[PATCH 3/4] IMAP: revamp _msgs_to_fetch()

[Nicolas Sebrecht]

Signed-off-by: Nicolas Sebrecht <nicolas.s-dev at laposte.net>
---
 offlineimap/folder/IMAP.py | 96 +++++++++++++---------------------------------
 1 file changed, 27 insertions(+), 69 deletions(-)

diff --git a/offlineimap/folder/IMAP.py b/offlineimap/folder/IMAP.py
index bf61ebe..834b446 100644
--- a/offlineimap/folder/IMAP.py
+++ b/offlineimap/folder/IMAP.py
@@ -153,94 +153,52 @@ class IMAPFolder(BaseFolder):
         Arguments:
         - imapobj: instance of IMAPlib
         - maxage (optional): only fetch messages up to maxage days ago
-        - min_uid (optional): only fetch messages with uid > min_uid
+        - min_uid (optional): only fetch messages with UID >= min_uid
 
-        This function should be called with at most one of maxage or
-        min_uid.
-
-        If using maxage, this finds the min uid of all messages within
-        maxage, and returns all messages with uid > this min. As maxage
-        is only set if this folder is the local folder, this ensures
-        consistency with remote (which only restricts to uid > this min)
-        in edge cases where the date is much earlier than messages with
-        similar UID's (e.g. the UID was reassigned much later).
+        This function should be called with at MOST one of maxage OR
+        min_uid set but not BOTH.
 
         Returns: range(s) for messages or None if no messages
         are to be fetched."""
 
         res_type, imapdata = imapobj.select(self.getfullname(), True, True)
         if imapdata == [None] or imapdata[0] == '0':
-            # Empty folder, no need to populate message list
+            # Empty folder, no need to populate message list.
             return None
 
-        # By default examine all messages in this folder
-        msgsToFetch = '1:*'
+        conditions = []
+
+        if min_uid != None:
+            conditions.append("UID %d:*"% min_uid)
+        elif maxage != None:
+            # Find out what the oldest message is that we should look at.
+            oldest_struct = time.gmtime(time.time() - (60*60*24*maxage))
+            if oldest_struct[0] < 1900:
+                raise OfflineImapError("maxage setting led to year %d. "
+                    "Abort syncing."% oldest_struct[0],
+                    OfflineImapError.ERROR.REPO)
+            conditions.append("SINCE %02d-%s-%d"%
+                oldest_struct[2],
+                MonthNames[oldest_struct[1]],
+                oldest_struct[0])
 
         maxsize = self.getmaxsize()
+        if maxsize != None:
+            conditions.append("SMALLER %d"% maxsize)
 
-        # Build search condition
-        if maxage or min_uid != None or maxsize != None:
-            search_cond = "(";
-
-            if maxage:
-                #find out what the oldest message is that we should look at
-                oldest_struct = time.gmtime(time.time() - (60*60*24*maxage))
-                if oldest_struct[0] < 1900:
-                    raise OfflineImapError("maxage setting led to year %d. "
-                        "Abort syncing."% oldest_struct[0],
-                        OfflineImapError.ERROR.REPO)
-                search_cond += "SINCE %02d-%s-%d"% (
-                    oldest_struct[2],
-                    MonthNames[oldest_struct[1]],
-                    oldest_struct[0])
-            if min_uid != None:
-                if maxage: # There are two conditions, add space
-                    search_cond += " "
-                search_cond += "UID %d:*"% min_uid
-
-            if maxsize != None:
-                if maxage or min_uid != None:
-                    # There are at least two conditions, add space
-                    search_cond += " "
-                search_cond += "SMALLER %d"% maxsize
-
-            search_cond += ")"
-
+        if len(conditions) > 1:
+            # Build SEARCH conditions.
+            search_cond = "(%s)"% ' '.join(conditions)
             res_type, res_data = imapobj.search(None, search_cond)
             if res_type != 'OK':
                 raise OfflineImapError("SEARCH in folder [%s]%s failed. "
                     "Search string was '%s'. Server responded '[%s] %s'"% (
                     self.getrepository(), self, search_cond, res_type, res_data),
                     OfflineImapError.ERROR.FOLDER)
-
-            if maxage:
-                # Found messages within maxage, but want all messages with UID
-                # > the min uid of the within-maxage messages. Ordering by UID
-                # is the same as ordering by MSN, so we get the messages with
-                # MSN > the min MSN of the within-maxage messages.
-                msg_seq_numbers = map(lambda s : int(s), res_data[0].split())
-                if msg_seq_numbers:
-                    min_msn = min(msg_seq_numbers)
-                else:
-                    return None
-                if maxsize == None:
-                    # If no maxsize, can just ask for all messages with MSN > min_msn
-                    return "%d:*"% min_msn
-                else:
-                    # Restrict the range min_msn:* to those with acceptable size.
-                    # Single-quotes prevent imaplib2 from quoting the sequence.
-                    search_cond = "'%d:* (SMALLER %d)'"% (min_msn, maxsize)
-                    res_type, res_data = imapobj.search(None, search_cond)
-                    if res_type != 'OK':
-                        raise OfflineImapError("SEARCH in folder [%s]%s failed. "
-                            "Search string was '%s'. Server responded '[%s] %s'"%
-                            (self.getrepository(), self, search_cond, res_type,
-                            res_data), OfflineImapError.ERROR.FOLDER)
-
             # Resulting MSN are separated by space, coalesce into ranges
-            msgsToFetch = imaputil.uid_sequence(res_data[0].split())
-
-        return msgsToFetch
+            return imaputil.uid_sequence(res_data[0].split())
+        # By default examine all messages in this folder.
+        return '1:*'
 
     # Interface from BaseFolder
     def msglist_item_initializer(self, uid):
-- 
2.3.1