#!/usr/bin/env python3

import json
import os
import socket
import sys
import time
import yaml
import platform
import asyncio
import paho.mqtt.client as mqtt
from typing import Dict, Any, List
import importlib.util
import glob
from datetime import datetime, timedelta

# Default configuration values used when config file or env vars are missing
CONFIG_DEFAULTS = {
    'mqtt': {
        'host': 'localhost',
        'port': 1883,
        'username': None,
        'password': None,
        'client_id': 'system2mqtt_{hostname}',
        'discovery_prefix': 'homeassistant'
    },
    'collectors': {
        'default_interval': 60,
        'intervals': {}
    }
}

class System2MQTT:
    def __init__(self, config_path: str = "config.yaml"):
        self.config = self._load_config(config_path)
        self.hostname = socket.gethostname()
        self.client = None  # paho MQTT client initialized in connect()
        self.connected = False
        self.device_info = self._get_device_info()
        self.collectors = self._load_collectors()
        self.last_run = {}  # Speichert den Zeitpunkt des letzten Laufs für jeden Sammler

    def _load_config(self, config_path: str) -> Dict[str, Any]:
        """Load configuration from YAML file, apply defaults and environment overrides.

        Precedence: CONFIG_DEFAULTS < config file < environment variables
        """
        # Determine config path: env var overrides parameter
        env_path = os.environ.get('SYSTEM2MQTT_CONFIG')
        if env_path:
            config_path = env_path

        config = {}
        # Start with defaults
        config.update(CONFIG_DEFAULTS)

        # Try loading YAML if present
        if os.path.exists(config_path):
            try:
                with open(config_path, 'r') as f:
                    loaded = yaml.safe_load(f) or {}
                    # Deep merge loaded config into defaults (shallow merge is enough for our shape)
                    for k, v in loaded.items():
                        if isinstance(v, dict) and k in config:
                            config[k].update(v)
                        else:
                            config[k] = v
            except Exception as e:
                print(f"Warning: failed to load config file {config_path}: {e}")
                print("Proceeding with defaults and environment overrides.")
        else:
            print(f"Config file '{config_path}' not found; using defaults and environment variables if set.")

        # Ensure necessary sub-keys exist
        config.setdefault('mqtt', CONFIG_DEFAULTS['mqtt'].copy())
        config.setdefault('collectors', CONFIG_DEFAULTS['collectors'].copy())
        config['collectors'].setdefault('intervals', {})

        # Apply environment variable overrides
        self._merge_env_overrides(config)

        return config

    def _merge_env_overrides(self, config: Dict[str, Any]):
        """Merge environment variable overrides into the config dict.

        Recognized env vars (examples): MQTT_HOST, MQTT_PORT, MQTT_USERNAME, MQTT_PASSWORD,
        MQTT_CLIENT_ID, MQTT_DISCOVERY_PREFIX, COLLECTORS_DEFAULT_INTERVAL, COLLECTOR_<NAME>_INTERVAL
        """
        # MQTT overrides
        if 'MQTT_HOST' in os.environ:
            config['mqtt']['host'] = os.environ['MQTT_HOST']
        if 'MQTT_PORT' in os.environ:
            try:
                config['mqtt']['port'] = int(os.environ['MQTT_PORT'])
            except ValueError:
                print("Warning: MQTT_PORT is not an integer; ignoring env override")
        if 'MQTT_USERNAME' in os.environ:
            config['mqtt']['username'] = os.environ['MQTT_USERNAME']
        if 'MQTT_PASSWORD' in os.environ:
            config['mqtt']['password'] = os.environ['MQTT_PASSWORD']
        if 'MQTT_CLIENT_ID' in os.environ:
            config['mqtt']['client_id'] = os.environ['MQTT_CLIENT_ID']
        if 'MQTT_DISCOVERY_PREFIX' in os.environ:
            config['mqtt']['discovery_prefix'] = os.environ['MQTT_DISCOVERY_PREFIX']

        # Collectors default interval
        if 'COLLECTORS_DEFAULT_INTERVAL' in os.environ:
            try:
                config['collectors']['default_interval'] = int(os.environ['COLLECTORS_DEFAULT_INTERVAL'])
            except ValueError:
                print("Warning: COLLECTORS_DEFAULT_INTERVAL is not an integer; ignoring env override")

        # Per-collector overrides
        for key, val in os.environ.items():
            if key.startswith('COLLECTOR_') and key.endswith('_INTERVAL'):
                # Example: COLLECTOR_system_metrics_INTERVAL
                parts = key.split('_')
                if len(parts) >= 3:
                    name = '_'.join(parts[1:-1])
                    try:
                        config['collectors']['intervals'][name] = int(val)
                    except ValueError:
                        print(f"Warning: {key} must be an integer; ignoring")

    def _setup_mqtt_client(self) -> mqtt.Client:
        """Setup paho-mqtt client with configuration (callback API v2 when available)."""
        client_id = self.config['mqtt'].get('client_id', 'system2mqtt_{hostname}').format(hostname=self.hostname)
        # Prefer callback API v2 to avoid deprecation warnings; fall back if older paho
        try:
            client = mqtt.Client(callback_api_version=mqtt.CallbackAPIVersion.VERSION2, client_id=client_id)
        except TypeError:
            client = mqtt.Client(client_id=client_id)
        username = self.config['mqtt'].get('username')
        password = self.config['mqtt'].get('password')
        if username or password:
            client.username_pw_set(username, password)
        client.on_connect = self._on_connect
        client.on_disconnect = self._on_disconnect
        return client

    def _on_connect(self, client, userdata, flags, rc, properties=None):
        """Callback when connected to broker (paho)."""
        try:
            rc_val = int(rc)
        except Exception:
            rc_val = 0
        if rc_val == 0:
            print("Connected to MQTT broker")
            self.connected = True
        else:
            print(f"Failed to connect to MQTT broker with code: {rc_val}")
            self.connected = False

    def _on_disconnect(self, client, userdata, rc, reason_code=None, properties=None):
        """Callback when disconnected (paho v2)."""
        print("Disconnected from MQTT broker")
        self.connected = False

    def _get_device_info(self) -> Dict[str, Any]:
        """Get device information for Home Assistant."""
        return {
            "identifiers": [f"system2mqtt_{self.hostname}"],
            "name": f"System {self.hostname}",
            "model": platform.machine(),
            "manufacturer": platform.system()
        }

    def _get_unique_id(self, sensor_id: str) -> str:
        """Generate unique_id from sensor_id."""
        return f"system2mqtt_{self.hostname}_{sensor_id}"

    def _get_state_topic(self, sensor_id: str) -> str:
        """Generate state topic from sensor_id."""
        return f"system2mqtt/{self.hostname}/{sensor_id}/state"

    def _load_collectors(self) -> List[Dict[str, Any]]:
        """Load all collector modules from the collectors directory."""
        collectors = []
        collector_dir = os.path.join(os.path.dirname(__file__), 'collectors')
        
        # Find all Python files in the collectors directory
        collector_files = glob.glob(os.path.join(collector_dir, '*.py'))
        
        for collector_file in collector_files:
            if collector_file.endswith('__init__.py'):
                continue
                
            module_name = os.path.splitext(os.path.basename(collector_file))[0]
            spec = importlib.util.spec_from_file_location(module_name, collector_file)
            module = importlib.util.module_from_spec(spec)
            spec.loader.exec_module(module)
            
            if hasattr(module, 'collect_metrics'):
                # Get interval from config or use collector's default
                default_interval = getattr(module, 'DEFAULT_INTERVAL', self.config['collectors']['default_interval'])
                interval = self.config['collectors']['intervals'].get(
                    module_name,
                    default_interval
                )
                
                collectors.append({
                    'module': module,
                    'name': module_name,
                    'interval': interval
                })
                print(f"Loaded collector: {module_name} (interval: {interval}s)")
        
        return collectors

    async def process_collector_data(self, data: Dict[str, Any]):
        """Process data from collectors and publish to MQTT."""
        if not self.connected:
            print("Not connected to MQTT broker")
            return

        # Publish discovery messages for each entity
        for entity in data['entities']:
            sensor_id = entity['sensor_id']
            unique_id = self._get_unique_id(sensor_id)
            state_topic = self._get_state_topic(sensor_id)
            discovery_topic = f"{self.config['mqtt']['discovery_prefix']}/sensor/{unique_id}/config"
            attributes_topic = f"{state_topic}/attributes"
            availability_topic = f"system2mqtt/{self.hostname}/status"
            
            # Prepare discovery message
            discovery_msg = {
                "name": entity['name'],
                "unique_id": unique_id,
                "state_topic": state_topic,
                "state_class": entity['state_class'],
                "unit_of_measurement": entity['unit_of_measurement'],
                "device_class": entity['device_class'],
                "device": self.device_info,
                "json_attributes_topic": attributes_topic,
                "availability_topic": availability_topic,
                "payload_available": "online",
                "payload_not_available": "offline"
            }

            # Include icon if provided by the collector
            if 'icon' in entity and entity['icon']:
                discovery_msg["icon"] = entity['icon']

            # Publish discovery message
            self.client.publish(discovery_topic, json.dumps(discovery_msg), qos=0, retain=True)
            # Publish availability (retained)
            self.client.publish(availability_topic, "online", qos=0, retain=True)

            # Publish state
            self.client.publish(state_topic, str(entity['value']), qos=0, retain=True)

            # Publish attributes if present
            if 'attributes' in entity:
                self.client.publish(attributes_topic, json.dumps(entity['attributes']), qos=0, retain=True)

    def should_run_collector(self, collector: Dict[str, Any]) -> bool:
        """Check if a collector should run based on its interval."""
        now = datetime.now()
        last_run = self.last_run.get(collector['name'])
        
        if last_run is None:
            return True
            
        interval = timedelta(seconds=collector['interval'])
        return (now - last_run) >= interval

    async def collect_and_publish(self):
        """Collect metrics from all collectors and publish them."""
        for collector in self.collectors:
            if not self.should_run_collector(collector):
                continue
                
            try:
                data = collector['module'].collect_metrics()
                await self.process_collector_data(data)
                self.last_run[collector['name']] = datetime.now()
                print(f"Updated {collector['name']} metrics")
            except Exception as e:
                print(f"Error collecting metrics from {collector['name']}: {e}")

    async def connect(self):
        """Connect to MQTT broker using paho-mqtt and wait briefly for on_connect."""
        try:
            self.client = self._setup_mqtt_client()
            self.client.connect(self.config['mqtt']['host'], self.config['mqtt']['port'])
            self.client.loop_start()
            # Wait up to 5 seconds for on_connect to fire
            for _ in range(50):
                if self.connected:
                    break
                await asyncio.sleep(0.1)
        except Exception as e:
            print(f"Error connecting to MQTT broker: {e}")
            sys.exit(1)

    async def disconnect(self):
        """Disconnect from MQTT broker (paho)."""
        try:
            if self.client:
                self.client.loop_stop()
                self.client.disconnect()
        finally:
            pass

async def async_main():
    """Async main function."""
    system2mqtt = System2MQTT()
    await system2mqtt.connect()

    try:
        # Initial collection
        await system2mqtt.collect_and_publish()

        # Main loop - check every second if any collector needs to run
        while True:
            await system2mqtt.collect_and_publish()
            await asyncio.sleep(1)

    except KeyboardInterrupt:
        print("\nShutting down...")
    finally:
        await system2mqtt.disconnect()

if __name__ == "__main__":
    asyncio.run(async_main())