SPlit up

server-rs/src/data/property/h3.rs

@@ -0,0 +1,34 @@
+//! H3 spatial cell precomputation for property rows.
+
+use anyhow::Context;
+use rayon::prelude::*;
+
+use crate::consts::H3_PRECOMPUTE_MAX;
+
+/// Precompute H3 cell IDs for all rows at the maximum resolution only.
+/// Parent cells for lower resolutions are derived on the fly via `CellIndex::parent()`.
+pub fn precompute_h3(lat: &[f32], lon: &[f32]) -> anyhow::Result<Vec<u64>> {
+    let res = H3_PRECOMPUTE_MAX;
+    tracing::info!("Precomputing H3 cells at resolution {}", res);
+
+    let h3_res =
+        h3o::Resolution::try_from(res).with_context(|| format!("Invalid H3 resolution: {res}"))?;
+
+    let cells: Vec<u64> = lat
+        .par_iter()
+        .zip(lon.par_iter())
+        .enumerate()
+        .map(|(i, (&latitude, &longitude))| {
+            let coord = h3o::LatLng::new(latitude as f64, longitude as f64).unwrap_or_else(|err| {
+                panic!(
+                    "Invalid coordinates at row {}: lat={}, lon={}: {}",
+                    i, latitude, longitude, err
+                )
+            });
+            u64::from(coord.to_cell(h3_res))
+        })
+        .collect();
+
+    tracing::info!("H3 precomputation complete ({} cells)", cells.len());
+    Ok(cells)
+}