from collections import deque
 from hashlib import sha1
 
-from mw.xml_dump import Iterator
+from mwxml import Dump
 
 from deltas.tokenizers import wikitext_split
 import mwpersistence
 TO_ENCODE = ('title', 'editor')
 PERSISTENCE_RADIUS=7
 from deltas import SequenceMatcher
+from deltas import SegmentMatcher
+
+class PersistMethod:
+    none = 0
+    sequence = 1
+    segment = 2
+    legacy = 3
 
 def calculate_persistence(tokens_added):
     return(sum([(len(x.revisions)-1) for x in tokens_added]),
            len(tokens_added))
 
-
 class WikiqIterator():
     def __init__(self, fh, collapse_user=False):
         self.fh = fh
         self.collapse_user = collapse_user
-        self.mwiterator = Iterator.from_file(self.fh)
+        self.mwiterator = Dump.from_file(self.fh)
+        self.namespace_map = { ns.id : ns.name for ns in
+                               self.mwiterator.site_info.namespaces }
         self.__pages = self.load_pages()
 
     def load_pages(self):
         for page in self.mwiterator:
-            yield WikiqPage(page, collapse_user=self.collapse_user)
+            yield WikiqPage(page,
+                            namespace_map = self.namespace_map,
+                            collapse_user=self.collapse_user)
 
     def __iter__(self):
         return self.__pages
                  'restrictions', 'mwpage', '__revisions',
                  'collapse_user')
     
-    def __init__(self, page, collapse_user=False):
+    def __init__(self, page, namespace_map, collapse_user=False):
         self.id = page.id
-        self.title = page.title
         self.namespace = page.namespace
-        self.redirect = page.redirect
+        # following mwxml, we assume namespace 0 in cases where
+        # page.namespace is inconsistent with namespace_map
+        if page.namespace not in namespace_map:
+            self.title = page.title
+            page.namespace = 0
+        if page.namespace != 0:
+            self.title = ':'.join([namespace_map[page.namespace], page.title])
+        else:
+            self.title = page.title
         self.restrictions = page.restrictions
-        
         self.collapse_user = collapse_user
         self.mwpage = page
         self.__revisions = self.rev_list()
             else:
                 if self.collapse_user:
                     # yield if this is the last edit in a seq by a user and reset
-                    if not rev.contributor.user_text == prev_rev.contributor.user_text:
+                    # also yield if we do know who the user is
+
+                    if rev.deleted.user or prev_rev.deleted.user:
+                        yield prev_rev
+                        collapsed_revs = 1
+                        rev.collapsed_revs = collapsed_revs
+
+                    elif not rev.user.text == prev_rev.user.text:
                         yield prev_rev
                         collapsed_revs = 1
                         rev.collapsed_revs = collapsed_revs
                     yield prev_rev
 
             prev_rev = rev
+
         # also yield the final time
         yield prev_rev
 
         return next(self.__revisions)
 
 class WikiqParser():
+    
+    def __init__(self, input_file, output_file, collapse_user=False, persist=None, urlencode=False):
+        """ 
+        Parameters:
+           persist : what persistence method to use. Takes a PersistMethod value
+        """
 
-
-    def __init__(self, input_file, output_file, collapse_user=False, persist=False, urlencode=False, persist_legacy=False):
-        
         self.input_file = input_file
         self.output_file = output_file
         self.collapse_user = collapse_user
         self.persist = persist
-        self.persist_legacy = persist_legacy
         self.printed_header = False
         self.namespaces = []
         self.urlencode = urlencode
         dump = WikiqIterator(self.input_file, collapse_user=self.collapse_user)
 
         # extract list of namspaces
-        self.namespaces = {ns.name : ns.id for ns in dump.mwiterator.namespaces}
+        self.namespaces = {ns.name : ns.id for ns in dump.mwiterator.site_info.namespaces}
 
         page_count = 0
         rev_count = 0
         for page in dump:
             rev_detector = mwreverts.Detector()
 
-            if self.persist or self.persist_legacy:
+            if self.persist != PersistMethod.none:
                 window = deque(maxlen=PERSISTENCE_RADIUS)
 
-                if not self.persist_legacy:
+                if self.persist == PersistMethod.sequence:
                     state = mwpersistence.DiffState(SequenceMatcher(tokenizer = wikitext_split),
                                                     revert_radius=PERSISTENCE_RADIUS)
 
+                elif self.persist == PersistMethod.segment:
+                    state = mwpersistence.DiffState(SegmentMatcher(tokenizer = wikitext_split),
+                                                    revert_radius=PERSISTENCE_RADIUS)
+
+                # self.persist == PersistMethod.legacy
                 else:
                     from mw.lib import persistence
                     state = persistence.State()
                 rev_data = {'revid' : rev.id,
                             'date_time' : rev.timestamp.strftime('%Y-%m-%d %H:%M:%S'),
                             'articleid' : page.id,
-                            'editor_id' : "" if rev.contributor.id == None else rev.contributor.id,
+                            'editor_id' : "" if rev.deleted.user == True or rev.user.id is None else rev.user.id,
                             'title' : '"' + page.title + '"',
-                            'namespace' : page.namespace if page.namespace else self.__get_namespace_from_title(page.title),
-                            'deleted' : "TRUE" if rev.text.deleted else "FALSE" } 
+                            'namespace' : page.namespace if page.namespace is not None else self.__get_namespace_from_title(page.title),
+                            'deleted' : "TRUE" if rev.deleted.text else "FALSE" } 
 
                 # if revisions are deleted, /many/ things will be missing
-                if rev.text.deleted:
+                if rev.deleted.text:
                     rev_data['text_chars'] = ""
                     rev_data['sha1'] = ""
                     rev_data['revert'] = ""
                     rev_data['reverteds'] = ""
 
                 else:
+                    # rev.text can be None if the page has no text
+                    if not rev.text:
+                        rev.text = ""
                     # if text exists, we'll check for a sha1 and generate one otherwise
+
                     if rev.sha1:
                         text_sha1 = rev.sha1
                     else:
+
                         text_sha1 = sha1(bytes(rev.text, "utf8")).hexdigest()
                     
                     rev_data['sha1'] = text_sha1
                 # if the fact that the edit was minor can be hidden, this might be an issue
                 rev_data['minor'] = "TRUE" if rev.minor else "FALSE"
 
-                if rev.contributor.user_text:
+                if not rev.deleted.user:
                     # wrap user-defined editors in quotes for fread
-                    rev_data['editor'] = '"' + rev.contributor.user_text + '"'
-                    rev_data['anon'] = "TRUE" if rev.contributor.id == None else "FALSE"
+                    rev_data['editor'] = '"' + rev.user.text + '"'
+                    rev_data['anon'] = "TRUE" if rev.user.id == None else "FALSE"
                     
                 else:
                     rev_data['anon'] = ""
                 if self.collapse_user:
                     rev_data['collapsed_revs'] = rev.collapsed_revs
 
-                if self.persist or self.persist_legacy:
-                    if rev.text.deleted:
+                if self.persist != PersistMethod.none:
+                    if rev.deleted.text:
                         for k in ["token_revs", "tokens_added", "tokens_removed", "tokens_window"]:
                             old_rev_data[k] = None
                     else:
 
-                        if not self.persist_legacy:
+                        if self.persist != PersistMethod.legacy:
                             _, tokens_added, tokens_removed = state.update(rev.text, rev.id)
 
                         else:
-                            _, tokens_added, tokens_removed = state.process(rev.text, rev.id,text_sha1)
+                            _, tokens_added, tokens_removed = state.process(rev.text, rev.id, text_sha1)
                             
                         window.append((rev.id, rev_data, tokens_added, tokens_removed))
                         
 
                 rev_count += 1
 
-            if self.persist or self.persist_legacy:
+            if self.persist != PersistMethod.none:
                 # print out metadata for the last RADIUS revisions
                 for i, item in enumerate(window):
                     # if the window was full, we've already printed item 0
         if self.urlencode:
             for field in TO_ENCODE:
                 rev_data[field] = quote(str(rev_data[field]))
-            
+
         if not self.printed_header:
             print("\t".join([str(k) for k in sorted(rev_data.keys())]), file=self.output_file)
             self.printed_header = True
 parser.add_argument('--collapse-user', dest="collapse_user", action="store_true",
                     help="Operate only on the final revision made by user a user within all sequences of consecutive edits made by a user. This can be useful for addressing issues with text persistence measures.")
 
-parser.add_argument('-p', '--persistence', dest="persist", action="store_true",
-                    help="Compute and report measures of content persistent: (1) persistent token revisions, (2) tokens added, and (3) number of revision used in computing the first measure.")
+parser.add_argument('-p', '--persistence', dest="persist", default=None, const='', type=str, choices = ['','segment','sequence','legacy'], nargs='?',
+                    help="Compute and report measures of content persistent: (1) persistent token revisions, (2) tokens added, and (3) number of revision used in computing the first measure. This may by slow.  Use -p=segment for advanced persistence calculation method that is robust to content moves. This might be very slow. Use -p=legacy for legacy behavior.")
 
 parser.add_argument('-u', '--url-encode', dest="urlencode", action="store_true",
                     help="Output url encoded text strings. This works around some data issues like newlines in editor names. In the future it may be used to output other text data.")
 
-parser.add_argument('--persistence-legacy', dest="persist_legacy", action="store_true",
-                    help="Legacy behavior for persistence calculation. Output url encoded text strings. This works around some data issues like newlines in editor names. In the future it may be used to output other text data.")
+parser.add_argument('-ns', '--namespace-filter', dest="namespace_filter", type=str, help="Comma-seperate list of namespaces numbers to include")
+
 
 args = parser.parse_args()
 
+# set persistence method
+
+if args.persist is None:
+    persist = PersistMethod.none
+elif args.persist == "segment":
+    persist = PersistMethod.segment
+elif args.persist == "legacy":
+    persist = PersistMethod.legacy
+else:
+    persist = PersistMethod.sequence
+
 if len(args.dumpfiles) > 0:
     for filename in args.dumpfiles:
         input_file = open_input_file(filename)
             filename = os.path.join(output_dir, os.path.basename(filename))
             output_file = open_output_file(filename)
 
-        wikiq = WikiqParser(input_file, output_file, 
+            wikiq = WikiqParser(input_file, output_file, 
                             collapse_user=args.collapse_user,
-                            persist=args.persist,
-                            persist_legacy=args.persist_legacy,
+                                persist=persist,
                             urlencode=args.urlencode)
 
 
 else:
     wikiq = WikiqParser(sys.stdin, sys.stdout,
                         collapse_user=args.collapse_user,
-                        persist=args.persist,
+                        persist=persist,
                         persist_legacy=args.persist_legacy,
                         urlencode=args.urlencode)
     wikiq.process()