Fix SnapshotProvider initialization stuff

lib/tfw/components/snapshot_provider.py

@@ -22,13 +22,52 @@ class SnapshotProvider:
             'GIT_PAGER': 'cat'
         }
 
-        self._check_environment()
+        self._init_repo()
         self.__last_valid_branch = self._branch
-        self._init_repo_if_needed()
+
+    def _init_repo(self):
+        self._check_environment()
+
+        if not self._repo_is_initialized:
+            self._run(('git', 'init'))
+
+        if self._number_of_commits == 0:
+            self._snapshot()
+
+        self._check_head_not_detached()
 
     def _check_environment(self):
         if not isdir(self.gitenv['GIT_DIR']) or not isdir(self.gitenv['GIT_WORK_TREE']):
             raise EnvironmentError('Directories "directory" and "git_dir" must exist!')
+
+    @property
+    def _repo_is_initialized(self):
+        return self._run(
+            ('git', 'status'),
+            check=False
+        ).returncode == 0
+
+    @property
+    def _number_of_commits(self):
+        return int(
+            self._get_stdout((
+                'git', 'rev-list',
+                '--all',
+                '--count'
+            ))
+        )
+
+    def _snapshot(self):
+        self._run((
+            'git', 'add',
+            '-A'
+        ))
+        self._run((
+            'git', 'commit',
+            '-m', 'Snapshot'
+        ))
+
+    def _check_head_not_detached(self):
         if self._head_detached:
             raise EnvironmentError(f'{self.__class__.__name__} cannot init from detached HEAD state!')
 
@@ -49,29 +88,16 @@ class SnapshotProvider:
         return stdout_bytes.decode().rstrip('\n')
 
     def _run(self, *args, **kwargs):
+        if 'check' not in kwargs:
             kwargs['check'] = True
         if 'env' not in kwargs:
             kwargs['env'] = self.gitenv
         return run(*args, **kwargs)
 
-    def _init_repo_if_needed(self):
-        if not self._repo_is_initialized():
-            self._run(('git', 'init'))
-
-    def _repo_is_initialized(self):
-        return self._run(('git', 'status')).returncode == 0
-
     def take_snapshot(self):
         if self._head_detached:
             self._checkout_new_branch_from_head()
-        self._run((
+        self._snapshot()
-            'git', 'add',
-            '-A'
-        ))
-        self._run((
-            'git', 'commit',
-            '-m', 'Snapshot'
-        ))
 
     def _checkout_new_branch_from_head(self):
         branch_name = uuid4()