"""Do the gridding of Solar Radiation Data

This used to use MERRAv2 for non-realtime data, but a crude assessment found
ERA5land to produce better results.

Called from:
 - RUN_MIDNIGHT.sh for previous day
 - RUN_0Z.sh for 8 days ago
 - RUN_10_AFTER.sh at 11 PM for the current day
"""

import subprocess
from datetime import datetime, timedelta
from pathlib import Path
from zoneinfo import ZoneInfo

import click
import numpy as np
import pygrib
import pyproj
import xarray as xr
from affine import Affine
from pyiem.grid.nav import get_nav
from pyiem.grid.util import grid_smear
from pyiem.iemre import DOMAINS as IEMRE_DOMAINS
from pyiem.iemre import hourly_offset, reproject2iemre, set_grids
from pyiem.util import archive_fetch, logger, ncopen, utc

LOG = logger()
P4326 = pyproj.Proj("EPSG:4326")
SWITCH_DATE = utc(2014, 10, 10, 20)


def try_era5land(ts: datetime, domain: str) -> np.ndarray | None:
    """Attempt to use ERA5Land data."""
    dd = "" if domain == "" else f"_{domain}"
    # inbound `ts` represents noon local time, we want values from 1 AM
    # till midnight
    one_am = ts.replace(hour=1).astimezone(ZoneInfo("UTC"))
    midnight = (
        (ts + timedelta(days=1)).replace(hour=0).astimezone(ZoneInfo("UTC"))
    )
    # If years are equal, we don't have to span files
    idx0 = hourly_offset(one_am)
    idx1 = hourly_offset(midnight) + 1
    ncfn = f"/mesonet/data/era5{dd}/{one_am.year}_era5land_hourly.nc"
    if not Path(ncfn).is_file():
        LOG.info("Missing %s", ncfn)
        return None
    if one_am.year == midnight.year:
        with ncopen(ncfn) as nc:
            total = np.ma.sum(nc.variables["rsds"][idx0:idx1, :, :], axis=0)
    else:
        with ncopen(ncfn) as nc:
            total = np.ma.sum(nc.variables["rsds"][idx0:, :, :], axis=0)
        ncfn = f"/mesonet/data/era5{dd}/{midnight.year}_era5land_hourly.nc"
        with ncopen(ncfn) as nc:
            total += np.ma.sum(nc.variables["rsds"][:idx1, :, :], axis=0)

    # If total is all missing, then we have no data
    if total.mask.all():
        return None
    # We wanna store as W m-2, so we just average out the data by hour
    total = total / 24.0

    # The affine defines the edges of the grid
    aff = get_nav("era5land", domain).affine
    vals = reproject2iemre(total, aff, P4326.crs, domain=domain)

    # ERA5Land is too tight to the coast, so we need to jitter the grid
    # 7 and 4 was found to be enough to appease DEP's needs
    # NOTE: HRRR and GFS do not need this
    vals = grid_smear(vals, shift=7)
    vals = grid_smear(vals, shift=4)

    return vals


def do_gfs(ts: datetime, domain: str) -> np.ndarray | None:
    """Attempt to use the GFS."""
    # Major complications with GFS 6 hour data being averaged and which
    # time period to use to get a "daily" value.
    # For europe, use 6z through 0z(tomorrow)
    # For china, use 0z through 18z
    dd = "" if domain == "" else f"_{domain}"

    # Rectify now back to hour modulo 6
    utcnow = ts.astimezone(ZoneInfo("UTC"))
    utcnow = utcnow.replace(
        hour=(utcnow.hour // 6) * 6, minute=0, second=0, microsecond=0
    ) - timedelta(hours=12)
    attempt = 4
    while attempt > 0:
        ppath = (
            f"{utcnow:%Y/%m/%d}/model/gfs/gfs_{utcnow:%Y%m%d%H}_iemre{dd}.nc"
        )
        with archive_fetch(ppath) as fn:
            if fn is None:
                attempt -= 1
                utcnow -= timedelta(hours=6)
                continue
            tidx = (ts.date() - utcnow.date()).days
            LOG.info("Using GFS %s for day index:%s", utcnow, tidx)
            with ncopen(fn) as nc:
                # convert MJ/d to W/m^2
                srad = nc.variables["srad"][tidx] * 1e6 / 86400.0
            return srad
    return None


def do_hrrr(ts: datetime) -> np.ndarray | None:
    """Convert the hourly HRRR data to IEMRE grid"""
    LCC = pyproj.Proj(
        "+lon_0=-97.5 +y_0=0.0 +R=6367470. +proj=lcc +x_0=0.0 "
        "+units=m +lat_2=38.5 +lat_1=38.5 +lat_0=38.5"
    )
    total = None
    # So IEMRE is storing data from coast to coast, so we should be
    # aggressive about running for an entire calendar date
    for hr in range(24):
        utcnow = ts.replace(hour=hr).astimezone(ZoneInfo("UTC"))
        LOG.info("Considering timestamp %s", utcnow)
        # Try the newer f01 files, which have better data!
        ppath = (utcnow - timedelta(hours=1)).strftime(
            "%Y/%m/%d/model/hrrr/%H/hrrr.t%Hz.3kmf01.grib2"
        )
        grbname = "Time-mean surface downward short-wave radiation flux"
        with archive_fetch(ppath) as fn:
            if fn is not None:
                try:
                    grbs = pygrib.open(fn)
                    selgrbs = grbs.select(name=grbname)
                except Exception:
                    LOG.warning("Read of %s failed", fn)
                    continue
                # sometimes we have multiple grids :/
                if len(selgrbs) >= 4:
                    LOG.info("Using %s", fn)
                    # Goodie
                    subtotal = None
                    for g in selgrbs:
                        if total is None:
                            lat1 = g["latitudeOfFirstGridPointInDegrees"]
                            lon1 = g["longitudeOfFirstGridPointInDegrees"]
                            llcrnrx, llcrnry = LCC(lon1, lat1)
                            dx = g["DxInMetres"]
                            dy = g["DyInMetres"]
                        if subtotal is None:
                            subtotal = g.values
                        else:
                            subtotal += g.values
                    if total is None:
                        total = subtotal / float(len(selgrbs))
                    else:
                        total += subtotal / float(len(selgrbs))
                    continue

        ppath = utcnow.strftime(
            "%Y/%m/%d/model/hrrr/%H/hrrr.t%Hz.3kmf00.grib2"
        )
        with archive_fetch(ppath) as fn:
            if fn is None:
                continue
            grbs = pygrib.open(fn)
            try:
                if utcnow >= SWITCH_DATE:
                    grb = grbs.select(
                        name="Downward short-wave radiation flux"
                    )
                else:
                    grb = grbs.select(parameterNumber=192)
            except ValueError:
                # don't complain about late evening no-solar
                if utcnow.hour > 10 and utcnow.hour < 24:
                    LOG.info(" %s had no solar rad", fn)
                continue
            if not grb:
                LOG.info("Could not find SWDOWN in HRR %s", fn)
                continue
            LOG.info("Using %s", fn)
            g = grb[0]
            if total is None:
                total = g.values
                lat1 = g["latitudeOfFirstGridPointInDegrees"]
                lon1 = g["longitudeOfFirstGridPointInDegrees"]
                llcrnrx, llcrnry = LCC(lon1, lat1)
                dx = g["DxInMetres"]
                dy = g["DyInMetres"]
            else:
                total += g.values

    if total is None:
        LOG.info("found no HRRR data for %s", ts.strftime("%d %b %Y"))
        return None

    # We wanna store as W m-2, so we just average out the data by hour
    total = total / 24.0
    # This is the edge and not the center of the UL pixel
    affine_in = Affine(
        dx, 0.0, llcrnrx - dx / 2.0, 0.0, dy, llcrnry + dy / 2.0
    )

    srad = reproject2iemre(total, affine_in, LCC.crs)
    return srad


def postprocess(srad: np.ndarray, ts: datetime, domain: str) -> bool:
    """Do the necessary work."""
    avgval = np.ma.mean(srad)
    # 50 was found to be too high in Europe
    if avgval < 10:
        LOG.warning("Average value is %.2f and below 10, skipping", avgval)
        return False

    ds = xr.Dataset(
        {
            "rsds": xr.DataArray(
                srad,
                dims=("y", "x"),
            )
        }
    )
    set_grids(ts.date(), ds, domain=domain)
    subprocess.call(
        [
            "python",
            "db_to_netcdf.py",
            f"--date={ts:%Y-%m-%d}",
            f"--domain={domain}",
            "--varname=rsds",
        ]
    )

    return True


@click.command()
@click.option("--date", "dt", required=False, type=click.DateTime())
@click.option("--year", required=False, type=int, help="Run for Year,month")
@click.option("--month", required=False, type=int, help="Run for Year,month")
def main(dt: datetime | None, year, month):
    """Go Main Go"""
    queue = []
    if year is not None and month is not None:
        now = datetime(year, month, 1, 12)
        while now.month == month:
            queue.append(now)
            now += timedelta(days=1)
    else:
        queue.append(dt.replace(hour=12))
    for sts_in in queue:
        for domain, dom in IEMRE_DOMAINS.items():
            sts = sts_in.replace(tzinfo=dom["tzinfo"])
            srad = try_era5land(sts, domain)
            if srad is not None and postprocess(srad, sts, domain):
                continue
            LOG.info("try_era5land failed to find data")
            if domain == "":
                srad = do_hrrr(sts)
                if srad is not None and postprocess(srad, sts, domain):
                    continue
                LOG.info("do_hrrr failed to find data")
            srad = do_gfs(sts, domain)
            if srad is None:
                LOG.info("do_gfs failed to find data")
                continue
            postprocess(srad, sts, domain)


if __name__ == "__main__":
    main()
