Configure Telegram API retries (#528)

Author: rob93c

src/main/java/com/github/stickerifier/stickerify/bot/Stickerify.java

@@ -23,6 +23,7 @@
 import com.pengrad.telegrambot.TelegramBot;
 import com.pengrad.telegrambot.TelegramException;
 import com.pengrad.telegrambot.UpdatesListener;
+import com.pengrad.telegrambot.model.ResponseParameters;
 import com.pengrad.telegrambot.model.Update;
 import com.pengrad.telegrambot.model.request.ReplyParameters;
 import com.pengrad.telegrambot.model.request.richmessages.InputRichMessage;
@@ -33,12 +34,14 @@
 import com.pengrad.telegrambot.request.richmessages.SendRichMessage;
 import com.pengrad.telegrambot.request.richmessages.SendRichMessageDraft;
 import com.pengrad.telegrambot.response.BaseResponse;
+import org.jspecify.annotations.Nullable;
 import org.slf4j.event.Level;
 
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.time.Duration;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.Executor;
@@ -230,9 +233,31 @@ private <T extends BaseRequest<T, R>, R extends BaseResponse> R execute(BaseRequ
 			return response;
 		}
 
+		for (int retry = 1; retry <= 3 && isRetriable(response.parameters()); retry++) {
+			var retryDelay = response.parameters().retryAfter();
+			LOGGER.at(Level.WARN).log("The {} request failed: retrying in {} seconds", request.getMethod(), retryDelay);
+
+			try {
+				Thread.sleep(Duration.ofSeconds(retryDelay));
+			} catch (InterruptedException _) {
+				Thread.currentThread().interrupt();
+				break;
+			}
+
+			response = bot.execute(request);
+
+			if (response.isOk()) {
+				return response;
+			}
+		}
+
 		throw new TelegramApiException(request.getMethod(), response.description());
 	}
 
+	private static boolean isRetriable(@Nullable ResponseParameters parameters) {
+		return parameters != null && parameters.retryAfter() != null;
+	}
+
 	private static void deleteTempFiles(Set<Path> pathsToDelete) {
 		for (var path : pathsToDelete) {
 			try {

src/test/java/com/github/stickerifier/stickerify/bot/MockResponses.java

@@ -13,6 +13,17 @@ public final class MockResponses {
 			}
 			""").build();
 
+	static final MockResponse FAILURE_RESPONSE = new MockResponse.Builder().body("""
+			{
+				ok: false,
+				error_code: 429,
+				description: "Too Many Requests: retry after 3",
+				parameters: {
+					retry_after: 3
+				}
+			}
+			""").build();
+
 	static final MockResponse START_MESSAGE = new MockResponse.Builder().body("""
 			{
 				ok: true,

src/test/java/com/github/stickerifier/stickerify/bot/StickerifyTest.java

@@ -404,4 +404,24 @@ void documentNotSupported() throws Exception {
 			assertResponseContainsMarkdownMessage(sendRichMessage, Answer.ERROR);
 		}
 	}
+
+	@Test
+	void retryApiCall() throws Exception {
+		server.enqueue(MockResponses.HELP_MESSAGE);
+		server.enqueue(MockResponses.FAILURE_RESPONSE);
+		server.enqueue(MockResponses.SUCCESS_RESPONSE);
+
+		try (var _ = runBot()) {
+			var getUpdates = server.takeRequest();
+			assertEquals("/api/token/getUpdates", getUpdates.getTarget());
+
+			var firstSendRichMessage = server.takeRequest();
+			assertEquals("/api/token/sendRichMessage", firstSendRichMessage.getTarget());
+
+			var secondSendRichMessage = server.takeRequest();
+			assertEquals("/api/token/sendRichMessage", secondSendRichMessage.getTarget());
+
+			assertResponseContainsMarkdownMessage(secondSendRichMessage, Answer.HELP);
+		}
+	}
 }