feat(tgbot): route admin notifications to a forum topic (#6879)

Admins who run the bot in a forum supergroup got every notification in the
General topic. An admin chat ID may now carry a topic, chatId:topicId, and the
bot's admin messages and reports go to that topic. Repeated chats collapse into
one entry and a second, different topic for the same chat is rejected, in the
panel and in the docs setup helper alike. The chat ID hint in every locale and
the English, Persian, Russian and Chinese guides describe the form.

internal/web/service/tgbot/tgbot_test.go

@@ -4,8 +4,12 @@ import (
 	"io"
 	"net"
 	"reflect"
+	"slices"
 	"testing"
 	"time"
+
+	"github.com/mymmrac/telego"
+	tu "github.com/mymmrac/telego/telegoutil"
 )
 
 func TestLoginAttemptDoesNotCarryPassword(t *testing.T) {
@@ -154,3 +158,67 @@ func TestIsCommandForBotKeepsLegacyBehaviorWhenUsernameUnavailable(t *testing.T)
 		t.Fatal("commands must remain accepted when the current bot username is unavailable")
 	}
 }
+
+func TestParseAdminChats(t *testing.T) {
+	cases := []struct {
+		name   string
+		raw    string
+		ids    []int64
+		topics map[int64]int
+	}{
+		{name: "empty", raw: "", ids: []int64{}, topics: map[int64]int{}},
+		{name: "plain ids", raw: "123,-1001", ids: []int64{123, -1001}, topics: map[int64]int{}},
+		{name: "topic", raw: "-1003855200872:42", ids: []int64{-1003855200872}, topics: map[int64]int{-1003855200872: 42}},
+		{name: "mixed with spaces", raw: " 123 , -1001 : 7 ", ids: []int64{123, -1001}, topics: map[int64]int{-1001: 7}},
+		{name: "general topic means no thread", raw: "-1001:1,123", ids: []int64{-1001, 123}, topics: map[int64]int{}},
+		{name: "duplicate chat collapses", raw: "-1001:7,-1001:7,-1001", ids: []int64{-1001}, topics: map[int64]int{-1001: 7}},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			ids, topics, err := parseAdminChats(tc.raw)
+			if err != nil {
+				t.Fatalf("parseAdminChats(%q) error: %v", tc.raw, err)
+			}
+			if !slices.Equal(ids, tc.ids) {
+				t.Fatalf("ids = %v, want %v", ids, tc.ids)
+			}
+			if len(topics) != len(tc.topics) {
+				t.Fatalf("topics = %v, want %v", topics, tc.topics)
+			}
+			for chat, topic := range tc.topics {
+				if topics[chat] != topic {
+					t.Fatalf("topics[%d] = %d, want %d", chat, topics[chat], topic)
+				}
+			}
+		})
+	}
+}
+
+func TestParseAdminChatsRejectsInvalid(t *testing.T) {
+	for _, raw := range []string{"abc", "123:", "123:abc", "123:0", "123:-5", "-1001:7,-1001:8", "123,"} {
+		if _, _, err := parseAdminChats(raw); err == nil {
+			t.Errorf("parseAdminChats(%q) accepted invalid input", raw)
+		}
+	}
+}
+
+func TestInAdminTopicRoutesConfiguredChat(t *testing.T) {
+	tgBotMutex.Lock()
+	orig := adminTopics
+	adminTopics = map[int64]int{-1001: 42}
+	tgBotMutex.Unlock()
+	t.Cleanup(func() {
+		tgBotMutex.Lock()
+		adminTopics = orig
+		tgBotMutex.Unlock()
+	})
+
+	doc := inAdminTopic(tu.Document(tu.ID(-1001), tu.FileFromBytes([]byte("x"), "x.db")))
+	if doc.MessageThreadID != 42 {
+		t.Fatalf("MessageThreadID = %d, want 42", doc.MessageThreadID)
+	}
+	doc = inAdminTopic(&telego.SendDocumentParams{ChatID: tu.ID(123)})
+	if doc.MessageThreadID != 0 {
+		t.Fatalf("MessageThreadID = %d for chat without topic, want 0", doc.MessageThreadID)
+	}
+}