/*
 * Copyright (C) 2020 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 android.service.search;

import static com.android.internal.util.function.pooled.PooledLambda.obtainMessage;

import android.annotation.CallSuper;
import android.annotation.MainThread;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.SystemApi;
import android.app.Service;
import android.app.search.ISearchCallback;
import android.app.search.Query;
import android.app.search.SearchContext;
import android.app.search.SearchSessionId;
import android.app.search.SearchTarget;
import android.app.search.SearchTargetEvent;
import android.content.Intent;
import android.content.pm.ParceledListSlice;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.RemoteException;
import android.service.search.ISearchUiService.Stub;
import android.util.Slog;

import java.util.List;
import java.util.function.Consumer;

/**
 * A service used to share the lifecycle of search UI (open, close, interaction)
 * and also to return search result on a query.
 *
 * To understand the lifecycle of search session and how a query get issued,
 * {@see SearchSession}
 *
 * @hide
 */
@SystemApi
public abstract class SearchUiService extends Service {

    private static final boolean DEBUG = false;
    private static final String TAG = "SearchUiService";

    /**
     * The {@link Intent} that must be declared as handled by the service.
     *
     * <p>The service must also require the {@link android.permission#MANAGE_SEARCH_UI}
     * permission.
     *
     * @hide
     */
    public static final String SERVICE_INTERFACE =
            "android.service.search.SearchUiService";

    private Handler mHandler;

    private final android.service.search.ISearchUiService mInterface = new Stub() {

        @Override
        public void onCreateSearchSession(SearchContext context, SearchSessionId sessionId) {
            mHandler.sendMessage(
                    obtainMessage(SearchUiService::onSearchSessionCreated,
                            SearchUiService.this, context, sessionId));
            // to be removed
            mHandler.sendMessage(
                    obtainMessage(SearchUiService::onCreateSearchSession,
                            SearchUiService.this, context, sessionId));
        }

        @Override
        public void onQuery(SearchSessionId sessionId, Query input,
                ISearchCallback callback) {
            mHandler.sendMessage(
                    obtainMessage(SearchUiService::onQuery,
                            SearchUiService.this, sessionId, input,
                            new CallbackWrapper(callback, null)));
        }

        @Override
        public void onNotifyEvent(SearchSessionId sessionId, Query query, SearchTargetEvent event) {
            mHandler.sendMessage(
                    obtainMessage(SearchUiService::onNotifyEvent,
                            SearchUiService.this, sessionId, query, event));
        }

        @Override
        public void onDestroy(SearchSessionId sessionId) {
            mHandler.sendMessage(
                    obtainMessage(SearchUiService::doDestroy,
                            SearchUiService.this, sessionId));
        }
    };

    @CallSuper
    @Override
    public void onCreate() {
        super.onCreate();
        mHandler = new Handler(Looper.getMainLooper(), null, true);
    }

    @Override
    @NonNull
    public final IBinder onBind(@NonNull Intent intent) {
        if (SERVICE_INTERFACE.equals(intent.getAction())) {
            return mInterface.asBinder();
        }
        Slog.w(TAG, "Tried to bind to wrong intent (should be "
                + SERVICE_INTERFACE + ": " + intent);
        return null;
    }

    /**
     * Creates a new search session.
     *
     * @deprecated this is method will be removed as soon as
     * {@link #onSearchSessionCreated(SearchContext, SearchSessionId)}
     * is adopted by the service.
     *
     * @removed
     */
    @Deprecated
    public void onCreateSearchSession(@NonNull SearchContext context,
            @NonNull SearchSessionId sessionId) {}

    /**
     * A new search session is created.
     */
    public void onSearchSessionCreated(@NonNull SearchContext context,
            @NonNull SearchSessionId sessionId) {}

    /**
     * Called by the client to request search results using a query string.
     */
    @MainThread
    public abstract void onQuery(@NonNull SearchSessionId sessionId,
            @NonNull Query query,
            @NonNull Consumer<List<SearchTarget>> callback);

    /**
     * Called by a client to indicate an interaction (tap, long press, drag, etc) on target(s)
     * and lifecycle event on the search surface (e.g., visibility change).
     *
     * {@see SearchTargetEvent}
     */
    @MainThread
    public abstract void onNotifyEvent(@NonNull SearchSessionId sessionId,
            @NonNull Query query,
            @NonNull SearchTargetEvent event);

    private void doDestroy(@NonNull SearchSessionId sessionId) {
        super.onDestroy();
        onDestroy(sessionId);
    }

    /**
     * Destroys a search session.
     */
    @MainThread
    public abstract void onDestroy(@NonNull SearchSessionId sessionId);

    private static final class CallbackWrapper implements Consumer<List<SearchTarget>>,
            IBinder.DeathRecipient {

        private ISearchCallback mCallback;
        private final Consumer<CallbackWrapper> mOnBinderDied;

        CallbackWrapper(ISearchCallback callback,
                @Nullable Consumer<CallbackWrapper> onBinderDied) {
            mCallback = callback;
            mOnBinderDied = onBinderDied;
            try {
                mCallback.asBinder().linkToDeath(this, 0);
            } catch (RemoteException e) {
                Slog.e(TAG, "Failed to link to death: " + e);
            }
        }

        @Override
        public void accept(List<SearchTarget> searchTargets) {
            try {
                if (mCallback != null) {
                    if (DEBUG) {
                        Slog.d(TAG, "CallbackWrapper.accept searchTargets=" + searchTargets);
                    }
                    mCallback.onResult(new ParceledListSlice(searchTargets));
                }
            } catch (RemoteException e) {
                Slog.e(TAG, "Error sending result:" + e);
            }
        }

        @Override
        public void binderDied() {
            mCallback.asBinder().unlinkToDeath(this, 0);
            mCallback = null;
            if (mOnBinderDied != null) {
                mOnBinderDied.accept(this);
            }
        }
    }
}