feat: implement MSSQL extractor, transformer, and Postgres loader for enhanced data migration

internal/app/etl/transformers/utils.go

@@ -0,0 +1,80 @@
+package transformers
+
+import (
+	"encoding/binary"
+	"errors"
+	"time"
+)
+
+func mssqlUuidToBigEndian(mssqlUuid []byte) ([]byte, error) {
+	if len(mssqlUuid) != 16 {
+		return nil, errors.New("Invalid uuid")
+	}
+
+	pgUuid := make([]byte, 16)
+	pgUuid[0], pgUuid[1], pgUuid[2], pgUuid[3] = mssqlUuid[3], mssqlUuid[2], mssqlUuid[1], mssqlUuid[0]
+	pgUuid[4], pgUuid[5] = mssqlUuid[5], mssqlUuid[4]
+	pgUuid[6], pgUuid[7] = mssqlUuid[7], mssqlUuid[6]
+	copy(pgUuid[8:], mssqlUuid[8:])
+
+	return pgUuid, nil
+}
+
+const sridFlag = 0x20000000
+
+func wkbToEwkbWithSrid(geometry []byte, srid int) ([]byte, error) {
+	if len(geometry) < 5 {
+		return nil, errors.New("Invalid wkb")
+	}
+
+	var byteOrder binary.ByteOrder
+	if geometry[0] == 0 {
+		byteOrder = binary.BigEndian
+	} else {
+		byteOrder = binary.LittleEndian
+	}
+
+	wkbType := byteOrder.Uint32(geometry[1:5])
+	if wkbType&sridFlag != 0 {
+		return geometry, nil
+	}
+
+	ewkbType := wkbType | sridFlag
+
+	result := make([]byte, len(geometry)+4)
+
+	result[0] = geometry[0]
+
+	byteOrder.PutUint32(result[1:5], ewkbType)
+
+	byteOrder.PutUint32(result[5:9], uint32(srid))
+
+	copy(result[9:], geometry[5:])
+
+	return result, nil
+}
+
+func ensureUTC(t time.Time) time.Time {
+	if t.Location() == time.UTC {
+		return t
+	}
+
+	return time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second(), t.Nanosecond(), time.UTC)
+}
+
+func ToInt64(v any) (int64, bool) {
+	switch t := v.(type) {
+	case int:
+		return int64(t), true
+	case int8:
+		return int64(t), true
+	case int16:
+		return int64(t), true
+	case int32:
+		return int64(t), true
+	case int64:
+		return int64(t), true
+	default:
+		return 0, false
+	}
+}