/*
 * 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.android.dialer.phonelookup.composite;

import android.content.Context;
import android.support.annotation.MainThread;
import android.support.annotation.NonNull;
import android.telecom.Call;
import com.android.dialer.DialerPhoneNumber;
import com.android.dialer.common.LogUtil;
import com.android.dialer.common.concurrent.Annotations.LightweightExecutor;
import com.android.dialer.common.concurrent.DialerFutures;
import com.android.dialer.phonelookup.PhoneLookup;
import com.android.dialer.phonelookup.PhoneLookupInfo;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Maps;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.MoreExecutors;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import javax.inject.Inject;

/**
 * {@link PhoneLookup} which delegates to a configured set of {@link PhoneLookup PhoneLookups},
 * iterating, prioritizing, and coalescing data as necessary.
 */
public final class CompositePhoneLookup implements PhoneLookup<PhoneLookupInfo> {

  private final ImmutableList<PhoneLookup> phoneLookups;
  private final ListeningExecutorService lightweightExecutorService;

  @Inject
  CompositePhoneLookup(
      ImmutableList<PhoneLookup> phoneLookups,
      @LightweightExecutor ListeningExecutorService lightweightExecutorService) {
    this.phoneLookups = phoneLookups;
    this.lightweightExecutorService = lightweightExecutorService;
  }

  /**
   * Delegates to a set of dependent lookups to build a complete {@link PhoneLookupInfo}.
   *
   * <p>Note: If any of the dependent lookups fails, the returned future will also fail. If any of
   * the dependent lookups does not complete, the returned future will also not complete.
   */
  @SuppressWarnings({"unchecked", "rawtype"})
  @Override
  public ListenableFuture<PhoneLookupInfo> lookup(@NonNull Call call) {
    // TODO(zachh): Add short-circuiting logic so that this call is not blocked on low-priority
    // lookups finishing when a higher-priority one has already finished.
    List<ListenableFuture<?>> futures = new ArrayList<>();
    for (PhoneLookup<?> phoneLookup : phoneLookups) {
      futures.add(phoneLookup.lookup(call));
    }
    return Futures.transform(
        Futures.allAsList(futures),
        infos -> {
          PhoneLookupInfo.Builder mergedInfo = PhoneLookupInfo.newBuilder();
          for (int i = 0; i < infos.size(); i++) {
            PhoneLookup phoneLookup = phoneLookups.get(i);
            phoneLookup.setSubMessage(mergedInfo, infos.get(i));
          }
          return mergedInfo.build();
        },
        lightweightExecutorService);
  }

  @Override
  public ListenableFuture<Boolean> isDirty(ImmutableSet<DialerPhoneNumber> phoneNumbers) {
    List<ListenableFuture<Boolean>> futures = new ArrayList<>();
    for (PhoneLookup<?> phoneLookup : phoneLookups) {
      futures.add(
          Futures.transform(
              phoneLookup.isDirty(phoneNumbers),
              isDirty -> {
                LogUtil.v(
                    "CompositePhoneLookup.isDirty",
                    "isDirty for %s: %b",
                    phoneLookup.getClass().getSimpleName(),
                    isDirty);
                return isDirty;
              },
              MoreExecutors.directExecutor()));
    }
    // Executes all child lookups (possibly in parallel), completing when the first composite lookup
    // which returns "true" completes, and cancels the others.
    return DialerFutures.firstMatching(
        futures, Preconditions::checkNotNull, false /* defaultValue */);
  }

  /**
   * Delegates to a set of dependent lookups and combines results.
   *
   * <p>Note: If any of the dependent lookups fails, the returned future will also fail. If any of
   * the dependent lookups does not complete, the returned future will also not complete.
   */
  @SuppressWarnings("unchecked")
  @Override
  public ListenableFuture<ImmutableMap<DialerPhoneNumber, PhoneLookupInfo>> getMostRecentInfo(
      ImmutableMap<DialerPhoneNumber, PhoneLookupInfo> existingInfoMap) {
    List<ListenableFuture<ImmutableMap<DialerPhoneNumber, ?>>> futures = new ArrayList<>();
    for (PhoneLookup phoneLookup : phoneLookups) {
      futures.add(buildSubmapAndGetMostRecentInfo(existingInfoMap, phoneLookup));
    }
    return Futures.transform(
        Futures.allAsList(futures),
        (allMaps) -> {
          ImmutableMap.Builder<DialerPhoneNumber, PhoneLookupInfo> combinedMap =
              ImmutableMap.builder();
          for (DialerPhoneNumber dialerPhoneNumber : existingInfoMap.keySet()) {
            PhoneLookupInfo.Builder combinedInfo = PhoneLookupInfo.newBuilder();
            for (int i = 0; i < allMaps.size(); i++) {
              ImmutableMap<DialerPhoneNumber, ?> map = allMaps.get(i);
              Object subInfo = map.get(dialerPhoneNumber);
              if (subInfo == null) {
                throw new IllegalStateException(
                    "A sublookup didn't return an info for number: "
                        + LogUtil.sanitizePhoneNumber(dialerPhoneNumber.getRawInput().getNumber()));
              }
              phoneLookups.get(i).setSubMessage(combinedInfo, subInfo);
            }
            combinedMap.put(dialerPhoneNumber, combinedInfo.build());
          }
          return combinedMap.build();
        },
        lightweightExecutorService);
  }

  private <T> ListenableFuture<ImmutableMap<DialerPhoneNumber, T>> buildSubmapAndGetMostRecentInfo(
      ImmutableMap<DialerPhoneNumber, PhoneLookupInfo> existingInfoMap,
      PhoneLookup<T> phoneLookup) {
    Map<DialerPhoneNumber, T> submap =
        Maps.transformEntries(
            existingInfoMap,
            (dialerPhoneNumber, phoneLookupInfo) ->
                phoneLookup.getSubMessage(existingInfoMap.get(dialerPhoneNumber)));
    return phoneLookup.getMostRecentInfo(ImmutableMap.copyOf(submap));
  }

  @Override
  public void setSubMessage(PhoneLookupInfo.Builder destination, PhoneLookupInfo source) {
    throw new UnsupportedOperationException(
        "This method is only expected to be called by CompositePhoneLookup itself");
  }

  @Override
  public PhoneLookupInfo getSubMessage(PhoneLookupInfo phoneLookupInfo) {
    throw new UnsupportedOperationException(
        "This method is only expected to be called by CompositePhoneLookup itself");
  }

  @Override
  public ListenableFuture<Void> onSuccessfulBulkUpdate() {
    List<ListenableFuture<Void>> futures = new ArrayList<>();
    for (PhoneLookup<?> phoneLookup : phoneLookups) {
      futures.add(phoneLookup.onSuccessfulBulkUpdate());
    }
    return Futures.transform(
        Futures.allAsList(futures), unused -> null, lightweightExecutorService);
  }

  @Override
  @MainThread
  public void registerContentObservers(
      Context appContext, ContentObserverCallbacks contentObserverCallbacks) {
    for (PhoneLookup phoneLookup : phoneLookups) {
      phoneLookup.registerContentObservers(appContext, contentObserverCallbacks);
    }
  }
}