// ========================================================================
// $Id: Resource.java,v 1.31 2005/10/21 11:36:56 gregwilkins Exp $
// Copyright 1996-2004 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// 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.mortbay.util;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.text.DateFormat;
import java.util.Arrays;
import java.util.Date;

import org.apache.commons.logging.Log;
import org.mortbay.log.LogFactory;


/* ------------------------------------------------------------ */
/** Abstract resource class.
 *
 * @version $Id: Resource.java,v 1.31 2005/10/21 11:36:56 gregwilkins Exp $
 * @author Nuno Preguiça
 * @author Greg Wilkins (gregw)
 */
public abstract class Resource implements Serializable
{
    private static Log log = LogFactory.getLog(Resource.class);

    Object _associate;
    
    /* ------------------------------------------------------------ */
    /** Construct a resource from a url.
     * @param url A URL.
     * @return A Resource object.
     */
    public static Resource newResource(URL url)
        throws IOException
    {
        if (url==null)
            return null;

        String urls=url.toExternalForm();
        if( urls.startsWith( "file:"))
        {
            try
            {
                FileResource fileResource= new FileResource(url);
                return fileResource;
            }
            catch(Exception e)
            {
                log.debug(LogSupport.EXCEPTION,e);
                return new BadResource(url,e.toString());
            }
        }
        else if( urls.startsWith( "jar:file:"))
        {
            return new JarFileResource(url);
        }
        else if( urls.startsWith( "jar:"))
        {
            return new JarResource(url);
        }

        return new URLResource(url,null);
    }

    /* ------------------------------------------------------------ */
    /** Construct a resource from a string.
     * @param resource A URL or filename.
     * @return A Resource object.
     */
    public static Resource newResource(String resource)
        throws MalformedURLException, IOException
    {
        URL url=null;
        try
        {
            // Try to format as a URL?
            url = new URL(resource);
        }
        catch(MalformedURLException e)
        {
            if(!resource.startsWith("ftp:") &&
               !resource.startsWith("file:") &&
               !resource.startsWith("jar:"))
            {
                try
                {
                    // It's a file.
                    if (resource.startsWith("./"))
                        resource=resource.substring(2);
                    
                    File file=new File(resource).getCanonicalFile();
                    url=file.toURI().toURL();                    
                    
                    URLConnection connection=url.openConnection();
                    FileResource fileResource= new FileResource(url,connection,file);
                    return fileResource;
                }
                catch(Exception e2)
                {
                    log.debug(LogSupport.EXCEPTION,e2);
                    throw e;
                }
            }
            else
            {
                log.warn("Bad Resource: "+resource);
                throw e;
            }
        }

        String nurl=url.toString();
        if (nurl.length()>0 &&
            nurl.charAt(nurl.length()-1)!=
            resource.charAt(resource.length()-1))
        {
            if ((nurl.charAt(nurl.length()-1)!='/' ||
                 nurl.charAt(nurl.length()-2)!=resource.charAt(resource.length()-1))
                &&
                (resource.charAt(resource.length()-1)!='/' ||
                 resource.charAt(resource.length()-2)!=nurl.charAt(nurl.length()-1)
                 ))
            {
                return new BadResource(url,"Trailing special characters stripped by URL in "+resource);
            }
        }
        return newResource(url);
    }

    /* ------------------------------------------------------------ */
    /** Construct a system resource from a string.
     * The resource is tried as classloader resource before being
     * treated as a normal resource.
     */
    public static Resource newSystemResource(String resource)
        throws IOException
    {
        URL url=null;
        // Try to format as a URL?
        ClassLoader
            loader=Thread.currentThread().getContextClassLoader();
        if (loader!=null)
        {
            url=loader.getResource(resource);
            if (url==null && resource.startsWith("/"))
                url=loader.getResource(resource.substring(1));
        }
        if (url==null)
        {
            loader=Resource.class.getClassLoader();
            if (loader!=null)
            {
                url=loader.getResource(resource);
                if (url==null && resource.startsWith("/"))
                    url=loader.getResource(resource.substring(1));
            }
        }
        
        if (url==null)
        {
            url=ClassLoader.getSystemResource(resource);
            if (url==null && resource.startsWith("/"))
                url=loader.getResource(resource.substring(1));
        }
        
        if (url==null)
            return null;
        
        return newResource(url);
    }

    /* ------------------------------------------------------------ */
    protected void finalize()
    {
        release();
    }

    /* ------------------------------------------------------------ */
    /** Release any resources held by the resource.
     */
    public abstract void release();
    

    /* ------------------------------------------------------------ */
    /**
     * Returns true if the respresened resource exists.
     */
    public abstract boolean exists();
    

    /* ------------------------------------------------------------ */
    /**
     * Returns true if the respresenetd resource is a container/directory.
     * If the resource is not a file, resources ending with "/" are
     * considered directories.
     */
    public abstract boolean isDirectory();

    /* ------------------------------------------------------------ */
    /**
     * Returns the last modified time
     */
    public abstract long lastModified();


    /* ------------------------------------------------------------ */
    /**
     * Return the length of the resource
     */
    public abstract long length();
    

    /* ------------------------------------------------------------ */
    /**
     * Returns an URL representing the given resource
     */
    public abstract URL getURL();
    

    /* ------------------------------------------------------------ */
    /**
     * Returns an File representing the given resource or NULL if this
     * is not possible.
     */
    public abstract File getFile()
        throws IOException;
    

    /* ------------------------------------------------------------ */
    /**
     * Returns the name of the resource
     */
    public abstract String getName();
    

    /* ------------------------------------------------------------ */
    /**
     * Returns an input stream to the resource
     */
    public abstract InputStream getInputStream()
        throws java.io.IOException;

    /* ------------------------------------------------------------ */
    /**
     * Returns an output stream to the resource
     */
    public abstract OutputStream getOutputStream()
        throws java.io.IOException, SecurityException;
    
    /* ------------------------------------------------------------ */
    /**
     * Deletes the given resource
     */
    public abstract boolean delete()
        throws SecurityException;
    
    /* ------------------------------------------------------------ */
    /**
     * Rename the given resource
     */
    public abstract boolean renameTo( Resource dest)
        throws SecurityException;
    
    /* ------------------------------------------------------------ */
    /**
     * Returns a list of resource names contained in the given resource
     * The resource names are not URL encoded.
     */
    public abstract String[] list();

    /* ------------------------------------------------------------ */
    /**
     * Returns the resource contained inside the current resource with the
     * given name.
     * @param path The path segment to add, which should be encoded by the
     * encode method. 
     */
    public abstract Resource addPath(String path)
        throws IOException,MalformedURLException;
    

    /* ------------------------------------------------------------ */
    /** Encode according to this resource type.
     * The default implementation calls URI.encodePath(uri)
     * @param uri 
     * @return String encoded for this resource type.
     */
    public String encode(String uri)
    {
        return URI.encodePath(uri);
    }
    
        
    /* ------------------------------------------------------------ */
    public Object getAssociate()
    {
        return _associate;
    }

    /* ------------------------------------------------------------ */
    public void setAssociate(Object o)
    {
        _associate=o;
    }
    
    /* ------------------------------------------------------------ */
    /**
     * @return The canonical Alias of this resource or null if none.
     */
    public URL getAlias()
    {
        return null;
    }
    

    /* ------------------------------------------------------------ */
    public CachedResource cache()
        throws IOException
    {
        return new CachedResource(this);
    }
    
    /* ------------------------------------------------------------ */
    /** Get the resource list as a HTML directory listing.
     * @param base The base URL
     * @param parent True if the parent directory should be included
     * @return String of HTML
     */
    public String getListHTML(String base,
                              boolean parent)
        throws IOException
    {
        if (!isDirectory())
            return null;
        
      
        String[] ls = list();
        if (ls==null)
            return null;
        Arrays.sort(ls);
        
        String title = "Directory: "+URI.decodePath(base);
        title=StringUtil.replace(StringUtil.replace(title,"<","&lt;"),">","&gt;");
        StringBuffer buf=new StringBuffer(4096);
        buf.append("<HTML><HEAD><TITLE>");
        buf.append(title);
        buf.append("</TITLE></HEAD><BODY>\n<H1>");
        buf.append(title);
        buf.append("</H1><TABLE BORDER=0>");
        
        if (parent)
        {
            buf.append("<TR><TD><A HREF=");
            buf.append(URI.encodePath(URI.addPaths(base,"../")));
            buf.append(">Parent Directory</A></TD><TD></TD><TD></TD></TR>\n");
        }
        
        DateFormat dfmt=DateFormat.getDateTimeInstance(DateFormat.MEDIUM,
                                                       DateFormat.MEDIUM);
        for (int i=0 ; i< ls.length ; i++)
        {   
            String encoded=URI.encodePath(ls[i]);
            Resource item = addPath(encoded);
            
            buf.append("<TR><TD><A HREF=\"");
            
            String path=URI.addPaths(base,encoded);
            
            if (item.isDirectory() && !path.endsWith("/"))
                path=URI.addPaths(path,"/");
            buf.append(path);
            buf.append("\">");
            buf.append(StringUtil.replace(StringUtil.replace(ls[i],"<","&lt;"),">","&gt;"));
            buf.append("&nbsp;");
            buf.append("</TD><TD ALIGN=right>");
            buf.append(item.length());
            buf.append(" bytes&nbsp;</TD><TD>");
            buf.append(dfmt.format(new Date(item.lastModified())));
            buf.append("</TD></TR>\n");
        }
        buf.append("</TABLE>\n");
	buf.append("</BODY></HTML>\n");
        
        return buf.toString();
    }
    
    /* ------------------------------------------------------------ */
    /** 
     * @param out 
     * @param start First byte to write
     * @param count Bytes to write or -1 for all of them.
     */
    public void writeTo(OutputStream out,long start,long count)
        throws IOException
    {
        InputStream in = getInputStream();
        try
        {
            in.skip(start);
            if (count<0)
                IO.copy(in,out);
            else
                IO.copy(in,out,(int)count);
        }
        finally
        {
            in.close();
        }
    }    
}
