Ability to add, remove, update radius and location of chatrooms with a leaflet

1 files changed, 45 insertions, 0 deletions

diff --git a/server/database/migrations/1648669551959-AddDistanceFunction.ts b/server/database/migrations/1648669551959-AddDistanceFunction.ts
new file mode 100644
index 0000000..0890936
--- /dev/null
+++ b/server/database/migrations/1648669551959-AddDistanceFunction.ts
@@ -0,0 +1,45 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+
+export class AddDistanceFunction1648669551959 implements MigrationInterface {
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    // From https://stackoverflow.com/questions/61135374/postgresql-calculate-distance-between-two-points-without-using-postgis
+    await queryRunner.query(`
+CREATE OR REPLACE FUNCTION calculate_distance(lat1 float, lon1 float, lat2 float, lon2 float, units varchar)
+  RETURNS float AS $dist$
+      DECLARE
+          dist float = 0;
+          radlat1 float;
+          radlat2 float;
+          theta float;
+          radtheta float;
+      BEGIN
+          IF lat1 = lat2 OR lon1 = lon2
+              THEN RETURN dist;
+          ELSE
+              radlat1 = pi() * lat1 / 180;
+              radlat2 = pi() * lat2 / 180;
+              theta = lon1 - lon2;
+              radtheta = pi() * theta / 180;
+              dist = sin(radlat1) * sin(radlat2) + cos(radlat1) * cos(radlat2) * cos(radtheta);
+  
+              IF dist > 1 THEN dist = 1; END IF;
+  
+              dist = acos(dist);
+              dist = dist * 180 / pi();
+              dist = dist * 60 * 1.1515;
+  
+              IF units = 'K' THEN dist = dist * 1.609344; END IF;
+              IF units = 'N' THEN dist = dist * 0.8684; END IF;
+  
+              RETURN dist;
+          END IF;
+      END;
+  $dist$ LANGUAGE plpgsql;`);
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `DROP FUNCTION IF EXISTS calculate_distance(lat1 float, lon1 float, lat2 float, lon2 float, units varchar);`,
+    );
+  }
+}