#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
import mimetypes
import re
import urllib
import urlparse
 
def canonurl(url):
    r"""Return the canonical, ASCII-encoded form of a UTF-8 encoded URL, or ''
    if the URL looks invalid.
    >>> canonurl('\xe2\x9e\xa1.ws')  # tinyarro.ws
    'http://xn--hgi.ws/'
    """
    # strip spaces at the ends and ensure it's prefixed with 'scheme://'
    url = url.strip()
    if not url:
        return ''
    if not urlparse.urlsplit(url).scheme:
        url = 'http://' + url
 
    # turn it into Unicode
    #try:
    #    url = unicode(url, 'utf-8')
    #except UnicodeDecodeError:
    #    return ''  # bad UTF-8 chars in URL
 
    # parse the URL into its components
    parsed = urlparse.urlsplit(url)
    scheme, netloc, path, query, fragment = parsed
 
    # ensure scheme is a letter followed by letters, digits, and '+-.' chars
    if not re.match(r'[a-z][-+.a-z0-9]*$', scheme, flags=re.I):
        return ''
    scheme = str(scheme)
 
    # ensure domain and port are valid, eg: sub.domain.<1-to-6-TLD-chars>[:port]
    match = re.match(r'(.+\.[a-z0-9]{1,6})(:\d{1,5})?$', netloc, flags=re.I)
    if not match:
        return ''
    domain, port = match.groups()
    netloc = domain + (port if port else '')
    netloc = netloc.encode('idna')
 
    # ensure path is valid and convert Unicode chars to %-encoded
    if not path:
        path = '/'  # eg: 'http://google.com' -> 'http://google.com/'
    path = urllib.quote(urllib.unquote(path.encode('utf-8')), safe='/;')
 
    # ensure query is valid
    query = urllib.quote(urllib.unquote(query.encode('utf-8')), safe='=&?/')
 
    # ensure fragment is valid
    fragment = urllib.quote(urllib.unquote(fragment.encode('utf-8')))
 
    # piece it all back together, truncating it to a maximum of 4KB
    url = urlparse.urlunsplit((scheme, netloc, path, query, fragment))
    return url[:4096]
 
#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):
    url = canonurl(url)
    hash = hashlib.md5(url).hexdigest().encode("utf-8")
    req = urllib2.Request(url)
    print "Fetching %s" % url
    if url.startswith("mailto") or url.startswith("javascript") or url.startswith("#") or url == None or url == "":
                print "Not a valid HTTP url"
                return (None,None,None)
    doc = docsdb.get(hash) 
    if doc == None:
        doc = {'_id': hash, 'agencyID': agencyID, 'url': url, 'fieldName':fieldName}
    else:
        if (('page_scraped' in doc) and (time.time() - doc['page_scraped']) < 999999):
                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['url'],doc['mime_type'],last_attachment)
        if scrape_again == False:
                print "Not scraping this URL again as requested"
                return (None,None,None)
 
    time.sleep(3) # wait 3 seconds to give webserver time to recover
    
    req.add_header("User-Agent", "Mozilla/4.0 (compatible; Prometheus webspider; owner maxious@lambdacomplex.org)")
    #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())
    try:
     url_handle = opener.open(req)
     doc['url'] = url_handle.geturl() # may have followed a redirect to a new url
     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['via'] = headers.getheader("Via") 
     doc['powered_by'] = headers.getheader("X-Powered-By") 
     doc['file_size'] = headers.getheader("Content-Length") 
     content_type = headers.getheader("Content-Type")
     if content_type != None:
        doc['mime_type'] = content_type.split(";")[0]
     else:
        (type,encoding) = mimetypes.guess_type(url)
        doc['mime_type'] = type
     if hasattr(url_handle, 'code'): 
        if url_handle.code == 304:
            print "the web page has not been modified"
            return (None,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['url'], doc['mime_type'], content)
            #store as attachment epoch-filename
    except urllib2.URLError as e:
        error = ""
        if hasattr(e, 'reason'):
                error = "error %s in downloading %s" % (str(e.reason), url)
        elif hasattr(e, 'code'):
                error = "error %s in downloading %s" % (e.code, url)
        print error
        doc['error'] = error
        docsdb.save(doc)
        return (None,None,None)
 
 
 
def scrapeAndStore(docsdb, url, depth, fieldName, agencyID):
    (url,mime_type,content) = fetchURL(docsdb, url, fieldName, agencyID)
    badURLs = ["http://www.ausport.gov.au/supporting/funding/grants_and_scholarships/grant_funding_report"]
    if content != None and depth > 0 and url != "http://www.ausport.gov.au/supporting/funding/grants_and_scholarships/grant_funding_report":
        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|left|right|sidebar|more-links|breadcrumb|footer|header'))
            for nav in navIDs:
                print "Removing element", nav['id']
                nav.extract()
            navClasses = soup.findAll(attrs={'class' : re.compile('nav|menu|bar|left|right|sidebar|more-links|breadcrumb|footer|header')})
            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
                        if link['href'].startswith("mailto"):
                                # not http
                                None
                        if link['href'].startswith("javascript"):
                                # not http
                                None
                        else:
                                # remove anchors and spaces in urls
                                link['href'] = link['href'].replace(" ","%20")
                                link['href'] = re.sub('#.*$','',link['href'])
                                linkurls.add(urljoin(url,link['href']))
            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':
                scrapeAndStore(docsdb, agency[key],0,key,agency['_id'])
        if key.endswith('URL'):
                print key 
                depth = 1
                if 'scrapeDepth' in agency.keys():
                        depth = agency['scrapeDepth']
                scrapeAndStore(docsdb, agency[key],depth,key,agency['_id'])
 
    agency['metadata']['lastScraped'] = time.time()
    agencydb.save(agency)