[HER-1601] Restletify: per-job operator arbitrary script execution

* ScriptResource.java
    textarea offering execution of any script supported by available JSR-223 script engines

engine/src/main/java/org/archive/crawler/restlet/ScriptResource.java

@@ -0,0 +1,171 @@
+/*
+ *  This file is part of the Heritrix web crawler (crawler.archive.org).
+ *
+ *  Licensed to the Internet Archive (IA) by one or more individual 
+ *  contributors. 
+ *
+ *  The IA 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.archive.crawler.restlet;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.io.Writer;
+import java.util.LinkedList;
+
+import javax.script.ScriptEngine;
+import javax.script.ScriptEngineFactory;
+import javax.script.ScriptEngineManager;
+import javax.script.ScriptException;
+
+import org.apache.commons.lang.StringEscapeUtils;
+import org.apache.commons.lang.StringUtils;
+import org.restlet.Context;
+import org.restlet.data.CharacterSet;
+import org.restlet.data.Form;
+import org.restlet.data.MediaType;
+import org.restlet.data.Request;
+import org.restlet.data.Response;
+import org.restlet.resource.Representation;
+import org.restlet.resource.ResourceException;
+import org.restlet.resource.Variant;
+import org.restlet.resource.WriterRepresentation;
+
+/**
+ * Restlet Resource which runs an arbitrary script, which is supplied
+ * with variables pointing to the job and appContext, from which all
+ * other live crawl objects are reachable. 
+ * 
+ * Any JSR-223 script engine that's properly discoverable on the 
+ * classpath will be available from a drop-down selector. 
+ * 
+ * @contributor gojomo
+ */
+public class ScriptResource extends JobRelatedResource {
+    static ScriptEngineManager MANAGER = new ScriptEngineManager();
+    // oddly, ordering is different each call to getEngineFactories, so cache
+    static LinkedList<ScriptEngineFactory> FACTORIES = new LinkedList<ScriptEngineFactory>();
+    static {
+        FACTORIES.addAll(MANAGER.getEngineFactories());
+    }
+    String script = "";
+    Exception ex = null;
+    String rawOutput = ""; 
+    String htmlOutput = "";
+    String chosenEngine = FACTORIES.isEmpty() ? "" : FACTORIES.getFirst().getNames().get(0);
+    
+    public ScriptResource(Context ctx, Request req, Response res) throws ResourceException {
+        super(ctx, req, res);
+        setModifiable(true);
+        getVariants().add(new Variant(MediaType.TEXT_HTML));
+    }
+    
+    @Override
+    public void acceptRepresentation(Representation entity) throws ResourceException {
+        Form form = getRequest().getEntityAsForm();
+        chosenEngine = form.getFirstValue("engine");
+        script = form.getFirstValue("script");
+        if(StringUtils.isBlank(script)) {
+            script="";
+        }
+
+        ScriptEngine eng = MANAGER.getEngineByName(chosenEngine);
+        
+        StringWriter rawString = new StringWriter(); 
+        PrintWriter rawOut = new PrintWriter(rawString);
+        eng.put("rawOut", rawOut);
+        StringWriter htmlString = new StringWriter(); 
+        PrintWriter htmlOut = new PrintWriter(htmlString);
+        eng.put("htmlOut", htmlOut);
+        eng.put("job", cj);
+        eng.put("appCtx", cj.getJobContext());
+        eng.put("scriptResource", this);
+        try {
+            eng.eval(script);
+        } catch (ScriptException e) {
+            ex = e;
+        } catch (RuntimeException e) {
+            ex = e;
+        } finally {
+            rawOut.flush();
+            rawOutput = rawString.toString();
+            htmlOut.flush();
+            htmlOutput = htmlString.toString();
+        }
+        
+        getResponse().setEntity(represent());
+    }
+    
+    public Representation represent(Variant variant) throws ResourceException {
+        Representation representation = new WriterRepresentation(
+                MediaType.TEXT_HTML) {
+            public void write(Writer writer) throws IOException {
+                ScriptResource.this.writeHtml(writer);
+            }
+        };
+        // TODO: remove if not necessary in future?
+        representation.setCharacterSet(CharacterSet.UTF_8);
+        return representation;
+    }
+
+    protected void writeHtml(Writer writer) {
+        PrintWriter pw = new PrintWriter(writer); 
+        pw.println("<h1>Execute script for job <i>"+cj.getShortName()+"</i></h1>");
+        // output of previous script, if any
+
+        if(ex!=null) {
+            pw.println("<pre style='color:red; height:150px; overflow:auto'>");
+            ex.printStackTrace(pw);
+            pw.println("</pre>");
+        }
+        if(StringUtils.isNotBlank(htmlOutput)) {
+            pw.println("<fieldset><legend>htmlOut</legend>");
+            pw.println(htmlOutput);
+            pw.println("</fieldset>");
+        }
+        
+        if(StringUtils.isNotBlank(rawOutput)) {
+            pw.println("<fieldset><legend>rawOut</legend><pre>");
+            pw.println(StringEscapeUtils.escapeHtml(rawOutput));
+            pw.println("</pre></fieldset>");
+        }
+
+        pw.println("<form method='POST'>");
+        pw.println("<input type='submit' value='execute'></input>");
+        pw.println("<select name='engine'>");;
+        for(ScriptEngineFactory f : FACTORIES) {
+            String opt = f.getNames().get(0);
+            pw.println("<option "
+                    +(opt.equals(chosenEngine)?" selected='selected' ":"")
+                    +"value='"+opt+"'>"+f.getLanguageName()+"</option>");
+        }
+        pw.println("</select>");
+        pw.println("<textarea rows='20' style='width:100%' name=\'script\'>"+script+"</textarea>");
+        pw.println("<input type='submit' value='execute'></input>");
+        pw.println("</form>");
+        pw.println(
+                "The script will be executed in an engine preloaded " +
+                "with (global) variables: <ul>\n" +
+                "<li>rawOut: a PrintWriter for arbitrary text output to this page</li>\n" +
+                "<li>htmlOut: a PrintWriter for HTML output to this page</li>\n" +
+                "<li>job: the current CrawlJob instance</li>\n" +
+                "<li>appCtx: current job ApplicationContext, if any</li>\n" +
+                "<li>scriptResource: the ScriptResource implementing this " +
+                "page, which offers utility methods</li>\n" +
+                "</ul>");
+
+        pw.close();
+    }
+}