From 3590d2a80f2183f595db5ccc3efef45c770be5f6 Mon Sep 17 00:00:00 2001
From: Oliv <6248122+Oliv4945@users.noreply.github.com>
Date: Mon, 5 Feb 2024 07:21:09 +0100
Subject: [PATCH] Add stop search by GPS boundary box (#152)

---
 lib/gtfs/stops.js       | 22 ++++++++++---
 lib/utils.js            | 32 +++++++++++++++++++
 test/mocha/get-stops.js | 69 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 119 insertions(+), 4 deletions(-)

diff --git a/lib/gtfs/stops.js b/lib/gtfs/stops.js
index a95fba09..221556e8 100644
--- a/lib/gtfs/stops.js
+++ b/lib/gtfs/stops.js
@@ -7,6 +7,7 @@ import {
   formatOrderByClause,
   formatSelectClause,
   formatWhereClause,
+  formatWhereClauseBoundaryBox,
   formatWhereClauses,
 } from '../utils.js';
 import { stopsToGeoJSON } from '../geojson-utils.js';
@@ -37,9 +38,10 @@ export function getStops(query = {}, fields = [], orderBy = [], options = {}) {
   const tableName = sqlString.escapeId(stops.filenameBase);
   const selectClause = formatSelectClause(fields);
   let whereClause = '';
+  let whereClauses = [];
   const orderByClause = formatOrderByClause(orderBy);
 
-  const stopQuery = omit(query, [
+  let stopQuery = omit(query, [
     'route_id',
     'trip_id',
     'service_id',
@@ -54,9 +56,21 @@ export function getStops(query = {}, fields = [], orderBy = [], options = {}) {
     'shape_id',
   ]);
 
-  const whereClauses = Object.entries(stopQuery).map(([key, value]) =>
-    formatWhereClause(key, value)
-  );
+  if (options.boundary_side_m === undefined) {
+    whereClauses = Object.entries(stopQuery).map(([key, value]) =>
+      formatWhereClause(key, value)
+    );
+  } else {
+    // Search inside a GPS coordinates boundary box
+    stopQuery = omit(query, [
+      'stop_lat',
+      'stop_lon',
+    ]);
+    whereClauses.push(...Object.entries(stopQuery).map(([key, value]) =>
+      formatWhereClause(key, value)
+    ));
+    whereClauses.push(formatWhereClauseBoundaryBox(query.stop_lat, query.stop_lon, options.boundary_side_m))
+  }
 
   if (Object.values(tripQuery).length > 0) {
     whereClauses.push(`stop_id IN (${buildStoptimeSubquery(tripQuery)})`);
diff --git a/lib/utils.js b/lib/utils.js
index d347cc55..a20aed58 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -92,6 +92,38 @@ export function formatJoinClause(joinObject) {
     .join(' ');
 }
 
+function degree2radian(angle) {
+  return angle * Math.PI / 180;
+}
+
+function radian2degree(angle) {
+  return angle / Math.PI * 180;
+}
+
+/*
+ * Search inside GPS coordinates boundary box
+ * Distance unit: meters
+ * */
+export function formatWhereClauseBoundaryBox(latitudeDegree, longitudeDegree, boxSide) {
+
+  const earthRadius = 6371000;
+  latitudeDegree = parseFloat(latitudeDegree);
+  longitudeDegree = parseFloat(longitudeDegree);
+
+  const latitudeRadian = degree2radian(latitudeDegree);
+  const radiusFromLatitude = Math.cos(latitudeRadian) * earthRadius;
+
+  // boxSide is divided by 2 as user specify the square side size
+  // but we are centering the coordinates in the middle of this square
+  const deltaLatitude = radian2degree(boxSide / 2 / earthRadius);
+  const deltaLongitude = radian2degree(boxSide / 2 / radiusFromLatitude);
+
+  let query = `stop_lat BETWEEN ${latitudeDegree - deltaLatitude} AND ${latitudeDegree + deltaLatitude}`;
+  query += ` AND stop_lon BETWEEN ${longitudeDegree - deltaLongitude} AND ${longitudeDegree + deltaLongitude}`;
+
+  return query;
+}
+
 export function formatWhereClause(key, value) {
   if (Array.isArray(value)) {
     let whereClause = `${sqlString.escapeId(key)} IN (${value
diff --git a/test/mocha/get-stops.js b/test/mocha/get-stops.js
index d6f8a086..9be4165d 100644
--- a/test/mocha/get-stops.js
+++ b/test/mocha/get-stops.js
@@ -266,4 +266,73 @@ describe('getStops():', () => {
       );
     }
   });
+
+  it('should return array of stops for specific GPS boundaries', () => {
+    const distance = 100;
+    const stopLatitude = 37.709538;
+    const stopLongitude = -122.401586;
+
+    const results = getStops({
+      stop_lat: stopLatitude,
+      stop_lon: stopLongitude,
+    },
+      [], [], { "boundary_side_m": distance }
+    );
+
+    const expectedResult = [
+      {
+        stop_id: 'ctba',
+        stop_code: null,
+        stop_name: 'Bayshore Caltrain',
+        tts_stop_name: null,
+        stop_desc: null,
+        stop_lat: 37.709544,
+        stop_lon: -122.401318,
+        zone_id: null,
+        stop_url: 'http://www.caltrain.com/stations/bayshorestation.html',
+        location_type: 1,
+        parent_station: null,
+        stop_timezone: null,
+        wheelchair_boarding: 1,
+        level_id: null,
+        platform_code: null
+      }, {
+        stop_id: '70032',
+        stop_code: '70032',
+        stop_name: 'Bayshore Caltrain',
+        tts_stop_name: null,
+        stop_desc: null,
+        stop_lat: 37.709544,
+        stop_lon: -122.40198,
+        zone_id: '1',
+        stop_url: 'http://www.caltrain.com/stations/bayshorestation.html',
+        location_type: 0,
+        parent_station: 'ctba',
+        stop_timezone: null,
+        wheelchair_boarding: 1,
+        level_id: null,
+        platform_code: 'SB'
+      }, {
+        stop_id: '70031',
+        stop_code: '70031',
+        stop_name: 'Bayshore Caltrain',
+        tts_stop_name: null,
+        stop_desc: null,
+        stop_lat: 37.709537,
+        stop_lon: -122.401586,
+        zone_id: '1',
+        stop_url: 'http://www.caltrain.com/stations/bayshorestation.html',
+        location_type: 0,
+        parent_station: 'ctba',
+        stop_timezone: null,
+        wheelchair_boarding: 1,
+        level_id: null,
+        platform_code: 'NB'
+      }
+    ];
+
+    should.exist(results);
+    results.length.should.equal(3);
+    results.should.match(expectedResult);
+  });
 });