/**
 * 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.nutch.protocol.selenium;

// JDK imports
import java.io.BufferedInputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.OutputStream;
import java.io.ByteArrayOutputStream;
import java.io.PushbackInputStream;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.URL;

import org.apache.hadoop.conf.Configuration;
import org.apache.nutch.crawl.CrawlDatum;
import org.apache.nutch.metadata.Metadata;
import org.apache.nutch.metadata.SpellCheckedMetadata;
import org.apache.nutch.net.protocols.HttpDateFormat;
import org.apache.nutch.net.protocols.Response;
import org.apache.nutch.protocol.ProtocolException;
import org.apache.nutch.protocol.http.api.HttpException;
import org.apache.nutch.protocol.http.api.HttpBase;

/* Most of this code was borrowed from protocol-htmlunit; which in turn borrowed it from protocol-httpclient */

public class HttpResponse implements Response {

  private Http http;
  private URL url;
  private String orig;
  private String base;
  private byte[] content;
  private int code;
  private Metadata headers = new SpellCheckedMetadata();

  /** The nutch configuration */
  private Configuration conf = null;

  public HttpResponse(Http http, URL url, CrawlDatum datum) throws ProtocolException, IOException {

    this.conf = http.getConf();
    this.http = http;
    this.url = url;
    this.orig = url.toString();
    this.base = url.toString();

    if (!"http".equals(url.getProtocol()))
      throw new HttpException("Not an HTTP url:" + url);

    if (Http.LOG.isTraceEnabled()) {
      Http.LOG.trace("fetching " + url);
    }

    String path = "".equals(url.getFile()) ? "/" : url.getFile();

    // some servers will redirect a request with a host line like
    // "Host: <hostname>:80" to "http://<hpstname>/<orig_path>"- they
    // don't want the :80...

    String host = url.getHost();
    int port;
    String portString;
    if (url.getPort() == -1) {
      port = 80;
      portString = "";
    } else {
      port = url.getPort();
      portString = ":" + port;
    }
    Socket socket = null;

    try {
      socket = new Socket(); // create the socket
      socket.setSoTimeout(http.getTimeout());

      // connect
      String sockHost = http.useProxy() ? http.getProxyHost() : host;
      int sockPort = http.useProxy() ? http.getProxyPort() : port;
      InetSocketAddress sockAddr = new InetSocketAddress(sockHost, sockPort);
      socket.connect(sockAddr, http.getTimeout());

      // make request
      OutputStream req = socket.getOutputStream();

      StringBuffer reqStr = new StringBuffer("GET ");
      if (http.useProxy()) {
        reqStr.append(url.getProtocol() + "://" + host + portString + path);
      } else {
        reqStr.append(path);
      }

      reqStr.append(" HTTP/1.0\r\n");

      reqStr.append("Host: ");
      reqStr.append(host);
      reqStr.append(portString);
      reqStr.append("\r\n");

      reqStr.append("Accept-Encoding: x-gzip, gzip, deflate\r\n");

      String userAgent = http.getUserAgent();
      if ((userAgent == null) || (userAgent.length() == 0)) {
        if (Http.LOG.isErrorEnabled()) {
          Http.LOG.error("User-agent is not set!");
        }
      } else {
        reqStr.append("User-Agent: ");
        reqStr.append(userAgent);
        reqStr.append("\r\n");
      }

      reqStr.append("Accept-Language: ");
      reqStr.append(this.http.getAcceptLanguage());
      reqStr.append("\r\n");

      reqStr.append("Accept: ");
      reqStr.append(this.http.getAccept());
      reqStr.append("\r\n");

      if (datum.getModifiedTime() > 0) {
        reqStr.append("If-Modified-Since: " + HttpDateFormat.toString(datum.getModifiedTime()));
        reqStr.append("\r\n");
      }
      reqStr.append("\r\n");

      byte[] reqBytes = reqStr.toString().getBytes();

      req.write(reqBytes);
      req.flush();

      PushbackInputStream in = // process response
          new PushbackInputStream(new BufferedInputStream(socket.getInputStream(), Http.BUFFER_SIZE),
              Http.BUFFER_SIZE);

      StringBuffer line = new StringBuffer();

      boolean haveSeenNonContinueStatus = false;
      while (!haveSeenNonContinueStatus) {
        // parse status code line
        this.code = parseStatusLine(in, line);
        // parse headers
        parseHeaders(in, line);
        haveSeenNonContinueStatus = code != 100; // 100 is "Continue"
      }

      // Get Content type header
      String contentType = getHeader(Response.CONTENT_TYPE);

      // handle with Selenium only if content type in HTML or XHTML 
      if (contentType != null) {
        if (contentType.contains("text/html") || contentType.contains("application/xhtml")) {
          readPlainContent(url);
        } else {
          try {
            int contentLength = Integer.MAX_VALUE;
            String contentLengthString = headers.get(Response.CONTENT_LENGTH);
            if (contentLengthString != null) {
              try {
                contentLength = Integer.parseInt(contentLengthString.trim());
              } catch (NumberFormatException ex) {
                throw new HttpException("bad content length: " + contentLengthString);
              }
            }

            if (http.getMaxContent() >= 0 && contentLength > http.getMaxContent()) {
              contentLength = http.getMaxContent();
            }

            byte[] buffer = new byte[HttpBase.BUFFER_SIZE];
            int bufferFilled = 0;
            int totalRead = 0;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            while ((bufferFilled = in.read(buffer, 0, buffer.length)) != -1
                && totalRead + bufferFilled <= contentLength) {
              totalRead += bufferFilled;
              out.write(buffer, 0, bufferFilled);
            }

            content = out.toByteArray();

          } catch (Exception e) {
            if (code == 200)
              throw new IOException(e.toString());
            // for codes other than 200 OK, we are fine with empty content
          } finally {
            if (in != null) {
              in.close();
            }
          }
        }
      } 

    } finally {
      if (socket != null)
        socket.close();
    }
  }

  /* ------------------------- *
   * <implementation:Response> *
   * ------------------------- */

  public URL getUrl() {
    return url;
  }

  public int getCode() {
    return code;
  }

  public String getHeader(String name) {
    return headers.get(name);
  }

  public Metadata getHeaders() {
    return headers;
  }

  public byte[] getContent() {
    return content;
  }

  /* ------------------------- *
   * <implementation:Response> *
   * ------------------------- */

  private void readPlainContent(URL url) throws IOException {
    String page = HttpWebClient.getHtmlPage(url.toString(), conf);

    content = page.getBytes("UTF-8");
  }

  private int parseStatusLine(PushbackInputStream in, StringBuffer line) throws IOException, HttpException {
    readLine(in, line, false);

    int codeStart = line.indexOf(" ");
    int codeEnd = line.indexOf(" ", codeStart + 1);

    // handle lines with no plaintext result code, ie:
    // "HTTP/1.1 200" vs "HTTP/1.1 200 OK"
    if (codeEnd == -1)
      codeEnd = line.length();

    int code;
    try {
      code = Integer.parseInt(line.substring(codeStart + 1, codeEnd));
    } catch (NumberFormatException e) {
      throw new HttpException("bad status line '" + line + "': " + e.getMessage(), e);
    }

    return code;
  }

  private void processHeaderLine(StringBuffer line) throws IOException, HttpException {

    int colonIndex = line.indexOf(":"); // key is up to colon
    if (colonIndex == -1) {
      int i;
      for (i = 0; i < line.length(); i++)
        if (!Character.isWhitespace(line.charAt(i)))
          break;
      if (i == line.length())
        return;
      throw new HttpException("No colon in header:" + line);
    }
    String key = line.substring(0, colonIndex);

    int valueStart = colonIndex + 1; // skip whitespace
    while (valueStart < line.length()) {
      int c = line.charAt(valueStart);
      if (c != ' ' && c != '\t')
        break;
      valueStart++;
    }
    String value = line.substring(valueStart);
    headers.set(key, value);
  }

  // Adds headers to our headers Metadata
  private void parseHeaders(PushbackInputStream in, StringBuffer line) throws IOException, HttpException {

    while (readLine(in, line, true) != 0) {

      // handle HTTP responses with missing blank line after headers
      int pos;
      if (((pos = line.indexOf("<!DOCTYPE")) != -1) || ((pos = line.indexOf("<HTML")) != -1)
          || ((pos = line.indexOf("<html")) != -1)) {

        in.unread(line.substring(pos).getBytes("UTF-8"));
        line.setLength(pos);

        try {
          //TODO: (CM) We don't know the header names here
          //since we're just handling them generically. It would
          //be nice to provide some sort of mapping function here
          //for the returned header names to the standard metadata
          //names in the ParseData class
          processHeaderLine(line);
        } catch (Exception e) {
          // fixme:
          Http.LOG.warn("Error: ", e);
        }
        return;
      }

      processHeaderLine(line);
    }
  }

  private static int readLine(PushbackInputStream in, StringBuffer line, boolean allowContinuedLine)
      throws IOException {
    line.setLength(0);
    for (int c = in.read(); c != -1; c = in.read()) {
      switch (c) {
      case '\r':
        if (peek(in) == '\n') {
          in.read();
        }
      case '\n':
        if (line.length() > 0) {
          // at EOL -- check for continued line if the current
          // (possibly continued) line wasn't blank
          if (allowContinuedLine)
            switch (peek(in)) {
            case ' ':
            case '\t': // line is continued
              in.read();
              continue;
            }
        }
        return line.length(); // else complete
      default:
        line.append((char) c);
      }
    }
    throw new EOFException();
  }

  private static int peek(PushbackInputStream in) throws IOException {
    int value = in.read();
    in.unread(value);
    return value;
  }
}
