From 651ab1d72f1856c4e16ade4b9155e5444193e1c4 Mon Sep 17 00:00:00 2001
From: Tim Van Baak <tim.vanbaak@gmail.com>
Date: Tue, 15 Jun 2021 23:02:51 -0700
Subject: [PATCH] Refactor db to lazy-load at the top level

---
 amanuensis/cli/__init__.py | 26 ++++++++++++++++++++++++--
 amanuensis/cli/admin.py    | 16 +++++-----------
 2 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/amanuensis/cli/__init__.py b/amanuensis/cli/__init__.py
index 7f50868..df98ead 100644
--- a/amanuensis/cli/__init__.py
+++ b/amanuensis/cli/__init__.py
@@ -1,10 +1,13 @@
-from argparse import ArgumentParser
+from argparse import ArgumentParser, Namespace
 import logging
 import logging.config
+import os
+from typing import Callable
 
 import amanuensis.cli.admin
 import amanuensis.cli.lexicon
 import amanuensis.cli.user
+from amanuensis.db import DbContext
 
 
 LOGGING_CONFIG = {
@@ -76,6 +79,18 @@ def init_logger(args):
     logging.config.dictConfig(LOGGING_CONFIG)
 
 
+def get_db_factory(parser: ArgumentParser, args: Namespace) -> Callable[[], DbContext]:
+    """Factory function for lazy-loading the database in subcommands."""
+
+    def get_db() -> DbContext:
+        """Lazy loader for the database connection."""
+        if not os.path.exists(args.db_path):
+            parser.error(f"No database found at {args.db_path}")
+        return DbContext(path=args.db_path, echo=args.verbose)
+
+    return get_db
+
+
 def main():
     """CLI entry point"""
     # Set up the top-level parser
@@ -83,8 +98,12 @@ def main():
     parser.set_defaults(
         parser=parser,
         func=lambda args: parser.print_usage(),
+        get_db=None,
     )
     parser.add_argument("--verbose", "-v", action="store_true", help="Verbose output")
+    parser.add_argument(
+        "--db", dest="db_path", default="db.sqlite", help="Path to Amanuensis database"
+    )
 
     # Add commands from cli submodules
     subparsers = parser.add_subparsers(metavar="COMMAND")
@@ -92,7 +111,10 @@ def main():
     add_subcommand(subparsers, amanuensis.cli.lexicon)
     add_subcommand(subparsers, amanuensis.cli.user)
 
-    # Parse args and execute the desired action
+    # Parse args and perform top-level arg processing
     args = parser.parse_args()
     init_logger(args)
+    args.get_db = get_db_factory(parser, args)
+
+    # Execute the desired action
     args.func(args)
diff --git a/amanuensis/cli/admin.py b/amanuensis/cli/admin.py
index dfc92d0..7eb1d99 100644
--- a/amanuensis/cli/admin.py
+++ b/amanuensis/cli/admin.py
@@ -14,23 +14,17 @@ COMMAND_HELP = "Interact with Amanuensis."
 LOG = logging.getLogger(__name__)
 
 
-@add_argument(
-    "path", metavar="DB_PATH", help="Path to where the database should be created"
-)
-@add_argument("--force", "-f", action="store_true", help="Overwrite existing database")
-@add_argument("--verbose", "-v", action="store_true", help="Enable db echo")
+@add_argument("--drop", "-d", action="store_true", help="Overwrite existing database")
 def command_init_db(args) -> int:
     """
     Initialize the Amanuensis database.
     """
-    # Check if force is required
-    if not args.force and os.path.exists(args.path):
-        args.parser.error(f"{args.path} already exists and --force was not specified")
+    if args.drop:
+        open(args.db_path, mode="w").close()
 
     # Initialize the database
-    LOG.info(f"Creating database at {args.path}")
-    db = DbContext(path=args.path, echo=args.verbose)
-    db.create_all()
+    LOG.info(f"Creating database at {args.db_path}")
+    args.get_db().create_all()
 
     LOG.info("Done")
     return 0