add yoyo-migrations library & config reader

.coveragerc

@@ -0,0 +1,4 @@
+[run]
+omit =
+    rose/__main__.py
+    setup.py

.gitignore

@@ -4,3 +4,5 @@ __pycache__
 .mypy_cache
 .coverage
 result
+db.sqlite3
+htmlcov

README.md

@@ -1,3 +1,16 @@
 # rose
 
 Rose is a Linux music library manager.
+
+## Configuration
+
+Rose reads its configuration from `${XDG_CONFIG_HOME:-$HOME/.config}/rose/config.toml`.
+
+The configuration parameters, with examples, are:
+
+```toml
+# The directory containing the music to manage.
+music_source_dir = "~/.music-src"
+# The directory to mount the library's virtual filesystem on.
+fuse_mount_dir = "~/music"
+```

flake.nix

@@ -19,6 +19,7 @@
         click
         fuse
         mutagen
+        yoyo-migrations
       ];
       dev-deps = with python.pkgs; [
         black

rose/base_error.py

@@ -0,0 +1,2 @@
+class RoseError(Exception):
+    pass

rose/config.py

@@ -0,0 +1,43 @@
+from __future__ import annotations
+
+import os
+from dataclasses import dataclass
+from pathlib import Path
+
+import tomllib
+
+from rose.base_error import RoseError
+
+CONFIG_HOME = Path(os.environ.get("XDG_CONFIG_HOME", os.environ["HOME"] + "/.config"))
+CONFIG_PATH = CONFIG_HOME / "rose" / "config.toml"
+
+
+class ConfigNotFoundError(RoseError):
+    pass
+
+
+class MissingConfigKeyError(RoseError):
+    pass
+
+
+@dataclass
+class Config:
+    music_source_dir: Path
+    fuse_mount_dir: Path
+
+    @classmethod
+    def read(cls, config_path_override: Path | None = None) -> Config:
+        cfgpath = config_path_override or CONFIG_PATH
+        try:
+            with cfgpath.open("rb") as fp:
+                data = tomllib.load(fp)
+        except FileNotFoundError as e:
+            raise ConfigNotFoundError(f"Configuration file not found ({CONFIG_PATH})") from e
+
+        try:
+            return cls(
+                music_source_dir=Path(data["music_source_dir"]).expanduser(),
+                fuse_mount_dir=Path(data["fuse_mount_dir"]).expanduser(),
+            )
+        except KeyError as e:
+            raise MissingConfigKeyError(f"Missing key in configuration file: {e}") from e

rose/config_test.py

@@ -0,0 +1,39 @@
+import os
+import tempfile
+from pathlib import Path
+
+import pytest
+
+from rose.config import Config, ConfigNotFoundError, MissingConfigKeyError
+
+
+def test_config() -> None:
+    with tempfile.TemporaryDirectory() as tmpdir:
+        path = Path(tmpdir) / "config.toml"
+        with path.open("w") as fp:
+            fp.write(
+                """\
+    music_source_dir = "~/.music-src"
+    fuse_mount_dir = "~/music"
+    """
+            )
+
+        c = Config.read(config_path_override=path)
+        assert str(c.music_source_dir) == os.environ["HOME"] + "/.music-src"
+        assert str(c.fuse_mount_dir) == os.environ["HOME"] + "/music"
+
+
+def test_config_not_found() -> None:
+    with tempfile.TemporaryDirectory() as tmpdir:
+        path = Path(tmpdir) / "config.toml"
+        with pytest.raises(ConfigNotFoundError):
+            Config.read(config_path_override=path)
+
+
+def test_config_missing_key() -> None:
+    with tempfile.TemporaryDirectory() as tmpdir:
+        path = Path(tmpdir) / "config.toml"
+        path.touch()
+        with pytest.raises(MissingConfigKeyError) as excinfo:
+            Config.read(config_path_override=path)
+        assert str(excinfo.value) == "Missing key in configuration file: 'music_source_dir'"

setup.py

@@ -13,5 +13,6 @@
         "click",
         "fuse-python",
         "mutagen",
+        "yoyo-migrations",
     ],
 )

yoyo.ini

@@ -0,0 +1,8 @@
+# This is for development use only.
+
+[DEFAULT]
+sources = migrations
+migration_table = _yoyo_migration
+batch_mode = off
+verbosity = 0
+database = sqlite:///db.sqlite3