home_control/service.py

#!/usr/bin/env python3
"""Configuration-driven event controller for home-control plugins."""

from __future__ import annotations

import argparse
import importlib
import logging
import signal
from pathlib import Path
from threading import Event
from typing import Any, Callable

import yaml


LOG = logging.getLogger("home_control")
EVENT_FIELDS = ("sender", "event", "id", "text")


def load_config(path: Path) -> dict:
    with path.open(encoding="utf-8") as stream:
        config = yaml.safe_load(stream)
    if not isinstance(config, dict):
        raise ValueError("configuration must be a YAML mapping")
    return config


def _configured_callable(spec: dict, key: str, default: str) -> Callable:
    module_name = spec.get("module")
    if not isinstance(module_name, str) or not module_name.startswith("lib."):
        raise ValueError("component module must be inside the lib package")
    attribute = spec.get(key, default)
    if not isinstance(attribute, str):
        raise ValueError(f"component {key} must be a string")
    try:
        function = getattr(importlib.import_module(module_name), attribute)
    except (ImportError, AttributeError) as error:
        raise ValueError(f"could not load {module_name}.{attribute}: {error}") from error
    if not callable(function):
        raise ValueError(f"configured component {module_name}.{attribute} is not callable")
    return function


class Controller:
    """Load, supervise, and route plugins without plugin-specific code."""

    def __init__(self, config: dict) -> None:
        self.config = config
        controller = config.get("controller", {})
        self.plugin_specs = controller.get("plugins", {})
        self.action_specs = controller.get("actions", {})
        if not isinstance(self.plugin_specs, dict):
            raise ValueError("controller.plugins must be a mapping")
        if not isinstance(self.action_specs, dict):
            raise ValueError("controller.actions must be a mapping")
        self.stopped = Event()
        self.plugins: list[Any] = []

    @staticmethod
    def _validate_event(message: dict) -> None:
        if not isinstance(message, dict):
            raise ValueError("plugin event must be a dictionary")
        missing = [field for field in EVENT_FIELDS if field not in message]
        if missing:
            raise ValueError(f"plugin event is missing fields: {', '.join(missing)}")
        if any(not isinstance(message[field], str) for field in EVENT_FIELDS):
            raise ValueError("plugin event fields must all be strings")

    def _component_config(self, spec: dict) -> dict:
        section = spec.get("config")
        if not isinstance(section, str):
            raise ValueError("component config must name a configuration section")
        component_config = self.config.get(section)
        if not isinstance(component_config, dict):
            raise ValueError(f"configuration section {section!r} is required")
        return component_config

    def handle_event(self, message: dict) -> None:
        """Route a validated plugin event to its configured action."""
        self._validate_event(message)
        plugin_spec = self.plugin_specs.get(message["sender"])
        if not isinstance(plugin_spec, dict):
            LOG.warning("no controller route for plugin %s", message["sender"])
            return
        configured_actions = plugin_spec.get("on_event")
        action_names = (
            [configured_actions]
            if isinstance(configured_actions, str)
            else configured_actions
        )
        if not isinstance(action_names, list) or any(
            not isinstance(name, str) for name in action_names
        ):
            raise ValueError(
                f"on_event for plugin {message['sender']!r} must be a string or list of strings"
            )

        for action_name in action_names:
            action_spec = self.action_specs.get(action_name)
            if not isinstance(action_spec, dict):
                raise ValueError(
                    f"unknown on_event action {action_name!r} "
                    f"for plugin {message['sender']!r}"
                )
            handler = _configured_callable(action_spec, "handler", "on_event")
            handler(self._component_config(action_spec), message)

    def _load_plugins(self) -> None:
        for name, spec in self.plugin_specs.items():
            if not isinstance(spec, dict):
                raise ValueError(f"controller plugin {name!r} must be a mapping")
            plugin_config = self._component_config(spec)
            if not plugin_config.get("enabled", True):
                LOG.info("plugin %s is disabled", name)
                continue
            factory = _configured_callable(spec, "factory", "create")
            plugin = factory(plugin_config, self.handle_event)
            self.plugins.append(plugin)

    def run(self) -> int:
        self._load_plugins()
        for plugin in self.plugins:
            plugin.start()
        try:
            while not self.stopped.wait(1):
                if any(not plugin.is_alive for plugin in self.plugins):
                    LOG.error("a controller plugin stopped unexpectedly")
                    return 1
        finally:
            for plugin in self.plugins:
                plugin.stop()
            for plugin in self.plugins:
                plugin.join(timeout=20)
        return 0

    def stop(self, *_: object) -> None:
        self.stopped.set()

    def check_once(self) -> int:
        self._load_plugins()
        result = 0
        for plugin in self.plugins:
            try:
                check_once = getattr(plugin, "check_once", None)
                if callable(check_once):
                    output = check_once()
                    if output:
                        print("\n".join(output) if isinstance(output, list) else output)
            except (OSError, RuntimeError) as error:
                LOG.error("plugin check failed: %s", error)
                result = 1
            finally:
                close = getattr(plugin, "close", None)
                if callable(close):
                    close()
        return result


def run(config: dict, once: bool = False) -> int:
    controller = Controller(config)
    signal.signal(signal.SIGTERM, controller.stop)
    signal.signal(signal.SIGINT, controller.stop)
    return controller.check_once() if once else controller.run()


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument("--config", type=Path, default=Path(__file__).with_name("service.yaml"))
    parser.add_argument("--once", action="store_true", help="check plugins once")
    args = parser.parse_args()
    config = load_config(args.config)
    logging_config = config.get("controller", {}).get("logging", {})
    logging.basicConfig(
        level=getattr(logging, str(logging_config.get("level", "INFO")).upper()),
        format="%(asctime)s %(levelname)s %(message)s",
    )
    return run(config, args.once)


if __name__ == "__main__":
    raise SystemExit(main())