fun queryHashes()

in firestore/app/src/main/java/com/google/example/firestore/kotlin/SolutionGeoqueries.kt [37:80]
29 lines of code
5 McCabe index (conditional complexity)

    fun queryHashes() {
        // [START fs_geo_query_hashes]
        // Find cities within 50km of London
        val center = GeoLocation(51.5074, 0.1278)
        val radiusInM = 50.0 * 1000.0

        // Each item in 'bounds' represents a startAt/endAt pair. We have to issue
        // a separate query for each pair. There can be up to 9 pairs of bounds
        // depending on overlap, but in most cases there are 4.
        val bounds = GeoFireUtils.getGeoHashQueryBounds(center, radiusInM)
        val tasks: MutableList<Task<QuerySnapshot>> = ArrayList()
        for (b in bounds) {
            val q = db.collection("cities")
                    .orderBy("geohash")
                    .startAt(b.startHash)
                    .endAt(b.endHash)
            tasks.add(q.get())
        }

        // Collect all the query results together into a single list
        Tasks.whenAllComplete(tasks)
                .addOnCompleteListener {
                    val matchingDocs: MutableList<DocumentSnapshot> = ArrayList()
                    for (task in tasks) {
                        val snap = task.result
                        for (doc in snap!!.documents) {
                            val lat = doc.getDouble("lat")!!
                            val lng = doc.getDouble("lng")!!

                            // We have to filter out a few false positives due to GeoHash
                            // accuracy, but most will match
                            val docLocation = GeoLocation(lat, lng)
                            val distanceInM = GeoFireUtils.getDistanceBetween(docLocation, center)
                            if (distanceInM <= radiusInM) {
                                matchingDocs.add(doc)
                            }
                        }
                    }

                    // matchingDocs contains the results
                    // ...
                }
        // [END fs_geo_query_hashes]
    }