refactor: implement bidirectional transformation support with PostgreSQL integration

internal/app/etl/transformers/utils.go

@@ -4,6 +4,8 @@ import (
 	"encoding/binary"
 	"errors"
 	"time"
+
+	mssqlclrgeo "github.com/gaspardle/go-mssqlclrgeo"
 )
 
 func mssqlUuidToBigEndian(mssqlUuid []byte) ([]byte, error) {
@@ -62,6 +64,51 @@ func ensureUTC(t time.Time) time.Time {
 	return time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), time.UTC)
 }
 
+func bigEndianToMssqlUuid(pgUuid []byte) ([]byte, error) {
+	if len(pgUuid) != 16 {
+		return nil, errors.New("Invalid uuid")
+	}
+
+	mssqlUuid := make([]byte, 16)
+	mssqlUuid[0], mssqlUuid[1], mssqlUuid[2], mssqlUuid[3] = pgUuid[3], pgUuid[2], pgUuid[1], pgUuid[0]
+	mssqlUuid[4], mssqlUuid[5] = pgUuid[5], pgUuid[4]
+	mssqlUuid[6], mssqlUuid[7] = pgUuid[7], pgUuid[6]
+	copy(mssqlUuid[8:], pgUuid[8:])
+
+	return mssqlUuid, nil
+}
+
+func ewkbToMssqlGeo(ewkb []byte, isGeography bool) ([]byte, error) {
+	if len(ewkb) < 5 {
+		return nil, errors.New("Invalid ewkb")
+	}
+
+	var byteOrder binary.ByteOrder
+	if ewkb[0] == 0 {
+		byteOrder = binary.BigEndian
+	} else {
+		byteOrder = binary.LittleEndian
+	}
+
+	wkbType := byteOrder.Uint32(ewkb[1:5])
+
+	var wkb []byte
+	if wkbType&sridFlag != 0 {
+		if len(ewkb) < 9 {
+			return nil, errors.New("Invalid ewkb: SRID flag set but data too short")
+		}
+		clearType := wkbType &^ uint32(sridFlag)
+		wkb = make([]byte, len(ewkb)-4)
+		wkb[0] = ewkb[0]
+		byteOrder.PutUint32(wkb[1:5], clearType)
+		copy(wkb[5:], ewkb[9:])
+	} else {
+		wkb = ewkb
+	}
+
+	return mssqlclrgeo.WkbToUdtGeo(wkb, isGeography)
+}
+
 func ToInt64(v any) (int64, bool) {
 	switch t := v.(type) {
 	case int: