feat: add Transformer

Add Transformer and related classes.

no-ticket

.gitignore

@@ -43,3 +43,5 @@ out/
 *.code-workspace
 # Local History for Visual Studio Code
 .history/
+.vscode/settings.json
+

src/main/java/to/wetransform/hale/transformer/CustomTarget.java

@@ -4,10 +4,17 @@
 import java.util.Map;
 
 import eu.esdihumboldt.hale.common.core.io.Value;
+import org.json.JSONObject;
 
 public record CustomTarget(String providerId, Map<String, Value> settings) {
 
     public CustomTarget(String providerId) {
         this(providerId, new HashMap<>());
     }
+
+    public void setProviderId(String string) {}
+
+    public JSONObject getSettings() {
+        return null;
+    }
 }

src/main/java/to/wetransform/hale/transformer/ResultCallbackHelper.java

@@ -0,0 +1,132 @@
+package to.wetransform.hale.transformer;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.util.Optional;
+import java.util.zip.GZIPOutputStream;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Helper to perform transformation result callbacks.
+ */
+public class ResultCallbackHelper {
+
+    /**
+     * The logger instance for this class.
+     */
+    private static Logger logger = LoggerFactory.getLogger(ResultCallbackHelper.class);
+
+    /**
+     * Perform the transformation result callback.
+     *
+     * @param success     Whether or not the transformation has been successful.
+     * @param logs        The transformation log.
+     * @param callbackUrl The callback url.
+     * @param token       The jwt token for the request.
+     * @param jobId       The transformation job id.
+     */
+    public static void performResultCallback(
+            boolean success,
+            String logs,
+            Optional<JSONObject> stats,
+            String callbackUrl,
+            String token,
+            Optional<String> jobId) {
+        try {
+            // Create transformation result object.
+            JSONObject resultObj = new JSONObject();
+            resultObj.put("success", success);
+
+            JSONObject propertiesObj = new JSONObject();
+            if (Optional.ofNullable(logs).isPresent()) {
+                propertiesObj.put("logs", logs);
+            }
+
+            if (jobId.isPresent()) {
+                propertiesObj.put("jobId", jobId.get());
+            } else {
+                logger.warn("Transformation result callback does not contain a jobId.");
+            }
+
+            if (stats.isPresent()) {
+                propertiesObj.put("stats", stats.get());
+            }
+
+            resultObj.put("properties", propertiesObj);
+
+            // Send result object to callback URL.
+            sendTransformationResult(resultObj, callbackUrl, token);
+
+        } catch (JSONException e) {
+            logger.warn("Failed to create result object to be sent ");
+        }
+    }
+
+    /**
+     * Send the transformation result object to the given url.
+     *
+     * @param result The transformation result object.
+     * @param url    The callback url.
+     * @param token  The jwt token.
+     */
+    private static void sendTransformationResult(JSONObject result, String url, String token) {
+
+        try {
+            logger.info("Sending transformation result to " + url.toString());
+
+            // Create http request to send result object.
+            URL sendUrl = new URL(url);
+            HttpURLConnection http = (HttpURLConnection) sendUrl.openConnection();
+            if (token != null) {
+                http.setRequestProperty("Authorization", "Bearer " + token);
+            } else {
+                logger.warn("Transformation callback is being performed without JWT token!");
+            }
+            http.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
+            http.setRequestProperty("Content-Encoding", "gzip");
+            http.setDoOutput(true);
+            http.setDoInput(true);
+            http.setRequestMethod("PUT");
+            http.setConnectTimeout(10000);
+
+            // write zipped content
+            OutputStream os = http.getOutputStream();
+            OutputStream gzip = new GZIPOutputStream(os);
+
+            try {
+                OutputStreamWriter osw = new OutputStreamWriter(gzip, StandardCharsets.UTF_8);
+                osw.write(result.toString());
+                osw.flush();
+                osw.close();
+            } catch (IOException e) {
+                logger.warn("Failed to write result callback request body.", e);
+            } finally {
+                os.close();
+                gzip.close();
+            }
+
+            // handle http response
+            int statusCode = http.getResponseCode();
+            String statusMessage = http.getResponseMessage();
+            String resLogMsg = "Transformation result callback endpoint responded with status code " + statusCode + ": "
+                    + statusMessage;
+            if (statusCode != 200) {
+                logger.warn(resLogMsg);
+            } else {
+                logger.info(resLogMsg);
+            }
+
+            http.disconnect();
+        } catch (Throwable t) {
+            logger.warn("Failed to perform transformation result callback.", t);
+        }
+    }
+}

src/main/java/to/wetransform/hale/transformer/RunContext.java

@@ -0,0 +1,28 @@
+package to.wetransform.hale.transformer;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.io.FileUtils;
+
+public class RunContext {
+
+    private final List<Path> tempFiles = new ArrayList<>();
+
+    public File createTempDir() throws IOException {
+        Path path = Files.createTempDirectory("hale-progen");
+        tempFiles.add(path);
+        return path.toFile();
+    }
+
+    public void cleanUp() throws IOException {
+        for (Path path : tempFiles) {
+            FileUtils.deleteDirectory(path.toFile());
+        }
+        tempFiles.clear();
+    }
+}