package org.litesoft.servlets;

import java.util.*;
import javax.servlet.*;

public abstract class UserAuthenticationService
{
    private static UserAuthenticationService sInstance = null;

    public static synchronized UserAuthenticationService getInstance( Servlet pServlet )
    {
        if ( sInstance != null )
        {
            return sInstance;
        }
        String zUASclassname = pServlet.getServletConfig().getServletContext().getInitParameter( "UserAuthenticationService" );
        if ( zUASclassname != null )
        {
            try
            {
                Class<?> zClass = Class.forName( zUASclassname );
                Object o = zClass.newInstance();
                return sInstance = (UserAuthenticationService) o;
            }
            catch ( Exception e )
            {
                throw new Error( "Unacceptable" + getCommonMessage( pServlet ), e );
            }
        }
        throw new Error( "No" + getCommonMessage( pServlet ) );
    }

    private static String getCommonMessage( Servlet pServlet )
    {
        return " web.xml servlet context init-param 'UserAuthenticationService': " + pServlet.getClass().getSimpleName();
    }

    private Map<String, String> mCookieUserMap = new HashMap<String, String>();
    private int mNextCookieValue = 12345;

    protected UserAuthenticationService()
    {
    }

    public synchronized String getUserForCookie( String pCookieValue )
    {
        return mCookieUserMap.get( pCookieValue );
    }

    public synchronized String createCookieForUser( String pUserName )
    {
        String zCookieValue = "UCV" + (mNextCookieValue++);
        mCookieUserMap.put( zCookieValue, pUserName );
        return zCookieValue;
    }

    public abstract boolean isUserValid( String pUserName, String pPassword );
}