/*
 * 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.juneau.http.part;

import static java.time.format.DateTimeFormatter.*;
import static java.time.temporal.ChronoUnit.*;
import static org.apache.juneau.commons.utils.Utils.*;

import java.time.*;
import java.time.format.*;
import java.util.*;
import java.util.function.*;

import org.apache.http.*;
import org.apache.juneau.assertions.*;

/**
 * A {@link NameValuePair} that consist of a single HTTP-date.
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JuneauRestCommonBasics">juneau-rest-common Basics</a>
 * </ul>
 */
public class BasicDatePart extends BasicPart {
   /**
    * Static creator with delayed value.
    *
    * <p>
    * Part value is re-evaluated on each call to {@link NameValuePair#getValue()}.
    *
    * @param name The part name.
    * @param value The part value supplier.
    * @return A new {@link BasicDatePart} object, or <jk>null</jk> if the name or supplier is <jk>null</jk>.
    */
   public static BasicDatePart of(String name, Supplier<ZonedDateTime> value) {
      if (e(name) || value == null)
         return null;
      return new BasicDatePart(name, value);
   }

   /**
    * Static creator.
    *
    * @param name The part name.
    * @param value The part value.
    * @return A new {@link BasicDatePart} object, or <jk>null</jk> if the name or value is <jk>null</jk>.
    */
   public static BasicDatePart of(String name, ZonedDateTime value) {
      if (e(name) || value == null)
         return null;
      return new BasicDatePart(name, value);
   }

   private final ZonedDateTime value;
   private final Supplier<ZonedDateTime> supplier;

   /**
    * Constructor.
    *
    * <p>
    * <jk>null</jk> and empty values are treated as <jk>null</jk>.
    * Otherwise parses using {@link DateTimeFormatter#ISO_DATE_TIME}.
    *
    * @param name The part name.  Must not be <jk>null</jk>.
    * @param value The part value.  Can be <jk>null</jk>.
    */
   public BasicDatePart(String name, String value) {
      super(name, value);
      this.value = e(value) ? null : ZonedDateTime.from(ISO_DATE_TIME.parse(value)).truncatedTo(SECONDS);
      this.supplier = null;
   }

   /**
    * Constructor.
    *
    * @param name The part name.  Must not be <jk>null</jk>.
    * @param value The part value supplier.  Can be <jk>null</jk> or supply <jk>null</jk>.
    */
   public BasicDatePart(String name, Supplier<ZonedDateTime> value) {
      super(name, value);
      this.value = null;
      supplier = value;
   }

   /**
    * Constructor.
    *
    * @param name The part name.  Must not be <jk>null</jk>.
    * @param value The part value.  Can be <jk>null</jk>.
    */
   public BasicDatePart(String name, ZonedDateTime value) {
      super(name, value);
      this.value = value;
      this.supplier = null;
   }

   /**
    * Provides the ability to perform fluent-style assertions on this part.
    *
    * @return A new fluent assertion object.
    * @throws AssertionError If assertion failed.
    */
   public FluentZonedDateTimeAssertion<BasicDatePart> assertZonedDateTime() {
      return new FluentZonedDateTimeAssertion<>(value(), this);
   }

   /**
    * Returns The part value as a {@link ZonedDateTime} wrapped in an {@link Optional}.
    *
    * @return The part value as a {@link ZonedDateTime} wrapped in an {@link Optional}.  Never <jk>null</jk>.
    */
   public Optional<ZonedDateTime> asZonedDateTime() {
      return opt(toZonedDateTime());
   }

   @Override /* Overridden from Header */
   public String getValue() {
      ZonedDateTime v = value();
      return v == null ? null : ISO_DATE_TIME.format(v);
   }

   /**
    * Return the value if present, otherwise return <c>other</c>.
    *
    * <p>
    * This is a shortened form for calling <c>asZonedDateTime().orElse(<jv>other</jv>)</c>.
    *
    * @param other The value to be returned if there is no value present, can be <jk>null</jk>.
    * @return The value, if present, otherwise <c>other</c>.
    */
   public ZonedDateTime orElse(ZonedDateTime other) {
      ZonedDateTime x = value();
      return nn(x) ? x : other;
   }

   /**
    * Returns The part value as a {@link ZonedDateTime}.
    *
    * @return The part value as a {@link ZonedDateTime}, or <jk>null</jk> if the value <jk>null</jk>.
    */
   public ZonedDateTime toZonedDateTime() {
      return value();
   }

   private ZonedDateTime value() {
      if (nn(supplier))
         return supplier.get();
      return value;
   }
}