/*
 * Copyright 2004-2005 Revolution Systems Inc.
 *
 * 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 com.revolsys.ui.web.config;

import java.util.AbstractMap;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.jexl.JexlContext;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.util.UrlPathHelper;

public class HttpServletRequestJexlContext implements JexlContext {

  private final ThreadLocal<Map<String, Object>> localAttributes = new ThreadLocal<>();

  private final ServletContext servletContext;

  private final UrlPathHelper urlPathHelper = new UrlPathHelper();

  public HttpServletRequestJexlContext(final ServletContext servletContext) {
    this.servletContext = servletContext;
  }

  public void clearAttributes() {
    this.localAttributes.remove();
  }

  public Object getAttribute(final String key) {
    final Map<String, Object> attributes = getAttributes();
    return attributes.get(key);
  }

  private Map<String, Object> getAttributes() {
    Map<String, Object> attributes = this.localAttributes.get();
    if (attributes == null) {
      attributes = new HashMap<>();
      this.localAttributes.set(attributes);
    }
    return attributes;
  }

  private HttpServletRequest getRequest() {
    final ServletRequestAttributes requestAttributes = (ServletRequestAttributes)RequestContextHolder
      .getRequestAttributes();
    final HttpServletRequest request = requestAttributes.getRequest();
    return request;
  }

  @Override
  public Map getVars() {
    return new AbstractMap<String, Object>() {
      @Override
      @SuppressWarnings("unchecked")
      public Set<Entry<String, Object>> entrySet() {
        final HttpServletRequest request = getRequest();
        final Map<String, Object> map = new HashMap<>();
        map.putAll(request.getParameterMap());
        for (final Enumeration<String> names = request.getAttributeNames(); names
          .hasMoreElements();) {
          final String name = names.nextElement();
          map.put(name, request.getAttribute(name));
        }
        if (HttpServletRequestJexlContext.this.servletContext != null) {
          for (final Enumeration<String> names = HttpServletRequestJexlContext.this.servletContext
            .getAttributeNames(); names.hasMoreElements();) {
            final String name = names.nextElement();
            map.put(name, HttpServletRequestJexlContext.this.servletContext.getAttribute(name));
          }
        }
        final Map<String, Object> attributes = HttpServletRequestJexlContext.this.localAttributes
          .get();
        if (attributes != null) {
          map.putAll(attributes);
        }
        map.put("request", request);
        map.put("requestURI",
          HttpServletRequestJexlContext.this.urlPathHelper.getOriginatingRequestUri(request));
        return map.entrySet();
      }
    };
  }

  public void setAttribute(final String key, final Object value) {
    final Map<String, Object> attributes = getAttributes();
    attributes.put(key, value);
  }

  public void setAttributes(final Map<String, ? extends Object> parameters) {
    getAttributes().putAll(parameters);
  }

  @Override
  public void setVars(final Map arg0) {
  }
}