[WIP]: closes #1248 . working on geohash functionality

internal/eval/geo/geohash.go

@@ -0,0 +1,107 @@
+package geo
+
+import (
+	"fmt"
+	"strings"
+)
+
+type Coordinates struct {
+	Longitude float64
+	Latitude float64
+}
+
+type GoeHash struct {
+	Hash string
+	Neighbors []GoeHash
+}
+
+var (
+	// base32 alphabets
+	base32 []string = []string{
+	"0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
+	"b", "c", "d", "e", "f", "g", "h", "j", "k", "m",
+	"n", "p", "q", "r", "s", "t", "u", "v", "w", "x",
+	"y", "z",
+	}
+
+	// This coordinate measures north-south position and ranges from -90° (South Pole) to +90° (North Pole).
+	latitudeRange = []int64{90,-90}
+
+	// This coordinate measures east-west position and ranges from -180° (Western Hemisphere) to +180° (Eastern Hemisphere).
+	longitudeRange = []int64{180,-180}
+
+	//
+	MIN_LATITUDE 	= -85.05112878
+
+	//
+	MAX_LATITUDE 	= 85.05112878
+
+	//
+	MIN_LONGITUDE = -180
+
+	//
+	MAX_LONGITUDE = 180
+
+
+	ErrInvalidInput = func (lat, long float64) error {
+		return fmt.Errorf("invalid positions provided (lat: %.4f, long: %.4f)", lat, long)
+	}
+
+	ErrInvalidHash = func (hash string) error {
+		return fmt.Errorf("invalid positions provided (hash: %s)", hash)
+	}
+)
+
+
+func Encode(lat, long float64, precision int) (string, error) {
+
+	if precision <= 0 {
+		precision = 12;
+	}
+
+	if long > float64(MAX_LONGITUDE) || long < float64(MIN_LONGITUDE) || lat < MIN_LATITUDE || lat > MAX_LATITUDE {
+		return "", ErrInvalidInput(lat, long)
+	}
+
+
+	// convert them to thier binary equivalent.
+	latBin := getBinaryString(latitudeRange,lat, precision)
+	longBin := getBinaryString(longitudeRange, long, precision)
+
+	fmt.Println("lat: ", latBin)
+	fmt.Println("long: ", longBin)
+
+
+	return "", nil
+
+}
+
+func Decode(hash string) (Coordinates, error) {
+
+	return Coordinates{}, nil
+}
+
+
+func getBinaryString(cRange []int64, target float64, precision int) string {
+	var stringBuilder = strings.Builder{}
+
+	max := float64(cRange[0])
+	min := float64(cRange[1])
+
+	for i := 0; i < precision; i++ {
+		mid := (float64(max) + float64(min)) / 2
+
+		if(target == float64(mid)) {
+			stringBuilder.WriteString("1")
+			min = mid;
+		}else if (target <= float64(mid)) {
+			stringBuilder.WriteString("0")
+			max = mid
+		}else if (target >= float64(mid)) {
+			stringBuilder.WriteString("1")
+			min = mid
+		}
+	}
+
+	return stringBuilder.String()
+}

internal/eval/geo/geohash_test.go

@@ -0,0 +1,17 @@
+package geo
+
+import "testing"
+
+
+
+func TestGeoHash_Encode(t *testing.T)  {
+
+}
+
+func TestGeoHash_Decode(t *testing.T) {
+
+}
+
+func TestGeoHash_Neighbors(t *testing.T) {
+
+}