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);`,
    );
  }
}