feat: AnswerChatJoinRequestQuery and SendChatJoinRequestWebApp

bots.setJoinChatResults: AnswerChatJoinRequestQuery maps approve/decline/queue to
JoinChatBotResult{Approved,Declined,Queued}; SendChatJoinRequestWebApp opens a Web
App via JoinChatBotResultWebView. Mapping confirmed against telegram-bot-api 10.1.
Hermetic tests; lint clean.

Author: ernado

chat_join_query.go

@@ -0,0 +1,69 @@
+package botapi
+
+import (
+	"context"
+	"strconv"
+
+	"github.com/gotd/td/tg"
+)
+
+// joinRequestQueryID parses a chat_join_request_query_id into the MTProto query
+// id.
+func joinRequestQueryID(id string) (int64, error) {
+	v, err := strconv.ParseInt(id, 10, 64)
+	if err != nil {
+		return 0, &Error{Code: 400, Description: "Bad Request: invalid chat_join_request_query_id"}
+	}
+
+	return v, nil
+}
+
+// AnswerChatJoinRequestQuery responds to a chat join request the bot is asked to
+// resolve. result must be one of "approve", "decline" or "queue" (queue defers
+// the decision to the chat's administrators).
+func (b *Bot) AnswerChatJoinRequestQuery(ctx context.Context, chatJoinRequestQueryID, result string) error {
+	queryID, err := joinRequestQueryID(chatJoinRequestQueryID)
+	if err != nil {
+		return err
+	}
+
+	var res tg.JoinChatBotResultClass
+
+	switch result {
+	case "approve":
+		res = &tg.JoinChatBotResultApproved{}
+	case "decline":
+		res = &tg.JoinChatBotResultDeclined{}
+	case "queue":
+		res = &tg.JoinChatBotResultQueued{}
+	default:
+		return &Error{Code: 400, Description: "Bad Request: result must be approve, decline or queue"}
+	}
+
+	if _, err := b.raw.BotsSetJoinChatResults(ctx, &tg.BotsSetJoinChatResultsRequest{
+		QueryID: queryID,
+		Result:  res,
+	}); err != nil {
+		return asAPIError(err)
+	}
+
+	return nil
+}
+
+// SendChatJoinRequestWebApp opens a Web App in response to a chat join request
+// the bot is asked to resolve, so the user can complete a verification flow.
+func (b *Bot) SendChatJoinRequestWebApp(ctx context.Context, chatJoinRequestQueryID, webAppURL string) error {
+	queryID, err := joinRequestQueryID(chatJoinRequestQueryID)
+	if err != nil {
+		return err
+	}
+
+	if _, err := b.raw.BotsSetJoinChatResults(ctx, &tg.BotsSetJoinChatResultsRequest{
+		QueryID: queryID,
+		Result:  &tg.JoinChatBotResultWebView{URL: webAppURL},
+	}); err != nil {
+		return asAPIError(err)
+	}
+
+	return nil
+}

chat_join_query_test.go

@@ -0,0 +1,70 @@
+package botapi
+
+import (
+	"context"
+	"testing"
+
+	"github.com/gotd/td/tg"
+)
+
+func TestAnswerChatJoinRequestQuery(t *testing.T) {
+	for _, c := range []struct {
+		result string
+		want   tg.JoinChatBotResultClass
+	}{
+		{"approve", &tg.JoinChatBotResultApproved{}},
+		{"decline", &tg.JoinChatBotResultDeclined{}},
+		{"queue", &tg.JoinChatBotResultQueued{}},
+	} {
+		t.Run(c.result, func(t *testing.T) {
+			inv := newMockInvoker()
+			inv.reply(tg.BotsSetJoinChatResultsRequestTypeID, &tg.BoolTrue{})
+
+			if err := newMockBot(inv).AnswerChatJoinRequestQuery(context.Background(), "123", c.result); err != nil {
+				t.Fatalf("AnswerChatJoinRequestQuery: %v", err)
+			}
+
+			var req tg.BotsSetJoinChatResultsRequest
+
+			inv.decode(t, tg.BotsSetJoinChatResultsRequestTypeID, &req)
+
+			if req.QueryID != 123 {
+				t.Fatalf("query id = %d", req.QueryID)
+			}
+
+			if req.Result.TypeID() != c.want.TypeID() {
+				t.Fatalf("result = %#v, want %#v", req.Result, c.want)
+			}
+		})
+	}
+}
+
+func TestAnswerChatJoinRequestQueryInvalid(t *testing.T) {
+	inv := newMockInvoker()
+
+	if err := newMockBot(inv).AnswerChatJoinRequestQuery(context.Background(), "123", "maybe"); err == nil {
+		t.Fatal("expected error for invalid result")
+	}
+
+	if err := newMockBot(inv).AnswerChatJoinRequestQuery(context.Background(), "notanumber", "approve"); err == nil {
+		t.Fatal("expected error for invalid query id")
+	}
+}
+
+func TestSendChatJoinRequestWebApp(t *testing.T) {
+	inv := newMockInvoker()
+	inv.reply(tg.BotsSetJoinChatResultsRequestTypeID, &tg.BoolTrue{})
+
+	if err := newMockBot(inv).SendChatJoinRequestWebApp(context.Background(), "456", "https://example.com/app"); err != nil {
+		t.Fatalf("SendChatJoinRequestWebApp: %v", err)
+	}
+
+	var req tg.BotsSetJoinChatResultsRequest
+
+	inv.decode(t, tg.BotsSetJoinChatResultsRequestTypeID, &req)
+
+	wv, ok := req.Result.(*tg.JoinChatBotResultWebView)
+	if !ok || wv.URL != "https://example.com/app" {
+		t.Fatalf("result = %#v", req.Result)
+	}
+}