import os
import json
import requests
from jinja2 import Environment, FileSystemLoader
from datetime import datetime

# --- Configuration ---
HA_URL = os.environ.get("HA_URL")
HA_TOKEN = os.environ.get("HA_TOKEN")
DATA_FILE = "/output/sensor_data.json"
HTML_FILE = "/output/index.html"
TEMPLATE_DIR = "templates"

# --- Error Handling ---
if not HA_URL or not HA_TOKEN:
    raise ValueError("HA_URL and HA_TOKEN environment variables must be set.")

# --- Functions ---

def get_ha_data():
    """Fetches all states from Home Assistant and filters for temp/humidity sensors."""
    headers = {
        "Authorization": f"Bearer {HA_TOKEN}",
        "content-type": "application/json",
    }
    url = f"{HA_URL}/api/states"
    try:
        response = requests.get(url, headers=headers)
        response.raise_for_status()  # Raise an exception for bad status codes
        states = response.json()
        
        sensors = [
            s for s in states 
            if "unit_of_measurement" in s["attributes"] and (
                s["attributes"]["unit_of_measurement"] == "°C" or 
                (s["attributes"]["unit_of_measurement"] == "%" and 
                 s["attributes"].get("device_class") != "battery")
            )
        ]
        return sensors

    except requests.exceptions.RequestException as e:
        print(f"Error connecting to Home Assistant: {e}")
        return None

def read_historical_data():
    """Reads historical sensor data from the JSON file."""
    if not os.path.exists(DATA_FILE):
        return []
    with open(DATA_FILE, "r") as f:
        return json.load(f)

def write_historical_data(new_data):
    """Appends new sensor data to the historical record."""
    historical_data = read_historical_data()
    timestamp = datetime.now().isoformat()
    
    for sensor in new_data:
        historical_data.append({
            "entity_id": sensor["entity_id"],
            "friendly_name": sensor["attributes"].get("friendly_name", sensor["entity_id"]),
            "state": sensor["state"],
            "unit": sensor["attributes"].get("unit_of_measurement"),
            "timestamp": timestamp,
        })

    with open(DATA_FILE, "w") as f:
        json.dump(historical_data, f, indent=4)

def generate_html_report(recent_data, historical_data, last_updated_time):
    """Generates an HTML report from the sensor data."""
    env = Environment(loader=FileSystemLoader(TEMPLATE_DIR))
    template = env.get_template("index.html.j2")
    
    html_content = template.render(
        recent_data=recent_data, 
        historical_data=historical_data,
        last_updated_time=last_updated_time
    )
    
    with open(HTML_FILE, "w") as f:
        f.write(html_content)
    print(f"Successfully generated HTML report: {HTML_FILE}")

# --- Main Execution ---

def main():
    """Main function to run the script."""
    print("Fetching data from Home Assistant...")
    recent_sensor_data = get_ha_data()
    
    if recent_sensor_data:
        print(f"Found {len(recent_sensor_data)} temperature/humidity sensors.")
        write_historical_data(recent_sensor_data)
        historical_data = read_historical_data()
        last_updated_time = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
        generate_html_report(recent_sensor_data, historical_data, last_updated_time)
    else:
        print("Could not fetch new data. Report generation skipped.")

if __name__ == "__main__":
    main()