From 3dad2071ff07770fe3b33ff2bc2b5fef25930a42 Mon Sep 17 00:00:00 2001
From: Marc Cataford <mcat@riseup.net>
Date: Sat, 13 Apr 2024 23:17:42 -0400
Subject: [PATCH] refactor: extract configuration handling to own class

---
 spud/base.py         |  9 +++++++--
 spud/cli.py          | 11 +++++++++--
 spud/config.py       | 36 ++++++++++++++++++++++++++++++++++++
 tests/test_config.py | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 84 insertions(+), 4 deletions(-)
 create mode 100644 spud/config.py
 create mode 100644 tests/test_config.py

diff --git a/spud/base.py b/spud/base.py
index bd95cdc..23c64bf 100644
--- a/spud/base.py
+++ b/spud/base.py
@@ -5,5 +5,10 @@ Models and datastructures
 import pydantic
 
 
-class Configuration(pydantic.BaseModel):
-    """Command line application configuration options"""
+class ContainerMetadata(pydantic.BaseModel):
+    """Metadata pulled from container status check"""
+
+    name: str
+    status: str
+    image: str
+    started: int
diff --git a/spud/cli.py b/spud/cli.py
index 4cdd78c..0c943b6 100644
--- a/spud/cli.py
+++ b/spud/cli.py
@@ -10,7 +10,7 @@ import pathlib
 import click
 import uvicorn
 
-from spud.base import Configuration
+from spud.config import Configuration
 
 DEFAULT_CONFIGURATION_PATH = "~/.config/spud/config.json"
 
@@ -27,7 +27,14 @@ def cli(context, config):
     """CLI root"""
     context.ensure_object(dict)
     config = config if config is not None else DEFAULT_CONFIGURATION_PATH
-    context.obj["config_path"] = pathlib.Path(config).expanduser()
+    config_path = pathlib.Path(config).expanduser()
+
+    context.obj["config_path"] = config_path
+
+    if config_path.exists():
+        context.obj["config"] = Configuration.from_file(config_path)
+    else:
+        context.obj["config"] = None
 
 
 @click.command()
diff --git a/spud/config.py b/spud/config.py
new file mode 100644
index 0000000..0d8e255
--- /dev/null
+++ b/spud/config.py
@@ -0,0 +1,36 @@
+import json
+import pathlib
+
+import pydantic
+
+
+class Configuration(pydantic.BaseModel):
+    """Command line application configuration options"""
+
+    @classmethod
+    def from_file(cls, path: pathlib.Path) -> "Configuration":
+        """
+        Generates a Configuration object from the file found at {path}.
+
+        Raises if:
+        - The file does not exist
+        - The file is not valid JSON
+        - The file does not respect the expected schema
+        """
+        if not path.exists():
+            raise RuntimeError(f"Configuration file not found: {str(path)}.")
+
+        with open(path, "r", encoding="utf8") as config_file:
+            config_data = config_file.read()
+
+        try:
+            parsed_configuration = json.loads(config_data)
+            return cls(**parsed_configuration)
+        except json.decoder.JSONDecodeError as exc:
+            raise RuntimeError(
+                f"Configuration file is not valid JSON ({str(path)})."
+            ) from exc
+        except pydantic.ValidationError as exc:
+            raise RuntimeError(
+                f"Configuration file has wrong schema ({str(path)})."
+            ) from exc
diff --git a/tests/test_config.py b/tests/test_config.py
new file mode 100644
index 0000000..0dbadce
--- /dev/null
+++ b/tests/test_config.py
@@ -0,0 +1,32 @@
+import json
+
+import pytest
+
+from spud.config import Configuration
+
+
+@pytest.fixture(name="sample_config")
+def sample_config_fixture():
+    return {}
+
+
+def test_from_file_creates_configuration_from_file(tmpdir, sample_config):
+    config_file = tmpdir / "config.json"
+    config_file.write(json.dumps(sample_config))
+
+    config = Configuration.from_file(config_file)
+
+    assert config.model_dump() == sample_config
+
+
+def test_from_file_raises_if_file_not_found(tmpdir):
+    with pytest.raises(RuntimeError):
+        Configuration.from_file(tmpdir / "nonfile.json")
+
+
+def test_from_file_raises_if_file_not_json(tmpdir):
+    config_file = tmpdir / "config.json"
+    config_file.write("notjson")
+
+    with pytest.raises(RuntimeError):
+        Configuration.from_file(config_file)