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package metar
import (
"context"
"encoding/xml"
"errors"
"net/http"
"net/url"
"strconv"
"strings"
"time"
)
type Client struct {
hc http.Client
}
const (
MostRecentConstraint = "constraint"
MostRecentPostFilter = "postfilter"
MostRecentTrue = "true"
)
type Response struct {
RequestIndex int `xml:"request_index"`
DataSource struct {
Name string `xml:"name,attr"`
} `xml:"data_source"`
Request struct {
Type string `xml:"type,attr"`
} `xml:"request"`
Errors []string `xml:"errors>error"`
Warnings []string `xml:"warnings>warning"`
TimeTakenMs int `xml:"time_taken_ms"`
Data struct {
NumResults int `xml:"num_results,attr"`
METARs []METAR `xml:"METAR"`
} `xml:"data"`
}
type METAR struct {
RawText string `xml:"raw_text"`
StationID string `xml:"station_id"`
ObservationTime string `xml:"observation_time"`
Latitude float32 `xml:"latitude"`
Longitude float32 `xml:"longitude"`
TempC float32 `xml:"temp_c"`
DewpointC float32 `xml:"dewpoint_c"`
WindDirDegrees int `xml:"wind_dir_degress"`
WindSpeedKt int `xml:"wind_speed_kt"`
WindGustKt int `xml:"wind_gust_kt"`
VisibilityStatuteMi float32 `xml:"visibility_statute_mi"`
AltimInHg float32 `xml:"altim_in_hg"`
SeaLevelPressureMb float32 `xml:"sea_level_pressure_mb"`
QualityControlFlags struct {
Corrected string `xml:"corrected"`
Auto string `xml:"auto"`
AutoStation string `xml:"auto_station"`
MaintenanceIndicatorOn string `xml:"maintenance_indicator_on"`
NoSignal string `xml:"no_signal"`
LightningSensorOff string `xml:"lightning_sensor_off"`
FreezingRainSensorOff string `xml:"freezing_rain_sensor_off"`
PresentWeatherSensorOff string `xml:"present_weather_sensor_off"`
} `xml:"quality_control_flags"`
WxString string `xml:"wx_string"`
SkyConditions []SkyCondition `xml:"sky_condition"`
FlightCategory string `xml:"flight_category"`
ThreeHrPressureTendencyMb float32 `xml:"three_hr_pressure_tendency_mb"`
MaxTC float32 `xml:"maxT_c"`
MinTC float32 `xml:"minT_c"`
MaxT24HrC float32 `xml:"maxT24hr_c"`
MinT24HrC float32 `xml:"minT24hr_c"`
PrecipIn float32 `xml:"precip_in"`
Pcp3HrIn float32 `xml:"pcp3hr_in"`
Pcp6HrIn float32 `xml:"pcp6hr_in"`
Pcp24HrIn float32 `xml:"pcp24hr_in"`
SnowIn float32 `xml:"snow_in"`
VertVisFt int `xml:"vert_vis_ft"`
METARType string `xml:"metar_type"`
ElevationM float32 `xml:"elevation_m"`
}
type SkyCondition struct {
SkyCover string `xml:"sky_cover,attr"`
CloudBaseFtAGL int `xml:"cloud_base_ft_agl,attr"`
}
type Request struct {
v url.Values
}
type requestArg func(*Request)
func NewRequest(args ...requestArg) *Request {
var r Request
for _, arg := range args {
arg(&r)
}
return &r
}
func StationString(s string) requestArg {
return func(r *Request) {
r.v.Add("stationString", s)
}
}
func TimeRange(from, to time.Time) requestArg {
return func(r *Request) {
r.v.Add("startTime", string(from.Unix()))
r.v.Add("endTime", string(to.Unix()))
}
}
func HoursBeforeNow(h float64) requestArg {
return func(r *Request) {
r.v.Add("hoursBeforeNow", strconv.FormatFloat(h, 'f', 64, -1))
}
}
func MostRecent(mr bool) requestArg {
return func(r *Request) {
r.v.Add("mostRecent", strconv.FormatBool(mr))
}
}
func MostRecentForEachStation(s string) requestArg {
return func(r *Request) {
r.v.Add("mostRecentForEachStation", s)
}
}
func LatLongRect(minLat, minLon, maxLat, maxLon float64) requestArg {
return func(r *Request) {
r.v.Add("minLat", strconv.FormatFloat(minLat, 'f', 64, -1))
r.v.Add("minLon", strconv.FormatFloat(minLon, 'f', 64, -1))
r.v.Add("maxLat", strconv.FormatFloat(maxLat, 'f', 64, -1))
r.v.Add("maxLon", strconv.FormatFloat(maxLon, 'f', 64, -1))
}
}
func RadialDistance(s string) requestArg {
return func(r *Request) {
r.v.Add("radialDistance", s)
}
}
func FlightPath(s string) requestArg {
return func(r *Request) {
r.v.Add("flightPath", s)
}
}
func MinDegreeDistance(d float64) requestArg {
return func(r *Request) {
r.v.Add("minDegreeDistance", strconv.FormatFloat(d, 'f', 64, -1))
}
}
func Fields(ss ...string) requestArg {
return func(r *Request) {
r.v.Add("fields", strings.Join(ss, ","))
}
}
func requestToQueryString(m *Request) string {
m.v.Add("dataSource", "metars")
m.v.Add("requestType", "retrieve")
m.v.Add("format", "xml")
return m.v.Encode()
}
func (c *Client) GetMETARs(ctx context.Context, req *Request) (*Response, error) {
u := url.URL{
Scheme: "https",
Host: "www.aviationweather.gov",
Path: "/adds/dataserver_current/httpparam",
RawQuery: requestToQueryString(req),
}
hr, err := http.NewRequestWithContext(ctx, "GET", u.String(), nil)
if err != nil {
return nil, err
}
hr.Header.Add("user-agent", "wxbot/1.0 +bnbl.io/wx")
resp, err := c.hc.Do(hr)
if err != nil {
return nil, err
}
if resp.StatusCode != http.StatusOK {
return nil, errors.New(resp.Status)
}
defer resp.Body.Close()
var r Response
if err := xml.NewDecoder(resp.Body).Decode(&r); err != nil {
return nil, err
}
return &r, nil
}
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