/*
 *  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
 *
 *      https://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.tools.ant.util;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;

This is a helper class used by ScriptRunnerHelper to
create a ScriptRunner based on a classloader and on a language.
/**
 * This is a helper class used by ScriptRunnerHelper to
 * create a ScriptRunner based on a classloader and on a language.
 */
public class ScriptRunnerCreator {
    private static final String AUTO = "auto";
    private static final String OATAU = "org.apache.tools.ant.util";
    private static final String UTIL_OPT = OATAU + ".optional";

    private static final String BSF = "bsf";
    private static final String BSF_PACK = "org.apache.bsf";
    private static final String BSF_MANAGER = BSF_PACK + ".BSFManager";
    private static final String BSF_RUNNER = UTIL_OPT + ".ScriptRunner";

    private static final String JAVAX = "javax";
    private static final String JAVAX_MANAGER = "javax.script.ScriptEngineManager";
    private static final String JAVAX_RUNNER = UTIL_OPT + ".JavaxScriptRunner";

    private Project     project;
    private String      manager;
    private String      language;
    private ClassLoader scriptLoader = null;

    
Constructor for creator.
Params:
project – the current project./**
     * Constructor for creator.
     * @param project the current project.
     */
    public ScriptRunnerCreator(Project project) {
        this.project = project;
    }

    
Create a ScriptRunner.
Params:
manager –      the script manager ("auto" | "bsf" | "javax")
language –     the language.
classLoader –  the classloader to use
Throws:
BuildException – if unable to create the ScriptRunner.
Returns:
the created script runner./**
     * Create a ScriptRunner.
     * @param manager      the script manager ("auto" | "bsf" | "javax")
     * @param language     the language.
     * @param classLoader  the classloader to use
     * @return the created script runner.
     * @throws BuildException if unable to create the ScriptRunner.
     */
    public synchronized ScriptRunnerBase createRunner(
        String manager, String language, ClassLoader classLoader) {
        this.manager      = manager;
        this.language     = language;
        this.scriptLoader = classLoader;

        if (language == null) {
            throw new BuildException("script language must be specified");
        }
        if (!manager.equals(AUTO) && !manager.equals(JAVAX) && !manager.equals(BSF)) {
            throw new BuildException("Unsupported language prefix " + manager);
        }

        // Check for bsf first then javax
        // This version does not check if the scriptManager
        // supports the language.

        ScriptRunnerBase ret = null;
        ret = createRunner(BSF, BSF_MANAGER, BSF_RUNNER);
        if (ret == null) {
            ret = createRunner(JAVAX, JAVAX_MANAGER, JAVAX_RUNNER);
        }
        if (ret != null) {
            return ret;
        }
        if (JAVAX.equals(manager)) {
            throw new BuildException(
                    "Unable to load the script engine manager " + "(" + JAVAX_MANAGER + ")");
        }
        if (BSF.equals(manager)) {
            throw new BuildException(
                    "Unable to load the BSF script engine manager " + "(" + BSF_MANAGER + ")");
        }
        throw new BuildException("Unable to load a script engine manager "
                + "(" + BSF_MANAGER + " or " + JAVAX_MANAGER + ")");
    }

    
Create a script runner if the scriptManager matches the passed
in manager.
This checks if the script manager exists in the scriptLoader
classloader and if so it creates and returns the script runner.
Params:
checkManager – check if the manager matches this value.
managerClass – the name of the script manager class.
runnerClass –   the name of ant's script runner for this manager.
Throws:
BuildException – if there is a problem creating the runner class.
Returns:
the script runner class./**
     * Create a script runner if the scriptManager matches the passed
     * in manager.
     * This checks if the script manager exists in the scriptLoader
     * classloader and if so it creates and returns the script runner.
     * @param checkManager check if the manager matches this value.
     * @param managerClass the name of the script manager class.
     * @param runnerClass   the name of ant's script runner for this manager.
     * @return the script runner class.
     * @throws BuildException if there is a problem creating the runner class.
     */
    private ScriptRunnerBase createRunner(
        String checkManager, String managerClass, String runnerClass) {
        ScriptRunnerBase runner = null;
        if (!manager.equals(AUTO) && !manager.equals(checkManager)) {
            return null;
        }
        if (managerClass.equals(BSF_MANAGER)) {
            if (scriptLoader.getResource(LoaderUtils.classNameToResource(managerClass)) == null) {
                return null;
            }
            new ScriptFixBSFPath().fixClassLoader(scriptLoader, language);
        } else {
            try {
                Class.forName(managerClass, true, scriptLoader);
            } catch (Exception ex) {
                return null;
            }
        }
        try {
            runner = (ScriptRunnerBase) Class.forName(
                    runnerClass, true, scriptLoader).newInstance();
            runner.setProject(project);
        } catch (Exception ex) {
            throw ReflectUtil.toBuildException(ex);
        }
        runner.setLanguage(language);
        runner.setScriptClassLoader(scriptLoader);
        return runner;
    }
}