feat(dev): Add provider example package

internal/provider/example/updater/api.go

@@ -0,0 +1,61 @@
+package updater
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+)
+
+var (
+	errHTTPStatusCodeNotOK = errors.New("HTTP status code not OK")
+)
+
+type apiData struct {
+	Servers []apiServer `json:"servers"`
+}
+
+type apiServer struct {
+	OpenVPNHostname   string `json:"openvpn_hostname"`
+	WireguardHostname string `json:"wireguard_hostname"`
+	Country           string `json:"country"`
+	Region            string `json:"region"`
+	City              string `json:"city"`
+	WgPubKey          string `json:"wg_public_key"`
+}
+
+func fetchAPI(ctx context.Context, client *http.Client) (
+	data apiData, err error) {
+	// TODO: adapt this URL and the structures above to match the real
+	// API models you have.
+	const url = "https://example.com/servers"
+
+	request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return data, err
+	}
+
+	response, err := client.Do(request)
+	if err != nil {
+		return data, err
+	}
+
+	if response.StatusCode != http.StatusOK {
+		_ = response.Body.Close()
+		return data, fmt.Errorf("%w: %d %s",
+			errHTTPStatusCodeNotOK, response.StatusCode, response.Status)
+	}
+
+	decoder := json.NewDecoder(response.Body)
+	if err := decoder.Decode(&data); err != nil {
+		_ = response.Body.Close()
+		return data, fmt.Errorf("failed unmarshaling response body: %w", err)
+	}
+
+	if err := response.Body.Close(); err != nil {
+		return data, fmt.Errorf("cannot close response body: %w", err)
+	}
+
+	return data, nil
+}