Refactor AgentGenerator class

- Add  --template-file and --output-dir options to generate-agents command, so we don't need to access the config in the AgentGenerator class

src/kafkaaggregator/cli.py

@@ -7,14 +7,13 @@
 
 from faust.cli import AppCommand, option
 
-from kafkaaggregator.app import app
-from kafkaaggregator.config import Configuration, ExampleConfiguration
+from kafkaaggregator.app import app, config
+from kafkaaggregator.config import ExampleConfiguration
 from kafkaaggregator.example.example import AggregationExample
 from kafkaaggregator.generator import AgentGenerator
 
 logger = logging.getLogger("kafkaaggregator")
 
-config = Configuration()
 example_config = ExampleConfiguration()
 
 
@@ -61,6 +60,20 @@ async def init_example(self: AppCommand) -> None:
 
 
 @app.command(
+    option(
+        "--template-file",
+        type=str,
+        default=config.agent_template_file,
+        help="Name of the agent Jinja2 template file.",
+        show_default=True,
+    ),
+    option(
+        "--output-dir",
+        type=str,
+        default=config.agents_output_dir,
+        help="Name of output directory for the agents' code.",
+        show_default=True,
+    ),
     option(
         "--config-file",
         type=str,
@@ -78,8 +91,14 @@ async def init_example(self: AppCommand) -> None:
     ),
 )
 async def generate_agents(
-    self: AppCommand, config_file: str, aggregated_topic: str
+    self: AppCommand,
+    config_file: str,
+    aggregated_topic: str,
+    template_file: str,
+    output_dir: str,
 ) -> None:
     """Generate Faust agents' code."""
-    agent_generator = AgentGenerator(Path(config_file), aggregated_topic)
+    agent_generator = AgentGenerator(
+        Path(config_file), aggregated_topic, template_file, output_dir
+    )
     await agent_generator.run()

src/kafkaaggregator/generator.py

@@ -1,4 +1,4 @@
-"""Generates Faust agents based on the agent.j2 template."""
+"""Generates Faust agents (stream processors) using the agent.j2 template."""
 
 __all__ = ["AgentGenerator"]
 
@@ -11,104 +11,96 @@
 from jinja2 import Environment, PackageLoader, Template, TemplateError
 
 from kafkaaggregator.aggregator_config import AggregatorConfig
-from kafkaaggregator.app import config
 
 logger = logging.getLogger("kafkaaggregator")
 
 
 class AgentGenerator:
-    """Generate Faust agents from a list of source topics.
+    """Generate a Faust agent for an aggregated topic.
 
     Creates the context and renders the agents code template.
 
     Parameters
     ----------
-    source_topic_names : `list`
-        List of source topic names.
-    """
+    config_file : `Path`
+        Aggregator configuration file.
+    aggegated_topic: str
+        Name of the aggregated topic.
+    template_file: str
+        Name of the agent Jinja2 template file
 
-    logger = logger
 
-    def __init__(self, config_file: Path, aggregated_topic: str) -> None:
+    """
 
-        self._aggregated_topic_name = aggregated_topic
+    logger = logger
 
-        # TODO: fix to aggregate multiple topics
-        config = AggregatorConfig(config_file).get(aggregated_topic)
+    def __init__(
+        self,
+        config_file: Path,
+        aggregated_topic: str,
+        template_file: str,
+        output_dir: str,
+    ) -> None:
+
+        self._aggregated_topic = aggregated_topic
+        aggregator_config = AggregatorConfig(config_file).get(
+            self._aggregated_topic
+        )
 
         # Supports the 1 source topic -> 1 aggregated topic case for the moment
-        self._source_topic_name = config.source_topics[0]
+        self._source_topic = aggregator_config.source_topics[0]
         self._template: Template = self._load_template()
-
-    @property
-    def template(self) -> Template:
-        """Get the agent template."""
-        return self._template
-
-    @staticmethod
-    def _create_filepath(source_topic_name: str) -> str:
-        """Return the file path for the agent.
-
-        The directory name comes from the agents_output_dir configuration
-        parameter and the file name is based on source topic name.
-
-        Parameters
-        ----------
-        source_topic_name : `str`
-            Name of the source topic to aggregate.
-        """
-        agents_output_dir = config.agents_output_dir
-
-        filepath = os.path.join(agents_output_dir, f"{source_topic_name}.py")
-
-        return filepath
+        self._window_size_secods = (
+            aggregator_config.window_aggregation.window_size_seconds
+        )
+        self._window_expiration_seconds = (
+            aggregator_config.window_aggregation.window_expiration_seconds
+        )
+        self._template_file = template_file
+        self._output_dir = output_dir
 
     def _create_context(self) -> Mapping[str, Any]:
         """Create the template context.
 
         The template context stores the values passed to the template.
 
-        Parameters
-        ----------
-        source_topic_name : `str`
-            Name of the source topic to aggregate
-
         Returns
         -------
         context : `dict`
             A dictionary with values passed to the template.
         """
-        cls_name = self._source_topic_name.title().replace("-", "")
+        cls_name = self._aggregated_topic.title().replace("-", "")
 
         context = dict(
             cls_name=cls_name,
-            source_topic_name=self._source_topic_name,
-            aggregation_topic_name=self._aggregated_topic_name,
+            source_topic=self._source_topic,
+            aggregated_topic=self._aggregated_topic,
         )
 
         return context
 
-    @staticmethod
-    def _load_template() -> Template:
+    def _load_template(self) -> Template:
         """Load the agent template file."""
-        agent_template_file = config.agent_template_file
-
         env = Environment(
             loader=PackageLoader("kafkaaggregator"), keep_trailing_newline=True
         )
         try:
-            template = env.get_template(agent_template_file)
+            template = env.get_template(self._template_file)
         except TemplateError as e:
             logger.error("Error loading the agent template file.")
             raise e
-
         return template
 
     async def run(self) -> None:
         """Run agents code generation."""
-        logger.info(f"Generating agent code for {self._source_topic_name}.")
-        filepath = self._create_filepath(self._source_topic_name)
+        logger.info(f"Generating agent code for {self._aggregated_topic}.")
+
+        template = self._load_template()
         context = self._create_context()
 
-        async with aiofiles.open(filepath, "w") as file:
-            await file.write(self._template.render(**context))
+        output_file = os.path.join(
+            self._output_dir, f"{self._aggregated_topic}.py"
+        )
+
+        async with aiofiles.open(output_file, "w") as f:
+            await f.write(template.render(**context))