/*
 * Copyright  2003-2004 The Apache Software Foundation
 *
 *  Licensed 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.tools.ant.launch;

import java.net.URL;
import java.net.URLClassLoader;
import java.net.MalformedURLException;
import java.io.File;
import java.util.StringTokenizer;
import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;


/**
 *  This is a launcher for Ant.
 *
 * @since Ant 1.6
 */
public class Launcher {
    /** The Ant Home property */
    public static final String ANTHOME_PROPERTY = "ant.home";

    /** The Ant Library Directory property */
    public static final String ANTLIBDIR_PROPERTY = "ant.library.dir";

    /** The location of a per-user library directory */
    public static final String USER_LIBDIR = ".ant/lib";

    /** The startup class that is to be run */
    public static final String MAIN_CLASS = "org.apache.tools.ant.Main";

    /**
     *  Entry point for starting command line Ant
     *
     * @param  args commandline arguments
     */
    public static void main(String[] args) {
        try {
            Launcher launcher = new Launcher();
            launcher.run(args);
        } catch (LaunchException e) {
            System.err.println(e.getMessage());
        } catch (Throwable t) {
            t.printStackTrace();
        }
    }


    /**
     * Run the launcher to launch Ant
     *
     * @param args the command line arguments
     *
     * @exception MalformedURLException if the URLs required for the classloader
     *            cannot be created.
     */
    private void run(String[] args) throws LaunchException, MalformedURLException {
        String antHomeProperty = System.getProperty(ANTHOME_PROPERTY);
        File antHome = null;

        File sourceJar = Locator.getClassSource(getClass());
        File jarDir = sourceJar.getParentFile();

        if (antHomeProperty != null) {
            antHome = new File(antHomeProperty);
        }

        if (antHome == null || !antHome.exists()) {
            antHome = jarDir.getParentFile();
            System.setProperty(ANTHOME_PROPERTY, antHome.getAbsolutePath());
        }

        if (!antHome.exists()) {
            throw new LaunchException("Ant home is set incorrectly or "
                + "ant could not be located");
        }

        List libPaths = new ArrayList();
        List argList = new ArrayList();
        String[] newArgs;

        for (int i = 0; i < args.length; ++i) {
            if (args[i].equals("-lib")) {
                if (i == args.length - 1) {
                    throw new LaunchException("The -lib argument must "
                        + "be followed by a library location");
                }
                libPaths.add(args[++i]);
            } else {
                argList.add(args[i]);
            }
        }

        if (libPaths.size() == 0) {
            newArgs = args;
        } else {
            newArgs = (String[]) argList.toArray(new String[0]);
        }

        List libPathURLs = new ArrayList();
        for (Iterator i = libPaths.iterator(); i.hasNext();) {
            String libPath = (String) i.next();
            StringTokenizer myTokenizer
                = new StringTokenizer(libPath, System.getProperty("path.separator"));
            while (myTokenizer.hasMoreElements()) {
                String elementName = myTokenizer.nextToken();
                File element = new File(elementName);
                if (elementName.indexOf("%") != -1 && !element.exists()) {
                    continue;
                }
                if (element.isDirectory()) {
                    // add any jars in the directory
                    URL[] dirURLs = Locator.getLocationURLs(element);
                    for (int j = 0; j < dirURLs.length; ++j) {
                        libPathURLs.add(dirURLs[j]);
                    }
                }

                libPathURLs.add(element.toURL());
            }
        }

        URL[] libJars = (URL[]) libPathURLs.toArray(new URL[0]);

        // Now try and find JAVA_HOME
        File toolsJar = Locator.getToolsJar();

        // determine ant library directory for system jars: use property
        // or default using location of ant-launcher.jar
        File antLibDir = null;
        String antLibDirProperty = System.getProperty(ANTLIBDIR_PROPERTY);
        if (antLibDirProperty != null) {
            antLibDir = new File(antLibDirProperty);
        }
        if ((antLibDir == null) || !antLibDir.exists()) {
            antLibDir = jarDir;
            System.setProperty(ANTLIBDIR_PROPERTY, antLibDir.getAbsolutePath());
        }
        URL[] systemJars = Locator.getLocationURLs(antLibDir);

        File userLibDir
            = new File(System.getProperty("user.home"), USER_LIBDIR);
        URL[] userJars = Locator.getLocationURLs(userLibDir);


        int numJars = libJars.length + userJars.length + systemJars.length;
        if (toolsJar != null) {
            numJars++;
        }
        URL[] jars = new URL[numJars];
        System.arraycopy(libJars, 0, jars, 0, libJars.length);
        System.arraycopy(userJars, 0, jars, libJars.length, userJars.length);
        System.arraycopy(systemJars, 0, jars, userJars.length + libJars.length,
            systemJars.length);

        if (toolsJar != null) {
            jars[jars.length - 1] = toolsJar.toURL();
        }


        // now update the class.path property
        StringBuffer baseClassPath
            = new StringBuffer(System.getProperty("java.class.path"));
        if (baseClassPath.charAt(baseClassPath.length() - 1)
                == File.pathSeparatorChar) {
            baseClassPath.setLength(baseClassPath.length() - 1);
        }

        for (int i = 0; i < jars.length; ++i) {
            baseClassPath.append(File.pathSeparatorChar);
            baseClassPath.append(Locator.fromURI(jars[i].toString()));
        }

        System.setProperty("java.class.path", baseClassPath.toString());

        URLClassLoader loader = new URLClassLoader(jars);
        Thread.currentThread().setContextClassLoader(loader);
        try {
            Class mainClass = loader.loadClass(MAIN_CLASS);
            AntMain main = (AntMain) mainClass.newInstance();
            main.startAnt(newArgs, null, null);
        } catch (Throwable t) {
            t.printStackTrace();
        }
    }
}