package org.apache.maven.plugin.resource.loader;

/*
 * 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
 *
 *   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.
 */

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Hashtable;
import java.util.List;

import org.apache.commons.collections.ExtendedProperties;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.runtime.resource.Resource;
import org.apache.velocity.runtime.resource.loader.ResourceLoader;
import org.apache.velocity.util.StringUtils;

/**
 * Resource Loader for external projects.
 * 
 * @version $Id$
 */
public class ProjectResourceLoader
    extends ResourceLoader
{
    /**
     * The paths to search for templates.
     */
    private List<String> paths = null;

    /**
     * Used to map the path that a template was found on so that we can properly check the modification times of the
     * files.
     */
    private Hashtable<String, String> templatePaths = new Hashtable<String, String>();

    public void init( ExtendedProperties configuration )
    {
        rsvc.getLog().info( "ProjectResourceLoader : initialization starting." );

        String separator = System.getProperty( "file.separator" );

        String path = System.getProperty( "user.dir" ) + separator + "src" + separator + "main" + separator
            + "resources" + separator;

        rsvc.getLog().info( "path :" + path );

        paths = new ArrayList<String>();

        paths.add( path );

        for ( String path1 : paths )
        {
            rsvc.getLog().info( "ProjectResourceLoader : adding path '" + path1 + "'" );
        }
        rsvc.getLog().info( "ProjectResourceLoader : initialization complete." );
    }

    /**
     * Get an InputStream so that the Runtime can build a template with it.
     *
     * @param templateName name of template to get
     * @return InputStream containing the template
     * @throws ResourceNotFoundException if template not found in the file template path.
     */
    public synchronized InputStream getResourceStream( String templateName )
        throws ResourceNotFoundException
    {
        /*
         * Make sure we have a valid templateName.
         */
        if ( templateName == null || templateName.length() == 0 )
        {
            /*
             * If we don't get a properly formed templateName then there's not much we can do. So we'll forget about
             * trying to search any more paths for the template.
             */
            throw new ResourceNotFoundException( "Need to specify a file name or file path!" );
        }

        String template = StringUtils.normalizePath( templateName );
        if ( template == null || template.length() == 0 )
        {
            String msg = "Project Resource loader error : argument " + template
                + " contains .. and may be trying to access " + "content outside of template root.  Rejected.";

            rsvc.getLog().error( "ProjectResourceLoader : " + msg );

            throw new ResourceNotFoundException( msg );
        }

        /*
         * if a / leads off, then just nip that :)
         */
        if ( template.startsWith( "/" ) )
        {
            template = template.substring( 1 );
        }

        // MCHANGES-118 adding the basedir path
        paths.add( (String) rsvc.getApplicationAttribute( "baseDirectory" ) );

        for ( String path : paths )
        {
            InputStream inputStream = findTemplate( path, template );

            if ( inputStream != null )
            {
                /*
                 * Store the path that this template came from so that we can check its modification time.
                 */

                templatePaths.put( templateName, path );
                return inputStream;
            }
        }

        /*
         * We have now searched all the paths for templates and we didn't find anything so throw an exception.
         */
        String msg = "ProjectResourceLoader Error: cannot find resource " + template;

        throw new ResourceNotFoundException( msg );
    }

    /**
     * Try to find a template given a normalized path.
     * 
     * @param path a normalized path
     * @return InputStream input stream that will be parsed
     */
    private InputStream findTemplate( String path, String template )
    {
        try
        {
            File file = new File( path, template );

            if ( file.canRead() )
            {
                return new BufferedInputStream( new FileInputStream( file.getAbsolutePath() ) );
            }
            else
            {
                return null;
            }
        }
        catch ( FileNotFoundException fnfe )
        {
            /*
             * log and convert to a general Velocity ResourceNotFoundException
             */
            return null;
        }
    }

    /**
     * How to keep track of all the modified times across the paths. Note that a file might have appeared in a directory
     * which is earlier in the path; so we should search the path and see if the file we find that way is the same as
     * the one that we have cached.
     */
    public boolean isSourceModified( Resource resource )
    {
        /*
         * we assume that the file needs to be reloaded; if we find the original file and it's unchanged, then we'll
         * flip this.
         */
        boolean modified = true;

        String fileName = resource.getName();
        String path = templatePaths.get( fileName );
        File currentFile = null;

        for ( int i = 0; currentFile == null && i < paths.size(); i++ )
        {
            String testPath = paths.get( i );
            File testFile = new File( testPath, fileName );
            if ( testFile.canRead() )
            {
                currentFile = testFile;
            }
        }
        File file = new File( path, fileName );
        if ( currentFile == null || !file.exists() )
        {
            /*
             * noop: if the file is missing now (either the cached file is gone, or the file can no longer be found)
             * then we leave modified alone (it's set to true); a reload attempt will be done, which will either use a
             * new template or fail with an appropriate message about how the file couldn't be found.
             */
        }
        else if ( currentFile.equals( file ) && file.canRead() )
        {
            /*
             * if only if currentFile is the same as file and file.lastModified() is the same as
             * resource.getLastModified(), then we should use the cached version.
             */
            modified = ( file.lastModified() != resource.getLastModified() );
        }

        /*
         * rsvc.debug("isSourceModified for " + fileName + ": " + modified);
         */
        return modified;
    }

    public long getLastModified( Resource resource )
    {
        String path = templatePaths.get( resource.getName() );
        File file = new File( path, resource.getName() );

        if ( file.canRead() )
        {
            return file.lastModified();
        }
        else
        {
            return 0;
        }
    }
}