from __future__ import annotations

import math

from pyproj import Geod

_WGS84 = Geod(ellps="WGS84")


def sample_line(
  from_lat: float,
  from_lng: float,
  to_lat: float,
  to_lng: float,
  step_m: float,
) -> list[tuple[float, float, float]]:
  """Return (lat, lng, distance_from_start_m) points along a geodesic line."""
  _, _, total_distance = _WGS84.inv(from_lng, from_lat, to_lng, to_lat)
  total_distance = abs(total_distance)

  if total_distance == 0:
    return [(from_lat, from_lng, 0.0)]

  num_steps = max(1, int(math.ceil(total_distance / step_m)))
  actual_step = total_distance / num_steps

  azimuth, _, _ = _WGS84.inv(from_lng, from_lat, to_lng, to_lat)
  points: list[tuple[float, float, float]] = []
  for step_index in range(num_steps + 1):
    distance = min(step_index * actual_step, total_distance)
    if step_index == num_steps:
      lat, lng = to_lat, to_lng
    else:
      lng, lat, _ = _WGS84.fwd(from_lng, from_lat, azimuth, distance)
    points.append((lat, lng, distance))

  return points


def line_distance_m(from_lat: float, from_lng: float, to_lat: float, to_lng: float) -> float:
  _, _, distance = _WGS84.inv(from_lng, from_lat, to_lng, to_lat)
  return abs(distance)


def los_height_at(distance_m: float, from_antenna_asl: float, to_antenna_asl: float, total_distance_m: float) -> float:
  if total_distance_m <= 0:
    return from_antenna_asl
  fraction = distance_m / total_distance_m
  return from_antenna_asl + (to_antenna_asl - from_antenna_asl) * fraction


def grid_in_circle(
  origin_lat: float,
  origin_lng: float,
  radius_m: float,
  resolution_m: float,
) -> list[tuple[float, float]]:
  """Generate grid points inside a circle around origin."""
  points: list[tuple[float, float]] = []
  steps = int(math.ceil(radius_m / resolution_m))

  for row in range(-steps, steps + 1):
    for col in range(-steps, steps + 1):
      easting = col * resolution_m
      northing = row * resolution_m
      if math.hypot(easting, northing) > radius_m:
        continue

      lng, lat, _ = _WGS84.fwd(origin_lng, origin_lat, 90.0, easting)
      lng, lat, _ = _WGS84.fwd(lng, lat, 0.0, northing)
      points.append((lat, lng))

  return points