/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.reef.webserver;

import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.net.URLDecoder;
import java.util.*;

/**
 * Parsed HttpServletRequest.
 */
public final class ParsedHttpRequest {
  private final String pathInfo;
  private final String method;
  private final String queryString;
  private final String requestUri;
  private final String requestUrl;
  private final byte[] inputStream;
  private final String targetSpecification;
  private final String version;
  private final String targetEntity;

  private final Map<String, String> headers = new HashMap();
  private final Map<String, List<String>> queryPairs = new LinkedHashMap<>();

  /**
   * parse HttpServletRequest.
   *
   * @param request
   * @throws IOException
   */
  public ParsedHttpRequest(final HttpServletRequest request) throws IOException {
    this.pathInfo = request.getPathInfo() != null ? request.getPathInfo() : "";
    this.method = request.getMethod() != null ? request.getMethod() : "";
    this.queryString = request.getQueryString() != null ? request.getQueryString() : "";
    this.requestUri = request.getRequestURI() != null ? request.getRequestURI() : "";
    this.requestUrl = request.getRequestURL().toString();

    for (final Enumeration en = request.getHeaderNames(); en.hasMoreElements();) {
      final String headerName = en.nextElement().toString();
      this.headers.put(headerName, request.getHeader(headerName));
    }

    final int len = request.getContentLength();
    if (len > 0) {
      this.inputStream = new byte[len];
      request.getInputStream().read(this.inputStream);
    } else {
      this.inputStream = new byte[0];
    }

    final String[] parts = this.requestUri.split("/");
    this.targetSpecification = parts.length > 1 ? parts[1] : null;
    this.version = parts.length > 2 ? parts[2] : null;
    this.targetEntity = parts.length > 3 ? parts[3] : null;

    if (!this.queryString.isEmpty()) {
      final String[] pairs = this.queryString.split("&");
      for (final String pair : pairs) {
        final int idx = pair.indexOf("=");
        if (idx != -1) {
          final String rKey = pair.substring(0, idx);
          final String rValue = pair.substring(idx + 1);
          final String key = URLDecoder.decode(rKey, "UTF-8");
          final String value = URLDecoder.decode(rValue, "UTF-8");
          List<String> valuesList = this.queryPairs.get(key.toLowerCase());
          if (valuesList == null) {
            valuesList = new ArrayList<>(1);
            this.queryPairs.put(key, valuesList);
          }
          valuesList.add(value);
        }
      }
    }
  }

  /**
   * get http header as a list of HeaderEntry.
   * @return
   */
  public List<HeaderEntry> getHeaderEntryList() {
    final List<HeaderEntry> list = new ArrayList<>();
    final Iterator it = this.headers.entrySet().iterator();
    while (it.hasNext()) {
      final Map.Entry pair = (Map.Entry)it.next();
      System.out.println(pair.getKey() + " = " + pair.getValue());
      final HeaderEntry e = HeaderEntry.newBuilder()
              .setKey((String) pair.getKey())
              .setValue((String) pair.getValue())
              .build();
      list.add(e);
      it.remove(); // avoids a ConcurrentModificationException
    }
    return list;
  }

  /**
   * get target to match specification like "Reef".
   *
   * @return specification
   */
  public String getTargetSpecification() {
    return this.targetSpecification;
  }

  /**
   * get query string like "id=12345" . If no query string is provided in request, return empty string.
   *
   * @return
   */
  public String getQueryString() {
    return this.queryString;
  }

  /**
   * get target target entity like "Evaluators".
   *
   * @return
   */
  public String getTargetEntity() {
    return this.targetEntity;
  }

  /**
   * get http request method like "Get".
   *
   * @return
   */
  public String getMethod() {
    return this.method;
  }

  /**
   * get input Stream.
   *
   * @return
   */
  public byte[] getInputStream() {
    return this.inputStream;
  }

  /**
   * get request headers.
   *
   * @return
   */
  public Map<String, String> getHeaders() {
    return this.headers;
  }

  /**
   * get parsed queries.
   *
   * @return
   */
  public Map<String, List<String>> getQueryMap() {
    return this.queryPairs;
  }

  /**
   * get URL like //http://localhost:8080/Reef/Evaluators/.
   *
   * @return
   */
  public String getRequestUrl() {
    return this.requestUrl;
  }

  /**
   * get path infor, like /Reef/Evaluators/.
   *
   * @return
   */
  public String getPathInfo() {
    return pathInfo;
  }

  /**
   * get URI, like /Reef/Evaluators/.
   *
   * @return
   */
  public String getRequestUri() {
    return this.requestUri;
  }

  /**
   * get version of the request for Rest API.
   *
   * @return
   */
  public String getVersion() {
    return version;
  }
}