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request.go
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request.go
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package maps
import (
"fmt"
"net/http"
"net/url"
"strconv"
"strings"
)
type BBOX struct {
MinX, MinY, MaxX, MaxY float64
}
type Request struct {
HTTP *http.Request
Query url.Values
Width int
Height int
BBOX BBOX
EPSGCode int
Format string
ScaleFactor float64
}
type MissingParamError struct {
Param string
}
func (e *MissingParamError) Error() string {
return fmt.Sprintf("Missing parameter '%s'", e.Param)
}
type InvalidParamError struct {
Param string
Value string
Msg string
}
func (e *InvalidParamError) Error() string {
return fmt.Sprintf("Invalid parameter '%s=%s' %v", e.Param, e.Value, e.Msg)
}
func parseQueryUpper(q string) (url.Values, error) {
origQuery, err := url.ParseQuery(q)
if err != nil {
return nil, err
}
query := make(url.Values)
for k, vs := range origQuery {
for _, v := range vs {
query.Add(strings.ToUpper(k), v)
}
}
return query, nil
}
func ParseMapRequest(r *http.Request) (*Request, error) {
query, err := parseQueryUpper(r.URL.RawQuery)
if err != nil {
return nil, err
}
req := &Request{
HTTP: r,
Query: query,
}
req.Width, req.Height, err = parseSize(req.Query)
if err != nil {
return nil, err
}
req.BBOX, err = parseBBOX(req.Query)
if err != nil {
return nil, err
}
req.EPSGCode, err = parseEPSGCode(req.Query)
if err != nil {
return nil, err
}
req.Format, err = parseFormat(req.Query)
if err != nil {
return nil, err
}
req.ScaleFactor, err = parseScaleFactor(req.Query)
if err != nil {
return nil, err
}
return req, nil
}
func parseSize(q url.Values) (width, height int, err error) {
w := q.Get("WIDTH")
if w == "" {
return width, height, &MissingParamError{"WIDTH"}
}
h := q.Get("HEIGHT")
if h == "" {
return width, height, &MissingParamError{"HEIGHT"}
}
var tmp uint64
tmp, err = strconv.ParseUint(w, 10, 32)
if err != nil || tmp == 0 {
return width, height, &InvalidParamError{Param: "WIDTH", Value: w}
}
width = int(tmp)
tmp, err = strconv.ParseUint(h, 10, 32)
if err != nil || tmp == 0 {
return width, height, &InvalidParamError{Param: "HEIGHT", Value: h}
}
height = int(tmp)
return width, height, nil
}
func parseBBOX(q url.Values) (BBOX, error) {
var err error
var bbox BBOX
bboxStr := q.Get("BBOX")
if bboxStr == "" {
return bbox, &MissingParamError{"BBOX"}
}
bboxParts := strings.Split(bboxStr, ",")
if len(bboxParts) != 4 {
return bbox, &InvalidParamError{Param: "BBOX", Value: bboxStr}
}
bbox.MinX, err = strconv.ParseFloat(bboxParts[0], 64)
if err != nil {
return bbox, &InvalidParamError{Param: "BBOX", Value: bboxStr}
}
bbox.MinY, err = strconv.ParseFloat(bboxParts[1], 64)
if err != nil {
return bbox, &InvalidParamError{Param: "BBOX", Value: bboxStr}
}
bbox.MaxX, err = strconv.ParseFloat(bboxParts[2], 64)
if err != nil {
return bbox, &InvalidParamError{Param: "BBOX", Value: bboxStr}
}
bbox.MaxY, err = strconv.ParseFloat(bboxParts[3], 64)
if err != nil {
return bbox, &InvalidParamError{Param: "BBOX", Value: bboxStr}
}
return bbox, nil
}
func parseEPSGCode(q url.Values) (int, error) {
srsStr := q.Get("SRS")
if srsStr == "" {
return 0, &MissingParamError{"SRS"}
}
if srsStr == "CRS:84" {
return 4326, nil
}
srsParts := strings.Split(srsStr, ":")
if len(srsParts) != 2 {
return 0, &InvalidParamError{Param: "SRS", Value: srsStr}
}
if !strings.HasPrefix(strings.ToUpper(srsStr), "EPSG") {
return 0, &InvalidParamError{Param: "SRS", Value: srsStr}
}
epsgCode, err := strconv.ParseUint(srsParts[1], 10, 32)
if err != nil {
return 0, &InvalidParamError{Param: "SRS", Value: srsStr}
}
if epsgCode == 900913 {
epsgCode = 3857
}
return int(epsgCode), nil
}
func parseFormat(q url.Values) (string, error) {
format := q.Get("FORMAT")
if format == "" {
return "png256", nil
}
if strings.HasPrefix(format, "image/png") {
if format == "image/png; mode=24bit" {
return "png32", nil
}
return "png256", nil
} else if strings.HasPrefix(format, "image/jpeg") {
return "jpeg", nil
} else {
return "png256", &InvalidParamError{Param: "FORMAT", Value: format}
}
}
func parseScaleFactor(q url.Values) (float64, error) {
v := q.Get("SCALE_FACTOR")
if v == "" {
return 1.0, nil
}
scalef, err := strconv.ParseFloat(v, 64)
if err != nil || scalef <= 0.01 || scalef >= 100.0 {
return 1.0, &InvalidParamError{Param: "SCALE_FACTOR", Value: v}
}
return scalef, nil
}