package org.varienaja.util;
   
   import java.io.IOException;
   import java.util.HashMap;
   import java.util.Map;
   import java.util.Map.Entry;
   
   import javax.servlet.FilterChain;
   import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.springframework.orm.hibernate3.support.OpenSessionInViewFilter;
  
  /**
   * The SelectiveOpenSessionInViewFilter selectively applies the 
   * OpenSessionInViewFilter, depending on the requestparameters.
   * @author Varienaja
   */
  public class SelectiveOpenSessionInViewFilter extends OpenSessionInViewFilter {
  	private static final String KEYVALUELIST = "keyvaluelist";
  	private Map<String,String> _filterMap;
  	
  	/**
  	 *  Creates a new SelectiveOpenSessionInViewFilter. When configuring this
  	 *  object, you must specify the keyvaluelist-property. This property should
  	 *  contain a list of K=V; elements.
  	 */
  	public SelectiveOpenSessionInViewFilter() {
  		addRequiredProperty(KEYVALUELIST);
  		_filterMap = new HashMap<String,String>();
  	}
  
  	/*
  	 * Intercept the requests for the StreamService and deny them the normal
  	 * opensessioninviewfilter-behaviour, if filtered.
  	 * (non-Javadoc)
  	 * @see org.springframework.orm.hibernate3.support.OpenSessionInViewFilter#doFilterInternal(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain)
  	 */
  	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
  		//MAJOR WTF BELOW
  		//We're reading request parameters here. But the SetupRequestEncoding
  		//class of Tapestry did not set the encoding yet. The encoding can only
  		//be set once, and it has to be before parameters are read, otherwise
  		//they are read as ASCII or something alike, which is not what we want.
  		//So here's teh very superspecial MusiController-setting which corrects
  		//everything: we just set the encoding to be UTF-8, since that is our
  		//encoding in MusiController. We read our parameters right, and Tapestry
  		//will decode them correctly later on as well. Everybody is happy.
  		request.setCharacterEncoding("UTF-8");
  		
  		
  		boolean matched = false;
  		for (Entry<String,String> entry : _filterMap.entrySet()) {
  			String values = request.getParameter(entry.getKey());
  			if (entry.getValue().equals(values)) {
  				matched = true;
  				break;
  			}
  		}
  		
  		if (matched) {
  			filterChain.doFilter(request, response);
  		} else { 
  			super.doFilterInternal(request, response, filterChain);
  		}
  	}
  	
  	/*
  	 * (non-Javadoc)
  	 * @see org.springframework.web.filter.GenericFilterBean#initFilterBean()
  	 */
  	protected void initFilterBean() throws ServletException {
  		String cfg = getFilterConfig().getInitParameter(KEYVALUELIST);
  		for (String pair : cfg.split(";")) {
  			String[] items = pair.split("=");
  			if (items.length==2) {
  				_filterMap.put(items[0], items[1]);
  			} else {
  				throw new ServletException("Erroneous config of " + getClass().getName() + ", cannot interpret: " + cfg);
  			}
  		}
  	}
  }