refactor: separate Overpass and installation services

server/providers/military-installations/query.js

@@ -0,0 +1,60 @@
+import { MILITARY_INSTALLATION_BBOX_STEP_DEG } from './constants.js';
+import { requiredFiniteQueryNumber } from '../common/query.js';
+
+/**
+ * Snap a request bbox outward onto the shared installation cache grid.
+ * @param {{south:number, west:number, north:number, east:number}} box
+ * @param {number} [stepDeg]
+ * @returns {{south:number, west:number, north:number, east:number}}
+ */
+function quantizeMilitaryInstallationBox(box, stepDeg = MILITARY_INSTALLATION_BBOX_STEP_DEG) {
+  // Round the ratio first: 29.9999/0.05 lands a hair under an exact grid line
+  // in binary floating point, which would otherwise snap a whole cell too far.
+  const snap = (value, grow) => {
+    const cells = Number((value / stepDeg).toFixed(9));
+    return Number(((grow > 0 ? Math.ceil(cells) : Math.floor(cells)) * stepDeg).toFixed(6));
+  };
+  return {
+    south: Math.max(-90, snap(box.south, -1)),
+    west: Math.max(-180, snap(box.west, -1)),
+    north: Math.min(90, snap(box.north, 1)),
+    east: Math.min(180, snap(box.east, 1)),
+  };
+}
+
+/**
+ * Stable disk/memory cache key for an installation bbox.
+ *
+ * The key's precision must match the precision of the bounds the QUERY uses, or
+ * two different queries collide on one entry. Snapped boxes live on a 0.05 deg
+ * grid, so 3 decimals is exact for them; an `exact=1` request carries the raw
+ * viewport at 5 decimals and must be keyed at 5, otherwise two nearby exact
+ * viewports would share an answer and the second would be missing the edge
+ * strip it just exposed.
+ * @param {{south:number, west:number, north:number, east:number}} box
+ * @param {number} [decimals]
+ */
+function militaryInstallationCacheKey(box, decimals = 3) {
+  return [box.south, box.west, box.north, box.east]
+    .map((value) => value.toFixed(decimals))
+    .join(',');
+}
+
+function validMilitaryInstallationBox(params) {
+  const south = requiredFiniteQueryNumber(params, 'south');
+  const west = requiredFiniteQueryNumber(params, 'west');
+  const north = requiredFiniteQueryNumber(params, 'north');
+  const east = requiredFiniteQueryNumber(params, 'east');
+  if (![south, west, north, east].every(Number.isFinite)) return null;
+  if (south < -90 || north > 90 || west < -180 || east > 180 || south >= north || west >= east) return null;
+  if (north - south > 10 || east - west > 10) return null;
+  return { south, west, north, east };
+}
+
+/** Safe, evidence-based reason for an installation upstream failure. */
+function militaryInstallationFailureReason(error) {
+  if (['rate_limited', 'timeout', 'query_failed'].includes(error?.installationReason)) return error.installationReason;
+  return ['AbortError', 'TimeoutError'].includes(error?.name) ? 'timeout' : 'unavailable';
+}
+
+export { validMilitaryInstallationBox, quantizeMilitaryInstallationBox, militaryInstallationCacheKey, militaryInstallationFailureReason };