#http://packages.python.org/CouchDB/client.html
import couchdb
import urllib2
from BeautifulSoup import BeautifulSoup
import re
import hashlib
from urlparse import urljoin
import time
import os
 
#http://diveintopython.org/http_web_services/etags.html
class NotModifiedHandler(urllib2.BaseHandler):  
    def http_error_304(self, req, fp, code, message, headers):
        addinfourl = urllib2.addinfourl(fp, headers, req.get_full_url())
        addinfourl.code = code
        return addinfourl
 
def fetchURL(docsdb, url, fieldName, agencyID, scrape_again=True):
    hash = hashlib.md5(url).hexdigest()
    req = urllib2.Request(url)
    print "Fetching %s" % url
    doc = docsdb.get(hash) 
    if doc == None:
        doc = {'_id': hash, 'agencyID': agencyID, 'url': url, 'fieldName':fieldName}
    else:
        if (time.time() - doc['page_scraped']) < 3600:
                print "Uh oh, trying to scrape URL again too soon!"
                last_attachment_fname = doc["_attachments"].keys()[-1]
                last_attachment = docsdb.get_attachment(doc,last_attachment_fname)
                return (doc['mime_type'],last_attachment)
        if scrape_again == False:
                print "Not scraping this URL again as requested"
                return (None,None)
 
    time.sleep(3) # wait 3 seconds to give webserver time to recover
    
    #if there is a previous version stored in couchdb, load caching helper tags
    if doc.has_key('etag'):
        req.add_header("If-None-Match", doc['etag'])
    if doc.has_key('last_modified'):
        req.add_header("If-Modified-Since", doc['last_modified'])
     
    opener = urllib2.build_opener(NotModifiedHandler())
    url_handle = opener.open(req)
    headers = url_handle.info() # the addinfourls have the .info() too
    doc['etag'] = headers.getheader("ETag")
    doc['last_modified'] = headers.getheader("Last-Modified") 
    doc['date'] = headers.getheader("Date") 
    doc['page_scraped'] = time.time() 
    doc['web_server'] = headers.getheader("Server") 
    doc['powered_by'] = headers.getheader("X-Powered-By") 
    doc['file_size'] = headers.getheader("Content-Length") 
    doc['mime_type'] = headers.getheader("Content-Type").split(";")[0]
    if hasattr(url_handle, 'code'): 
        if url_handle.code == 304:
            print "the web page has not been modified"
            return (None,None)
        else: 
            content = url_handle.read()
            docsdb.save(doc)
            doc = docsdb.get(hash) # need to get a _rev
            docsdb.put_attachment(doc, content, str(time.time())+"-"+os.path.basename(url), doc['mime_type']) 
            return (doc['mime_type'], content)
    #store as attachment epoch-filename
    else:
        print "error %s in downloading %s" % url_handle.code, URL
        doc['error'] = "error %s in downloading %s" % url_handle.code, URL    
        docsdb.save(doc)
        return (None,None)
 
 
 
def scrapeAndStore(docsdb, url, depth, fieldName, agencyID):
    (mime_type,content) = fetchURL(docsdb, url, fieldName, agencyID)
    if content != None and depth > 0:
        if mime_type == "text/html" or mime_type == "application/xhtml+xml" or mime_type =="application/xml":
            # http://www.crummy.com/software/BeautifulSoup/documentation.html
            soup = BeautifulSoup(content)
            navIDs = soup.findAll(id=re.compile('nav|Nav|menu|bar'))
            for nav in navIDs:
                print "Removing element", nav['id']
                nav.extract()
            navClasses = soup.findAll(attrs={'class' : re.compile('nav|menu|bar')})
            for nav in navClasses:
                print "Removing element", nav['class']
                nav.extract()
            links = soup.findAll('a') # soup.findAll('a', id=re.compile("^p-"))
            linkurls = set([])
            for link in links:
                if link.has_key("href"):
                        if link['href'].startswith("http"):
                                # lets not do external links for now
                                # linkurls.add(link['href'])
                                None
                        else:
                                linkurls.add(urljoin(url,link['href'].replace(" ","%20")))
            for linkurl in linkurls:
                #print linkurl
                scrapeAndStore(docsdb, linkurl, depth-1, fieldName, agencyID)    
 
couch = couchdb.Server('http://127.0.0.1:5984/')
 
# select database
agencydb = couch['disclosr-agencies']
docsdb = couch['disclosr-documents']
 
for row in agencydb.view('app/getScrapeRequired'): #not recently scraped agencies view?
    agency = agencydb.get(row.id)
    print agency['name']
    for key in agency.keys():
        if key == 'website' or key.endswith('URL'):
                print key
                scrapeAndStore(docsdb, agency[key],agency['scrapeDepth'],key,agency['_id'])
    agency['metadata']['lastscraped'] = time.time()
    agencydb.save(agency)