Record hash of last commit

ugit/base.py

@@ -81,7 +81,11 @@ def commit(message):
     commit += "\n"
     commit += f"{message}\n"
 
-    return data.hash_object(commit.encode(), "commit")
+    oid = data.hash_object(commit.encode(), "commit")
+
+    data.set_HEAD(oid)
+
+    return oid
 
 
 def is_ignored(path):

ugit/data.py

@@ -10,6 +10,11 @@ def init():
     Path.mkdir(f"{GIT_DIR}/objects")
 
 
+def set_HEAD(oid):
+    with open(f"{GIT_DIR}/HEAD", "w") as f:
+        f.write(oid)
+
+
 def hash_object(data, type_="blob"):
     obj = type_.encode() + b"\x00" + data
     oid = hashlib.sha1(obj).hexdigest()