/*
 * FindBugs - Find Bugs in Java programs
 * Copyright (C) 2006, University of Maryland
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.classfile.impl;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.LinkedList;

import edu.umd.cs.findbugs.RecursiveFileSearch;
import edu.umd.cs.findbugs.classfile.ICodeBaseEntry;
import edu.umd.cs.findbugs.classfile.ICodeBaseIterator;
import edu.umd.cs.findbugs.classfile.ICodeBaseLocator;

/**
 * IScannableCodeBase implementation to read resources from a filesystem
 * directory.
 *
 * @author David Hovemeyer
 */
public class DirectoryCodeBase extends AbstractScannableCodeBase {
    private class DirectoryCodeBaseIterator implements ICodeBaseIterator {

        Iterator<String> fileNameIterator = rfs.fileNameIterator();

        /*
         * (non-Javadoc)
         *
         * @see edu.umd.cs.findbugs.classfile.ICodeBaseIterator#hasNext()
         */
        @Override
        public boolean hasNext() throws InterruptedException {
            return fileNameIterator.hasNext();
        }

        /*
         * (non-Javadoc)
         *
         * @see edu.umd.cs.findbugs.classfile.ICodeBaseIterator#next()
         */
        @Override
        public ICodeBaseEntry next() throws InterruptedException {
            final String fileName = fileNameIterator.next();

            // Make the filename relative to the directory
            String resourceName = getResourceName(fileName);

            // Update last modified time
            File file = new File(fileName);
            long modTime = file.lastModified();
            addLastModifiedTime(modTime);

            return new DirectoryCodeBaseEntry(DirectoryCodeBase.this, resourceName);
        }
    }

    private File directory;

    private RecursiveFileSearch rfs;

    private boolean searchPerformed;

    /**
     * Constructor.
     *
     * @param codeBaseLocator
     *            the codebase locator for this codebase
     * @param directory
     *            the filesystem directory
     */
    public DirectoryCodeBase(ICodeBaseLocator codeBaseLocator, File directory) {
        super(codeBaseLocator);
        if (!directory.isDirectory()) {
            throw new IllegalArgumentException();
        }
        this.directory = directory;
        this.rfs = new RecursiveFileSearch(directory.getPath(), new FileFilter() {
            /*
             * (non-Javadoc)
             *
             * @see java.io.FileFilter#accept(java.io.File)
             */
            @Override
            public boolean accept(File pathname) {
                return true;
            }
        });
        this.searchPerformed = false;
    }

    /*
     * (non-Javadoc)
     *
     * @see edu.umd.cs.findbugs.classfile.IScannableCodeBase#iterator()
     */
    @Override
    public ICodeBaseIterator iterator() throws InterruptedException {
        if (!searchPerformed) {
            rfs.search();
            searchPerformed = true;
        }

        return new DirectoryCodeBaseIterator();
    }

    /*
     * (non-Javadoc)
     *
     * @see edu.umd.cs.findbugs.classfile.ICodeBase#getPathName()
     */
    @Override
    public String getPathName() {
        return directory.getPath();
    }

    /*
     * (non-Javadoc)
     *
     * @see edu.umd.cs.findbugs.classfile.ICodeBase#close()
     */
    @Override
    public void close() {
        // Nothing to do
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * edu.umd.cs.findbugs.classfile.ICodeBase#lookupResource(java.lang.String)
     */
    @Override
    public ICodeBaseEntry lookupResource(String resourceName) {
        // Translate resource name, in case a resource name
        // has been overridden and the resource is being accessed
        // using the overridden name.
        resourceName = translateResourceName(resourceName);

        File file = getFullPathOfResource(resourceName);
        if (!file.exists()) {
            return null;
        }
        return new DirectoryCodeBaseEntry(this, resourceName);
    }

    InputStream openFile(String resourceName) throws FileNotFoundException, IOException {
        File path = getFullPathOfResource(resourceName);
        return new BufferedInputStream(new FileInputStream(path));
    }

    /**
     * Get the full path of given resource.
     */
    File getFullPathOfResource(String resourceName) {
        return new File(directory, resourceName);
    }

    /**
     * Get the resource name given a full filename.
     *
     * @param fileName
     *            the full filename (which must be inside the directory)
     * @return the resource name (i.e., the filename with the directory stripped
     *         off)
     */
    String getResourceName(String fileName) {
        // FIXME: there is probably a more robust way to do this

        // Strip off the directory part.
        String dirPath = directory.getPath();
        if (!fileName.startsWith(dirPath)) {
            throw new IllegalStateException("Filename " + fileName + " not inside directory " + dirPath);
        }

        // The problem here is that we need to take the relative part of the
        // filename
        // and break it into components that we can then reconstruct into
        // a resource name (using '/' characters to separate the components).
        // Unfortunately, the File class does not make this task particularly
        // easy.

        String relativeFileName = fileName.substring(dirPath.length());
        File file = new File(relativeFileName);
        LinkedList<String> partList = new LinkedList<String>();
        do {
            partList.addFirst(file.getName());
        } while ((file = file.getParentFile()) != null);

        StringBuilder buf = new StringBuilder();
        for (String part : partList) {
            if (buf.length() > 0) {
                buf.append('/');
            }
            buf.append(part);
        }

        return buf.toString();
    }

    /*
     * (non-Javadoc)
     *
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return directory.getPath();
    }
}
