fix(telegram): improve media notification template

internal/service/telegram_api.go

@@ -1,11 +1,13 @@
 package service
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
+	"mime/multipart"
 	"net/http"
 	"net/url"
 	"os"
@@ -120,6 +122,81 @@ func telegramPostJSON(ctx context.Context, cfg map[string]string, method string,
 	return telegramDoWithFallback(ctx, cfg, http.MethodPost, apiURL, string(body), "application/json", timeout)
 }
 
+func telegramPostMultipart(ctx context.Context, cfg map[string]string, method string, fields map[string]string, fileField, fileName string, file []byte, timeout time.Duration) error {
+	apiURL, err := telegramMethodURL(cfg, cfg["bot_token"], method)
+	if err != nil {
+		return err
+	}
+	var body bytes.Buffer
+	writer := multipart.NewWriter(&body)
+	for key, value := range fields {
+		if strings.TrimSpace(value) == "" {
+			continue
+		}
+		if err := writer.WriteField(key, value); err != nil {
+			_ = writer.Close()
+			return err
+		}
+	}
+	part, err := writer.CreateFormFile(fileField, fileName)
+	if err != nil {
+		_ = writer.Close()
+		return err
+	}
+	if _, err := part.Write(file); err != nil {
+		_ = writer.Close()
+		return err
+	}
+	if err := writer.Close(); err != nil {
+		return err
+	}
+	return telegramDoWithFallback(ctx, cfg, http.MethodPost, apiURL, body.String(), writer.FormDataContentType(), timeout)
+}
+
+func telegramFetchRemotePhoto(ctx context.Context, cfg map[string]string, rawURL string, timeout time.Duration) ([]byte, string, error) {
+	rawURL = strings.TrimSpace(rawURL)
+	if rawURL == "" {
+		return nil, "", errors.New("telegram photo url required")
+	}
+	var lastErr error
+	for _, client := range telegramHTTPClients(timeout, cfg) {
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, rawURL, nil)
+		if err != nil {
+			return nil, "", err
+		}
+		req.Header.Set("User-Agent", "MediaStationGo/1.0")
+		resp, err := client.Do(req)
+		if err != nil {
+			lastErr = sanitizeTelegramError(err)
+			continue
+		}
+		body, readErr := io.ReadAll(io.LimitReader(resp.Body, 10*1024*1024+1))
+		_ = resp.Body.Close()
+		if readErr != nil {
+			lastErr = readErr
+			continue
+		}
+		if resp.StatusCode >= 400 {
+			lastErr = fmt.Errorf("photo fetch error %d", resp.StatusCode)
+			continue
+		}
+		if len(body) == 0 {
+			lastErr = errors.New("photo fetch returned empty body")
+			continue
+		}
+		if len(body) > 10*1024*1024 {
+			lastErr = errors.New("photo too large")
+			continue
+		}
+		contentType := strings.TrimSpace(resp.Header.Get("Content-Type"))
+		return body, contentType, nil
+	}
+	if lastErr != nil {
+		return nil, "", lastErr
+	}
+	return nil, "", errors.New("photo fetch failed")
+}
+
 func deleteTelegramWebhook(ctx context.Context, cfg map[string]string) error {
 	payload := map[string]any{
 		"drop_pending_updates": false,