content: /*
   *  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.causeway.applib.services.iactnlayer;
  
  import java.io.Serializable;
  import java.time.Instant;
  import java.time.ZoneId;
  import java.time.ZoneOffset;
  import java.util.Locale;
  import java.util.Optional;
  import java.util.function.UnaryOperator;
  import java.util.stream.Stream;
  
  import org.apache.causeway.applib.clock.VirtualClock;
  import org.apache.causeway.applib.locale.UserLocale;
  import org.apache.causeway.applib.services.iactn.Interaction;
  import org.apache.causeway.applib.services.user.UserMemento;
  
  import lombok.AccessLevel;
  import lombok.Builder;
  import lombok.EqualsAndHashCode;
  import lombok.Getter;
  import org.jspecify.annotations.NonNull;
  import lombok.ToString;
  import lombok.With;
  
  /**
   * Provides the user and scenario specific environment for an {@link Interaction}.
   *
   * @since 2.0 {@index}
   */
  @Getter
  @lombok.experimental.FieldDefaults(makeFinal=false, level= AccessLevel.PRIVATE)
  @ToString
  @EqualsAndHashCode
  @Builder
  public class InteractionContext implements Serializable {
  
      private static final long serialVersionUID = -220896735209733865L;
  
      // -- FACTORIES
  
      /**
       * Creates a new {@link InteractionContext} with the specified user and
       * system defaults for clock, locale and time-zone.
       */
      public static InteractionContext ofUserWithSystemDefaults(
              final @NonNull UserMemento user) {
          return InteractionContext.builder()
                  .user(user)
                  .clock(VirtualClock.system())
                  .timeZone(ZoneId.systemDefault())
                  .build();
      }
  
      // -- IMMUTABLE FIELDS
  
      /**
       * The (programmatically) simulated (or actual) user.
       *
       * @apiNote practically immutable, allows an {@link Interaction} to (logically) run with its
       * own simulated (or actual) user
       *
       */
      @With @Getter @Builder.Default
      final @NonNull UserMemento user = UserMemento.system();
  
      /**
       * The (programmatically) simulated (or actual) clock.
       *
       * @apiNote immutable, allows an {@link Interaction} to (logically) run with its
       * own simulated (or actual) clock
       */
      @With @Getter @Builder.Default
      final @NonNull VirtualClock clock = VirtualClock.system();
  
      @With UserLocale locale;
      public UserLocale getLocale(){
          if(locale!=null) {
              return locale; // if set, overrides any user preferences
          }
          return Optional.ofNullable(getUser())
                  .map(UserMemento::asUserLocale)
                  .orElseGet(UserLocale::getDefault);
      }
  
      @With @Getter @Builder.Default
      final @NonNull ZoneId timeZone = ZoneId.systemDefault();
      /**
       * Only override if zoneIdIfAny is present, otherwise acts as identity operation.
       */
      public InteractionContext withTimeZoneIfAny(final Optional<ZoneId> zoneIdIfAny) {
          return zoneIdIfAny
                  .map(this::withTimeZone)
                  .orElse(this);
      }
  
      /**
       * Convenience method for use with {@link org.apache.causeway.applib.services.sudo.SudoService}, returning a
       * {@link UnaryOperator} that will act upon the provided {@link InteractionContext} to return the same but with
       * the specified {@link UserMemento}.
       */
      public static UnaryOperator<InteractionContext> switchUser(final @NonNull UserMemento userMemento) {
          return interactionContext -> interactionContext.withUser(userMemento);
      }
  
      /**
       * Convenience method for use with {@link org.apache.causeway.applib.services.sudo.SudoService}, returning a
       * {@link UnaryOperator} that will act upon the provided {@link InteractionContext} to return the same but with
       * the specified {@link VirtualClock}.
       */
      public static UnaryOperator<InteractionContext> switchClock(final @NonNull VirtualClock clock) {
          return interactionContext -> interactionContext.withClock(clock);
      }
  
      /**
       * Convenience method for use with {@link org.apache.causeway.applib.services.sudo.SudoService}, returning a
       * {@link UnaryOperator} that will act upon the provided {@link InteractionContext} to return the same but with
       * the specified {@link Locale}.
       */
      public static UnaryOperator<InteractionContext> switchLocale(final @NonNull UserLocale locale) {
          return interactionContext -> interactionContext.withLocale(locale);
      }
  
      /**
       * Convenience method for use with {@link org.apache.causeway.applib.services.sudo.SudoService}, returning a
       * {@link UnaryOperator} that will act upon the provided {@link InteractionContext} to return the same but with
       * the specified {@link ZoneId}.
       */
      public static UnaryOperator<InteractionContext> switchTimeZone(final @NonNull ZoneId timeZone) {
          return interactionContext -> interactionContext.withTimeZone(timeZone);
      }
  
      /**
       * Convenience method to combine {@link UnaryOperator}s, for example as per {@link #switchUser(UserMemento)} and {@link #switchTimeZone(ZoneId)}.
       *
       * <p>
       * NOTE: this implementation can result in heap pollution; better to use the {@link #combine(Stream) overload}.
       * </p>
       *
       * @see #combine(Stream)
       */
      @SafeVarargs
      public static <T> UnaryOperator<T> combine(final UnaryOperator<T>... mappers) {
          return combine(Stream.of(mappers));
      }
  
      /**
       * Convenience method to combine {@link UnaryOperator}s, for example as per {@link #switchUser(UserMemento)} and {@link #switchTimeZone(ZoneId)}.
       *
       * credit: https://stackoverflow.com/a/51065029/56880
       */
      public static <T> UnaryOperator<T> combine(final Stream<UnaryOperator<T>> mappers) {
          return mappers.reduce(t -> t, (a,b) -> a.andThen(b)::apply);
      }
  
      /**
       * Returns the {@link ZoneOffset} at the current time {@link Instant}
       * (at which {@link ZoneId} rules apply to calculate the offset).
       */
      public ZoneOffset getTimeZoneOffsetNow() {
          return getTimeZone().getRules().getOffset(Instant.now());
      }
  
  }
  