//
//  ========================================================================
//  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.util.resource;

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

import org.eclipse.jetty.util.IO;
import org.eclipse.jetty.util.Loader;
import org.eclipse.jetty.util.StringUtil;
import org.eclipse.jetty.util.URIUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/* ------------------------------------------------------------ */
/** 
 * Abstract resource class.
 */
public abstract class Resource implements ResourceFactory
{
	private static final Logger LOG = LoggerFactory.getLogger(Resource.class);
	public static boolean __defaultUseCaches = true;
	volatile Object _associate;

	/* ------------------------------------------------------------ */
	/**
	 * Change the default setting for url connection caches.
	 * Subsequent URLConnections will use this default.
	 * @param useCaches
	 */
	public static void setDefaultUseCaches (boolean useCaches)
	{
		__defaultUseCaches=useCaches;
	}

	/* ------------------------------------------------------------ */
	public static boolean getDefaultUseCaches ()
	{
		return __defaultUseCaches;
	}
	
	/* ------------------------------------------------------------ */
	/** Construct a resource from a uri.
	 * @param uri A URI.
	 * @return A Resource object.
	 * @throws IOException Problem accessing URI
	 */
	public static Resource newResource(URI uri)
		throws IOException
	{
		return newResource(uri.toURL());
	}
	
	/* ------------------------------------------------------------ */
	/** Construct a resource from a url.
	 * @param url A URL.
	 * @return A Resource object.
	 * @throws IOException Problem accessing URL
	 */
	public static Resource newResource(URL url)
		throws IOException
	{
		return newResource(url, __defaultUseCaches);
	}
	
	/* ------------------------------------------------------------ */   
	/**
	 * Construct a resource from a url.
	 * @param url the url for which to make the resource
	 * @param useCaches true enables URLConnection caching if applicable to the type of resource
	 * @return
	 */
	static Resource newResource(URL url, boolean useCaches)
	{
		if (url==null)
			return null;

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

		return new URLResource(url,null,useCaches);
	}

	
	
	/* ------------------------------------------------------------ */
	/** 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
	{
		return newResource(resource, __defaultUseCaches);
	}
	
	/* ------------------------------------------------------------ */
	/** Construct a resource from a string.
	 * @param resource A URL or filename.
	 * @param useCaches controls URLConnection caching
	 * @return A Resource object.
	 */
	public static Resource newResource (String resource, boolean useCaches)       
	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=Resource.toURL(file);            
					
					URLConnection connection=url.openConnection();
					connection.setUseCaches(useCaches);
					return new FileResource(url,connection,file);
				}
				catch(Exception e2)
				{
					LOG.debug("EXCEPTION",e2);
					throw e;
				}
			}
			else
			{
				LOG.warn("Bad Resource: "+resource);
				throw e;
			}
		}

		return newResource(url);
	}

	/* ------------------------------------------------------------ */
	public static Resource newResource (File file)
	throws MalformedURLException, IOException
	{
		file = file.getCanonicalFile();
		URL url = Resource.toURL(file);

		URLConnection connection = url.openConnection();
		FileResource fileResource = new FileResource(url, connection, file);
		return fileResource;
	}

	/* ------------------------------------------------------------ */
	/** Construct a system resource from a string.
	 * The resource is tried as classloader resource before being
	 * treated as a normal resource.
	 * @param resource Resource as string representation 
	 * @return The new Resource
	 * @throws IOException Problem accessing 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)
		{
			try
			{
				url = loader.getResource(resource);
				if (url == null && resource.startsWith("/"))
					url = loader.getResource(resource.substring(1));
			}
			catch (IllegalArgumentException e)
			{
				// Catches scenario where a bad Windows path like "C:\dev" is
				// improperly escaped, which various downstream classloaders
				// tend to have a problem with
				url = null;
			}
		}
		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=ClassLoader.getSystemResource(resource.substring(1));
		}
		
		if (url==null)
			return null;
		
		return newResource(url);
	}

	/* ------------------------------------------------------------ */
	/** Find a classpath resource.
	 */
	public static Resource newClassPathResource(String resource)
	{
		return newClassPathResource(resource,true,false);
	}

	/* ------------------------------------------------------------ */
	/** Find a classpath resource.
	 * The {@link java.lang.Class#getResource(String)} method is used to lookup the resource. If it is not
	 * found, then the {@link Loader#getResource(Class, String, boolean)} method is used.
	 * If it is still not found, then {@link ClassLoader#getSystemResource(String)} is used.
	 * Unlike {@link ClassLoader#getSystemResource(String)} this method does not check for normal resources.
	 * @param name The relative name of the resource
	 * @param useCaches True if URL caches are to be used.
	 * @param checkParents True if forced searching of parent Classloaders is performed to work around 
	 * loaders with inverted priorities
	 * @return Resource or null
	 */
	public static Resource newClassPathResource(String name,boolean useCaches,boolean checkParents)
	{
		URL url=Resource.class.getResource(name);
		
		if (url==null)
			url=Loader.getResource(Resource.class,name,checkParents);
		if (url==null)
			return null;
		return newResource(url,useCaches);
	}
	
	/* ------------------------------------------------------------ */
	public static boolean isContainedIn (Resource r, Resource containingResource) throws MalformedURLException
	{
		return r.isContainedIn(containingResource);
	}

	/* ------------------------------------------------------------ */
	@Override
	protected void finalize()
	{
		release();
	}
	
	/* ------------------------------------------------------------ */
	public abstract boolean isContainedIn (Resource r) throws MalformedURLException;
	
	
	/* ------------------------------------------------------------ */
	/** Release any temporary 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 URI representing the given resource
	 */
	public URI getURI()
	{
		try
		{
			return getURL().toURI();
		}
		catch(Exception e)
		{
			throw new RuntimeException(e);
		}
	}
	

	/* ------------------------------------------------------------ */
	/**
	 * 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;

	/* ------------------------------------------------------------ */
	/** Get a resource from withing this resource.
	 * <p>
	 * This method is essentially an alias for {@link #addPath(String)}, but without checked exceptions.
	 * This method satisfied the {@link ResourceFactory} interface.
	 * @see org.eclipse.jetty.util.resource.ResourceFactory#getResource(java.lang.String)
	 */
	public Resource getResource(String path)
	{
		try
		{
			return addPath(path);
		}
		catch(Exception e)
		{
			LOG.debug("",e);
			return null;
		}
	}

	/* ------------------------------------------------------------ */
	/** 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 URIUtil.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;
	}
	
	/* ------------------------------------------------------------ */
	/** 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
	{
		base=URIUtil.canonicalPath(base);
		if (base==null || !isDirectory())
			return null;
		
		String[] ls = list();
		if (ls==null)
			return null;
		Arrays.sort(ls);
		
		String decodedBase = URIUtil.decodePath(base);
		String title = "Directory: "+deTag(decodedBase);

		StringBuilder buf=new StringBuilder(4096);
		buf.append("<HTML><HEAD>");
		buf.append("<LINK HREF=\"").append("jetty-dir.css").append("\" REL=\"stylesheet\" TYPE=\"text/css\"/><TITLE>");
		buf.append(title);
		buf.append("</TITLE></HEAD><BODY>\n<H1>");
		buf.append(title);
		buf.append("</H1>\n<TABLE BORDER=0>\n");
		
		if (parent)
		{
			buf.append("<TR><TD><A HREF=\"");
			buf.append(URIUtil.addPaths(base,"../"));
			buf.append("\">Parent Directory</A></TD><TD></TD><TD></TD></TR>\n");
		}
		
		String encodedBase = hrefEncodeURI(base);
		
		DateFormat dfmt=DateFormat.getDateTimeInstance(DateFormat.MEDIUM,
													   DateFormat.MEDIUM);
		for (int i=0 ; i< ls.length ; i++)
		{
			Resource item = addPath(ls[i]);
			
			buf.append("\n<TR><TD><A HREF=\"");
			String path=URIUtil.addPaths(encodedBase,URIUtil.encodePath(ls[i]));
			
			buf.append(path);
			
			if (item.isDirectory() && !path.endsWith("/"))
				buf.append(URIUtil.SLASH);
			
			// URIUtil.encodePath(buf,path);
			buf.append("\">");
			buf.append(deTag(ls[i]));
			buf.append("&nbsp;");
			buf.append("</A></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>");
		}
		buf.append("</TABLE>\n");
	buf.append("</BODY></HTML>\n");
		
		return buf.toString();
	}
	
	/**
	 * Encode any characters that could break the URI string in an HREF.
	 * Such as <a href="/path/to;<script>Window.alert("XSS"+'%20'+"here");</script>">Link</a>
	 * 
	 * The above example would parse incorrectly on various browsers as the "<" or '"' characters
	 * would end the href attribute value string prematurely.
	 * 
	 * @param raw the raw text to encode.
	 * @return the defanged text.
	 */
	private static String hrefEncodeURI(String raw) 
	{
		StringBuffer buf = null;

		loop:
		for (int i=0;i<raw.length();i++)
		{
			char c=raw.charAt(i);
			switch(c)
			{
				case '\'':
				case '"':
				case '<':
				case '>':
					buf=new StringBuffer(raw.length()<<1);
					break loop;
			}
		}
		if (buf==null)
			return raw;

		for (int i=0;i<raw.length();i++)
		{
			char c=raw.charAt(i);       
			switch(c)
			{
			  case '"':
				  buf.append("%22");
				  continue;
			  case '\'':
				  buf.append("%27");
				  continue;
			  case '<':
				  buf.append("%3C");
				  continue;
			  case '>':
				  buf.append("%3E");
				  continue;
			  default:
				  buf.append(c);
				  continue;
			}
		}

		return buf.toString();
	}
	
	private static String deTag(String raw) 
	{
		return StringUtil.replace( StringUtil.replace(raw,"<","&lt;"), ">", "&gt;");
	}
	
	/* ------------------------------------------------------------ */
	/** 
	 * @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,count);
		}
		finally
		{
			in.close();
		}
	}    
	
	/* ------------------------------------------------------------ */
	public void copyTo(File destination)
		throws IOException
	{
		if (destination.exists())
			throw new IllegalArgumentException(destination+" exists");
		writeTo(new FileOutputStream(destination),0,-1);
	}

	/* ------------------------------------------------------------ */
	/** Generate a properly encoded URL from a {@link File} instance.
	 * @param file Target file. 
	 * @return URL of the target file.
	 * @throws MalformedURLException 
	 */
	public static URL toURL(File file) throws MalformedURLException
	{
		return file.toURI().toURL();
	}
}