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/*

Copyright (c) 2019 Board of Trustees of Leland Stanford Jr. University,
all rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.

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. Neither the name of the copyright holder nor the names of its contributors
may be used to endorse or promote products derived from this software without
specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS 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 THE COPYRIGHT HOLDER OR 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.

 */
package org.lockss.laaws.rs.impl;

import java.util.List;
import org.lockss.log.L4JLogger;
import org.lockss.util.StringUtil;
import org.lockss.util.UrlUtil;

/**
 * The continuation token used to paginate through a list of archival unit
 * identifiers.
 * 
 * @author Fernando García-Loygorri
 */
public class AuidContinuationToken {
  private final static L4JLogger log = L4JLogger.getLogger();
  private static final String separator = ":";

  private String auid = null;
  private Integer iteratorHashCode = null;

  /**
   * Constructor from a web request continuation token.
   * 
   * @param webRequestContinuationToken
   *          A String with the web request continuation token.
   * @throws IllegalArgumentException
   *           if the web request continuation token is not syntactically valid.
   */
  public AuidContinuationToken(String webRequestContinuationToken)
      throws IllegalArgumentException {
    log.debug2("webRequestContinuationToken = {}", webRequestContinuationToken);

    String message = "Invalid web request continuation token '"
	+ webRequestContinuationToken + "'";

    // Check whether a non-empty web request continuation token has been passed.
    if (webRequestContinuationToken != null
	&& !webRequestContinuationToken.trim().isEmpty()) {
      // Yes: Parse it.
      List tokenItems = null;

      try {
	tokenItems =
	    StringUtil.breakAt(webRequestContinuationToken.trim(), separator);
	log.trace("tokenItems = {}", tokenItems);

	auid = UrlUtil.decodeUrl(tokenItems.get(0).trim());
	log.trace("auid = {}", auid);

	iteratorHashCode = Integer.valueOf(tokenItems.get(1).trim());
	log.trace("iteratorHashCode = {}", iteratorHashCode);
      } catch (Exception e) {
	log.warn(message, e);
	throw new IllegalArgumentException(message, e);
      }

      // Validate the format of the web request continuation token.
      if (tokenItems.size() != 2) {
	log.warn(message);
	throw new IllegalArgumentException(message);
      }

      validateMembers();
    }
  }

  /**
   * Constructor from members.
   * 
   * @param auid
   *          A String with the last archival unit identifier transferred.
   * @param iteratorHashCode
   *          An Integer with the hash code of the iterator used.
   */
  public AuidContinuationToken(String auid, Integer iteratorHashCode) {
    this.auid = auid;
    this.iteratorHashCode = iteratorHashCode;

    validateMembers();
  }

  /**
   * Provides the last archival unit identifier transferred.
   * 
   * @return a String with the last archival unit identifier transferred.
   */
  public String getAuid() {
    return auid;
  }

  /**
   * Provides the hash code of the iterator used.
   * 
   * @return an Integer with the hash code of the iterator used.
   */
  public Integer getIteratorHashCode() {
    return iteratorHashCode;
  }

  /**
   * Provides this object in the form of a web response continuation token.
   * 
   * @return a String with this object in the form of a web response
   *         continuation token.
   */
  public String toWebResponseContinuationToken() {
    if (auid != null && iteratorHashCode != null) {
      String encodedToken =
	  UrlUtil.encodeUrl(auid) + separator + iteratorHashCode;
      log.trace("encodedToken = {}", encodedToken);
      return encodedToken;
    }

    String message = "Cannot get web request continuation token from " + this;
    log.warn(message);
    throw new IllegalArgumentException(message);
  }

  @Override
  public String toString() {
    return "[AuidContinuationToken auid=" + auid
	+ ", iteratorHashCode=" + iteratorHashCode + "]";
  }

  /**
   * Verifies the validity of the members of this class.
   */
  private void validateMembers() {
    // Validate that both members are both null or both non-null. 
    if ((auid == null && iteratorHashCode != null)
	|| (auid != null && iteratorHashCode == null)) {
      String message = "Invalid member combination: auid = '" + auid
	  + "', iteratorHashCode = '" + iteratorHashCode + "'";
      log.warn(message);
      throw new IllegalArgumentException(message);
    }

    // Validate that the auid is not empty.
    if (auid != null && auid.isEmpty()) {
      String message = "Invalid member: auid = '" + auid + "'";
      log.warn(message);
      throw new IllegalArgumentException(message);
    }

    // Validate that the iterator hash code is not negative.
    if (iteratorHashCode != null && iteratorHashCode.intValue() < 0) {
      String message =
	  "Invalid member: iteratorHashCode = '" + iteratorHashCode + "'";
      log.warn(message);
      throw new IllegalArgumentException(message);
    }
  }
}