reckless: add installation metadata

The metadata includes an original retrieval source, timestamp, and commit
hash.  This will allow a future update command to more easily evaluate the
status of the existing installation.

tools/reckless

@@ -1,19 +1,21 @@
 #!/usr/bin/env python3
 
-from subprocess import Popen, PIPE, TimeoutExpired, run
 import sys
-import json
-import os
 import argparse
+import copy
+import datetime
+from enum import Enum
+import json
+import logging
+import os
 from pathlib import Path, PosixPath
 import shutil
+from subprocess import Popen, PIPE, TimeoutExpired, run
 import tempfile
+import time
 from typing import Union
 from urllib.parse import urlparse
 from urllib.request import urlopen
-import logging
-import copy
-from enum import Enum
 
 
 logging.basicConfig(
@@ -654,6 +656,26 @@ def get_temp_reckless_dir() -> PosixPath:
     return new_path
 
 
+def add_installation_metadata(installed: InstInfo,
+                              original_request: InstInfo):
+    """Document the install request and installation details for use when
+    updating the plugin."""
+    install_dir = Path(installed.source_loc)
+    assert install_dir.is_dir()
+    data = ('installation date\n'
+            f'{datetime.date.today().isoformat()}\n'
+            'installation time\n'
+            f'{int(time.time())}\n'
+            'original source\n'
+            f'{original_request.source_loc}\n'
+            'requested commit\n'
+            f'{original_request.commit}\n'
+            'installed commit\n'
+            f'{installed.commit}\n')
+    with open(install_dir / '.metadata', 'w') as metadata:
+        metadata.write(data)
+
+
 def _install_plugin(src: InstInfo) -> Union[InstInfo, None]:
     """make sure the repo exists and clone it."""
     logging.debug(f'Install requested from {src}.')
@@ -777,6 +799,7 @@ def _install_plugin(src: InstInfo) -> Union[InstInfo, None]:
 
     # Find this cute little plugin a forever home
     shutil.copytree(str(staging_path), inst_path)
+    add_installation_metadata(staged_src, src)
     print(f'plugin installed: {inst_path}')
     remove_dir(clone_path)
     return staged_src