"""
Present observational weather data to Prometheus
"""

import json
import os
from typing import Dict, List

import requests  # type: ignore
from flask import Flask, Response  # type: ignore

app = Flask(__name__)


def fetch_carbon_data(postcode: str) -> Dict:
    """
    Fetch current data for the carbon intensity of the provided region
    """

    obs_data = requests.get(
        f'https://api.carbonintensity.org.uk/regional/postcode/{postcode}'
    )

    return json.loads(obs_data.content)


@app.route('/metrics')
def metrics():
    """
    Output Prometheus-style metrics
    """
    postcode = os.environ.get('CARBON_POSTCODE')

    latest_data = fetch_carbon_data(postcode)['data'][0]

    ret_data: List = list()
    for generation in latest_data['data'][0]['generationmix']:
        ret_data.append(
            {
                'key': f'sensor_carbon_generation_{generation["fuel"]}_perc',
                'labels': {
                    'region': latest_data['dnoregion'],
                },
                'type': 'gauge',
                'value': float(generation['perc'])
            }
        )

    ret_data.append(
        {
            'key': 'sensor_carbon_intensity_forecast',
            'labels': {
                'region': latest_data['dnoregion'],
            },
            'type': 'gauge',
            'value': float(latest_data['data'][0]['intensity']['forecast']),
        }
    )

    ret_strs = list()
    for item in ret_data:
        ret_strs.append(f'# HELP {item["key"]} Carbon metric')
        ret_strs.append(f'# TYPE {item["key"]} {item["type"]}')
        ret_strs.append(
            item["key"]
            + '{'
            + " ".join([f'{key}="{val}"' for key, val in item["labels"].items()])
            + '} '
            + str(item["value"])
        )

    resp = Response('\n'.join(ret_strs))
    resp.headers['Content-type'] = 'text/plain'

    return resp


if __name__ == '__main__':
    app.run(host='0.0.0.0')