feat: add alert notifications and sync roadmap

server/internal/httpapi/telegram.go

@@ -0,0 +1,62 @@
+package httpapi
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+)
+
+type telegramNotificationSender struct {
+	endpoint string
+	client   *http.Client
+}
+
+func NewTelegramNotificationSender(token string) (NotificationSender, error) {
+	token = strings.TrimSpace(token)
+	if len(token) < 20 || len(token) > 256 || strings.ContainsAny(token, "\r\n\t /?") {
+		return nil, errors.New("Telegram bot token is invalid")
+	}
+	return &telegramNotificationSender{
+		endpoint: "https://api.telegram.org/bot" + token + "/sendMessage",
+		client:   &http.Client{Timeout: 15 * time.Second},
+	}, nil
+}
+
+func (s *telegramNotificationSender) SendNotification(ctx context.Context, destination, title, body string) error {
+	if !validTelegramChatID(destination) {
+		return errors.New("Telegram chat ID is invalid")
+	}
+	text := strings.TrimSpace(title) + "\n\n" + strings.TrimSpace(body)
+	if len(text) > 4096 {
+		text = text[:4096]
+	}
+	payload, err := json.Marshal(map[string]any{
+		"chat_id":                  destination,
+		"text":                     text,
+		"disable_web_page_preview": true,
+	})
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, s.endpoint, bytes.NewReader(payload))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	response, err := s.client.Do(req)
+	if err != nil {
+		return fmt.Errorf("send Telegram notification: %w", err)
+	}
+	defer response.Body.Close()
+	_, _ = io.Copy(io.Discard, io.LimitReader(response.Body, 32<<10))
+	if response.StatusCode < 200 || response.StatusCode >= 300 {
+		return fmt.Errorf("Telegram API returned HTTP %d", response.StatusCode)
+	}
+	return nil
+}