102 lines
2.7 KiB
Go
102 lines
2.7 KiB
Go
package service
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import (
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"encoding/json"
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"fmt"
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"io/ioutil"
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"log"
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"net/http"
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"sync"
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"time"
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)
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type GeocodingService interface {
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GetAddressFromCoordinates(latitude, longitude float64) (string, error)
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}
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type nominatimGeocoder struct {
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client *http.Client
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cache sync.Map // key: "lat,lon" → string address
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}
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func NewGeocodingService() GeocodingService {
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client := &http.Client{
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Timeout: 10 * time.Second,
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}
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return &nominatimGeocoder{
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client: client,
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}
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}
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type NominatimResponse struct {
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DisplayName string `json:"display_name"`
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Error string `json:"error"`
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}
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func (g *nominatimGeocoder) GetAddressFromCoordinates(latitude, longitude float64) (string, error) {
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if latitude < -90 || latitude > 90 || longitude < -180 || longitude > 180 {
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return "", fmt.Errorf("invalid coordinates: lat=%f, lon=%f", latitude, longitude)
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}
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// Check in-memory cache first — avoids repeated Nominatim calls for same device
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cacheKey := fmt.Sprintf("%.6f,%.6f", latitude, longitude)
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if cached, ok := g.cache.Load(cacheKey); ok {
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return cached.(string), nil
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}
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url := fmt.Sprintf(
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"https://nominatim.openstreetmap.org/reverse?format=json&lat=%f&lon=%f&zoom=18&addressdetails=1",
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latitude, longitude,
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)
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req, err := http.NewRequest("GET", url, nil)
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if err != nil {
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log.Printf("Request creation error: %v", err)
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return "", err
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}
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req.Header.Set("User-Agent", "AssetManagementApp")
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resp, err := g.client.Do(req)
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if err != nil {
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log.Printf("HTTP request error: %v", err)
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return "", err
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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log.Printf("Nominatim returned HTTP %d for lat=%f lon=%f", resp.StatusCode, latitude, longitude)
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return "", fmt.Errorf("geocoding service returned status %d", resp.StatusCode)
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}
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bodyBytes, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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log.Printf("Error reading response body: %v", err)
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return "", err
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}
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if len(bodyBytes) > 0 && bodyBytes[0] == '<' {
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log.Printf("Nominatim returned HTML instead of JSON (possible rate limit) for lat=%f lon=%f", latitude, longitude)
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return "", fmt.Errorf("geocoding service unavailable (rate limited or network error)")
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}
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var result NominatimResponse
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if err := json.Unmarshal(bodyBytes, &result); err != nil {
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log.Printf("JSON unmarshal error: %v", err)
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return "", err
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}
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if result.Error != "" {
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log.Printf("Nominatim API Error: %s", result.Error)
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return "", fmt.Errorf("geocoding error: %s", result.Error)
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}
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if result.DisplayName == "" {
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log.Printf("No address found for coordinates: %f, %f", latitude, longitude)
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return "", fmt.Errorf("no address found for these coordinates")
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}
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// Store in cache for future calls
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g.cache.Store(cacheKey, result.DisplayName)
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return result.DisplayName, nil
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} |