/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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.opencastproject.urlsigning.common;
  
  import static java.util.Objects.requireNonNull;
  
  import com.google.common.base.Optional;
  import com.google.common.net.InetAddresses;
  
  import org.apache.commons.lang3.StringUtils;
  import org.joda.time.DateTime;
  
  import java.net.InetAddress;
  
  /**
   * Represents a policy for a signed resource that looks like
   *
   */
  public final class Policy {
  
    /** The base URL for the resource being requested. */
    private final String baseUrl;
  
    /** The date and time when the resource expires. */
    private final DateTime validUntil;
  
    /** The date and time when the resource will become available. */
    private final Optional<DateTime> validFrom;
  
    /** An optional client IP address that made the original request. */
    private final Optional<InetAddress> clientIpAddress;
  
    /** The required strategy to convert a base url to the resource url. */
    private ResourceStrategy resourceStrategy = new BasicResourceStrategyImpl();
  
    /**
     * Create a new Policy.
     *
     * @param baseUrl
     *          The base url that points to the resource that is being made available.
     * @param validUntil
     *          The date and time the resource is available until.
     * @param validFrom
     *          An optional date and time the resource will first become available.
     * @param clientIpAddress
     *          An optional client IP address to restrict the viewing of the resource to.
     * @param resourceStrategy
     *          The strategy for getting the resource from the policy.
     */
    private Policy(String baseUrl, DateTime validUntil, DateTime validFrom, String clientIpAddress) {
      requireNonNull(baseUrl);
      requireNonNull(validUntil);
  
      this.baseUrl = baseUrl;
      this.validUntil = validUntil;
      this.validFrom = Optional.fromNullable(validFrom);
      if (StringUtils.isNotBlank(clientIpAddress)) {
        this.clientIpAddress = Optional.of(InetAddresses.forString(clientIpAddress));
      } else {
        this.clientIpAddress = Optional.absent();
      }
    }
  
    /**
     * Create a {@link Policy} with only the required properties.
     *
     * @param baseUrl
     *          The url to the resource that will be signed.
     * @param validUntil
     *          The date and time the resource will be available until
     * @return A new {@link Policy} with the parameters set.
     */
    public static Policy mkSimplePolicy(String baseUrl, DateTime validUntil) {
      return new Policy(baseUrl, validUntil, null, null);
    }
  
    /**
     * Create a {@link Policy} with a date and time the resource will become available.
     *
     * @param baseUrl
     *          The url to the resource being signed.
    * @param validUntil
    *          The date and time the resource is available until.
    * @param validFrom
    *          The date and time the resource will become available.
    * @return A new {@link Policy} for limiting access to the resource.
    */
   public static Policy mkPolicyValidFrom(String baseUrl, DateTime validUntil, DateTime validFrom) {
     return new Policy(baseUrl, validUntil, validFrom, null);
   }
 
   /**
    * Create a {@link Policy} with the only ip address that will be allowed to view the resource.
    *
    * @param baseUrl
    *          The url to the resource being signed.
    * @param validUntil
    *          The date the resource will be available until.
    * @param ipAddress
    *          The ip of the client that will be allowed to view the resource.
    * @return A new {@link Policy} for limiting access to the resource.
    */
   public static Policy mkPolicyValidWithIP(String baseUrl, DateTime validUntil, String ipAddress) {
     return new Policy(baseUrl, validUntil, null, ipAddress);
   }
 
   /**
    * Create a {@link Policy} with both a date and time the resource will become available and a client ip address to
    * restrict it to.
    *
    * @param baseUrl
    *          The url to the resource that is being signed.
    * @param validUntil
    *          The date and time the resource will be available until.
    * @param validFrom
    *          The date and time the resource will become available.
    * @param ipAddress
    *          The ip of the client that will be allowed to view the resource.
    * @return A new {@link Policy} for limiting access to the resource.
    */
   public static Policy mkPolicyValidFromWithIP(String baseUrl, DateTime validUntil, DateTime validFrom,
           String ipAddress) {
     return new Policy(baseUrl, validUntil, validFrom, ipAddress);
   }
 
   /**
    * @return Get the url to the resource that is being signed with this policy.
    */
   public String getBaseUrl() {
     return baseUrl;
   }
 
   /**
    * @return Get the date this resource is valid until.
    */
   public DateTime getValidUntil() {
     return validUntil;
   }
 
   /**
    * @return Get the url for the resource in this {@link Policy}.
    */
   public String getResource() {
     return resourceStrategy.getResource(baseUrl);
   }
 
   /**
    * Set a new {@link ResourceStrategy} to transform the base url to a resource url.
    *
    * @param resourceStrategy
    *          The resource strategy to apply to transform the base url.
    */
   public void setResourceStrategy(ResourceStrategy resourceStrategy) {
     this.resourceStrategy = resourceStrategy;
   }
 
   /**
    * @return Get the optional ip address of the client that this resource will be restricted to.
    */
   public Optional<InetAddress> getClientIpAddress() {
     return clientIpAddress;
   }
 
   /**
    * @return Get the optional date and time this resource will become available.
    */
   public Optional<DateTime> getValidFrom() {
     return validFrom;
   }
 
 }