"""Geo service for building search zones and querying OpenStreetMap data.

B16: данные берутся из ЛОКАЛЬНОГО PostGIS (services/osm_local.py, таблицы
planet_osm_* залиты osm2pgsql). Overpass — только fallback, если локальных
таблиц нет (osm_available() == False). Никаких внешних вызовов при
локальном режиме.
"""
import asyncio
import math
import json
import hashlib
import logging
import time
from datetime import datetime, timedelta
from pathlib import Path
from typing import List, Dict, Optional, Tuple
import httpx
from pydantic import BaseModel

from services.osm_local import get_zone_features_postgis, osm_available


class Zone(BaseModel):
    """Search zone with geographic features."""
    direction: str  # N, NE, E, SE, S, SW, W, NW
    distance_km: float
    forest_pct: float
    road_density: float  # km of roads per km²
    water_distance_km: Optional[float]
    settlement_distance_km: Optional[float]


# Cache configuration
CACHE_DIR = Path("/tmp/overpass_cache")
CACHE_TTL_HOURS = 24
# Порядок зеркал: основной сервер имеет AAAA, но на хостах без IPv6-маршрута
# (наш LXC в VPN-контуре) httpx падает на ConnectError ещё до IPv4-фолбэка.
# Поэтому основной — зеркало без AAAA (maps.mail.ru), overpass-api.de — резерв.
OVERPASS_URLS = [
    "https://maps.mail.ru/osm/tools/overpass/api/interpreter",
    "https://overpass-api.de/api/interpreter",
]
OVERPASS_URL = OVERPASS_URLS[0]  # обратная совместимость для импортов

logger = logging.getLogger('vector.geo')

# --- Overpass circuit breaker ---------------------------------------------
# build_search_zones issues ~128 Overpass calls per analysis. When the host has
# no outbound connectivity every one of them burns the full connect timeout,
# which turns a single analysis into several minutes of waiting for results
# that are empty anyway. After OVERPASS_FAILURE_THRESHOLD consecutive
# transport failures we stop calling out until OVERPASS_COOLDOWN_SECONDS have
# passed. Callers get the same {'elements': []} they already got on error.
OVERPASS_FAILURE_THRESHOLD = 3
OVERPASS_COOLDOWN_SECONDS = 60.0
OVERPASS_CONNECT_TIMEOUT = 5.0

_overpass_failures = 0
_overpass_open_until = 0.0


def _overpass_circuit_open() -> bool:
    """True while the breaker is tripped (skip network, return empty fast)."""
    if _overpass_failures < OVERPASS_FAILURE_THRESHOLD:
        return False
    if time.monotonic() >= _overpass_open_until:
        _reset_overpass_circuit()
        return False
    return True


def _record_overpass_failure() -> None:
    global _overpass_failures, _overpass_open_until
    _overpass_failures += 1
    if _overpass_failures == OVERPASS_FAILURE_THRESHOLD:
        _overpass_open_until = time.monotonic() + OVERPASS_COOLDOWN_SECONDS
        logger.warning(
            "Overpass API недоступен (%d подряд неудачных запросов). "
            "Геоданные отключены на %.0f c, анализ продолжается без них.",
            _overpass_failures,
            OVERPASS_COOLDOWN_SECONDS,
        )


def _reset_overpass_circuit() -> None:
    global _overpass_failures, _overpass_open_until
    _overpass_failures = 0
    _overpass_open_until = 0.0


# Direction mappings
SEARCH_DISTANCES = [500, 1000, 2000, 5000]

DIRECTIONS = ["N", "NE", "E", "SE", "S", "SW", "W", "NW"]
DIRECTION_ANGLES = {
    "N": 0,
    "NE": 45,
    "E": 90,
    "SE": 135,
    "S": 180,
    "SW": 225,
    "W": 270,
    "NW": 315
}

# Search distances computed dynamically from max_distance_km
def _build_search_distances(max_distance_km: float) -> list:
    max_m = int(max_distance_km * 1000)
    raw = [int(max_m * 0.25), int(max_m * 0.50), int(max_m * 0.75), max_m]
    clamped = [max(200, min(5000, d)) for d in raw]
    return sorted(set(clamped))


def haversine(lat1: float, lon1: float, lat2: float, lon2: float) -> float:
    """
    Calculate distance between two points on Earth using Haversine formula.

    Args:
        lat1, lon1: First point coordinates
        lat2, lon2: Second point coordinates

    Returns:
        Distance in kilometers
    """
    R = 6371  # Earth radius in km

    lat1_rad = math.radians(lat1)
    lat2_rad = math.radians(lat2)
    dlat = math.radians(lat2 - lat1)
    dlon = math.radians(lon2 - lon1)

    a = (math.sin(dlat / 2) ** 2 +
         math.cos(lat1_rad) * math.cos(lat2_rad) * math.sin(dlon / 2) ** 2)
    c = 2 * math.asin(math.sqrt(a))

    return R * c


def get_sector_bounds(lat: float, lon: float, direction: str, radius_m: int) -> Tuple[float, float, float, float]:
    """
    Calculate bounding box for a sector.

    Args:
        lat, lon: Center point
        direction: Sector direction (N, NE, E, etc.)
        radius_m: Radius in meters

    Returns:
        (min_lat, min_lon, max_lat, max_lon)
    """
    # Convert radius to degrees (approximate)
    radius_deg = radius_m / 111320  # 1 degree ≈ 111.32 km at equator

    angle = DIRECTION_ANGLES[direction]
    angle_rad = math.radians(angle)

    # Calculate sector boundaries (45° sectors)
    angle_start = angle - 22.5
    angle_end = angle + 22.5

    # Simple bounding box (can be optimized for actual sector shape)
    lat_offset = radius_deg * math.cos(angle_rad)
    lon_offset = radius_deg * math.sin(angle_rad) / math.cos(math.radians(lat))

    min_lat = min(lat, lat + lat_offset) - radius_deg * 0.5
    max_lat = max(lat, lat + lat_offset) + radius_deg * 0.5
    min_lon = min(lon, lon + lon_offset) - radius_deg * 0.5
    max_lon = max(lon, lon + lon_offset) + radius_deg * 0.5

    return (min_lat, min_lon, max_lat, max_lon)


def get_cache_key(query: str) -> str:
    """Generate cache key from query."""
    return hashlib.md5(query.encode()).hexdigest()


def get_cached_result(cache_key: str) -> Optional[Dict]:
    """Get cached Overpass API result if not expired."""
    CACHE_DIR.mkdir(exist_ok=True)
    cache_file = CACHE_DIR / f"{cache_key}.json"

    if not cache_file.exists():
        return None

    try:
        with open(cache_file, 'r') as f:
            cached = json.load(f)

        cached_time = datetime.fromisoformat(cached['timestamp'])
        if datetime.now() - cached_time > timedelta(hours=CACHE_TTL_HOURS):
            cache_file.unlink()
            return None

        return cached['data']
    except Exception:
        return None


def save_to_cache(cache_key: str, data: Dict):
    """Save Overpass API result to cache."""
    CACHE_DIR.mkdir(exist_ok=True)
    cache_file = CACHE_DIR / f"{cache_key}.json"

    try:
        with open(cache_file, 'w') as f:
            json.dump({
                'timestamp': datetime.now().isoformat(),
                'data': data
            }, f)
    except Exception:
        pass


async def query_overpass(query: str) -> Dict:
    """
    Query Overpass API with caching.

    Args:
        query: Overpass QL query

    Returns:
        API response as dict
    """
    cache_key = get_cache_key(query)

    # Check cache
    cached = get_cached_result(cache_key)
    if cached is not None:
        return cached

    # Skip the network entirely while the breaker is tripped.
    if _overpass_circuit_open():
        return {'elements': []}

    # Query API — по цепочке зеркал (первый успешный ответ кэшируется)
    timeout = httpx.Timeout(30.0, connect=OVERPASS_CONNECT_TIMEOUT)
    async with httpx.AsyncClient(timeout=timeout) as client:
        for overpass_url in OVERPASS_URLS:
            try:
                response = await client.post(
                    overpass_url,
                    data={'data': query},
                    headers={'Content-Type': 'application/x-www-form-urlencoded'}
                )
                response.raise_for_status()
                data = response.json()

                # Save to cache
                save_to_cache(cache_key, data)

                _reset_overpass_circuit()
                return data
            except Exception as e:
                logger.info("Overpass %s недоступен: %s", overpass_url, e)
                continue
        # Все зеркала недоступны
        _record_overpass_failure()
        # Return empty result on error
        return {'elements': []}


def calculate_road_length(elements: List[Dict]) -> float:
    """
    Calculate total road length from Overpass way elements.

    Args:
        elements: List of way elements from Overpass

    Returns:
        Total length in kilometers
    """
    total_length = 0.0

    for element in elements:
        if element.get('type') != 'way':
            continue

        nodes = element.get('geometry', [])
        if len(nodes) < 2:
            continue

        # Calculate length by summing distances between consecutive nodes
        for i in range(len(nodes) - 1):
            lat1, lon1 = nodes[i]['lat'], nodes[i]['lon']
            lat2, lon2 = nodes[i + 1]['lat'], nodes[i + 1]['lon']
            total_length += haversine(lat1, lon1, lat2, lon2)

    return total_length


def find_nearest_distance(lat: float, lon: float, elements: List[Dict]) -> Optional[float]:
    """
    Find distance to nearest element.

    Args:
        lat, lon: Reference point
        elements: List of node elements from Overpass

    Returns:
        Distance in kilometers, or None if no elements
    """
    if not elements:
        return None

    min_distance = float('inf')

    for element in elements:
        if element.get('type') != 'node':
            continue

        elem_lat = element.get('lat')
        elem_lon = element.get('lon')

        if elem_lat is None or elem_lon is None:
            continue

        distance = haversine(lat, lon, elem_lat, elem_lon)
        min_distance = min(min_distance, distance)

    return min_distance if min_distance != float('inf') else None


def calculate_forest_coverage(elements: List[Dict], radius_m: int) -> float:
    """
    Estimate forest coverage percentage.

    Args:
        elements: List of way elements from Overpass
        radius_m: Search radius in meters

    Returns:
        Forest coverage as percentage (0-100)
    """
    if not elements:
        return 0.0

    # Approximate: count forest ways and estimate coverage
    # This is a simplified calculation
    forest_ways = len([e for e in elements if e.get('type') == 'way'])

    # Rough heuristic: each forest way covers ~0.1 km²
    # Total search area = π * r²
    search_area_km2 = math.pi * (radius_m / 1000) ** 2
    estimated_forest_km2 = forest_ways * 0.1

    # Контракт: ДОЛЯ 0..1 (scoring_service читает forest_pct как долю —
    # weight × forest_pct; раньше отдавались проценты 0..100, что делало
    # лес доминирующим фактором со 100× весом).
    coverage = min(1.0, estimated_forest_km2 / search_area_km2)

    return round(coverage, 3)


async def get_zone_features(lat: float, lon: float, direction: str, radius_m: int) -> Dict:
    """Характеристики сектора. B16: локальный PostGIS; Overpass — fallback.

    Returns:
        Dict with roads_km, road_density, water_distance_km, settlement_distance_km, forest_pct
    """
    if osm_available():
        return get_zone_features_postgis(lat, lon, direction, radius_m)

    # Fallback: живой Overpass (старое поведение, пока B16-данные не залиты)
    # Query roads
    roads_query = f"""
    [out:json];
    (
      way[highway](around:{radius_m},{lat},{lon});
    );
    out geom;
    """

    # Query water bodies
    water_query = f"""
    [out:json];
    (
      node[natural=water](around:{radius_m},{lat},{lon});
      way[natural=water](around:{radius_m},{lat},{lon});
    );
    out center;
    """


    # Query settlements
    settlement_query = f"""
    [out:json];
    (
      node[place~"village|town|city"](around:{radius_m},{lat},{lon});
    );
    out;
    """


    # Query forests
    forest_query = f"""
    [out:json];
    (
      way[landuse=forest](around:{radius_m},{lat},{lon});
      way[natural=wood](around:{radius_m},{lat},{lon});
    );
    out geom;
    """


    # The four queries are independent - issue them concurrently.
    roads_data, water_data, settlement_data, forest_data = await asyncio.gather(
        query_overpass(roads_query),
        query_overpass(water_query),
        query_overpass(settlement_query),
        query_overpass(forest_query),
    )

    roads_km = calculate_road_length(roads_data.get('elements', []))
    water_distance = find_nearest_distance(lat, lon, water_data.get('elements', []))
    settlement_distance = find_nearest_distance(lat, lon, settlement_data.get('elements', []))
    forest_pct = calculate_forest_coverage(forest_data.get('elements', []), radius_m)

    # Calculate road density (km of roads per km²)
    search_area_km2 = math.pi * (radius_m / 1000) ** 2
    road_density = roads_km / search_area_km2 if search_area_km2 > 0 else 0.0

    return {
        'roads_km': roads_km,
        'road_density': round(road_density, 2),
        'water_distance_km': water_distance,
        'settlement_distance_km': settlement_distance,
        'forest_pct': forest_pct
    }


async def build_search_zones(lat: float, lon: float, case_data: dict, max_distance_km: float = 3.0) -> List[Zone]:
    """
    Build search zones around a point.

    Creates 8 directional sectors (N, NE, E, SE, S, SW, W, NW) at multiple distances
    (500m, 1000m, 2000m, 5000m) and queries geographic features for each.

    Args:
        lat: Latitude of search origin
        lon: Longitude of search origin
        case_data: Case information (for future enhancements)

    Returns:
        List of Zone objects with geographic features
    """
    zones = []

    for distance_m in _build_search_distances(max_distance_km):
        for direction in DIRECTIONS:
            # Get features for this zone
            features = await get_zone_features(lat, lon, direction, distance_m)

            zone = Zone(
                direction=direction,
                distance_km=distance_m / 1000,
                forest_pct=features['forest_pct'],
                road_density=features['road_density'],
                water_distance_km=features['water_distance_km'],
                settlement_distance_km=features['settlement_distance_km']
            )

            zones.append(zone)

    return zones