Implement ConcatFilesTask from Groovy to Java issues#34459

buildSrc/src/main/java/org/elasticsearch/gradle/ConcatFilesTask.java

@@ -0,0 +1,96 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.elasticsearch.gradle;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.StandardOpenOption;
+import java.util.LinkedHashSet;
+
+import org.gradle.api.DefaultTask;
+import org.gradle.api.file.FileTree;
+import org.gradle.api.tasks.Input;
+import org.gradle.api.tasks.InputFiles;
+import org.gradle.api.tasks.Optional;
+import org.gradle.api.tasks.OutputFile;
+import org.gradle.api.tasks.TaskAction;
+
+/**
+ * Concatenates a list of files into one and removes duplicate lines.
+ */
+public class ConcatFilesTask extends DefaultTask {
+
+    public ConcatFilesTask() {
+        setDescription("Concat a list of files into one.");
+    }
+
+    /** List of files to concatenate */
+    private FileTree files;
+
+    /** line to add at the top of the target file */
+    private String headerLine;
+
+    private File target;
+
+    public void setFiles(FileTree files) {
+        this.files = files;
+    }
+
+    @InputFiles
+    public FileTree getFiles() { return files; }
+
+    public void setHeaderLine(String headerLine) {
+        this.headerLine = headerLine;
+    }
+
+    @Input
+    @Optional
+    public String getHeaderLine() { return headerLine; }
+
+    public void setTarget(File target) {
+        this.target = target;
+    }
+
+    @OutputFile
+    public File getTarget() {
+        return target;
+    }
+
+    @TaskAction
+    public void concatFiles() throws IOException {
+        if (getHeaderLine() != null) {
+            Files.write(
+                getTarget().toPath(),
+                (getHeaderLine() + '\n').getBytes(StandardCharsets.UTF_8)
+            );
+        }
+
+        // To remove duplicate lines
+        LinkedHashSet<String> uniqueLines = new LinkedHashSet<>();
+        for (File f : getFiles()) {
+            uniqueLines.addAll(Files.readAllLines(f.toPath(), StandardCharsets.UTF_8));
+        }
+        Files.write(
+            getTarget().toPath(), uniqueLines, StandardCharsets.UTF_8, StandardOpenOption.APPEND
+        );
+    }
+
+}

buildSrc/src/test/java/org/elasticsearch/gradle/ConcatFilesTaskTests.java

@@ -0,0 +1,92 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.elasticsearch.gradle;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.Arrays;
+
+import org.elasticsearch.gradle.test.GradleUnitTestCase;
+import org.gradle.api.Project;
+import org.gradle.testfixtures.ProjectBuilder;
+
+public class ConcatFilesTaskTests extends GradleUnitTestCase {
+
+    public void testHeaderAdded() throws IOException {
+
+        Project project = createProject();
+        ConcatFilesTask concatFilesTask = createTask(project);
+
+        concatFilesTask.setHeaderLine("Header");
+
+        File file = new File(project.getProjectDir(), "src/main/java/Code.java");
+        file.getParentFile().mkdirs();
+        file.createNewFile();
+        concatFilesTask.setTarget(file);
+        concatFilesTask.setFiles(project.fileTree("tmp/"));
+
+        concatFilesTask.concatFiles();
+
+        assertEquals(Arrays.asList("Header"), Files.readAllLines(concatFilesTask.getTarget().toPath(), StandardCharsets.UTF_8));
+
+        file.delete();
+    }
+
+    public void testConcatenationWithUnique() throws IOException {
+
+        Project project = createProject();
+        ConcatFilesTask concatFilesTask = createTask(project);
+
+        File file = new File(project.getProjectDir(), "src/main/java/Code.java");
+        file.getParentFile().mkdirs();
+        file.createNewFile();
+        concatFilesTask.setTarget(file);
+
+        File file1 = new File(project.getProjectDir(), "src/main/input/java/file1.java");
+        File file2 = new File(project.getProjectDir(), "src/main/input/text/file2.txt");
+        file1.getParentFile().mkdirs();
+        file2.getParentFile().mkdirs();
+        file1.createNewFile();
+        file2.createNewFile();
+        Files.write(file1.toPath(), "Hello\nHello".getBytes());
+        Files.write(file2.toPath(), "Hello\nनमस्ते".getBytes());
+
+        concatFilesTask.setFiles(project.fileTree(file1.getParentFile().getParentFile()));
+
+        concatFilesTask.concatFiles();
+
+        assertEquals(
+            Arrays.asList("Hello", "नमस्ते"),
+            Files.readAllLines(concatFilesTask.getTarget().toPath(), StandardCharsets.UTF_8)
+        );
+
+    }
+
+    private Project createProject() {
+        Project project = ProjectBuilder.builder().build();
+        return project;
+    }
+
+    private ConcatFilesTask createTask(Project project) {
+        return project.getTasks().create("concatFilesTask", ConcatFilesTask.class);
+    }
+
+}