/*
 * Copyright 2003-2007 the original author or authors.
 *
 * 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.codehaus.groovy.ant;

import java.io.File;
import java.util.Iterator;
import java.util.NoSuchElementException;

import org.apache.tools.ant.DirectoryScanner;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.types.FileSet;

/** 
 * <p><code>FileIterator</code> is an iterator over a 
 * number of files from a collection of FileSet instances.
 *
 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
 * @version $Revision$
 */
public class FileIterator implements Iterator {

    /** The iterator over the FileSet objects */
    private Iterator fileSetIterator;
    
    /** The Ant project */
    private Project project;
    
    /** The directory scanner */
    private DirectoryScanner ds;
    
    /** The file names in the current FileSet scan */
    private String[] files;
    
    /** The current index into the file name array */
    private int fileIndex = -1;
    
    /** The next File object we'll iterate over */
    private File nextFile;

    /** Have we set a next object? */
    private boolean nextObjectSet = false;

    /** Return only directories? */
    private boolean iterateDirectories = false;

    public FileIterator(Project project,
                        Iterator fileSetIterator) {
        this( project, fileSetIterator, false);
    }

    public FileIterator(Project project,
                        Iterator fileSetIterator,
                        boolean iterateDirectories) {
        this.project = project;
        this.fileSetIterator = fileSetIterator;
        this.iterateDirectories = iterateDirectories;
    }
    
    // Iterator interface
    //-------------------------------------------------------------------------
    
    /** @return true if there is another object that matches the given predicate */
    public boolean hasNext() {
        if ( nextObjectSet ) {
            return true;
        } 
        else {
            return setNextObject();
        }
    }

    /** @return the next object which matches the given predicate */
    public Object next() {
        if ( !nextObjectSet ) {
            if (!setNextObject()) {
                throw new NoSuchElementException();
            }
        }
        nextObjectSet = false;
        return nextFile;
    }
    
    /**
     * throws UnsupportedOperationException 
     */
    public void remove() {
        throw new UnsupportedOperationException();
    }

    // Implementation methods
    //-------------------------------------------------------------------------

    /**
     * Set nextObject to the next object. If there are no more 
     * objects then return false. Otherwise, return true.
     */
    private boolean setNextObject() {
        while (true) {
            while (ds == null) {
                if ( ! fileSetIterator.hasNext() ) {
                    return false;
                }
                FileSet fs = (FileSet) fileSetIterator.next();
                ds = fs.getDirectoryScanner(project);
                ds.scan();
                if (iterateDirectories) {
                    files = ds.getIncludedDirectories();
                } 
                else {
                    files = ds.getIncludedFiles();
                }
                if ( files.length > 0 ) {
                    fileIndex = -1;
                    break;
                }
                else {
                    ds = null;
                }
            }
        
            if ( ds != null && files != null ) {
                if ( ++fileIndex < files.length ) {
                    nextFile = new File( ds.getBasedir(), files[fileIndex] );
                    nextObjectSet = true;
                    return true;
                }
                else {
                    ds = null;
                }
            }
        }
    }
}