feat: add phone frequency controls and modularize codebase

gateway/internal/inbound/transport.go

@@ -0,0 +1,84 @@
+package inbound
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strings"
+	"time"
+)
+
+func (s Server) post(ctx context.Context, path string, payload any, result any) error {
+	client := s.HTTPClient
+	if client == nil {
+		client = &http.Client{Timeout: defaultHTTPTimeout}
+	}
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, strings.TrimRight(apiBaseURL(s.APIBaseURL), "/")+path, bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	responseBody, err := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
+	if err != nil {
+		return fmt.Errorf("read api response: %w", err)
+	}
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		detail := strings.TrimSpace(string(responseBody))
+		if detail == "" {
+			return fmt.Errorf("api returned %s", resp.Status)
+		}
+		return fmt.Errorf("api returned %s: %s", resp.Status, detail)
+	}
+	if result != nil {
+		if len(responseBody) == 0 {
+			return io.EOF
+		}
+		return json.Unmarshal(responseBody, result)
+	}
+	return nil
+}
+
+func apiBaseURL(value string) string {
+	if value == "" {
+		return "http://127.0.0.1:3000/api"
+	}
+	return value
+}
+
+func remoteIP(addr net.Addr) string {
+	if tcp, ok := addr.(*net.TCPAddr); ok {
+		return tcp.IP.String()
+	}
+	host, _, err := net.SplitHostPort(addr.String())
+	if err == nil {
+		return host
+	}
+	return addr.String()
+}
+
+func defaultString(value string, fallback string) string {
+	if value == "" {
+		return fallback
+	}
+	return value
+}
+
+func formatRFC3339Nano(value time.Time) string {
+	if value.IsZero() {
+		return ""
+	}
+	return value.UTC().Format(time.RFC3339Nano)
+}