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"""
Proyecciones y transformaciones geodésicas unificadas para PVPlant.

Reemplaza el uso disperso de la librería 'utm' con pyproj (PROJ),
soporte multi-zona UTM y transformaciones entre datums.

Uso básico:
    from lib.projection import latlon_to_utm, utm_to_latlon, get_utm_zone
"""

import FreeCAD
from pyproj import CRS, Transformer
from pyproj.aoi import AreaOfInterest
from pyproj.database import query_utm_crs_info

# WGS84 – sistema de coordenadas geográfico de referencia
_WGS84 = CRS.from_epsg(4326)

# Cache de transformadores UTM por zona (lazy)
_utm_transformers = {}


def _get_utm_transformer(lat, lon):
    """Obtiene (o crea en caché) un transformador UTM para la zona de las coordenadas dadas.
    Returns:
        tuple: (transformer, zone_number, zone_letter)
    """
    # Determinar la zona UTM a partir de lat/lon
    zone_number = int((lon + 180) / 6) + 1

    if lat >= 0:
        zone_letter = 'N'
        epsg = 32600 + zone_number
    else:
        zone_letter = 'S'
        epsg = 32700 + zone_number

    cache_key = (zone_number, zone_letter)
    if cache_key not in _utm_transformers:
        utm_crs = CRS.from_epsg(epsg)
        _utm_transformers[cache_key] = Transformer.from_crs(
            _WGS84, utm_crs, always_xy=True
        )

    return _utm_transformers[cache_key], zone_number, zone_letter


def latlon_to_utm(lat, lon):
    """Convierte coordenadas geográficas (WGS84) a UTM (este, norte, zona, letra).

    Args:
        lat (float): Latitud en grados.
        lon (float): Longitud en grados.

    Returns:
        tuple: (easting, northing, zone_number, zone_letter)
               easting/northing en metros.
    """
    transformer, zone_number, zone_letter = _get_utm_transformer(lat, lon)
    easting, northing = transformer.transform(lon, lat)
    return easting, northing, zone_number, zone_letter


def utm_to_latlon(easting, northing, zone_number, zone_letter='N'):
    """Convierte coordenadas UTM a geográficas (WGS84).

    Args:
        easting (float): Coordenada E en metros.
        northing (float): Coordenada N en metros.
        zone_number (int): Número de zona UTM (1-60).
        zone_letter (str): Letra de zona ('N' o 'S').

    Returns:
        tuple: (latitude, longitude) en grados.
    """
    if zone_letter.upper() not in ('N', 'S'):
        zone_letter = 'N'

    epsg = 32600 + zone_number if zone_letter.upper() == 'N' else 32700 + zone_number
    utm_crs = CRS.from_epsg(epsg)
    transformer = Transformer.from_crs(utm_crs, _WGS84, always_xy=True)
    lon, lat = transformer.transform(easting, northing)
    return lat, lon


def get_utm_zone(lat, lon):
    """Obtiene la zona UTM para unas coordenadas dadas.

    Args:
        lat (float): Latitud en grados.
        lon (float): Longitud en grados.

    Returns:
        tuple: (zone_number, zone_letter)
    """
    _, _, zone_number, zone_letter = latlon_to_utm(lat, lon)
    return zone_number, zone_letter


def latlon_to_utm_vector(lat, lon, elevation=0.0):
    """Convierte lat/lon/elevación a un FreeCAD.Vector en UTM (mm).

    Args:
        lat (float): Latitud en grados.
        lon (float): Longitud en grados.
        elevation (float): Elevación en metros (default 0).

    Returns:
        FreeCAD.Vector: Coordenadas UTM en milímetros.
    """
    transformer, _, _ = _get_utm_transformer(lat, lon)
    easting, northing = transformer.transform(lon, lat)
    return FreeCAD.Vector(
        round(easting, 0),
        round(northing, 0),
        round(elevation, 0)
    ) * 1000