Download skills if they're stale or in unknown state

Checks if the skills haven't been updated for more than 2 weeks or if
the last_download is undefined. last_download may be undefined if
the .msm file is missing or if the list of installed requirements is
missing so skill requirements may be missing.

This also makes sure the skills are normally loaded before the an update
attemt is tried.

mycroft/skills/__main__.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 #
 import time
+import datetime as dt
 from threading import Timer
 import mycroft.lock
 from mycroft import dialog
@@ -89,6 +90,14 @@ def _starting_up():
     # Wait until priority skills have been loaded before checking
     # network connection
     skill_manager.load_priority()
+
+    # If device has been offline for more than 2 weeks or
+    # skill state is in a limbo
+    update_limit = dt.datetime.now() - dt.timedelta(days=14)
+    if (not skill_manager.last_download or
+            skill_manager.last_download < update_limit):
+        skill_manager.download_skills(quick=True)
+
     skill_manager.start()
     check_connection()
 

mycroft/skills/skill_manager.py

@@ -15,6 +15,7 @@
 import gc
 import sys
 import time
+from datetime import datetime
 from glob import glob
 from itertools import chain
 
@@ -103,9 +104,13 @@ class SkillManager(Thread):
         # Update immediately if the .msm or installed skills file is missing
         # otherwise according to timestamp on .msm
         if exists(self.dot_msm) and exists(self.installed_skills_file):
-            self.next_download = os.path.getmtime(self.dot_msm) + \
-                                 self.update_interval
+            mtime = os.path.getmtime(self.dot_msm)
+            self.next_download = mtime + self.update_interval
+            self.last_download = datetime.fromtimestamp(mtime)
         else:
+            # Last update can't be found or the requirements don't seem to be
+            # installed trigger update before skill loading
+            self.last_download = None
             self.next_download = time.time() - 1
 
         # Conversation management
@@ -380,10 +385,6 @@ class SkillManager(Thread):
         # Scan the file folder that contains Skills.  If a Skill is updated,
         # unload the existing version from memory and reload from the disk.
         while not self._stop_event.is_set():
-            # Update skills once an hour if update is enabled
-            if time.time() >= self.next_download and update:
-                self.download_skills()
-
             # Look for recently changed skill(s) needing a reload
             # checking skills dir and getting all skills there
             skill_paths = glob(join(self.msm.skills_dir, '*/'))
@@ -406,6 +407,10 @@ class SkillManager(Thread):
             # Pause briefly before beginning next scan
             time.sleep(2)
 
+            # Update skills once an hour if update is enabled
+            if time.time() >= self.next_download and update:
+                self.download_skills()
+
     def send_skill_list(self, message=None):
         """
             Send list of loaded skills.