Stats processing: don`t create file names that are too long

sitescripts/stats/common.py

Index: sitescripts/stats/common.py
===================================================================
--- a/sitescripts/stats/common.py
+++ b/sitescripts/stats/common.py
@@ -10,32 +10,41 @@
 # Adblock Plus is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
 
-import re
+import re, hashlib
 
 def filename_encode(name):
   """
     This encodes any string to a valid file name while ensuring that the
     original string can still be reconstructed. All characters except 0-9, A-Z,
     the period and underscore are encoded as "-12cd" where "12cd" stands for the
-    hexadecimal representation of the character's ordinal.
+    hexadecimal representation of the character's ordinal. File names longer
+    than 200 characters will be still be unique but no longer reversible due to
+    file system limitations.
   """
-  return re.sub(r"[^\w\.]", lambda match: "-%04x" % ord(match.group(0)), name)
+  result = re.sub(r"[^\w\.]", lambda match: "-%04x" % ord(match.group(0)), name)
+  if len(result) > 200:
+    hash = hashlib.md5()
+    hash.update(result[200:])
+    result = result[:200] + "--%s" % hash.hexdigest()
+  return result
 
 def filename_decode(path):
   """
     This reconstructs a string encoded with filename_encode().
   """
-  return re.sub(r"-([0-9a-f]{4})", lambda match: unichr(int(match.group(1), 16)), path)
+  path = re.sub(r"--[0-9A-Fa-f]{32}", u"\u2026", path)
+  path = re.sub(r"-([0-9a-f]{4})", lambda match: unichr(int(match.group(1), 16)), path)
+  return path
 
 basic_fields = [
   {
     "name": "day",
     "title": "Days of month",
     "coltitle": "Day",
     "showaverage": True,
     "sort": lambda obj: sorted(obj.items(), key=lambda (k,v): int(k)),