From 0b3b6f50feec2e10e4d9c7db9a6a700b34e28e3a Mon Sep 17 00:00:00 2001
From: Campbell Alden <campbellsalden@gmail.com>
Date: Sat, 1 Aug 2026 01:08:41 +0900
Subject: [PATCH] Add unconnected database support

Also adds a helper for doing nested config parsing since we're getting
more and more
---
 .gitignore             |  1 +
 src/config/__init__.py | 20 +++++++++-----------
 src/config/database.py | 16 ++++++++++++++++
 src/config/parse.py    | 13 ++++++++++++-
 src/infra/db.py        | 15 +++++++++++++++
 5 files changed, 53 insertions(+), 12 deletions(-)
 create mode 100644 src/config/database.py
 create mode 100644 src/infra/db.py

diff --git a/.gitignore b/.gitignore
index ebb8a8d..676ddc8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@ __pycache__/*
 config.json
 result
 todo.md
+*.db
diff --git a/src/config/__init__.py b/src/config/__init__.py
index c83bc3e..32b37b3 100644
--- a/src/config/__init__.py
+++ b/src/config/__init__.py
@@ -4,7 +4,8 @@ from typing import Any
 
 from .logging import Logging
 from .email import Email
-from .parse import ConfigParseError, assert_key_of_type
+from .database import Database
+from .parse import assert_key_of_type, parse_nested_config
 
 
 @dataclass
@@ -13,6 +14,7 @@ class Config:
     port: int | None
     logging: Logging
     email: Email
+    database: Database
 
     @classmethod
     def from_dict(cls, config: dict[str, Any]) -> 'Config':
@@ -20,17 +22,13 @@ class Config:
         assert_key_of_type(config, 'email', dict)
         assert_key_of_type(config, 'host', str)
         assert_key_of_type(config, 'port', int)
-        try:
-            log_config = Logging.from_dict(config['logging'])
-        except ConfigParseError as e:
-            raise ConfigParseError(['logging', *e.keypath], e.issue) from e
+        log_config = parse_nested_config(config, 'logging', Logging.from_dict)
+        email_config = parse_nested_config(config, 'email', Email.from_dict)
+        db_config = parse_nested_config(config, 'database', Database.from_dict)
 
-        try:
-            email_config = Email.from_dict(config['email'])
-        except ConfigParseError as e:
-            raise ConfigParseError(['email', *e.keypath], e.issue) from e
-
-        return Config(host=config['host'], port=config['port'], email=email_config, logging=log_config)
+        return Config(
+            host=config['host'], port=config['port'], email=email_config, logging=log_config, database=db_config
+        )
 
 
 def parse_config(filename: str) -> Config:
diff --git a/src/config/database.py b/src/config/database.py
new file mode 100644
index 0000000..625473d
--- /dev/null
+++ b/src/config/database.py
@@ -0,0 +1,16 @@
+from src.config.parse import assert_key_of_type
+from typing import Any
+from dataclasses import dataclass
+
+
+@dataclass
+class Database:
+    url: str
+    echo: bool
+
+    @classmethod
+    def from_dict(cls, config: dict[str, Any]) -> 'Database':
+        assert_key_of_type(config, 'url', str)
+        assert_key_of_type(config, 'echo', bool)
+
+        return Database(url=config['url'], echo=config['echo'])
diff --git a/src/config/parse.py b/src/config/parse.py
index c940175..c50df3f 100644
--- a/src/config/parse.py
+++ b/src/config/parse.py
@@ -1,4 +1,4 @@
-from typing import Any
+from typing import Any, TypeVar, Callable
 
 
 class ConfigParseError(Exception):
@@ -18,3 +18,14 @@ def assert_key_of_type(config: dict[str, Any], key: str, kind: Any):
 
     if not isinstance(config[key], kind):
         raise ConfigParseError([key], f'type of "{key}" was {type(config[key])}, expected {kind}')
+
+
+T = TypeVar('T')
+
+
+def parse_nested_config(config: dict[str, Any], key: str, parse: Callable[[dict[str, Any]], T]) -> T:
+    assert_key_of_type(config, key, dict)
+    try:
+        return parse(config[key])
+    except ConfigParseError as e:
+        raise ConfigParseError([key, *e.keypath], e.issue)
diff --git a/src/infra/db.py b/src/infra/db.py
new file mode 100644
index 0000000..841cbb8
--- /dev/null
+++ b/src/infra/db.py
@@ -0,0 +1,15 @@
+from sqlalchemy.orm import DeclarativeBase
+from src.config.database import Database as DatabaseConfig
+from sqlalchemy import create_engine
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+def get_database(config: DatabaseConfig):
+    engine = create_engine(config.url, echo=config.echo)
+    # Ensure that all tables exist in the database
+    Base.metadata.create_all(engine)
+
+    return engine