import datetime
import os.path

import requests


def get_weather_json(lat, lon):
    """
    fetches weather from the Norwegian meteorological institute
    for a given latitude and longitude. Returns an object with a 
    3-day forecast with morning, afternoon, evening and overnight
    periods. NOTE: This is not tidied up. Use get_forecast for 
    nicer formatted stuff.
    """
    url = "https://api.met.no/weatherapi/locationforecast/1.9/.json"
    params = { "lat": lat, "lon": lon }

    # https://api.met.no/weatherapi/locationforecast/1.9/.json?lat=52.50639&lon=13.4063
    resp = requests.get(url=url, params=params)
    return resp.json()

def get_forecast(lat, lon):
    """
    returns a list of forecast dicts:
      forecast = { "fromtime": datetime, "totime": datetime,
                   "symbol": "pathto.svg", "mintemp": "12.7",
                   "maxtemp": "16.8", "period": "Morning"}
    """
    thisdir = os.path.dirname(os.path.abspath(__file__))
    periods = {6: "Morning", 12: "Afternoon", 18: "Evening", 0: "Night"}

    # Berlin - "52.5", "13.4"
    w = get_weather_json(lat, lon)

    forecasts = []
    for t in w["product"]["time"]:
        # need to strip the trainling 'Z' char which indicates UTC
        fr = datetime.datetime.fromisoformat(t["from"][:-1])
        to = datetime.datetime.fromisoformat(t["to"][:-1])
        dtdelta = datetime.date.today() - fr.date()

        if dtdelta == datetime.timedelta(days=0):
            day_of = "Today"
        elif dtdelta == datetime.timedelta(days=-1):
            day_of = "Tomorrow"
        else:
            days = ("Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday")
            day_of = days[fr.weekday()]

        if fr.hour not in (0, 6, 12, 18):
            continue
        if(to-fr == datetime.timedelta(hours=6)):
            mintemp = t["location"]["minTemperature"]["value"] 
            maxtemp = t["location"]["maxTemperature"]["value"]
            symbol = t["location"]["symbol"]["id"].lower()
            png = symbol
            if fr.hour in (18, 0):
                symbol += "-night.svg"
                png += "-night.png"
            else:
                symbol += ".svg"
                png += ".png"
            icon = os.path.join(thisdir, "weather_icons", symbol)
            png = os.path.join(thisdir, "weather_icons", png)
            forecast = {"fromtime": fr, "totime": to, "symbol": icon,
                        "mintemp": mintemp, "maxtemp": maxtemp, "png": png, 
                        "period": periods[fr.hour], "day": day_of}
            forecasts.append(forecast)

    return forecasts


if __name__ == "__main__":
    from pprint import pprint
    pprint(get_forecast("52.5","13.4"))