if link.attrs['href'] not in externalLinks:

externalLinks.append(link.attrs['href'])

return externalLinks

def splitAddress(address):

addressParts = address.replace("http://", "").split("/")

return addressParts

def getRandomExternalLink(startingPage):

html = urlopen(startingPage)

bsObj = BeautifulSoup(html, "html.parser")

externalLinks = getExternalLinks(bsObj, splitAddress(startingPage)[0])

if len(externalLinks) == 0:

internalLinks = getInternalLinks(startingPage)

return getNextExternalLink(internalLinks[random.randint(0,

len(internalLinks)-1)])

else:

return externalLinks[random.randint(0, len(externalLinks)-1)]

def followExternalOnly(startingSite):

externalLink = getRandomExternalLink("http://oreilly.com")

print("Random external link is: "+externalLink)

followExternalOnly(externalLink)

followExternalOnly("http://oreilly.com")