prepare for admin chat reporting banned users

app/bot/bot.go

@@ -3,6 +3,7 @@ package bot
 import (
 	"fmt"
 	"net/http"
+	"strings"
 	"time"
 )
 
@@ -92,5 +93,5 @@ func DisplayName(msg Message) string {
 	if displayUsername == "" {
 		displayUsername = fmt.Sprintf("%d", msg.From.ID)
 	}
-	return displayUsername
+	return strings.TrimSpace(displayUsername)
 }

app/bot/spam.go

@@ -138,7 +138,8 @@ func (s *SpamFilter) OnMessage(msg Message) (response Response) {
 		return Response{}
 	}
 
-	displayUsername := strings.TrimSpace(DisplayName(msg))
+	displayUsername := DisplayName(msg)
+
 	isEmojiSpam, _ := s.tooManyEmojis(msg.Text, s.MaxAllowedEmoji)
 	stopWordsSpam := s.hasStopWords(msg.Text)
 	similaritySpam := s.isSpamSimilarityHigh(msg.Text)

app/events/telegram.go

@@ -2,6 +2,7 @@ package events
 
 import (
 	"context"
+	"crypto/sha1"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -28,10 +29,16 @@ type TelegramListener struct {
 	SpamLogger   SpamLogger
 	Bot          Bot
 	Group        string // can be int64 or public group username (without "@" prefix)
+	AdminGroup   string // can be int64 or public group username (without "@" prefix)
 	IdleDuration time.Duration
 	SuperUsers   SuperUser
 	StartupMsg   string
-	chatID       int64
+
+	AdminURL    string
+	AdminSecret string
+
+	chatID      int64
+	adminChatID int64
 
 	msgs struct {
 		once sync.Once
@@ -74,6 +81,13 @@ func (l *TelegramListener) Do(ctx context.Context) error {
 		return fmt.Errorf("failed to get chat ID for group %q: %w", l.Group, getChatErr)
 	}
 
+	if l.AdminGroup != "" {
+		if l.adminChatID, getChatErr = l.getChatID(l.AdminGroup); getChatErr != nil {
+			return fmt.Errorf("failed to get chat ID for admin group %q: %w", l.AdminGroup, getChatErr)
+		}
+		log.Printf("[INFO] admin chat ID: %d", l.adminChatID)
+	}
+
 	l.msgs.once.Do(func() {
 		l.msgs.ch = make(chan bot.Response, 100)
 		if l.IdleDuration == 0 {
@@ -159,6 +173,11 @@ func (l *TelegramListener) procEvents(update tbapi.Update) error {
 			errors = multierror.Append(errors, fmt.Errorf("failed to ban %s: %w", banUserStr, err))
 		} else {
 			log.Print(banSuccessMessage)
+			if l.adminChatID != 0 && msg.From.ID != 0 {
+				forwardMsg := fmt.Sprintf("**permanently banned [%s](tg://user?id=%d)**\n[unban](%s) if it was a mistake\n\n%s\n----",
+					banUserStr, msg.From.ID, l.unbanURL(msg.From.ID), strings.ReplaceAll(msg.Text, "\n", " "))
+				l.sendBotResponse(bot.Response{Send: true, Text: forwardMsg, ParseMode: tbapi.ModeMarkdown}, l.adminChatID)
+			}
 		}
 	}
 
@@ -237,7 +256,7 @@ func (l *TelegramListener) SubmitHTML(ctx context.Context, text string) error {
 }
 
 func (l *TelegramListener) getChatID(group string) (int64, error) {
-	chatID, err := strconv.ParseInt(l.Group, 10, 64)
+	chatID, err := strconv.ParseInt(group, 10, 64)
 	if err == nil {
 		return chatID, nil
 	}
@@ -398,3 +417,9 @@ func (l *TelegramListener) transformEntities(entities []tbapi.MessageEntity) *[]
 
 	return &result
 }
+
+func (l *TelegramListener) unbanURL(userID int64) string {
+	// key is SHA1 of user ID + secret
+	key := fmt.Sprintf("%x", sha1.Sum([]byte(fmt.Sprintf("%d%s", userID, l.AdminSecret))))
+	return fmt.Sprintf("%s/%d?key=%s", l.AdminURL, userID, key)
+}

app/main.go

@@ -21,12 +21,15 @@ import (
 
 var opts struct {
 	Telegram struct {
-		Token        string        `long:"token" env:"TOKEN" description:"telegram bot token" default:"test"`
-		Group        string        `long:"group" env:"GROUP" description:"group name/id" default:"test"`
+		Token        string        `long:"token" env:"TOKEN" description:"telegram bot token" required:"true"`
+		Group        string        `long:"group" env:"GROUP" description:"group name/id" required:"true"`
+		AdminGroup   string        `long:"admin-group" env:"ADMIN_GROUP" description:"admin group name/id"`
 		Timeout      time.Duration `long:"timeout" env:"TIMEOUT" default:"30s" description:"http client timeout for telegram" `
 		IdleDuration time.Duration `long:"idle" env:"IDLE" default:"30s" description:"idle duration"`
 	} `group:"telegram" namespace:"telegram" env-namespace:"TELEGRAM"`
 
+	AdminURL string `long:"admin-url" env:"ADMIN_URL" description:"admin root url"`
+
 	LogsPath   string           `short:"l" long:"logs" env:"TELEGRAM_LOGS" default:"logs" description:"path to logs"`
 	SuperUsers events.SuperUser `long:"super" description:"super-users"`
 
@@ -122,6 +125,7 @@ func execute(ctx context.Context) error {
 	tgListener := events.TelegramListener{
 		TbAPI:        tbAPI,
 		Group:        opts.Telegram.Group,
+		AdminGroup:   opts.Telegram.AdminGroup,
 		IdleDuration: opts.Telegram.IdleDuration,
 		SuperUsers:   opts.SuperUsers,
 		Bot:          spamBot,