/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF 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.apache.maven.shared.scriptinterpreter;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.PrintStream;
  import java.io.UncheckedIOException;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.util.List;
  import java.util.Map;
  
  import groovy.lang.Binding;
  import groovy.lang.GroovyShell;
  import org.codehaus.groovy.control.CompilerConfiguration;
  import org.codehaus.groovy.tools.RootLoader;
  
  /**
   * Provides a facade to evaluate Groovy scripts.
   *
   * @author Benjamin Bentmann
   */
  class GroovyScriptInterpreter implements ScriptInterpreter {
  
      private final RootLoader childFirstLoader =
              new RootLoader(new URL[] {}, Thread.currentThread().getContextClassLoader());
  
      @Override
      public void setClassPath(List<String> classPath) {
          if (classPath == null || classPath.isEmpty()) {
              return;
          }
  
          classPath.stream().map(this::toUrl).forEach(childFirstLoader::addURL);
      }
  
      private URL toUrl(String path) {
          try {
              return new File(path).toURI().toURL();
          } catch (MalformedURLException e) {
              throw new UncheckedIOException(e);
          }
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public Object evaluateScript(String script, Map<String, ?> globalVariables, PrintStream scriptOutput)
              throws ScriptEvaluationException {
          PrintStream origOut = System.out;
          PrintStream origErr = System.err;
  
          ClassLoader curentClassLoader = Thread.currentThread().getContextClassLoader();
          try {
  
              if (scriptOutput != null) {
                  System.setErr(scriptOutput);
                  System.setOut(scriptOutput);
              }
  
              GroovyShell interpreter = new GroovyShell(
                      childFirstLoader,
                      new Binding(globalVariables),
                      new CompilerConfiguration(CompilerConfiguration.DEFAULT));
  
              Thread.currentThread().setContextClassLoader(childFirstLoader);
              return interpreter.evaluate(script);
          } catch (Throwable e) {
              throw new ScriptEvaluationException(e);
          } finally {
              Thread.currentThread().setContextClassLoader(curentClassLoader);
              System.setErr(origErr);
              System.setOut(origOut);
          }
      }
  
      @Override
      public void close() throws IOException {
          childFirstLoader.close();
      }
  }