/*
 * Copyright 2012 LinkedIn Corp.
 *
 * 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 azkaban.webapp.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.tools.generic.EscapeTool;

import azkaban.utils.Utils;

/**
 * A page to display
 */
public class Page {
  private static final String DEFAULT_MIME_TYPE = "text/html";
  @SuppressWarnings("unused")
  private final HttpServletRequest request;
  private final HttpServletResponse response;
  private final VelocityEngine engine;
  private final VelocityContext context;
  private final String template;
  private String mimeType = DEFAULT_MIME_TYPE;

  /**
   * Creates a page and sets up the velocity engine to render
   *
   * @param request
   * @param response
   * @param engine
   * @param template
   */
  public Page(HttpServletRequest request, HttpServletResponse response,
      VelocityEngine engine, String template) {
    this.request = Utils.nonNull(request);
    this.response = Utils.nonNull(response);
    this.engine = Utils.nonNull(engine);
    this.template = Utils.nonNull(template);
    this.context = new VelocityContext();
    this.context.put("esc", new EscapeTool());
    this.context.put("session", request.getSession(true));
    this.context.put("context", request.getContextPath());
  }

  /**
   * Renders the page in UTF-8
   */
  public void render() {
    try {
      response.setHeader("Content-type", "text/html; charset=UTF-8");
      response.setCharacterEncoding("UTF-8");
      response.setContentType(mimeType);
      engine.mergeTemplate(template, "UTF-8", context, response.getWriter());
    } catch (Exception e) {
      throw new PageRenderException(e);
    }
  }

  /**
   * Adds variables to the velocity context.
   */
  public void add(String name, Object value) {
    context.put(name, value);
  }

  public void setMimeType(String type) {
    mimeType = type;
  }
}