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package ewkb
import (
"bytes"
"encoding/binary"
"encoding/hex"
"errors"
"io"
"github.com/paulmach/orb"
"github.com/paulmach/orb/encoding/internal/wkbcommon"
)
var (
// ErrUnsupportedDataType is returned by Scan methods when asked to scan
// non []byte data from the database. This should never happen
// if the driver is acting appropriately.
ErrUnsupportedDataType = errors.New("wkb: scan value must be []byte")
// ErrNotEWKB is returned when unmarshalling EWKB and the data is not valid.
ErrNotEWKB = errors.New("wkb: invalid data")
// ErrIncorrectGeometry is returned when unmarshalling EWKB data into the wrong type.
// For example, unmarshaling linestring data into a point.
ErrIncorrectGeometry = errors.New("wkb: incorrect geometry")
// ErrUnsupportedGeometry is returned when geometry type is not supported by this lib.
ErrUnsupportedGeometry = errors.New("wkb: unsupported geometry")
)
var commonErrorMap = map[error]error{
wkbcommon.ErrUnsupportedDataType: ErrUnsupportedDataType,
wkbcommon.ErrNotWKB: ErrNotEWKB,
wkbcommon.ErrNotWKBHeader: ErrNotEWKB,
wkbcommon.ErrIncorrectGeometry: ErrIncorrectGeometry,
wkbcommon.ErrUnsupportedGeometry: ErrUnsupportedGeometry,
}
func mapCommonError(err error) error {
e, ok := commonErrorMap[err]
if ok {
return e
}
return err
}
// DefaultByteOrder is the order used for marshalling or encoding is none is specified.
var DefaultByteOrder binary.ByteOrder = binary.LittleEndian
// DefaultSRID is set to 4326, a common SRID, which represents spatial data using
// longitude and latitude coordinates on the Earth's surface as defined in the WGS84 standard,
// which is also used for the Global Positioning System (GPS).
// This will be used by the encoder if non is specified.
var DefaultSRID int = 4326
// An Encoder will encode a geometry as EWKB to the writer given at creation time.
type Encoder struct {
srid int
e *wkbcommon.Encoder
}
// MustMarshal will encode the geometry and panic on error.
// Currently there is no reason to error during geometry marshalling.
func MustMarshal(geom orb.Geometry, srid int, byteOrder ...binary.ByteOrder) []byte {
d, err := Marshal(geom, srid, byteOrder...)
if err != nil {
panic(err)
}
return d
}
// Marshal encodes the geometry with the given byte order.
// An SRID of 0 will not be included in the encoding and the result will be a wkb encoding of the geometry.
func Marshal(geom orb.Geometry, srid int, byteOrder ...binary.ByteOrder) ([]byte, error) {
buf := bytes.NewBuffer(make([]byte, 0, wkbcommon.GeomLength(geom, srid != 0)))
e := NewEncoder(buf)
e.SetSRID(srid)
if len(byteOrder) > 0 {
e.SetByteOrder(byteOrder[0])
}
err := e.Encode(geom)
if err != nil {
return nil, err
}
if buf.Len() == 0 {
return nil, nil
}
return buf.Bytes(), nil
}
// MarshalToHex will encode the geometry into a hex string representation of the binary ewkb.
func MarshalToHex(geom orb.Geometry, srid int, byteOrder ...binary.ByteOrder) (string, error) {
data, err := Marshal(geom, srid, byteOrder...)
if err != nil {
return "", err
}
return hex.EncodeToString(data), nil
}
// MustMarshalToHex will encode the geometry and panic on error.
// Currently there is no reason to error during geometry marshalling.
func MustMarshalToHex(geom orb.Geometry, srid int, byteOrder ...binary.ByteOrder) string {
d, err := MarshalToHex(geom, srid, byteOrder...)
if err != nil {
panic(err)
}
return d
}
// NewEncoder creates a new Encoder for the given writer.
func NewEncoder(w io.Writer) *Encoder {
e := wkbcommon.NewEncoder(w)
e.SetByteOrder(DefaultByteOrder)
return &Encoder{e: e, srid: DefaultSRID}
}
// SetByteOrder will override the default byte order set when
// the encoder was created.
func (e *Encoder) SetByteOrder(bo binary.ByteOrder) *Encoder {
e.e.SetByteOrder(bo)
return e
}
// SetSRID will override the default srid.
func (e *Encoder) SetSRID(srid int) *Encoder {
e.srid = srid
return e
}
// Encode will write the geometry encoded as EWKB to the given writer.
func (e *Encoder) Encode(geom orb.Geometry, srid ...int) error {
s := e.srid
if len(srid) > 0 {
s = srid[0]
}
return e.e.Encode(geom, s)
}
// Decoder can decoder WKB geometry off of the stream.
type Decoder struct {
d *wkbcommon.Decoder
}
// Unmarshal will decode the type into a Geometry.
func Unmarshal(data []byte) (orb.Geometry, int, error) {
g, srid, err := wkbcommon.Unmarshal(data)
if err != nil {
return nil, 0, mapCommonError(err)
}
return g, srid, nil
}
// NewDecoder will create a new EWKB decoder.
func NewDecoder(r io.Reader) *Decoder {
return &Decoder{
d: wkbcommon.NewDecoder(r),
}
}
// Decode will decode the next geometry off of the stream.
func (d *Decoder) Decode() (orb.Geometry, int, error) {
g, srid, err := d.d.Decode()
if err != nil {
return nil, 0, mapCommonError(err)
}
return g, srid, nil
}
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