/*
 * Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
 * 
 * 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 freemarker.ext.servlet;

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

import freemarker.template.SimpleCollection;
import freemarker.template.SimpleScalar;
import freemarker.template.TemplateCollectionModel;
import freemarker.template.TemplateHashModelEx;
import freemarker.template.TemplateModel;

/**
 * TemplateHashModel wrapper for a HttpServletRequest parameters.
 */

public class HttpRequestParametersHashModel
    implements
    TemplateHashModelEx {
    private final HttpServletRequest request;
    private List keys;
        
    public HttpRequestParametersHashModel(HttpServletRequest request) {
        this.request = request;
    }

    public TemplateModel get(String key) {
        String value = request.getParameter(key);
        return value == null ? null : new SimpleScalar(value);
    }

    public boolean isEmpty() {
        return !request.getParameterNames().hasMoreElements();
    }
    
    public int size() {
        return getKeys().size();
    }
    
    public TemplateCollectionModel keys() {
        return new SimpleCollection(getKeys().iterator());
    }
    
    public TemplateCollectionModel values() {
        final Iterator iter = getKeys().iterator();
        return new SimpleCollection(
            new Iterator() {
                public boolean hasNext() {
                    return iter.hasNext();
                }
                public Object next() {
                    return request.getParameter((String) iter.next()); 
                }
                public void remove() {
                    throw new UnsupportedOperationException();
                }
            });
    }

    protected String transcode(String string) {
        return string;
    }

    private synchronized List getKeys() {
        if (keys == null) {
            keys = new ArrayList();
            for (Enumeration enumeration = request.getParameterNames(); enumeration.hasMoreElements(); ) {
                keys.add(enumeration.nextElement());
            }
        }
        return keys;
    }
}