"""NOAA HURDAT2 - historial de huracanes Atlantico.

Dataset: https://www.nhc.noaa.gov/data/#hurdat
Format spec: https://www.nhc.noaa.gov/data/hurdat/hurdat2-format.pdf

Descarga el archivo en data/hurdat2.txt en el primer uso (lazy).
Re-descarga si tiene mas de 365 dias.

Para una direccion dada (lat/lng), devuelve huracanes que pasaron a menos
de N millas (default 150) en los ultimos K anos (default 20).

Returns:
    {
      "lookback_years": 20,
      "max_distance_mi": 150,
      "total_hurricanes_nearby": <int>,
      "hurricanes": [
          {"name": "Ian", "year": 2022, "category": 4,
           "max_wind_mph": 155, "closest_pass_miles": 12},
          ...
      ]
    }
"""

from __future__ import annotations

import math
import os
import time
from datetime import datetime
from pathlib import Path

import requests

from .base import FetcherError, USER_AGENT, DEFAULT_TIMEOUT


# URLs candidatas (NOAA renombra el archivo cada ano).
# Si todas fallan, FetcherError.
HURDAT2_URL_CANDIDATES = [
    "https://www.nhc.noaa.gov/data/hurdat/hurdat2-1851-2024-040425.txt",
    "https://www.nhc.noaa.gov/data/hurdat/hurdat2-1851-2023-051124.txt",
    "https://www.nhc.noaa.gov/data/hurdat/hurdat2-1851-2022-050423.txt",
]

HURDAT2_MAX_AGE_DAYS = 365


def _saffir_simpson(max_wind_mph: float) -> int:
    """Categoria Saffir-Simpson basada en max sustained wind (mph). 0 = TS (no huracan)."""
    if max_wind_mph >= 157:
        return 5
    if max_wind_mph >= 130:
        return 4
    if max_wind_mph >= 111:
        return 3
    if max_wind_mph >= 96:
        return 2
    if max_wind_mph >= 74:
        return 1
    return 0  # tropical storm or less


def _haversine_mi(lat1: float, lng1: float, lat2: float, lng2: float) -> float:
    """Distancia great-circle entre dos puntos en millas."""
    R_MI = 3958.8
    p1 = math.radians(lat1)
    p2 = math.radians(lat2)
    dp = math.radians(lat2 - lat1)
    dl = math.radians(lng2 - lng1)
    a = math.sin(dp/2)**2 + math.cos(p1) * math.cos(p2) * math.sin(dl/2)**2
    return 2 * R_MI * math.asin(math.sqrt(a))


def _parse_coord(s: str) -> float | None:
    """Parse '26.5N' o '80.3W' a float (West/South negativos)."""
    s = s.strip()
    if not s or len(s) < 2:
        return None
    try:
        val = float(s[:-1])
        d = s[-1].upper()
        if d in ("S", "W"):
            val = -val
        return val
    except ValueError:
        return None


def _download_hurdat2(dest_path: Path) -> None:
    """Intenta descargar HURDAT2 desde varias URLs candidatas."""
    dest_path.parent.mkdir(parents=True, exist_ok=True)
    last_err = None
    for url in HURDAT2_URL_CANDIDATES:
        try:
            r = requests.get(url, headers={"User-Agent": USER_AGENT}, timeout=30)
            if r.status_code == 200 and len(r.text) > 10000:
                dest_path.write_text(r.text, encoding="utf-8")
                return
            last_err = f"HTTP {r.status_code} from {url}"
        except requests.RequestException as e:
            last_err = f"{url}: {e}"
            continue
    raise FetcherError(f"No pude descargar HURDAT2 desde ninguna URL. Ultimo error: {last_err}")


def _ensure_hurdat2_local(local_path: str | Path) -> Path:
    """Garantiza que el archivo local exista y este fresco. Descarga si hace falta."""
    p = Path(local_path)
    needs_download = (
        not p.exists()
        or (time.time() - p.stat().st_mtime) / 86400 > HURDAT2_MAX_AGE_DAYS
    )
    if needs_download:
        _download_hurdat2(p)
    return p


def fetch_hurricanes(
    lat: float,
    lng: float,
    years_back: int = 20,
    max_distance_mi: float = 150.0,
    hurdat2_path: str | Path = "data/hurdat2.txt",
) -> dict:
    """Busca huracanes que pasaron cerca de (lat, lng) en los ultimos N anos.

    'Cerca' = al menos un track-point del huracan estuvo a <= max_distance_mi.
    Solo cuenta sistemas que alcanzaron category 1+ (max_wind >= 74 mph) en algun
    momento de su track.
    """
    if lat is None or lng is None:
        raise FetcherError("lat/lng requeridos")

    p = _ensure_hurdat2_local(hurdat2_path)
    current_year = datetime.now().year
    min_year = current_year - years_back

    text = p.read_text(encoding="utf-8", errors="replace")
    lines = text.splitlines()

    hurricanes_nearby = []
    i = 0
    n = len(lines)
    while i < n:
        line = lines[i].strip()
        if not line:
            i += 1
            continue

        parts = [x.strip() for x in line.split(",")]
        # Header: AL112022, IAN, 65,
        if len(parts) >= 3 and parts[0].startswith("AL") and len(parts[0]) >= 8:
            atcf_id = parts[0]
            name = parts[1]
            try:
                num_records = int(parts[2])
                year = int(atcf_id[4:8])
            except (ValueError, IndexError):
                i += 1
                continue

            if year < min_year:
                # Skip todos los track lines de este huracan
                i += 1 + num_records
                continue

            max_wind_kt = 0
            min_dist_mi = float("inf")
            for j in range(num_records):
                tl_idx = i + 1 + j
                if tl_idx >= n:
                    break
                track_parts = [x.strip() for x in lines[tl_idx].split(",")]
                if len(track_parts) < 7:
                    continue
                # 0:date  1:time  2:record_id  3:status  4:lat  5:lng  6:wind
                tlat = _parse_coord(track_parts[4])
                tlng = _parse_coord(track_parts[5])
                try:
                    wind = int(track_parts[6])
                except ValueError:
                    wind = 0
                if tlat is None or tlng is None:
                    continue
                dist = _haversine_mi(lat, lng, tlat, tlng)
                if dist < min_dist_mi:
                    min_dist_mi = dist
                if wind > max_wind_kt:
                    max_wind_kt = wind

            max_wind_mph = max_wind_kt * 1.15078  # kt -> mph
            category = _saffir_simpson(max_wind_mph)

            # Solo contamos huracanes (cat 1+) que pasaron cerca
            if category >= 1 and min_dist_mi <= max_distance_mi:
                hurricanes_nearby.append({
                    "name": name if name else "UNNAMED",
                    "year": year,
                    "category": category,
                    "max_wind_mph": int(round(max_wind_mph)),
                    "closest_pass_miles": int(round(min_dist_mi)),
                })

            i += 1 + num_records
        else:
            i += 1

    # Ordenar: mas reciente y mas fuerte primero
    hurricanes_nearby.sort(key=lambda h: (-h["year"], -h["category"]))

    return {
        "lookback_years": years_back,
        "max_distance_mi": max_distance_mi,
        "total_hurricanes_nearby": len(hurricanes_nearby),
        "hurricanes": hurricanes_nearby,
        "source": "NOAA HURDAT2",
    }