#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 urllib
import urlparse
 
def mkhash(input):
    return hashlib.md5(input).hexdigest().encode("utf-8")
 
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]
 
def fullurl(url,href):
    href = href.replace(" ","%20")
    href = re.sub('#.*$','',href)
    return urljoin(url,href)
 
#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 getLastAttachment(docsdb,url):
    hash = mkhash(url)
    doc = docsdb.get(hash)
    if doc != None:
        last_attachment_fname = doc["_attachments"].keys()[-1]
        last_attachment = docsdb.get_attachment(doc,last_attachment_fname)
        return last_attachment
    else:
        return None
 
def fetchURL(docsdb, url, fieldName, agencyID, scrape_again=True):
    url = canonurl(url)
    hash = mkhash(url)
    req = urllib2.Request(url)
    print "Fetching %s (%s)" % (url,hash)
    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']) < 60*24*14*1000):
            print "Uh oh, trying to scrape URL again too soon!"+hash
            last_attachment_fname = doc["_attachments"].keys()[-1]
            last_attachment = docsdb.get_attachment(doc,last_attachment_fname)
            content = last_attachment
            return (doc['url'],doc['mime_type'],content.read())
        if scrape_again == False:
            print "Not scraping this URL again as requested"
            return (doc['url'],doc['mime_type'],content.read())
 
    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"+hash
                last_attachment_fname = doc["_attachments"].keys()[-1]
                last_attachment = docsdb.get_attachment(doc,last_attachment_fname)
                content = last_attachment
                return (doc['url'],doc['mime_type'],content.read())
            else:
                print "new webpage loaded"
                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:
            print "error!"
            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(<