content: /*
   * Copyright (C) 2017 The Android Open Source Project
   *
   * 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.exoplayer2.scheduler;
  
  import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
  
  import android.content.BroadcastReceiver;
  import android.content.Context;
  import android.content.Intent;
  import android.content.IntentFilter;
  import android.net.ConnectivityManager;
  import android.net.Network;
  import android.net.NetworkCapabilities;
  import android.os.Handler;
  import android.os.Looper;
  import android.os.PowerManager;
  import androidx.annotation.Nullable;
  import androidx.annotation.RequiresApi;
  import com.google.android.exoplayer2.util.Util;
  
  /**
   * Watches whether the {@link Requirements} are met and notifies the {@link Listener} on changes.
   */
  public final class RequirementsWatcher {
  
    /**
     * Notified when RequirementsWatcher instance first created and on changes whether the {@link
     * Requirements} are met.
     */
    public interface Listener {
      /**
       * Called when there is a change on the met requirements.
       *
       * @param requirementsWatcher Calling instance.
       * @param notMetRequirements {@link Requirements.RequirementFlags RequirementFlags} that are not
       *     met, or 0.
       */
      void onRequirementsStateChanged(
          RequirementsWatcher requirementsWatcher,
          @Requirements.RequirementFlags int notMetRequirements);
    }
  
    private final Context context;
    private final Listener listener;
    private final Requirements requirements;
    private final Handler handler;
  
    @Nullable private DeviceStatusChangeReceiver receiver;
  
    private @Requirements.RequirementFlags int notMetRequirements;
    @Nullable private NetworkCallback networkCallback;
  
    /**
     * @param context Any context.
     * @param listener Notified whether the {@link Requirements} are met.
     * @param requirements The requirements to watch.
     */
    public RequirementsWatcher(Context context, Listener listener, Requirements requirements) {
      this.context = context.getApplicationContext();
      this.listener = listener;
      this.requirements = requirements;
      handler = Util.createHandlerForCurrentOrMainLooper();
    }
  
    /**
     * Starts watching for changes. Must be called from a thread that has an associated {@link
     * Looper}. Listener methods are called on the caller thread.
     *
     * @return Initial {@link Requirements.RequirementFlags RequirementFlags} that are not met, or 0.
     */
    public @Requirements.RequirementFlags int start() {
      notMetRequirements = requirements.getNotMetRequirements(context);
  
      IntentFilter filter = new IntentFilter();
      if (requirements.isNetworkRequired()) {
        if (Util.SDK_INT >= 24) {
          registerNetworkCallbackV24();
        } else {
          filter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        }
      }
      if (requirements.isChargingRequired()) {
        filter.addAction(Intent.ACTION_POWER_CONNECTED);
        filter.addAction(Intent.ACTION_POWER_DISCONNECTED);
      }
      if (requirements.isIdleRequired()) {
        if (Util.SDK_INT >= 23) {
          filter.addAction(PowerManager.ACTION_DEVICE_IDLE_MODE_CHANGED);
        } else {
          filter.addAction(Intent.ACTION_SCREEN_ON);
          filter.addAction(Intent.ACTION_SCREEN_OFF);
        }
      }
      if (requirements.isStorageNotLowRequired()) {
        filter.addAction(Intent.ACTION_DEVICE_STORAGE_LOW);
        filter.addAction(Intent.ACTION_DEVICE_STORAGE_OK);
      }
      receiver = new DeviceStatusChangeReceiver();
      context.registerReceiver(receiver, filter, /* broadcastPermission= */ null, handler);
      return notMetRequirements;
    }
  
    /** Stops watching for changes. */
    public void stop() {
      context.unregisterReceiver(checkNotNull(receiver));
      receiver = null;
      if (Util.SDK_INT >= 24 && networkCallback != null) {
        unregisterNetworkCallbackV24();
      }
    }
  
    /** Returns watched {@link Requirements}. */
    public Requirements getRequirements() {
      return requirements;
    }
  
    @RequiresApi(24)
    private void registerNetworkCallbackV24() {
      ConnectivityManager connectivityManager =
          checkNotNull((ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE));
      networkCallback = new NetworkCallback();
      connectivityManager.registerDefaultNetworkCallback(networkCallback);
    }
  
    @RequiresApi(24)
    private void unregisterNetworkCallbackV24() {
      ConnectivityManager connectivityManager =
          checkNotNull((ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE));
      connectivityManager.unregisterNetworkCallback(checkNotNull(networkCallback));
      networkCallback = null;
    }
  
    private void checkRequirements() {
      @Requirements.RequirementFlags
      int notMetRequirements = requirements.getNotMetRequirements(context);
      if (this.notMetRequirements != notMetRequirements) {
        this.notMetRequirements = notMetRequirements;
        listener.onRequirementsStateChanged(this, notMetRequirements);
      }
    }
  
    /**
     * Re-checks the requirements if there are network requirements that are currently not met.
     *
     * <p>When we receive an event that implies newly established network connectivity, we re-check
     * the requirements by calling {@link #checkRequirements()}. This check sometimes sees that there
     * is still no active network, meaning that any network requirements will remain not met. By
     * calling this method when we receive other events that imply continued network connectivity, we
     * can detect that the requirements are met once an active network does exist.
     */
    private void recheckNotMetNetworkRequirements() {
      if ((notMetRequirements & (Requirements.NETWORK | Requirements.NETWORK_UNMETERED)) == 0) {
        // No unmet network requirements to recheck.
        return;
      }
      checkRequirements();
    }
  
    private class DeviceStatusChangeReceiver extends BroadcastReceiver {
      @Override
      public void onReceive(Context context, Intent intent) {
        if (!isInitialStickyBroadcast()) {
          checkRequirements();
        }
      }
    }
  
    @RequiresApi(24)
    private final class NetworkCallback extends ConnectivityManager.NetworkCallback {
  
      private boolean receivedCapabilitiesChange;
      private boolean networkValidated;
  
      @Override
      public void onAvailable(Network network) {
        postCheckRequirements();
      }
  
      @Override
      public void onLost(Network network) {
        postCheckRequirements();
      }
  
      @Override
      public void onBlockedStatusChanged(Network network, boolean blocked) {
        if (!blocked) {
          postRecheckNotMetNetworkRequirements();
        }
      }
  
      @Override
      public void onCapabilitiesChanged(Network network, NetworkCapabilities networkCapabilities) {
        boolean networkValidated =
            networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED);
        if (!receivedCapabilitiesChange || this.networkValidated != networkValidated) {
          receivedCapabilitiesChange = true;
          this.networkValidated = networkValidated;
          postCheckRequirements();
        } else if (networkValidated) {
          postRecheckNotMetNetworkRequirements();
        }
      }
  
      private void postCheckRequirements() {
        handler.post(
            () -> {
              if (networkCallback != null) {
                checkRequirements();
              }
            });
      }
  
      private void postRecheckNotMetNetworkRequirements() {
        handler.post(
            () -> {
              if (networkCallback != null) {
                recheckNotMetNetworkRequirements();
              }
            });
      }
    }
  }
  