Add REST API for Caruna/Helen parser

rest-api/build.gradle

@@ -0,0 +1,11 @@
+dependencies {
+    implementation 'io.javalin:javalin:3.13.8'
+    implementation "org.thymeleaf:thymeleaf:3.0.11.RELEASE"
+
+    implementation project(':composite-parsers')
+
+    implementation 'org.apache.logging.log4j:log4j-core:2.11.0'
+    implementation 'org.apache.logging.log4j:log4j-slf4j-impl:2.11.0'
+}
+
+application.mainClass='com.devsoap.parsers.api.Api'

rest-api/src/main/java/com/devsoap/parsers/api/Api.java

@@ -0,0 +1,84 @@
+package com.devsoap.parsers.api;
+
+import com.devsoap.parsers.composites.CarunaHelenParser;
+import io.javalin.Javalin;
+import io.javalin.http.Context;
+import io.javalin.http.UploadedFile;
+import org.apache.log4j.Logger;
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.config.Configurator;
+import org.apache.logging.log4j.core.config.builder.api.ConfigurationBuilderFactory;
+
+import java.io.*;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.util.function.Consumer;
+
+import static io.javalin.apibuilder.ApiBuilder.*;
+
+public class Api {
+
+    static {
+        var logBuilder = ConfigurationBuilderFactory.newConfigurationBuilder();
+        logBuilder.add(logBuilder.newAppender("stdout", "Console"));
+
+        var rootLogger = logBuilder.newRootLogger(Level.INFO);
+        rootLogger.add(logBuilder.newAppenderRef("stdout"));
+        logBuilder.add(rootLogger);
+
+        Configurator.initialize(logBuilder.build());
+    }
+
+    private static final Logger LOGGER = Logger.getLogger(Api.class);
+
+    public static void main(String[] args) {
+        var app = Javalin.create().start(7000);
+        app.routes(() -> {
+            get(ctx -> { ctx.result("PDF Parsers REST API"); });
+            path("parsers", () -> {
+                path(CarunaHelenParser.class.getSimpleName(), () -> {
+                    get(ctx -> ctx.render(renderParserStaticPage(CarunaHelenParser.class, "upload.html")));
+                    post(ctx -> {
+                        withUploadedFile(ctx.uploadedFiles().get(1), carunaFile -> {
+                            withUploadedFile(ctx.uploadedFiles().get(0), helenFile -> {
+                                var resultStream = new ByteArrayOutputStream();
+                                try (var result = new PrintStream(resultStream)) {
+                                    CarunaHelenParser.run(carunaFile, helenFile, result);
+                                }
+                                renderReport(ctx, new ByteArrayInputStream(resultStream.toByteArray()),
+                                        "caruna-helen-report.csv");
+                            });
+                        });
+                    });
+                });
+            });
+        });
+    }
+
+    private static void withUploadedFile(UploadedFile fileUpload, Consumer<Path> processor) {
+        try {
+            var file = Files.createTempFile(fileUpload.getFilename(), fileUpload.getExtension());
+            Files.copy(fileUpload.getContent(), file, StandardCopyOption.REPLACE_EXISTING);
+            try {
+                processor.accept(file);
+            } finally {
+                file.toFile().delete();
+            }
+        } catch (IOException e) {
+            LOGGER.error("Failed to process file " + fileUpload.getFilename(), e);
+            return;
+        }
+    }
+
+    private static void renderReport(Context context, InputStream result, String filename) {
+        context.result(result)
+            .header("Content-Type", "text/csv; charset=utf-8")
+            .header("Content-Disposition","inline; filename=\""+filename+"\"");
+    }
+
+    private static String renderParserStaticPage(Class<?> clazz, String page) {
+        var folder = clazz.getPackageName().replace(".", "/");
+        return folder + "/" + page;
+    }
+}