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/2.0/complete"
    headers = { "User-Agent": "https://gitlab.com/bhowell/the-screenless-office" }
    # the 2.0+ api only allows a max resolution of four decimals (for cacheing)
    params = { "lat": format(lat, ".4"), "lon": format(lon, ".4")}

    # https://api.met.no/weatherapi/locationforecast/2.0/classic?lat=52.50639&lon=13.4063
    resp = requests.get(url=url, params=params, headers=headers)
    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: "Overnight"}

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

    forecasts = []
    for t in w["properties"]["timeseries"]:
        # need to strip the trainling 'Z' char which indicates UTC
        tdate = datetime.datetime.fromisoformat(t["time"][:-1])
        to = tdate + datetime.timedelta(hours=6)
        dtdelta = datetime.date.today() - tdate.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[tdate.weekday()]

        if tdate.hour not in (0, 6, 12, 18):
            continue

        if not("next_6_hours" in t["data"]):
            continue

        mintemp = t["data"]["next_6_hours"]["details"]["air_temperature_min"]
        maxtemp = t["data"]["next_6_hours"]["details"]["air_temperature_max"]
        symbol = t["data"]["next_6_hours"]["summary"]["symbol_code"]
        png = symbol
        symbol += ".svg"
        png += ".png"
        icon = os.path.join(thisdir, "weather_icons", symbol)
        png = os.path.join(thisdir, "weather_icons", png)
        forecast = {"fromtime": tdate, "totime": to, "symbol": icon,
                    "mintemp": mintemp, "maxtemp": maxtemp, "png": png, 
                    "period": periods[tdate.hour], "day": day_of}
        forecasts.append(forecast)

    return forecasts


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