Optical Character Recognition (OCR) Tutorial

// Get a reference to the Pub/Sub component
const {PubSub} = require('@google-cloud/pubsub');
const pubsub = new PubSub();

// Get a reference to the Cloud Storage component
const {Storage} = require('@google-cloud/storage');
const storage = new Storage();

// Get a reference to the Cloud Vision API component
const Vision = require('@google-cloud/vision');
const vision = new Vision.ImageAnnotatorClient();

// Get a reference to the Translate API component
const {Translate} = require('@google-cloud/translate').v2;
const translate = new Translate();

const functions = require('@google-cloud/functions-framework');

import base64
import json
import os

from cloudevents.http import CloudEvent

import functions_framework

from google.cloud import pubsub_v1
from google.cloud import storage
from google.cloud import translate_v2 as translate
from google.cloud import vision


vision_client = vision.ImageAnnotatorClient()
translate_client = translate.Client()
publisher = pubsub_v1.PublisherClient()
storage_client = storage.Client()

project_id = os.environ.get("GCP_PROJECT")

// Package ocr contains Go samples for creating OCR
// (Optical Character Recognition) Cloud functions.
package ocr

import (
	"context"
	"fmt"
	"os"
	"strings"

	"cloud.google.com/go/pubsub"
	"cloud.google.com/go/storage"
	"cloud.google.com/go/translate"
	vision "cloud.google.com/go/vision/apiv1"
	"golang.org/x/text/language"
)

type ocrMessage struct {
	Text     string       `json:"text"`
	FileName string       `json:"fileName"`
	Lang     language.Tag `json:"lang"`
	SrcLang  language.Tag `json:"srcLang"`
}

// Eventarc sends a MessagePublishedData object.
// See the documentation for additional fields and more details:
// https://cloud.google.com/eventarc/docs/cloudevents#pubsub_1
type MessagePublishedData struct {
	Message PubSubMessage
}

// PubSubMessage is the payload of a Pub/Sub event.
// See the documentation for additional fields and more details:
// https://cloud.google.com/pubsub/docs/reference/rest/v1/PubsubMessage
type PubSubMessage struct {
	Data []byte `json:"data"`
}

var (
	visionClient    *vision.ImageAnnotatorClient
	translateClient *translate.Client
	pubsubClient    *pubsub.Client
	storageClient   *storage.Client

	projectID      string
	resultBucket   string
	resultTopic    string
	toLang         []string
	translateTopic string
)

func setup(ctx context.Context) error {
	projectID = os.Getenv("GCP_PROJECT")
	resultBucket = os.Getenv("RESULT_BUCKET")
	resultTopic = os.Getenv("RESULT_TOPIC")
	toLang = strings.Split(os.Getenv("TO_LANG"), ",")
	translateTopic = os.Getenv("TRANSLATE_TOPIC")

	var err error // Prevent shadowing clients with :=.

	if visionClient == nil {
		visionClient, err = vision.NewImageAnnotatorClient(ctx)
		if err != nil {
			return fmt.Errorf("vision.NewImageAnnotatorClient: %w", err)
		}
	}

	if translateClient == nil {
		translateClient, err = translate.NewClient(ctx)
		if err != nil {
			return fmt.Errorf("translate.NewClient: %w", err)
		}
	}

	if pubsubClient == nil {
		pubsubClient, err = pubsub.NewClient(ctx, projectID)
		if err != nil {
			return fmt.Errorf("translate.NewClient: %w", err)
		}
	}

	if storageClient == nil {
		storageClient, err = storage.NewClient(ctx)
		if err != nil {
			return fmt.Errorf("storage.NewClient: %w", err)
		}
	}
	return nil
}

public class OcrProcessImage implements CloudEventsFunction {
  // TODO<developer> set these environment variables
  private static final String PROJECT_ID = System.getenv("GCP_PROJECT");
  private static final String TRANSLATE_TOPIC_NAME = System.getenv("TRANSLATE_TOPIC");
  private static final String[] TO_LANGS = System.getenv("TO_LANG") == null ? new String[] { "es" }
      : System.getenv("TO_LANG").split(",");

  private static final Logger logger = Logger.getLogger(OcrProcessImage.class.getName());
  private static final String LOCATION_NAME = LocationName.of(PROJECT_ID, "global").toString();
  private Publisher publisher;

  public OcrProcessImage() throws IOException {
    publisher = Publisher.newBuilder(ProjectTopicName.of(PROJECT_ID, TRANSLATE_TOPIC_NAME)).build();
  }

}

/**
 * This function is exported by index.js, and is executed when
 * a file is uploaded to the Cloud Storage bucket you created
 * for uploading images.
 *
 * @param {object} cloudEvent A CloudEvent containing the Cloud Storage File object.
 * https://cloud.google.com/storage/docs/json_api/v1/objects
 */
functions.cloudEvent('processImage', async cloudEvent => {
  const {bucket, name} = cloudEvent.data;

  if (!bucket) {
    throw new Error(
      'Bucket not provided. Make sure you have a "bucket" property in your request'
    );
  }
  if (!name) {
    throw new Error(
      'Filename not provided. Make sure you have a "name" property in your request'
    );
  }

  await detectText(bucket, name);
  console.log(`File ${name} processed.`);
});

@functions_framework.cloud_event
def process_image(cloud_event: CloudEvent) -> None:
    """Cloud Function triggered by Cloud Storage when a file is changed.

    Gets the names of the newly created object and its bucket then calls
    detect_text to find text in that image.

    detect_text finishes by sending PubSub messages requesting another service
    then complete processing those texts by translating them and saving the
    translations.
    """

    # Check that the received event is of the expected type, return error if not
    expected_type = "google.cloud.storage.object.v1.finalized"
    received_type = cloud_event["type"]
    if received_type != expected_type:
        raise ValueError(f"Expected {expected_type} but received {received_type}")

    # Extract the bucket and file names of the uploaded image for processing
    data = cloud_event.data
    bucket = data["bucket"]
    filename = data["name"]

    # Process the information in the new image
    detect_text(bucket, filename)

    print(f"File {filename} processed.")

package ocr

import (
	"context"
	"fmt"
	"log"

	"github.com/GoogleCloudPlatform/functions-framework-go/functions"
	"github.com/cloudevents/sdk-go/v2/event"
	"github.com/googleapis/google-cloudevents-go/cloud/storagedata"
	"google.golang.org/protobuf/encoding/protojson"
)

func init() {
	functions.CloudEvent("process-image", ProcessImage)
}

// ProcessImage is executed when a file is uploaded to the Cloud Storage bucket you
// created for uploading images. It runs detectText, which processes the image for text.
func ProcessImage(ctx context.Context, cloudevent event.Event) error {
	if err := setup(ctx); err != nil {
		return fmt.Errorf("ProcessImage: %w", err)
	}

	var data storagedata.StorageObjectData
	if err := protojson.Unmarshal(cloudevent.Data(), &data); err != nil {
		return fmt.Errorf("protojson.Unmarshal: Failed to parse CloudEvent data: %w", err)
	}
	if data.GetBucket() == "" {
		return fmt.Errorf("empty file.Bucket")
	}
	if data.GetName() == "" {
		return fmt.Errorf("empty file.Name")
	}
	if err := detectText(ctx, data.GetBucket(), data.GetName()); err != nil {
		return fmt.Errorf("detectText: %w", err)
	}
	log.Printf("File %s processed.", data.GetName())
	return nil
}

import com.google.cloud.functions.CloudEventsFunction;
import com.google.cloud.pubsub.v1.Publisher;
import com.google.cloud.translate.v3.DetectLanguageRequest;
import com.google.cloud.translate.v3.DetectLanguageResponse;
import com.google.cloud.translate.v3.LocationName;
import com.google.cloud.translate.v3.TranslationServiceClient;
import com.google.cloud.vision.v1.AnnotateImageRequest;
import com.google.cloud.vision.v1.AnnotateImageResponse;
import com.google.cloud.vision.v1.Feature;
import com.google.cloud.vision.v1.Image;
import com.google.cloud.vision.v1.ImageAnnotatorClient;
import com.google.cloud.vision.v1.ImageSource;
import com.google.events.cloud.storage.v1.StorageObjectData;
import com.google.protobuf.ByteString;
import com.google.protobuf.InvalidProtocolBufferException;
import com.google.protobuf.util.JsonFormat;
import com.google.pubsub.v1.ProjectTopicName;
import com.google.pubsub.v1.PubsubMessage;
import io.cloudevents.CloudEvent;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.logging.Level;
import java.util.logging.Logger;

  @Override
  public void accept(CloudEvent event) throws InvalidProtocolBufferException {
    // Unmarshal data from CloudEvent
    String cloudEventData = new String(event.getData().toBytes(), StandardCharsets.UTF_8);
    StorageObjectData.Builder builder = StorageObjectData.newBuilder();
    JsonFormat.parser().merge(cloudEventData, builder);
    StorageObjectData gcsEvent = builder.build();

    String bucket = gcsEvent.getBucket();
    if (bucket.isEmpty()) {
      throw new IllegalArgumentException("Missing bucket parameter");
    }
    String filename = gcsEvent.getName();
    if (filename.isEmpty()) {
      throw new IllegalArgumentException("Missing name parameter");
    }

    detectText(bucket, filename);
  }
}

/**
 * Detects the text in an image using the Google Vision API.
 *
 * @param {string} bucketName Cloud Storage bucket name.
 * @param {string} filename Cloud Storage file name.
 * @returns {Promise}
 */
const detectText = async (bucketName, filename) => {
  console.log(`Looking for text in image ${filename}`);
  const [textDetections] = await vision.textDetection(
    `gs://${bucketName}/${filename}`
  );
  const [annotation] = textDetections.textAnnotations;
  const text = annotation ? annotation.description.trim() : '';
  console.log('Extracted text from image:', text);

  let [translateDetection] = await translate.detect(text);
  if (Array.isArray(translateDetection)) {
    [translateDetection] = translateDetection;
  }
  console.log(
    `Detected language "${translateDetection.language}" for ${filename}`
  );

  // Submit a message to the bus for each language we're going to translate to
  const TO_LANGS = process.env.TO_LANG.split(',');
  const topicName = process.env.TRANSLATE_TOPIC;

  const tasks = TO_LANGS.map(lang => {
    const messageData = {
      text: text,
      filename: filename,
      lang: lang,
    };

    // Helper function that publishes translation result to a Pub/Sub topic
    // For more information on publishing Pub/Sub messages, see this page:
    //   https://cloud.google.com/pubsub/docs/publisher
    return publishResult(topicName, messageData);
  });

  return Promise.all(tasks);
};

def detect_text(bucket: str, filename: str) -> None:
    """Extract the text from an image uploaded to Cloud Storage, then
    publish messages requesting subscribing services translate the text
    to each target language and save the result.

    Args:
        bucket: name of GCS bucket in which the file is stored.
        filename: name of the file to be read.
    """

    print(f"Looking for text in image {filename}")

    # Use the Vision API to extract text from the image
    image = vision.Image(
        source=vision.ImageSource(gcs_image_uri=f"gs://{bucket}/{filename}")
    )
    text_detection_response = vision_client.text_detection(image=image)
    annotations = text_detection_response.text_annotations

    if annotations:
        text = annotations[0].description
    else:
        text = ""
    print(f"Extracted text {text} from image ({len(text)} chars).")

    detect_language_response = translate_client.detect_language(text)
    src_lang = detect_language_response["language"]
    print(f"Detected language {src_lang} for text {text}.")

    # Submit a message to the bus for each target language
    futures = []  # Asynchronous publish request statuses

    to_langs = os.environ.get("TO_LANG", "").split(",")
    for target_lang in to_langs:
        topic_name = os.environ.get("TRANSLATE_TOPIC")
        if src_lang == target_lang or src_lang == "und":
            topic_name = os.environ.get("RESULT_TOPIC")

        message = {
            "text": text,
            "filename": filename,
            "lang": target_lang,
            "src_lang": src_lang,
        }

        message_data = json.dumps(message).encode("utf-8")
        topic_path = publisher.topic_path(project_id, topic_name)
        future = publisher.publish(topic_path, data=message_data)
        futures.append(future)

    # Wait for each publish request to be completed before exiting
    for future in futures:
        future.result()

package ocr

import (
	"context"
	"encoding/json"
	"fmt"
	"log"

	"cloud.google.com/go/pubsub"
	"cloud.google.com/go/vision/v2/apiv1/visionpb"
	"golang.org/x/text/language"
)

// detectText detects the text in an image using the Google Vision API.
func detectText(ctx context.Context, bucketName, fileName string) error {
	log.Printf("Looking for text in image %v", fileName)
	maxResults := 1
	image := &visionpb.Image{
		Source: &visionpb.ImageSource{
			GcsImageUri: fmt.Sprintf("gs://%s/%s", bucketName, fileName),
		},
	}
	annotations, err := visionClient.DetectTexts(ctx, image, &visionpb.ImageContext{}, maxResults)
	if err != nil {
		return fmt.Errorf("DetectTexts: %w", err)
	}
	text := ""
	if len(annotations) > 0 {
		text = annotations[0].Description
	}
	if len(annotations) == 0 || len(text) == 0 {
		log.Printf("No text detected in image %q. Returning early.", fileName)
		return nil
	}
	log.Printf("Extracted text %q from image (%d chars).", text, len(text))

	detectResponse, err := translateClient.DetectLanguage(ctx, []string{text})
	if err != nil {
		return fmt.Errorf("DetectLanguage: %w", err)
	}
	if len(detectResponse) == 0 || len(detectResponse[0]) == 0 {
		return fmt.Errorf("DetectLanguage gave empty response")
	}
	srcLang := detectResponse[0][0].Language.String()
	log.Printf("Detected language %q for text %q.", srcLang, text)

	// Submit a message to the bus for each target language
	for _, targetLang := range toLang {
		topicName := translateTopic
		if srcLang == targetLang || srcLang == "und" { // detection returns "und" for undefined language
			topicName = resultTopic
		}
		targetTag, err := language.Parse(targetLang)
		if err != nil {
			return fmt.Errorf("language.Parse: %w", err)
		}
		srcTag, err := language.Parse(srcLang)
		if err != nil {
			return fmt.Errorf("language.Parse: %w", err)
		}
		message, err := json.Marshal(ocrMessage{
			Text:     text,
			FileName: fileName,
			Lang:     targetTag,
			SrcLang:  srcTag,
		})
		if err != nil {
			return fmt.Errorf("json.Marshal: %w", err)
		}
		topic := pubsubClient.Topic(topicName)
		ok, err := topic.Exists(ctx)
		if err != nil {
			return fmt.Errorf("Exists: %w", err)
		}
		if !ok {
			topic, err = pubsubClient.CreateTopic(ctx, topicName)
			if err != nil {
				return fmt.Errorf("CreateTopic: %w", err)
			}
		}
		msg := &pubsub.Message{
			Data: []byte(message),
		}
		log.Printf("Sending pubsub message: %s", message)
		if _, err = topic.Publish(ctx, msg).Get(ctx); err != nil {
			return fmt.Errorf("Get: %w", err)
		}
	}
	return nil
}

private void detectText(String bucket, String filename) {
  logger.info("Looking for text in image " + filename);

  List<AnnotateImageRequest> visionRequests = new ArrayList<>();
  String gcsPath = String.format("gs://%s/%s", bucket, filename);

  ImageSource imgSource = ImageSource.newBuilder().setGcsImageUri(gcsPath).build();
  Image img = Image.newBuilder().setSource(imgSource).build();

  Feature textFeature = Feature.newBuilder().setType(Feature.Type.TEXT_DETECTION).build();
  AnnotateImageRequest visionRequest = AnnotateImageRequest.newBuilder()
      .addFeatures(textFeature).setImage(img)
      .build();
  visionRequests.add(visionRequest);

  // Detect text in an image using the Cloud Vision API
  AnnotateImageResponse visionResponse;
  try (ImageAnnotatorClient client = ImageAnnotatorClient.create()) {
    visionResponse = client.batchAnnotateImages(visionRequests).getResponses(0);
    if (visionResponse == null || !visionResponse.hasFullTextAnnotation()) {
      logger.info(String.format("Image %s contains no text", filename));
      return;
    }

    if (visionResponse.hasError()) {
      // Log error
      logger.log(
          Level.SEVERE, "Error in vision API call: " + visionResponse.getError().getMessage());
      return;
    }
  } catch (IOException e) {
    // Log error (since IOException cannot be thrown by a Cloud Function)
    logger.log(Level.SEVERE, "Error detecting text: " + e.getMessage(), e);
    return;
  }

  String text = visionResponse.getFullTextAnnotation().getText();
  logger.info("Extracted text from image: " + text);

  // Detect language using the Cloud Translation API
  DetectLanguageRequest languageRequest = DetectLanguageRequest.newBuilder()
      .setParent(LOCATION_NAME)
      .setMimeType("text/plain")
      .setContent(text)
      .build();
  DetectLanguageResponse languageResponse;
  try (TranslationServiceClient client = TranslationServiceClient.create()) {
    languageResponse = client.detectLanguage(languageRequest);
  } catch (IOException e) {
    // Log error (since IOException cannot be thrown by a function)
    logger.log(Level.SEVERE, "Error detecting language: " + e.getMessage(), e);
    return;
  }

  if (languageResponse.getLanguagesCount() == 0) {
    logger.info("No languages were detected for text: " + text);
    return;
  }

  String languageCode = languageResponse.getLanguages(0).getLanguageCode();
  logger.info(String.format("Detected language %s for file %s", languageCode, filename));

  // Send a Pub/Sub translation request for every language we're going to
  // translate to
  for (String targetLanguage : TO_LANGS) {
    logger.info("Sending translation request for language " + targetLanguage);
    OcrTranslateApiMessage message = new OcrTranslateApiMessage(text, filename, targetLanguage);
    ByteString byteStr = ByteString.copyFrom(message.toPubsubData());
    PubsubMessage pubsubApiMessage = PubsubMessage.newBuilder().setData(byteStr).build();
    try {
      publisher.publish(pubsubApiMessage).get();
    } catch (InterruptedException | ExecutionException e) {
      // Log error
      logger.log(Level.SEVERE, "Error publishing translation request: " + e.getMessage(), e);
      return;
    }
  }
}

/**
 * This function is exported by index.js, and is executed when
 * a message is published to the Cloud Pub/Sub topic specified
 * by the TRANSLATE_TOPIC environment variable. The function
 * translates text using the Google Translate API.
 *
 * @param {object} cloudEvent The CloudEvent containing the Pub/Sub Message object
 * https://cloud.google.com/storage/docs/json_api/v1/objects
 */
functions.cloudEvent('translateText', async cloudEvent => {
  const pubsubData = cloudEvent.data;
  const jsonStr = Buffer.from(pubsubData.message, 'base64').toString();
  const {text, filename, lang} = JSON.parse(jsonStr);

  if (!text) {
    throw new Error(
      'Text not provided. Make sure you have a "text" property in your request'
    );
  }
  if (!filename) {
    throw new Error(
      'Filename not provided. Make sure you have a "filename" property in your request'
    );
  }
  if (!lang) {
    throw new Error(
      'Language not provided. Make sure you have a "lang" property in your request'
    );
  }

  console.log(`Translating text into ${lang}`);
  const [translation] = await translate.translate(text, lang);

  console.log('Translated text:', translation);

  const messageData = {
    text: translation,
    filename: filename,
    lang: lang,
  };

  await publishResult(process.env.RESULT_TOPIC, messageData);
  console.log(`Text translated to ${lang}`);
});

@functions_framework.cloud_event
def translate_text(cloud_event: CloudEvent) -> None:
    """Cloud Function triggered by PubSub when a message is received from
    a subscription.

    Translates the text in the message from the specified source language
    to the requested target language, then sends a message requesting another
    service save the result.
    """

    # Check that the received event is of the expected type, return error if not
    expected_type = "google.cloud.pubsub.topic.v1.messagePublished"
    received_type = cloud_event["type"]
    if received_type != expected_type:
        raise ValueError(f"Expected {expected_type} but received {received_type}")

    # Extract the message body, expected to be a JSON representation of a
    # dictionary, and extract the fields from that dictionary.
    data = cloud_event.data["message"]["data"]
    try:
        message_data = base64.b64decode(data)
        message = json.loads(message_data)

        text = message["text"]
        filename = message["filename"]
        target_lang = message["lang"]
        src_lang = message["src_lang"]
    except Exception as e:
        raise ValueError(f"Missing or malformed PubSub message {data}: {e}.")

    # Translate the text and publish a message with the translation
    print(f"Translating text into {target_lang}.")

    translated_text = translate_client.translate(
        text, target_language=target_lang, source_language=src_lang
    )

    topic_name = os.environ["RESULT_TOPIC"]
    message = {
        "text": translated_text["translatedText"],
        "filename": filename,
        "lang": target_lang,
    }
    message_data = json.dumps(message).encode("utf-8")
    topic_path = publisher.topic_path(project_id, topic_name)
    future = publisher.publish(topic_path, data=message_data)
    future.result()  # Wait for operation to complete

package ocr

import (
	"context"
	"encoding/json"
	"fmt"
	"log"

	"cloud.google.com/go/pubsub"
	"cloud.google.com/go/translate"
	"github.com/GoogleCloudPlatform/functions-framework-go/functions"
	"github.com/cloudevents/sdk-go/v2/event"
)

func init() {
	functions.CloudEvent("translate-text", TranslateText)
}

// TranslateText is executed when a message is published to the Cloud Pub/Sub
// topic specified by the TRANSLATE_TOPIC environment variable, and translates
// the text using the Google Translate API.
func TranslateText(ctx context.Context, cloudevent event.Event) error {
	var event MessagePublishedData
	if err := setup(ctx); err != nil {
		return fmt.Errorf("setup: %w", err)
	}
	if err := cloudevent.DataAs(&event); err != nil {
		return fmt.Errorf("Failed to parse CloudEvent data: %w", err)
	}
	if event.Message.Data == nil {
		log.Printf("event: %s", event)
		return fmt.Errorf("empty data")
	}
	var message ocrMessage
	if err := json.Unmarshal(event.Message.Data, &message); err != nil {
		return fmt.Errorf("json.Unmarshal: %w", err)
	}

	log.Printf("Translating text into %s.", message.Lang.String())
	opts := translate.Options{
		Source: message.SrcLang,
	}
	translateResponse, err := translateClient.Translate(ctx, []string{message.Text}, message.Lang, &opts)
	if err != nil {
		return fmt.Errorf("Translate: %w", err)
	}
	if len(translateResponse) == 0 {
		return fmt.Errorf("Empty Translate response")
	}
	translatedText := translateResponse[0]

	messageData, err := json.Marshal(ocrMessage{
		Text:     translatedText.Text,
		FileName: message.FileName,
		Lang:     message.Lang,
		SrcLang:  message.SrcLang,
	})
	if err != nil {
		return fmt.Errorf("json.Marshal: %w", err)
	}

	topic := pubsubClient.Topic(resultTopic)
	ok, err := topic.Exists(ctx)
	if err != nil {
		return fmt.Errorf("Exists: %w", err)
	}
	if !ok {
		topic, err = pubsubClient.CreateTopic(ctx, resultTopic)
		if err != nil {
			return fmt.Errorf("CreateTopic: %w", err)
		}
	}
	msg := &pubsub.Message{
		Data: messageData,
	}
	if _, err = topic.Publish(ctx, msg).Get(ctx); err != nil {
		return fmt.Errorf("Get: %w", err)
	}
	log.Printf("Sent translation: %q", translatedText.Text)
	return nil
}

import com.google.cloud.functions.CloudEventsFunction;
import com.google.cloud.pubsub.v1.Publisher;
import com.google.cloud.translate.v3.LocationName;
import com.google.cloud.translate.v3.TranslateTextRequest;
import com.google.cloud.translate.v3.TranslateTextResponse;
import com.google.cloud.translate.v3.TranslationServiceClient;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonParseException;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.ProjectTopicName;
import com.google.pubsub.v1.PubsubMessage;
import functions.eventpojos.MessagePublishedData;
import io.cloudevents.CloudEvent;
import java.io.IOException;
import java.lang.reflect.Type;
import java.nio.charset.StandardCharsets;
import java.time.OffsetDateTime;
import java.util.concurrent.ExecutionException;
import java.util.logging.Level;
import java.util.logging.Logger;

public class OcrTranslateText implements CloudEventsFunction {
  private static final Logger logger = Logger.getLogger(OcrTranslateText.class.getName());

  // TODO<developer> set these environment variables
  private static final String PROJECT_ID = getenv("GCP_PROJECT");
  private static final String RESULTS_TOPIC_NAME = getenv("RESULT_TOPIC");
  private static final String LOCATION_NAME = LocationName.of(PROJECT_ID, "global").toString();

  private Publisher publisher;

  public OcrTranslateText() throws IOException {
    publisher = Publisher.newBuilder(ProjectTopicName.of(PROJECT_ID, RESULTS_TOPIC_NAME)).build();
  }

  // Create custom deserializer to handle timestamps in event data
  class DateDeserializer implements JsonDeserializer<OffsetDateTime> {
    @Override
    public OffsetDateTime deserialize(
        JsonElement json, Type typeOfT, JsonDeserializationContext context)
        throws JsonParseException {
      return OffsetDateTime.parse(json.getAsString());
    }
  }

  Gson gson =
      new GsonBuilder().registerTypeAdapter(OffsetDateTime.class, new DateDeserializer()).create();

  @Override
  public void accept(CloudEvent event) throws InterruptedException, IOException {
    MessagePublishedData data =
        gson.fromJson(
            new String(event.getData().toBytes(), StandardCharsets.UTF_8),
            MessagePublishedData.class);
    OcrTranslateApiMessage ocrMessage =
        OcrTranslateApiMessage.fromPubsubData(
            data.getMessage().getData().getBytes(StandardCharsets.UTF_8));

    String targetLang = ocrMessage.getLang();
    logger.info("Translating text into " + targetLang);

    // Translate text to target language
    String text = ocrMessage.getText();
    TranslateTextRequest request =
        TranslateTextRequest.newBuilder()
            .setParent(LOCATION_NAME)
            .setMimeType("text/plain")
            .setTargetLanguageCode(targetLang)
            .addContents(text)
            .build();

    TranslateTextResponse response;
    try (TranslationServiceClient client = TranslationServiceClient.create()) {
      response = client.translateText(request);
    } catch (IOException e) {
      // Log error (since IOException cannot be thrown by a function)
      logger.log(Level.SEVERE, "Error translating text: " + e.getMessage(), e);
      return;
    }
    if (response.getTranslationsCount() == 0) {
      return;
    }

    String translatedText = response.getTranslations(0).getTranslatedText();
    logger.info("Translated text: " + translatedText);

    // Send translated text to (subsequent) Pub/Sub topic
    String filename = ocrMessage.getFilename();
    OcrTranslateApiMessage translateMessage =
        new OcrTranslateApiMessage(translatedText, filename, targetLang);
    try {
      ByteString byteStr = ByteString.copyFrom(translateMessage.toPubsubData());
      PubsubMessage pubsubApiMessage = PubsubMessage.newBuilder().setData(byteStr).build();
      publisher.publish(pubsubApiMessage).get();
      logger.info("Text translated to " + targetLang);
    } catch (InterruptedException | ExecutionException e) {
      // Log error (since these exception types cannot be thrown by a function)
      logger.log(Level.SEVERE, "Error publishing translation save request: " + e.getMessage(), e);
    }
  }

  // Avoid ungraceful deployment failures due to unset environment variables.
  // If you get this warning you should redeploy with the variable set.
  private static String getenv(String name) {
    String value = System.getenv(name);
    if (value == null) {
      logger.warning("Environment variable " + name + " was not set");
      value = "MISSING";
    }
    return value;
  }
}

/**
 * This function is exported by index.js, and is executed when
 * a message is published to the Cloud Pub/Sub topic specified
 * by the RESULT_TOPIC environment variable. The function saves
 * the data packet to a file in GCS.
 *
 * @param {object} cloudEvent The CloudEvent containing the Pub/Sub Message object.
 * https://cloud.google.com/storage/docs/json_api/v1/objects
 */
functions.cloudEvent('saveResult', async cloudEvent => {
  const pubsubData = cloudEvent.data;
  const jsonStr = Buffer.from(pubsubData.message, 'base64').toString();
  const {text, filename, lang} = JSON.parse(jsonStr);

  if (!text) {
    throw new Error(
      'Text not provided. Make sure you have a "text" property in your request'
    );
  }
  if (!filename) {
    throw new Error(
      'Filename not provided. Make sure you have a "filename" property in your request'
    );
  }
  if (!lang) {
    throw new Error(
      'Language not provided. Make sure you have a "lang" property in your request'
    );
  }

  console.log(`Received request to save file ${filename}`);

  const bucketName = process.env.RESULT_BUCKET;
  const newFilename = renameImageForSave(filename, lang);
  const file = storage.bucket(bucketName).file(newFilename);

  console.log(`Saving result to ${newFilename} in bucket ${bucketName}`);

  await file.save(text);
  console.log('File saved.');
});

@functions_framework.cloud_event
def save_result(cloud_event: CloudEvent) -> None:
    """Cloud Function triggered by PubSub when a message is received from
    a subscription.

    Saves translated text to a Cloud Storage object as requested.
    """
    # Check that the received event is of the expected type, return error if not
    expected_type = "google.cloud.pubsub.topic.v1.messagePublished"
    received_type = cloud_event["type"]
    if received_type != expected_type:
        raise ValueError(f"Expected {expected_type} but received {received_type}")

    # Extract the message body, expected to be a JSON representation of a
    # dictionary, and extract the fields from that dictionary.
    data = cloud_event.data["message"]["data"]
    try:
        message_data = base64.b64decode(data)
        message = json.loads(message_data)

        text = message["text"]
        filename = message["filename"]
        lang = message["lang"]
    except Exception as e:
        raise ValueError(f"Missing or malformed PubSub message {data}: {e}.")

    print(f"Received request to save file {filename}.")

    # Save the translation in RESULT_BUCKET
    bucket_name = os.environ["RESULT_BUCKET"]
    result_filename = f"{filename}_{lang}.txt"
    bucket = storage_client.get_bucket(bucket_name)
    blob = bucket.blob(result_filename)

    print(f"Saving result to {result_filename} in bucket {bucket_name}.")

    blob.upload_from_string(text)

    print("File saved.")

package ocr

import (
	"context"
	"encoding/json"
	"fmt"
	"log"

	"github.com/GoogleCloudPlatform/functions-framework-go/functions"
	"github.com/cloudevents/sdk-go/v2/event"
)

func init() {
	functions.CloudEvent("save-result", SaveResult)
}

// SaveResult is executed when a message is published to the Cloud Pub/Sub topic
// specified by the RESULT_TOPIC environment vairable, and saves the data packet
// to a file in GCS.
func SaveResult(ctx context.Context, cloudevent event.Event) error {
	var event MessagePublishedData
	if err := setup(ctx); err != nil {
		return fmt.Errorf("ProcessImage: %w", err)
	}
	if err := cloudevent.DataAs(&event); err != nil {
		return fmt.Errorf("Failed to parse CloudEvent data: %w", err)
	}
	var message ocrMessage
	if event.Message.Data == nil {
		return fmt.Errorf("Empty data")
	}
	if err := json.Unmarshal(event.Message.Data, &message); err != nil {
		return fmt.Errorf("json.Unmarshal: %w", err)
	}
	log.Printf("Received request to save file %q.", message.FileName)

	resultFilename := fmt.Sprintf("%s_%s.txt", message.FileName, message.Lang)
	bucket := storageClient.Bucket(resultBucket)

	log.Printf("Saving result to %q in bucket %q.", resultFilename, resultBucket)

	w := bucket.Object(resultFilename).NewWriter(ctx)
	defer w.Close()
	fmt.Fprint(w, message.Text)

	log.Printf("File saved.")
	return nil
}

import com.google.cloud.functions.CloudEventsFunction;
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.BlobInfo;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonParseException;
import functions.eventpojos.MessagePublishedData;
import io.cloudevents.CloudEvent;
import java.lang.reflect.Type;
import java.nio.charset.StandardCharsets;
import java.time.OffsetDateTime;
import java.util.logging.Logger;

public class OcrSaveResult implements CloudEventsFunction {
  // TODO<developer> set this environment variable
  private static final String RESULT_BUCKET = System.getenv("RESULT_BUCKET");

  private static final Storage STORAGE = StorageOptions.getDefaultInstance().getService();
  private static final Logger logger = Logger.getLogger(OcrSaveResult.class.getName());

  // Configure Gson with custom deserializer to handle timestamps in event data
  class DateDeserializer implements JsonDeserializer<OffsetDateTime> {
    @Override
    public OffsetDateTime deserialize(
        JsonElement json, Type typeOfT, JsonDeserializationContext context)
        throws JsonParseException {
      return OffsetDateTime.parse(json.getAsString());
    }
  }

  Gson gson =
      new GsonBuilder().registerTypeAdapter(OffsetDateTime.class, new DateDeserializer()).create();

  @Override
  public void accept(CloudEvent event) {
    // Unmarshal data from CloudEvent
    MessagePublishedData data =
        gson.fromJson(
            new String(event.getData().toBytes(), StandardCharsets.UTF_8),
            MessagePublishedData.class);
    OcrTranslateApiMessage ocrMessage =
        OcrTranslateApiMessage.fromPubsubData(
            data.getMessage().getData().getBytes(StandardCharsets.UTF_8));

    logger.info("Received request to save file " + ocrMessage.getFilename());

    String newFileName =
        String.format("%s_to_%s.txt", ocrMessage.getFilename(), ocrMessage.getLang());

    // Save file to RESULT_BUCKET with name newFileName
    logger.info(String.format("Saving result to %s in bucket %s", newFileName, RESULT_BUCKET));
    BlobInfo blobInfo = BlobInfo.newBuilder(BlobId.of(RESULT_BUCKET, newFileName)).build();
    STORAGE.create(blobInfo, ocrMessage.getText().getBytes(StandardCharsets.UTF_8));
    logger.info("File saved");
  }
}