// This Source Code is in the Public Domain per: http://unlicense.org
package org.litesoft.servlet.imageservlet;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

import org.litesoft.commonfoundation.typeutils.*;
import org.litesoft.configuration.*;

public class ImageServlet extends HttpServlet
{
    private static final long serialVersionUID = 1L;

    private static final String IMAGES_BASE_PATH = "ImagesBasePath";

    private File mImagesBasePath = null;

    @Override
    public void init()
            throws ServletException
    {
        super.init();
        if ( !Configuration.isInstantiated() )
        {
            new ServerConfiguration( new MapConfigDataAccessorFactory( "No Config File - Testing?", IMAGES_BASE_PATH, "/TestImages" ) );
        }
        String zImagesBasePath = Configuration.getStringRequired( IMAGES_BASE_PATH );
        File zDir = new File( zImagesBasePath );
        if ( !zDir.exists() )
        {
            if ( !zDir.mkdir() )
            {
                throw new ServletException( "Unable to create Image Base Path (" + zImagesBasePath + ") Directory!" );
            }
        }
        if ( !zDir.isDirectory() )
        {
            throw new ServletException( "Image Base Path (" + zImagesBasePath + "), not a Directory!" );
        }
        if ( !zDir.canWrite() )
        {
            throw new ServletException( "Image Base Path (" + zImagesBasePath + ") Directory NOT writable!" );
        }
        mImagesBasePath = zDir;
    }

    private String normalize( String pPathInfo )
            throws FileNotFoundException
    {
        if ( pPathInfo != null )
        {
            // switch any separators and insure that we start w/ a '/'
            pPathInfo = "/" + Strings.noSpaces( pPathInfo.replace( '\\', '/' ) );
            // change all "//"s to '/'
            for ( int at; -1 != (at = pPathInfo.indexOf( "//" )); )
            {
                pPathInfo = pPathInfo.substring( 0, at + 1 ) + pPathInfo.substring( at + 2 );
            }
            // change all "/./"s to '/'
            for ( int at; -1 != (at = pPathInfo.indexOf( "/./" )); )
            {
                pPathInfo = pPathInfo.substring( 0, at + 1 ) + pPathInfo.substring( at + 3 );
            }
            if ( !pPathInfo.contains( "/../" ) ) // No Up Dirs!
            {
                while ( pPathInfo.startsWith( "/" ) )
                {
                    pPathInfo = pPathInfo.substring( 1 );
                }
                File zFile = new File( mImagesBasePath, pPathInfo );
                if ( zFile.isFile() )
                {
                    if ( zFile.canRead() )
                    {
                        return zFile.getAbsolutePath();
                    }
                    throw new FileNotFoundException( "Can't Read: " + pPathInfo + " -> " + zFile.getAbsolutePath() );
                }
            }
        }
        throw new FileNotFoundException( "No Resource of: " + pPathInfo );
    }

    // This method is called by the servlet container to process a GET request.
    public void doGet( HttpServletRequest pReq, HttpServletResponse pResp )
            throws IOException
    {
        // http://localhost:8080/Images/Fred.jpg  ->  /Fred.jpg

        String filename = normalize( pReq.getPathInfo() );

        ServletContext sc = getServletContext();

        // Get the MIME type of the image
        String mimeType = sc.getMimeType( filename.toLowerCase() );
        if ( mimeType == null )
        {
            sc.log( "Could not get MIME type of " + filename );
            pResp.setStatus( HttpServletResponse.SC_INTERNAL_SERVER_ERROR );
            return;
        }

        // Set content type
        pResp.setContentType( mimeType );

        // Set content size
        File file = new File( filename );
        pResp.setContentLength( (int) file.length() );

        // Open the file and output streams
        InputStream in = new FileInputStream( file );
        try
        {
            OutputStream out = pResp.getOutputStream();

            try
            {
                // Copy the contents of the file to the output stream
                byte[] buf = new byte[1024];
                for ( int count; (count = in.read( buf )) > 0; )
                {
                    out.write( buf, 0, count );
                }
                Closeable zCloseable = out;
                out = null;
                zCloseable.close();
            }
            finally
            {
                if ( out != null )
                {
                    try
                    {
                        out.close();
                    }
                    catch ( IOException e )
                    {
                        // Whatever
                    }
                }
            }
        }
        finally
        {
            try
            {
                in.close();
            }
            catch ( IOException e )
            {
                // Whatever
            }
        }
    }
}