refactor: use tailscale api for user checking instead of tsnet

internal/service/simple_req.go

@@ -0,0 +1,43 @@
+package service
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+)
+
+func simpleReq[T any](client *http.Client, url string, headers map[string]string) (*T, error) {
+	var decodedRes T
+
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	for key, value := range headers {
+		req.Header.Add(key, value)
+	}
+
+	res, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode < 200 || res.StatusCode >= 300 {
+		return nil, fmt.Errorf("request failed with status: %s", res.Status)
+	}
+
+	body, err := io.ReadAll(res.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	err = json.Unmarshal(body, &decodedRes)
+	if err != nil {
+		return nil, err
+	}
+
+	return &decodedRes, nil
+}