package main

import (
	"encoding/binary"
)

func mssqlUuidToBigEndian(mssqlUuid []byte) []byte {
	if len(mssqlUuid) != 16 {
		return mssqlUuid
	}
	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
}

const sridFlag = 0x20000000

func wkbToEwkbWithSrid(geometry []byte, srid int) []byte {
	if len(geometry) < 5 {
		return geometry
	}

	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
	}

	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
}