/*
 * Copyright 2022 Google LLC
 *
 * Licensed 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 com.google.android.libraries.mobiledatadownload.downloader;

import com.google.auto.value.AutoValue;
import com.google.common.collect.ImmutableSet;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.EnumSet;
import java.util.Set;

/** Possible constraints that a download request requires. */
@AutoValue
public abstract class DownloadConstraints {

  DownloadConstraints() {}

  /**
   * Special value of {@code DownloadConstraints}. If this value is specified, no constraint checks
   * are performed, even if no network is present at all!
   */
  public static final DownloadConstraints NONE =
      DownloadConstraints.builder()
          .setRequiredNetworkTypes(EnumSet.noneOf(NetworkType.class))
          .setRequireUnmeteredNetwork(false)
          .build();

  /**
   * Common value to indicate that the active network must be unmetered. This value permits any
   * network type as long as it doesn't indicate it is metered in some way.
   */
  public static final DownloadConstraints NETWORK_UNMETERED =
      DownloadConstraints.builder()
          .setRequiredNetworkTypes(EnumSet.of(NetworkType.ANY))
          .setRequireUnmeteredNetwork(true)
          .build();

  /**
   * Common value to indicate that the required network must simply be connected in some way, and
   * otherwise doesn't have any restrictions. Any network type is allowed.
   *
   * <p>This is the default value for download requests.
   */
  public static final DownloadConstraints NETWORK_CONNECTED =
      DownloadConstraints.builder()
          .setRequiredNetworkTypes(EnumSet.of(NetworkType.ANY))
          .setRequireUnmeteredNetwork(false)
          .build();

  /**
   * The type of network that is required. This is a subset of the network types enumerated by
   * {@link android.net.ConnectivityManager}.
   */
  public enum NetworkType {
    /** Special network type to allow any type of network, even if it not one of the known types. */
    ANY,
    /** Equivalent to {@link android.net.NetworkCapabilities#TRANSPORT_BLUETOOTH} */
    BLUETOOTH,
    /** Equivalent to {@link android.net.NetworkCapabilities#TRANSPORT_ETHERNET} */
    ETHERNET,
    /** Equivalent to {@link android.net.NetworkCapabilities#TRANSPORT_CELLULAR} */
    CELLULAR,
    /** Equivalent to {@link android.net.NetworkCapabilities#TRANSPORT_WIFI} */
    WIFI,
  }

  /**
   * Whether the connection must be unmetered to pass connectivity checks. See {@link
   * androidx.core.net.ConnectivityManagerCompat#isActiveNetworkMetered} for more details on this
   * variable.
   *
   * <p>False by default.
   */
  public abstract boolean requireUnmeteredNetwork();

  /**
   * The types of networks that are allowed for the request to pass connectivity checks. The
   * currently active network type must be one of the values in this set. This set may not be empty.
   */
  public abstract ImmutableSet<NetworkType> requiredNetworkTypes();

  /** Creates a {@code DownloadConstraints.Builder} instance. */
  public static Builder builder() {
    return new AutoValue_DownloadConstraints.Builder().setRequireUnmeteredNetwork(false);
  }

  /** Converts this instance to a builder for modifications. */
  public abstract Builder toBuilder();

  /** Builder for creating instances of {@link DownloadConstraints}. */
  @AutoValue.Builder
  public abstract static class Builder {
    Builder() {}

    public abstract Builder setRequiredNetworkTypes(Set<NetworkType> networkTypes);

    abstract ImmutableSet.Builder<NetworkType> requiredNetworkTypesBuilder();

    @CanIgnoreReturnValue
    public final Builder addRequiredNetworkType(NetworkType networkType) {
      requiredNetworkTypesBuilder().add(networkType);
      return this;
    }

    public abstract Builder setRequireUnmeteredNetwork(boolean requireUnmeteredNetwork);

    public abstract DownloadConstraints build();
  }
}