nearest query

const earthRadius = 6371.0

async function getNearNannies(req, res, next) {
  const params = req.query;
  let nannies = []
  let {lat, lon, distance} = req.body
  lat = parseFloat(lat)
  lon = parseFloat(lon)
  distance = parseFloat(distance) || 1
  const {swLat, swLon, neLat, neLon} = boundingBox(lat, lon, distance)

  if (!lat || !lon || !distance) {
    res.json({success: false, error: 'Missing params'})
  } else {
    await db.sequelize.query(`SELECT "User"."id", "User"."email", "User"."phone", "User"."first_name", "User"."last_name", "User"."avatar", "employee"."latitude" AS "latitude", "employee"."longitude" AS "longitude", ${earthRadius} * 2 * ASIN(SQRT(POWER(SIN(( ${lat} - employee.latitude) * PI() / 180 / 2), 2) + COS( ${lat} * PI() / 180) * COS(employee.latitude * PI() / 180) * POWER(SIN(( ${lon} - employee.longitude) * PI() / 180 / 2), 2))) AS distance FROM "users" AS "User" INNER JOIN "employees" AS "employee" ON "User"."id" = "employee"."user_id" AND "employee"."latitude" IS NOT NULL WHERE ( employee.latitude BETWEEN ${swLat} AND ${neLat} AND employee.longitude BETWEEN ${swLon} AND ${neLon} AND ( ${earthRadius} * 2 * ASIN(SQRT(POWER(SIN(( ${lat} - employee.latitude) * PI() / 180 / 2), 2) + COS( ${lat} * PI() / 180) * COS(employee.latitude * PI() / 180) * POWER(SIN(( ${lon} - employee.longitude) * PI() / 180 / 2), 2))) ) BETWEEN 0.0 AND ${distance} ) ORDER BY distance ASC`).spread((results, metadata) => {
      results.map(user => {
        nannies.push({
          id: user.id,
          email: user.email,
          phone: user.phone,
          first_name: user.first_name,
          last_name: user.last_name,
          avatar_url: `https://kiidu.s3-ap-southeast-1.amazonaws.com/uploads/user/avatar/${user.id}/${user.avatar}`,
          latitude: user.latitude,
          longitude: user.longitude,
          distance: user.distance
        })
      })
    })
    res.json({success: true, length: nannies.length, nannies: nannies})
  }
}

const boundingBox = (lat, lon, distance) => {
  return {
    swLat: lat - (distance / latitudeDegreeDistance()),
    swLon: lon - (distance / longitudeDegreeDistance(lat)),
    neLat: lat + (distance / latitudeDegreeDistance()),
    neLon: lon + (distance / longitudeDegreeDistance(lat))
  }
}

const latitudeDegreeDistance = () => {
  return (2 * Math.PI * earthRadius / 360)
}

const longitudeDegreeDistance = (latitude) => {
  return latitudeDegreeDistance() * Math.cos(toRadians(latitude))
}

const toRadians = (arg) => {
  return (arg * (Math.PI / 180))
}