import csv
import logging
from datetime import datetime, timezone, timedelta
from threading import Thread, Event

import pytz
import requests

from core.constants import HTTP_HEADERS, BANDS
from solarconditionsproviders.solar_conditions_provider import SolarConditionsProvider

POLL_INTERVAL = 3600  # 1 hour
STATIONS_INDEX = "datafiles/didbase-stations.csv"
LGDC_URL = "https://lgdc.uml.edu/common/DIDBGetValues"
HISTORY_HOURS = 24
HF_BANDS = [b for b in BANDS if b.is_ham_hf]


class GIROIonosonde(SolarConditionsProvider):
    """Solar conditions provider using ionosonde data from the GIRO Data Center.
    Queries foF2, MUF, and LUF measurements for all stations in datafiles/didbase-stations.csv."""

    def __init__(self, provider_config):
        super().__init__(provider_config)
        self._stations = self._load_stations()
        self._thread = None
        self._stop_event = Event()

    def _load_stations(self):
        """Load the CSV file containing the list of URSIs and Station Names for currently active ionosondes."""

        stations = []
        with open(STATIONS_INDEX, newline='') as f:
            for row in csv.reader(f):
                if len(row) >= 2:
                    stations.append({"ursi": row[0].strip(), "name": row[1].strip()})
        return stations

    def setup(self, solar_conditions, solar_conditions_cache):
        """Prepopulate the ionosonde_data map with known URSI and station names, so that the API exposes this structure
        even before we actually have any data in it."""

        super().setup(solar_conditions, solar_conditions_cache)
        self.update_data({"ionosonde_data": {
            s["ursi"]: {"ursi": s["ursi"], "name": s["name"], "fof2": None, "muf": None, "luf": None,
                        "band_states": None}
            for s in self._stations
        }})

    def start(self):
        logging.info(f"Set up query of GIRO ionosonde data API every {POLL_INTERVAL} seconds.")
        self._thread = Thread(target=self._run, daemon=True)
        self._thread.start()

    def stop(self):
        self._stop_event.set()

    def _run(self):
        while True:
            self._poll()
            if self._stop_event.wait(timeout=POLL_INTERVAL):
                break

    def _poll(self):
        try:
            logging.debug(f"Polling GIRO ionosonde data...")
            now = datetime.now(timezone.utc)
            from_time = now - timedelta(hours=HISTORY_HOURS)
            ionosonde_data = dict(self._solar_conditions.ionosonde_data or {})
            updated_count = 0

            for station in self._stations:
                if self._stop_event.is_set():
                    break
                ursi = station["ursi"]
                name = station["name"]
                try:
                    fof2, muf, luf = self._fetch_station_data(ursi, from_time, now)
                    if fof2 and muf:
                        band_states = self._compute_band_statess(fof2, muf, luf or {})
                        ionosonde_data[ursi] = {"ursi": ursi, "name": name, "fof2": fof2, "muf": muf,
                                                "luf": luf or None, "band_states": band_states}
                        updated_count += 1
                except Exception:
                    logging.warning(f"Could not fetch ionosonde data for {ursi} ({name})")

            self.update_data({"ionosonde_data": ionosonde_data})
            self.status = "OK"
            self.last_update_time = datetime.now(pytz.UTC)
            logging.debug(f"Updated ionosonde data for {updated_count} stations.")

        except Exception:
            self.status = "Error"
            logging.exception(f"Exception in GIRO Ionosonde data provider")
            self._stop_event.wait(timeout=1)

    def _fetch_station_data(self, ursi, from_time, to_time):
        """Fetch foF2, MUF and LUF readings for a station. Returns (fof2_dict, muf_dict, luf_dict) keyed by UNIX timestamp."""

        from_str = from_time.strftime("%Y.%m.%d+%H:%M:%S")
        to_str = to_time.strftime("%Y.%m.%d+%H:%M:%S")
        url = f"{LGDC_URL}?ursiCode={ursi}&charName=foF2,MUFD,fmin&DMUF=3000&fromDate={from_str}&toDate={to_str}"
        response = requests.get(url, headers=HTTP_HEADERS, timeout=(5, 15))
        if response.status_code != 200:
            return None, None, None
        return self._parse_all(response.text)

    @staticmethod
    def _latest(d):
        """Return the value with the highest timestamp key, or None if the dict is empty."""
        return d[max(d.keys())] if d else None

    @staticmethod
    def _compute_band_statess(fof2_dict, muf_dict, luf_dict):
        """Compute HF band states from the latest foF2, MUF and LUF values.

        States:
          Closed if band frequency is below LUF (if known) or above MUF
          Short if band frequency is >= LUF and < foF2 (good for NVIS)
          Long if band frequency is >= foF2 and < MUF (good for DX)
        """

        # We have a list of timestamped data for each value, but for this we only want the latest value
        fof2 = GIROIonosonde._latest(fof2_dict)
        muf = GIROIonosonde._latest(muf_dict)
        luf = GIROIonosonde._latest(luf_dict)
        if fof2 is None or muf is None:
            return {}
        band_states = {}

        # Iterate over all ham HF bands, we don't care about the others at this point
        for band in HF_BANDS:
            freq = band.start_freq / 1000000
            if freq > muf or (luf is not None and freq < luf):
                band_states[band.name] = "Closed"
            elif freq < fof2:
                band_states[band.name] = "Short"
            else:
                band_states[band.name] = "Long"
        return band_states

    @staticmethod
    def _parse_all(text):
        """Parse web server response and return (fof2_dict, muf_dict, luf_dict) keyed by UNIX timestamp."""

        fof2_data = {}
        muf_data = {}
        luf_data = {}
        for line in text.splitlines():
            line = line.strip()
            if not line or line.startswith('#'):
                continue
            # Data rows have the following format: timestamp CS foF2 QD MUFD QD fmin QD
            parts = line.split()
            if len(parts) >= 5:
                try:
                    # Python 3.8 TZ parsing fudge
                    ts = datetime.fromisoformat(parts[0].replace('Z', '+00:00')).timestamp()
                except ValueError:
                    continue
                try:
                    fof2_data[ts] = float(parts[2])
                except ValueError:
                    pass
                try:
                    muf_data[ts] = float(parts[4])
                except ValueError:
                    pass
                if len(parts) >= 7:
                    try:
                        luf_data[ts] = float(parts[6])
                    except ValueError:
                        pass
        return fof2_data, muf_data, luf_data