/*
    * Copyright 2023 LINE Corporation
    *
    * LINE Corporation 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:
    *
    *   https://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 com.linecorp.centraldogma.server;
  
  import java.util.List;
  
  import javax.annotation.Nullable;
  
  import com.fasterxml.jackson.annotation.JsonCreator;
  import com.fasterxml.jackson.annotation.JsonProperty;
  import com.google.common.base.MoreObjects;
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.Streams;
  
  /**
   * CORS configuration.
   */
  public final class CorsConfig {
  
      private static final int DEFAULT_MAX_AGE = 7200;
  
      private final List<String> allowedOrigins;
      private final int maxAgeSeconds;
  
      /**
       * Creates an instance with the specified {@code allowedOrigins} and
       * {@code maxAgeSeconds}.
       */
      @JsonCreator
      public CorsConfig(@JsonProperty("allowedOrigins") Object allowedOrigins,
                        @JsonProperty("maxAgeSeconds") @Nullable Integer maxAgeSeconds) {
          if (allowedOrigins instanceof Iterable &&
              Streams.stream((Iterable<?>) allowedOrigins).allMatch(String.class::isInstance)) {
              this.allowedOrigins = ImmutableList.copyOf((Iterable<String>) allowedOrigins);
          } else if (allowedOrigins instanceof String) {
              final String origin = (String) allowedOrigins;
              this.allowedOrigins = ImmutableList.of(origin);
          } else {
              throw new IllegalArgumentException(
                      "allowedOrigins: " + allowedOrigins +
                      " (expected: either a string or an array of strings)");
          }
          if (this.allowedOrigins.isEmpty()) {
              throw new IllegalArgumentException(
                      "allowedOrigins: " + allowedOrigins +
                      " (expected: the list of origins must not be empty)");
          }
  
          if (maxAgeSeconds == null) {
              maxAgeSeconds = DEFAULT_MAX_AGE;
          }
          if (maxAgeSeconds <= 0) {
              throw new IllegalArgumentException(
                      "maxAgeSeconds: " + maxAgeSeconds +
                      " (expected: maxAgeSeconds must be positive)");
          }
          this.maxAgeSeconds = maxAgeSeconds;
      }
  
      /**
       * Returns the list of origins which are allowed a CORS policy.
       */
      @JsonProperty
      public List<String> allowedOrigins() {
          return allowedOrigins;
      }
  
      /**
       * Returns how long in seconds the results of a preflight request can be cached.
       * If unspecified, the default of {@code 7200} seconds is returned.
       */
      @JsonProperty
      public int maxAgeSeconds() {
          return maxAgeSeconds;
      }
  
      @Override
      public String toString() {
          return MoreObjects.toStringHelper(this)
                            .add("allowedOrigins", allowedOrigins)
                            .add("maxAgeSeconds", maxAgeSeconds)
                            .toString();
      }
  }