edr-platform/apps/edr-freight-api/src/common/mile-distance.util.ts

import { DataSource } from 'typeorm';

/** Great-circle distance in km between two WGS84 points (haversine). */
export function haversineKm(lat1: number, lng1: number, lat2: number, lng2: number): number {
  const toRad = (d: number) => (d * Math.PI) / 180;
  const dLat = toRad(lat2 - lat1);
  const dLng = toRad(lng2 - lng1);
  const a =
    Math.sin(dLat / 2) ** 2 + Math.cos(toRad(lat1)) * Math.cos(toRad(lat2)) * Math.sin(dLng / 2) ** 2;
  return 2 * 6371 * Math.asin(Math.sqrt(a));
}

/**
 * Estimated road-leg distance for a booking's first/last mile: straight-line km
 * from the yard (freight.yard_locations) to the customer's pickup/delivery GPS
 * point on the booking. FIRST = origin yard → pickup point, LAST = destination
 * yard → delivery point. Null when either end has no coordinates.
 *
 * ponytail: haversine straight-line, not road routing — plug a routing API in
 * here if real road km is ever required.
 */
export async function estimateMileKm(
  dataSource: DataSource,
  bookingId: string,
  mile: 'FIRST' | 'LAST',
): Promise<number | null> {
  const [row] = await dataSource.query(
    mile === 'LAST'
      ? `SELECT b.last_mile_delivery_lat AS lat, b.last_mile_delivery_lng AS lng,
                l.latitude AS yard_lat, l.longitude AS yard_lng
           FROM freight.bookings b
           LEFT JOIN freight.yard_locations l
             ON l.yard_id = b.destination_yard_id AND l.deleted_at IS NULL
          WHERE b.id = $1 AND b.deleted_at IS NULL`
      : `SELECT b.first_mile_pickup_lat AS lat, b.first_mile_pickup_lng AS lng,
                l.latitude AS yard_lat, l.longitude AS yard_lng
           FROM freight.bookings b
           LEFT JOIN freight.yard_locations l
             ON l.yard_id = b.origin_yard_id AND l.deleted_at IS NULL
          WHERE b.id = $1 AND b.deleted_at IS NULL`,
    [bookingId],
  );
  if (!row || row.lat == null || row.lng == null || row.yard_lat == null || row.yard_lng == null) {
    return null;
  }
  const km = haversineKm(Number(row.yard_lat), Number(row.yard_lng), Number(row.lat), Number(row.lng));
  return Math.round(km * 100) / 100;
}