/*
 * Copyright  2003-2005 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.
 *
 */

/*
 * This code is based on code Copyright (c) 2002, Landmark Graphics
 * Corp that has been kindly donated to the Apache Software
 * Foundation.
 */

package org.apache.tools.ant.taskdefs;

import java.io.File;

import java.util.HashSet;
import java.util.Set;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.DirectoryScanner;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.types.AbstractFileSet;
import org.apache.tools.ant.types.FileSet;

/**
 * Synchronize a local target directory from the files defined
 * in one or more filesets.
 *
 * <p>Uses a &lt;copy&gt; task internally, but forbidding the use of
 * mappers and filter chains. Files of the destination directory not
 * present in any of the source fileset are removed.</p>
 *
 * @version $Revision$
 * @since Ant 1.6
 *
 * revised by <a href="mailto:daniel.armbrust@mayo.edu">Dan Armbrust</a>
 * to remove orphaned directories.
 *
 * @ant.task category="filesystem"
 */
public class Sync extends Task {

    // Same as regular <copy> task... see at end-of-file!
    private MyCopy myCopy;

    // Similar to a fileset, but doesn't allow dir attribute to be set
    private SyncTarget syncTarget;

    // Override Task#init
    /**
     * @see Task#init()
     */
    public void init()
        throws BuildException {
        // Instantiate it
        myCopy = new MyCopy();
        configureTask(myCopy);

        // Default config of <mycopy> for our purposes.
        myCopy.setFiltering(false);
        myCopy.setIncludeEmptyDirs(false);
        myCopy.setPreserveLastModified(true);
    }

    private void configureTask(Task helper) {
        helper.setProject(getProject());
        helper.setTaskName(getTaskName());
        helper.setOwningTarget(getOwningTarget());
        helper.init();
    }

    // Override Task#execute
    /**
     * @see Task#execute()
     */
    public void execute()
        throws BuildException {
        // The destination of the files to copy
        File toDir = myCopy.getToDir();

        // The complete list of files to copy
        Set allFiles = myCopy.nonOrphans;

        // If the destination directory didn't already exist,
        // or was empty, then no previous file removal is necessary!
        boolean noRemovalNecessary = !toDir.exists() || toDir.list().length < 1;

        // Copy all the necessary out-of-date files
        log("PASS#1: Copying files to " + toDir, Project.MSG_DEBUG);
        myCopy.execute();

        // Do we need to perform further processing?
        if (noRemovalNecessary) {
            log("NO removing necessary in " + toDir, Project.MSG_DEBUG);
            return; // nope ;-)
        }

        // Get rid of all files not listed in the source filesets.
        log("PASS#2: Removing orphan files from " + toDir, Project.MSG_DEBUG);
        int[] removedFileCount = removeOrphanFiles(allFiles, toDir);
        logRemovedCount(removedFileCount[0], "dangling director", "y", "ies");
        logRemovedCount(removedFileCount[1], "dangling file", "", "s");

        // Get rid of empty directories on the destination side
        if (!myCopy.getIncludeEmptyDirs()) {
            log("PASS#3: Removing empty directories from " + toDir,
                Project.MSG_DEBUG);
            int removedDirCount = removeEmptyDirectories(toDir, false);
            logRemovedCount(removedDirCount, "empty director", "y", "ies");
        }
    }

    private void logRemovedCount(int count, String prefix,
                                 String singularSuffix, String pluralSuffix) {
        File toDir = myCopy.getToDir();

        String what = (prefix == null) ? "" : prefix;
        what += (count < 2) ? singularSuffix : pluralSuffix;

        if (count > 0) {
            log("Removed " + count + " " + what + " from " + toDir,
                Project.MSG_INFO);
        } else {
            log("NO " + what + " to remove from " + toDir,
                Project.MSG_VERBOSE);
        }
    }

    /**
     * Removes all files and folders not found as keys of a table
     * (used as a set!).
     *
     * <p>If the provided file is a directory, it is recursively
     * scanned for orphaned files which will be removed as well.</p>
     *
     * <p>If the directory is an orphan, it will also be removed.</p>
     *
     * @param  nonOrphans the table of all non-orphan <code>File</code>s.
     * @param  file the initial file or directory to scan or test.
     * @return the number of orphaned files and directories actually removed.
     * Position 0 of the array is the number of orphaned directories.
     * Position 1 of the array is the number or orphaned files.
     */
    private int[] removeOrphanFiles(Set nonOrphans, File toDir) {
        int[] removedCount = new int[] {0, 0};
        String[] excls =
            (String[]) nonOrphans.toArray(new String[nonOrphans.size() + 1]);
        // want to keep toDir itself
        excls[nonOrphans.size()] = "";

        DirectoryScanner ds = null;
        if (syncTarget != null) {
            syncTarget.setTargetDir(toDir);
            ds = syncTarget.getDirectoryScanner(getProject());
        } else {
            ds = new DirectoryScanner();
            ds.setBasedir(toDir);
        }
        ds.addExcludes(excls);

        ds.scan();
        String[] files = ds.getIncludedFiles();
        for (int i = 0; i < files.length; i++) {
            File f = new File(toDir, files[i]);
            log("Removing orphan file: " + f, Project.MSG_DEBUG);
            f.delete();
            ++removedCount[1];
        }
        String[] dirs = ds.getIncludedDirectories();
        // ds returns the directories as it has visited them.
        // iterating through the array backwards means we are deleting
        // leaves before their parent nodes - thus making sure (well,
        // more likely) that the directories are empty when we try to
        // delete them.
        for (int i = dirs.length - 1; i >= 0; --i) {
            File f = new File(toDir, dirs[i]);
            log("Removing orphan directory: " + f, Project.MSG_DEBUG);
            f.delete();
            ++removedCount[0];
        }
        return removedCount;
    }

    /**
     * Removes all empty directories from a directory.
     *
     * <p><em>Note that a directory that contains only empty
     * directories, directly or not, will be removed!</em></p>
     *
     * <p>Recurses depth-first to find the leaf directories
     * which are empty and removes them, then unwinds the
     * recursion stack, removing directories which have
     * become empty themselves, etc...</p>
     *
     * @param  dir the root directory to scan for empty directories.
     * @param  removeIfEmpty whether to remove the root directory
     *         itself if it becomes empty.
     * @return the number of empty directories actually removed.
     */
    private int removeEmptyDirectories(File dir, boolean removeIfEmpty) {
        int removedCount = 0;
        if (dir.isDirectory()) {
            File[] children = dir.listFiles();
            for (int i = 0; i < children.length; ++i) {
                File file = children[i];
                // Test here again to avoid method call for non-directories!
                if (file.isDirectory()) {
                    removedCount += removeEmptyDirectories(file, true);
                }
            }
            if (children.length > 0) {
                // This directory may have become empty...
                // We need to re-query its children list!
                children = dir.listFiles();
            }
            if (children.length < 1 && removeIfEmpty) {
                log("Removing empty directory: " + dir, Project.MSG_DEBUG);
                dir.delete();
                ++removedCount;
            }
        }
        return removedCount;
    }


    //
    // Various copy attributes/subelements of <copy> passed thru to <mycopy>
    //

    /**
     * Sets the destination directory.
     * @param destDir the destination directory
     */
    public void setTodir(File destDir) {
        myCopy.setTodir(destDir);
    }

    /**
     * Used to force listing of all names of copied files.
     * @param verbose if true force listing of all names of copied files.
     */
    public void setVerbose(boolean verbose) {
        myCopy.setVerbose(verbose);
    }

    /**
     * Overwrite any existing destination file(s).
     * @param overwrite if true overwrite any existing destination file(s).
     */
    public void setOverwrite(boolean overwrite) {
        myCopy.setOverwrite(overwrite);
    }

    /**
     * Used to copy empty directories.
     * @param includeEmpty If true copy empty directories.
     */
    public void setIncludeEmptyDirs(boolean includeEmpty) {
        myCopy.setIncludeEmptyDirs(includeEmpty);
    }

    /**
     * If false, note errors to the output but keep going.
     * @param failonerror true or false
     */
    public void setFailOnError(boolean failonerror) {
        myCopy.setFailOnError(failonerror);
    }

    /**
     * Adds a set of files to copy.
     * @param set a fileset
     */
    public void addFileset(FileSet set) {
        myCopy.addFileset(set);
    }

    /**
     * The number of milliseconds leeway to give before deciding a
     * target is out of date.
     *
     * <p>Default is 0 milliseconds, or 2 seconds on DOS systems.</p>
     * @param granularity a <code>long</code> value
     * @since Ant 1.6.2
     */
    public void setGranularity(long granularity) {
        myCopy.setGranularity(granularity);
    }

    /**
     * A container for patterns and selectors that can be used to
     * specify files that should be kept in the target even if they
     * are not present in any source directory.
     *
     * <p>You must not invoke this method more than once.</p>
     *
     * @since Ant 1.7
     */
    public void addDeleteFromTarget(SyncTarget s) {
        if (syncTarget != null) {
            throw new BuildException("you must not specify multiple "
                                     + "deletefromtaget elements.");
        }
        syncTarget = s;
    }

    /**
     * Subclass Copy in order to access it's file/dir maps.
     */
    public static class MyCopy extends Copy {

        // List of files that must be copied, irrelevant from the
        // fact that they are newer or not than the destination.
        private Set nonOrphans = new HashSet();

        /** Constructor for MyCopy. */
        public MyCopy() {
        }

        /**
         * @see Copy#scan(File, File, String[], String[])
         */
        protected void scan(File fromDir, File toDir, String[] files,
                            String[] dirs) {
            assertTrue("No mapper", mapperElement == null);

            super.scan(fromDir, toDir, files, dirs);

            for (int i = 0; i < files.length; ++i) {
                nonOrphans.add(files[i]);
            }
            for (int i = 0; i < dirs.length; ++i) {
                nonOrphans.add(dirs[i]);
            }
        }

        /**
         * Get the destination directory.
         * @return the destination directory
         */
        public File getToDir() {
            return destDir;
        }

        /**
         * Get the includeEmptyDirs attribute.
         * @return true if emptyDirs are to be included
         */
        public boolean getIncludeEmptyDirs() {
            return includeEmpty;
        }

    }

    /**
     * Inner class used to hold exclude patterns and selectors to save
     * stuff that happens to live in the target directory but should
     * not get removed.
     *
     * @since Ant 1.7
     */
    public static class SyncTarget extends AbstractFileSet {

        public SyncTarget() {
            super();
            setDefaultexcludes(false);
        }

        public void setDir(File dir) throws BuildException {
            throw new BuildException("synctarget doesn't support the dir "
                                     + "attribute");
        }

        private void setTargetDir(File dir) throws BuildException {
            super.setDir(dir);
        }

    }

    /**
     * Pseudo-assert method.
     */
    private static void assertTrue(String message, boolean condition) {
        if (!condition) {
            throw new BuildException("Assertion Error: " + message);
        }
    }

}