"""
Service Health Detector
Monitors if specific processes/services are running.

Environment variables:
    AGGREGATOR_URL  - URL of the aggregator (default: http://localhost:5000)
    CHECK_INTERVAL  - Seconds between checks (default: 30)
    SERVICES        - Comma-separated list of process names to monitor (required)
                      Example: "nginx,postgres,redis"
"""

import os
import sys
import time
import psutil
import requests

# Configuration from environment
AGGREGATOR_URL = os.environ.get("AGGREGATOR_URL", "http://localhost:5000")
CHECK_INTERVAL = int(os.environ.get("CHECK_INTERVAL", 30))
SERVICES = os.environ.get("SERVICES", "")


def get_running_processes():
    """Get set of running process names."""
    running = set()
    for proc in psutil.process_iter(['name']):
        try:
            name = proc.info['name']
            if name:
                # Store both with and without common extensions
                running.add(name.lower())
                if name.lower().endswith('.exe'):
                    running.add(name.lower()[:-4])
        except (psutil.NoSuchProcess, psutil.AccessDenied):
            pass
    return running


def send_event(event_id, priority, message):
    """Send an event to the aggregator with heartbeat TTL."""
    ttl = CHECK_INTERVAL * 2
    try:
        response = requests.post(
            f"{AGGREGATOR_URL}/event",
            json={"id": event_id, "priority": priority, "message": message, "ttl": ttl},
            timeout=5
        )
        print(f"[EVENT] {event_id}: {message} (priority {priority}, ttl {ttl}s) -> {response.status_code}")
    except requests.RequestException as e:
        print(f"[ERROR] Failed to send event: {e}")


def clear_event(event_id):
    """Clear the event from the aggregator."""
    try:
        response = requests.post(
            f"{AGGREGATOR_URL}/clear",
            json={"id": event_id},
            timeout=5
        )
        if response.status_code == 200:
            print(f"[CLEAR] {event_id}")
    except requests.RequestException as e:
        print(f"[ERROR] Failed to clear event: {e}")


def main():
    if not SERVICES:
        print("ERROR: SERVICES environment variable is required")
        print("Example: SERVICES=nginx,postgres,redis python detectors/service.py")
        sys.exit(1)

    services = [s.strip().lower() for s in SERVICES.split(",") if s.strip()]

    print(f"Service Health Detector started")
    print(f"  Aggregator: {AGGREGATOR_URL}")
    print(f"  Interval: {CHECK_INTERVAL}s")
    print(f"  Monitoring: {', '.join(services)}")
    print()

    # Track which services have active alerts
    active_alerts = set()

    while True:
        running = get_running_processes()
        current_alerts = set()

        for service in services:
            event_id = f"service_{service}"

            if service not in running:
                send_event(event_id, 1, f"Service '{service}' is not running")
                current_alerts.add(event_id)
            else:
                print(f"[OK] Service '{service}' is running")

        # Clear alerts for services that are now running
        for event_id in active_alerts - current_alerts:
            clear_event(event_id)

        active_alerts = current_alerts

        time.sleep(CHECK_INTERVAL)


if __name__ == "__main__":
    main()