import gc
import requests


from datetime import datetime, timedelta
from requests.utils import urlparse
from zoneinfo import ZoneInfo

from fastapi import FastAPI, BackgroundTasks
from fastapi.responses import JSONResponse
from fastapi.middleware import Middleware
from starlette.middleware.cors import CORSMiddleware
from fastapi_utils.tasks import repeat_every

from app.settings import *

# App
middleware = [
    Middleware(
        CORSMiddleware,
        allow_origins=["*"],
        allow_credentials=True,
        allow_methods=["*"],
        allow_headers=["*"],
    ),
]
app = FastAPI(title="noaa", middleware=middleware)


# API
# GET 'test'
@app.get("/test/")
async def get_test():
    # check source availability
    # fresh one might be missing and old ones get deleted, so check yesterday's
    yesterday_news = datetime.now(tz=ZoneInfo("US/Eastern")) - timedelta(days=1)
    url = form_gfswave_link(target_time=yesterday_news)
    if not is_reachable(url):  # just one should be fine
        print(url, " is not reachable at this time")
        # TODO: should we actually error out?
    return JSONResponse(content={"status": "success"})


# GET 'test_background'
@app.get("/test_background/{field_1}")
async def get_test_background(field_1: str, background_tasks: BackgroundTasks):
    # background_tasks - for "heavy" processes
    # TODO
    background_tasks.add_task(service_example.run_test, field_1)
    return JSONResponse(content={"status": "Background task started"})


# Tasks
# gc
@app.on_event("startup")
@repeat_every(seconds=(1 * 60))
async def task_gc() -> None:
    gc.collect()


def is_reachable(url: str):
    """Check if url is reachable at all with the current setup

    :param url: URL to check
    :return: True if url is reachable, False otherwise
    """
    if requests.head(url):
        return True
    return False


def form_gfs_link(target_time=None, prod_hour=384):
    """Return well formed link to gfs data which
    should be available by given time

    :param target_time: time to check, defaults to current time
    :param prod_hour: forecast hour to link to, defaults to 384
    :returns: URL to gfs file
    """
    if not target_time:
        target_time = datetime.now(
            tz=ZoneInfo("US/Eastern")
        )  # noaa is located in washington

    looking_at = "atmos"

    date_str = target_time.strftime("%Y%m%d")
    hour_str = str((target_time.hour // 6) * 6).zfill(2)
    target_url = f"https://nomads.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/gfs.{date_str}/{hour_str}/{looking_at}/gfs.t{hour_str}z.pgrb2.0p25.f{prod_hour}"
    return target_url


def form_gfswave_link(target_time=None, prod_hour=384):
    """Return well formed link to gfs data which
    should be available by given time

    :param target_time: time to check, defaults to current time
    :param prod_hour: forecast hour to link to, defaults to 384
    :returns: URL to gfs file
    """
    if not target_time:
        target_time = datetime.now(
            tz=ZoneInfo("US/Eastern")
        )  # noaa is located in washington

    looking_at = "wave"

    date_str = target_time.strftime("%Y%m%d")
    hour_str = str((target_time.hour // 6) * 6).zfill(2)
    target_url = f"https://nomads.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/gfs.{date_str}/{hour_str}/{looking_at}/gridded/gfs{looking_at}.t{hour_str}z.global.0p25.f{prod_hour}.grib2"
    return target_url