/**
 * Redistribution and use of this software and associated documentation ("Software"), with or
 * without modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright statements and notices. Redistributions
 * must also contain a copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided with
 * the distribution.
 *
 * 3. The name "Exolab" must not be used to endorse or promote products derived from this Software
 * without prior written permission of Intalio, Inc. For written permission, please contact
 * info@exolab.org.
 *
 * 4. Products derived from this Software may not be called "Exolab" nor may "Exolab" appear in
 * their names without prior written permission of Intalio, Inc. Exolab is a registered trademark of
 * Intalio, Inc.
 *
 * 5. Due credit should be given to the Exolab Project (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY INTALIO, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESSED OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTALIO, INC. OR ITS
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Copyright 2002-2003 (C) Intalio, Inc. All Rights Reserved.
 *
 * $Id$
 */
package org.exolab.castor.net.util;


import java.io.*;
import java.net.URL;
import java.net.MalformedURLException;
import java.util.Stack;
import java.util.StringTokenizer;

import org.apache.commons.lang3.StringUtils;

/**
 * A utility class for URI handling
 *
 * @author <a href="mailto:kvisco-at-intalio.com">Keith Visco</a>
 **/
public class URIUtils {

  /**
   * the File protocol
   **/
  private static final String FILE_PROTOCOL_PREFIX = "file:///";

  /**
   * the path separator for an URI
   */
  private static final char HREF_PATH_SEP = '/';

  /**
   * the path separate for a URL as a String
   */
  private static final String URL_PATH_SEP_STR = "/";

  /**
   * The current directory designator
   */
  private static final String CURRENT_DIR_OP = ".";

  /**
   * The parent directory designator
   */
  private static final String PARENT_DIR_OP = "..";

  /**
   * Returns an InputStream for the file represented by the href argument
   * 
   * @param href the href of the file to get the input stream for.
   * @param documentBase the document base of the href argument, if it is a relative href set
   *        documentBase to null if there is none.
   * @return an InputStream to the desired resource
   * @throws java.io.FileNotFoundException when the file could not be found
   * @throws java.io.IOException
   */
  public static InputStream getInputStream(String href, String documentBase)
      throws java.io.FileNotFoundException, java.io.IOException {

    // -- check for absolute url
    URL url = null;
    try {
      url = new URL(href);
      return url.openStream();
    } catch (MalformedURLException muex) {
    }

    // -- join document base + href
    String xHref = null;
    if ((documentBase != null) && (documentBase.length() > 0)) {
      int idx = documentBase.lastIndexOf(HREF_PATH_SEP);
      if (idx == (documentBase.length() - 1))
        xHref = documentBase + href;
      else
        xHref = documentBase + HREF_PATH_SEP + href;
    } else
      xHref = href;

    // -- check for relative url
    try {
      url = new URL(xHref);
      return url.openStream();
    } catch (MalformedURLException muex) {
    }

    // Try local files
    File iFile = new File(href);
    if (iFile.isAbsolute())
      return new FileInputStream(iFile);

    iFile = new File(xHref);
    return new FileInputStream(iFile);

  } // -- getInputStream

  /**
   * Returns a Reader for the file represented by the href argument
   * 
   * @param href the href of the file to get the input stream for.
   * @param documentBase the document base of the href argument, if it is a relative href set
   *        documentBase to null if there is none.
   * @return an InputStream to the desired resource
   * @exception java.io.FileNotFoundException when the file could not be found
   **/
  public static Reader getReader(String href, String documentBase)
      throws java.io.FileNotFoundException, java.io.IOException {
    InputStream is = getInputStream(href, documentBase);
    return new InputStreamReader(is);
  } // -- getReader

  /**
   * Returns the document base of the href argument
   * 
   * @return the document base of the given href
   **/
  public static String getDocumentBase(String href) {

    String docBase = "";

    if (href == null)
      return docBase;

    int idx = -1;
    // -- check for URL
    try {
      // -- try to create a new URL and see if MalformedURLExcetion is
      // -- ever thrown
      new URL(href);
      idx = href.lastIndexOf(HREF_PATH_SEP);
    } catch (MalformedURLException muex) {
      // -- The following contains a fix from Shane Hathaway
      // -- to handle the case when both "\" and "/" appear in filename
      int idx2 = href.lastIndexOf(HREF_PATH_SEP);
      idx = href.lastIndexOf(File.separator);
      if (idx2 > idx)
        idx = idx2;
    }

    if (idx >= 0)
      docBase = href.substring(0, idx);

    return docBase;
  } // -- getDocumentBase

  /**
   * Returns the relative URI of the href argument
   *
   * @return the relative URI the given href
   **/
  public static String getRelativeURI(String href) {

    if (href == null)
      return href;

    int idx = -1;
    // -- check for URL
    try {
      // -- try to create a new URL and see if MalformedURLExcetion is
      // -- ever thrown
      new URL(href);
      idx = href.lastIndexOf(HREF_PATH_SEP);
    } catch (MalformedURLException muex) {
      // -- The following contains a fix from Shane Hathaway
      // -- to handle the case when both "\" and "/" appear in filename
      int idx2 = href.lastIndexOf(HREF_PATH_SEP);
      idx = href.lastIndexOf(File.separator);
      if (idx2 > idx)
        idx = idx2;
    }

    if (idx >= 0)
      return href.substring(idx + 1);

    return href;
  } // -- getRelativeURI

  /**
   * This method removes "." or ".." from absolute URL. I needed this method because the JDK doesn't
   * do this automatically when creating URLs.
   *
   * @param absoluteURL the absolute URI to normalize
   */
  public static String normalize(String absoluteURL) throws MalformedURLException {
    if (absoluteURL == null)
      return absoluteURL;
    if (absoluteURL.indexOf('.') < 0)
      return absoluteURL;

    // -- Note: using StringTokenizer and Stacks
    // -- is not very efficient, this may need
    // -- some optimizing
    Stack tokens = new Stack();
    StringTokenizer st = new StringTokenizer(absoluteURL, URL_PATH_SEP_STR, true);
    String last = null;
    while (st.hasMoreTokens()) {
      String token = st.nextToken();
      if (URL_PATH_SEP_STR.equals(token)) {
        if (URL_PATH_SEP_STR.equals(last)) {
          tokens.push("");
        }
      } else if (PARENT_DIR_OP.equals(token)) {
        if (tokens.empty()) {
          // -- this should be an error
          throw new MalformedURLException("invalid absolute URL: " + absoluteURL);
        }
        tokens.pop();
      } else {
        if (!CURRENT_DIR_OP.equals(token)) {
          tokens.push(token);
        }
      }
      last = token;
    }

    // -- rebuild URL
    return StringUtils.join(tokens, HREF_PATH_SEP);
  } // -- normalize


  /**
   *
  **/
  public static String resolveAsString(String href, String documentBase) {

    try {
      // -- try to create a new URL and see if MalformedURLExcetion is
      // -- ever thrown
      new URL(href);
      return href;
    } catch (MalformedURLException muex) {
    }


    // -- join document base + href
    String absolute = null;
    if ((documentBase != null) && (documentBase.length() > 0)) {
      int idx = documentBase.lastIndexOf(HREF_PATH_SEP);
      if (idx == (documentBase.length() - 1))
        absolute = documentBase + href;
      else
        absolute = documentBase + HREF_PATH_SEP + href;


    } else
      absolute = href;


    try {
      // -- try to create a new URL and see if MalformedURLExcetion is
      // -- ever thrown

      if (absolute.indexOf("./") >= 0) {
        // -- normalize . or .. from URL
        absolute = normalize(absolute);
      }
      new URL(absolute);
      return absolute;
    } catch (MalformedURLException muex) {
      // -- check for unrecognized protocol
      int idx = absolute.indexOf(':');
      if (idx >= 0) {
        String scheme = absolute.substring(0, idx);
        // -- a bit of a hack, but good enough for now
        String error = "unknown protocol: " + scheme;
        if (error.equals(muex.getMessage())) {
          return absolute;
        }
      }

    }


    // Try local files
    String fileURL = absolute;
    File iFile = new File(href);
    boolean exists = iFile.exists();
    fileURL = createFileURL(iFile.getAbsolutePath());
    if (!iFile.isAbsolute()) {
      iFile = new File(absolute);
      if (iFile.exists() || (!exists)) {
        fileURL = createFileURL(iFile.getAbsolutePath());
      }
    }

    // -- one last sanity check
    try {
      // -- try to create a new URL and see if MalformedURLExcetion is
      // -- ever thrown
      new URL(fileURL);
      return fileURL;
    } catch (MalformedURLException muex) {
    }

    // -- At this point we we're unsucessful at trying to resolve
    // -- the href + documentbase, this could be due to a custom
    // -- protocol or typo in the URI, just return documentBase +
    // -- href
    return absolute;
  } // -- resolveHref

  /**
   * Creates a File URL for the given file name
   *
   * @param filename the name of the file
   * @return the String representation of the File URL
   **/
  private static String createFileURL(String filename) {

    if (filename == null)
      return FILE_PROTOCOL_PREFIX;
    int size = filename.length() + FILE_PROTOCOL_PREFIX.length();
    StringBuilder sb = new StringBuilder(size);
    sb.append(FILE_PROTOCOL_PREFIX);
    char[] chars = filename.toCharArray();
    for (char ch : chars) {
      if ('\\' == ch) {
        sb.append(HREF_PATH_SEP);
      } else {
        sb.append(ch);
      }
    }
    return sb.toString();
  } // -- createFileURL


} // -- URIUtils
