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use super::Location;
use std::f64::consts::PI;
use std::fmt;
pub struct Distance(f64);
impl fmt::Display for Distance {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{} meters", self.meters())
}
}
impl Distance {
pub fn from_meters<P: Into<f64>>(m: P) -> Self {
return Distance(m.into());
}
pub fn meters(&self) -> f64 {
return self.0;
}
}
pub struct DistanceResult {
pub distance: Distance,
_initial_bearing: Option<f64>,
_final_bearing: Option<f64>,
_iterations: i32,
}
pub fn vincenty_inverse(
start: &Location,
end: &Location,
_accuracy: f64,
_precision: f64,
) -> Result<DistanceResult, String> {
let a: f64 = 6378137.0;
let b: f64 = 6356752.314245;
let f: f64 = 1.0 / 298.257223563;
let p1 = (start.0.to_radians(), start.1.to_radians());
let p2 = (end.0.to_radians(), end.1.to_radians());
let l = p2.1 - p1.1;
let (tan_u1, tan_u2) = ((1.0 - f) * p1.0.tan(), (1.0 - f) * p2.0.tan());
let (cos_u1, cos_u2) = (
1.0 / (1.0 + tan_u1 * tan_u1).sqrt(),
1.0 / (1.0 + tan_u2 * tan_u2).sqrt(),
);
let (sin_u1, sin_u2) = (tan_u1 * cos_u1, tan_u2 * cos_u2);
let mut lambda = l;
let mut iter_limit = 100;
let mut cos_sq_alpha = 0.0;
let (mut sin_sigma, mut cos_sigma, mut cos2_sigma_m, mut sigma) = (0.0, 0.0, 0.0, 0.0);
let (mut _sin_lambda, mut _cos_lambda) = (0.0, 0.0);
loop {
_sin_lambda = lambda.sin();
_cos_lambda = lambda.cos();
let sin_sq_sigma = (cos_u2 * _sin_lambda) * (cos_u2 * _sin_lambda)
+ (cos_u1 * sin_u2 - sin_u1 * cos_u2 * _cos_lambda)
* (cos_u1 * sin_u2 - sin_u1 * cos_u2 * _cos_lambda);
if sin_sq_sigma == 0.0 {
break;
}
sin_sigma = sin_sq_sigma.sqrt();
cos_sigma = sin_u1 * sin_u2 + cos_u1 * cos_u2 * _cos_lambda;
sigma = sin_sigma.atan2(cos_sigma);
let sin_alpha = cos_u1 * cos_u2 * _sin_lambda / sin_sigma;
cos_sq_alpha = 1.0 - sin_alpha * sin_alpha;
cos2_sigma_m = if cos_sq_alpha != 0.0 {
cos_sigma - 2.0 * sin_u1 * sin_u2 / cos_sq_alpha
} else {
0.0
};
let c = f / 16.0 * cos_sq_alpha * (4.0 + f * (4.0 - 3.0 * cos_sq_alpha));
let lambda_prime = lambda;
lambda = l
+ (1.0 - c)
* f
* sin_alpha
* (sigma
+ c * sin_sigma
* (cos2_sigma_m
+ c * cos_sigma * (-1.0 + 2.0 * cos2_sigma_m * cos2_sigma_m)));
iter_limit -= 1;
if (lambda - lambda_prime).abs() > 1e-12 && iter_limit > 0 {
continue;
}
break;
}
if iter_limit <= 0 {
return Err("formula failed to converge".to_string());
}
let u_sq = cos_sq_alpha * (a * a - b * b) / (b * b);
let cap_a = 1.0 + u_sq / 16384.0 * (4096.0 + u_sq * (-768.0 + u_sq * (320.0 - 175.0 * u_sq)));
let cap_b = u_sq / 1024.0 * (256.0 + u_sq * (-128.0 + u_sq * (74.0 - 47.0 * u_sq)));
let delta_sigma = cap_b
* sin_sigma
* (cos2_sigma_m
+ cap_b / 4.0
* (cos_sigma * (-1.0 + 2.0 * cos2_sigma_m * cos2_sigma_m)
- cap_b / 6.0
* cos2_sigma_m
* (-3.0 + 4.0 * sin_sigma * sin_sigma)
* (-3.0 + 4.0 * cos2_sigma_m * cos2_sigma_m)));
let s = b * cap_a * (sigma - delta_sigma);
let mut alpha_1 = cos_u2 * _sin_lambda.atan2(cos_u1 * sin_u2 - sin_u1 * cos_u2 * _cos_lambda);
let mut alpha_2 = cos_u1 * _sin_lambda.atan2(-sin_u1 * cos_u2 + cos_u1 * sin_u2 * _cos_lambda);
alpha_1 = (alpha_1 + 2.0 * PI) % (2.0 * PI);
alpha_2 = (alpha_2 + 2.0 * PI) % (2.0 * PI);
Ok(DistanceResult {
distance: Distance::from_meters((s * 1000.0).round() / 1000.0),
_initial_bearing: if s == 0.0 {
None
} else {
Some(alpha_1.to_degrees())
},
_final_bearing: if s == 0.0 {
None
} else {
Some(alpha_2.to_degrees())
},
_iterations: iter_limit,
})
}
pub fn center_of_coords(coords: &[&Location]) -> Location {
let (mut x, mut y, mut z) = (0.0, 0.0, 0.0);
for loc in coords.iter() {
let lat = loc.0.to_radians();
let lon = loc.1.to_radians();
x += lat.cos() * lon.cos();
y += lat.cos() * lon.sin();
z += lat.sin();
}
let number_of_locations = coords.len() as f64;
x /= number_of_locations;
y /= number_of_locations;
z /= number_of_locations;
let hyp = (x * x + y * y).sqrt();
let lon = y.atan2(x);
let lat = z.atan2(hyp);
let lon = lon.to_degrees();
let lon = (lon * 10.0_f64.powi(6)).round() / 10.0_f64.powi(6);
let lat = lat.to_degrees();
let lat = (lat * 10.0_f64.powi(6)).round() / 10.0_f64.powi(6);
Location(lat, lon)
}
pub fn haversine_distance_to(start: &Location, end: &Location) -> Distance {
let haversine_fn = |theta: f64| (1.0 - theta.cos()) / 2.0;
let phi1 = start.latitude().to_radians();
let phi2 = end.latitude().to_radians();
let lambda1 = start.longitude().to_radians();
let lambda2 = end.longitude().to_radians();
let hav_delta_phi = haversine_fn(phi2 - phi1);
let hav_delta_lambda = phi1.cos() * phi2.cos() * haversine_fn(lambda2 - lambda1);
let total_delta = hav_delta_phi + hav_delta_lambda;
let dist = (2.0 * 6371e3 * total_delta.sqrt().asin() * 1000.0).round() / 1000.0;
Distance::from_meters(dist)
}