feat: use the haversine formula to get distance from lightning to you

src/main.rs

@@ -48,9 +48,25 @@ fn in_bounds(lat: f64, lon: f64, center_lat: f64, center_lon: f64, delta: f64) -
     (lat >= lat_min && lat <= lat_max) && (lon >= lon_min && lon <= lon_max)
 }
 
+fn haversine_distance(lat1: f64, lon1: f64, lat2: f64, lon2: f64) -> f64 {
+    let r = 6371.0; // Earth radius in km
+    let dlat = (lat2 - lat1).to_radians();
+    let dlon = (lon2 - lon1).to_radians();
+    let a = (dlat / 2.0).sin().powi(2)
+        + lat1.to_radians().cos() * lat2.to_radians().cos() * (dlon / 2.0).sin().powi(2);
+    let c = 2.0 * a.sqrt().atan2((1.0 - a).sqrt());
+    r * c
+}
+
 #[tokio::main]
 async fn main() {
     let args = Args::parse();
+    println!("Boot arguments:");
+    println!("  center_lat: {}", args.center_lat);
+    println!("  center_lon: {}", args.center_lon);
+    println!("  delta: {}", args.delta);
+    println!("  ntfy_topic: {}", args.ntfy_topic);
+    println!("  detector_fetch: {}", args.detector_fetch);
 
     CryptoProvider::install_default(rustls_rustcrypto::provider())
         .expect("install rustcrypto provider");
@@ -155,9 +171,12 @@ async fn main() {
                     let lon = all.lon + all.lonc as f64;
                     let lat = all.lat + all.latc as f64;
                     if in_bounds(lat, lon, args.center_lat, args.center_lon, args.delta) {
+                        let distance_km =
+                            haversine_distance(args.center_lat, args.center_lon, lat, lon);
+
                         println!(
-                            "Delay: {}ms, offset to now: {}ms, status: {}, region: {} | \n Strike at: {}, {}",
+                            "Delay: {}ms, offset to now: {}ms, status: {}, region: {} | \n Strike at: {}, {} | Distance to you: {:.2} km",
-                            all.delay, offset_ms, all.status, all.region, lon, lat
+                            all.delay, offset_ms, all.status, all.region, lon, lat, distance_km
                         );
 
                         let mut detector_details: Vec<String> = Vec::new();
@@ -199,6 +218,7 @@ async fn main() {
                             • Status: {}\n\
                             • Region: {}\n\
                             • Location: {:.5}, {:.5}\n\
+                            • Distance to you: {:.2} km\n\
                             • Used detectors:\n{}\n\
                             Stay safe! 🌩️",
                             all.delay,
@@ -206,6 +226,7 @@ async fn main() {
                             all.region,
                             lon,
                             lat,
+                            distance_km,
                             {
                                 if args.detector_fetch {
                                     let shown = 2;