/*
 * Copyright (C) 2019 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.car.assist.client;

import static android.app.Notification.Action.SEMANTIC_ACTION_MARK_AS_READ;
import static android.app.Notification.Action.SEMANTIC_ACTION_REPLY;
import static android.service.voice.VoiceInteractionSession.SHOW_SOURCE_NOTIFICATION;

import static com.android.car.assist.CarVoiceInteractionSession.EXCEPTION_NOTIFICATION_LISTENER_PERMISSIONS_MISSING;

import android.annotation.Nullable;
import android.app.ActivityManager;
import android.app.Notification;
import android.app.RemoteInput;
import android.content.Context;
import android.os.Bundle;
import android.provider.Settings;
import android.service.notification.StatusBarNotification;
import android.util.Log;

import androidx.annotation.StringDef;
import androidx.core.app.NotificationCompat;
import androidx.core.app.NotificationCompat.Action;

import com.android.car.assist.CarVoiceInteractionSession;
import com.android.internal.app.AssistUtils;
import com.android.internal.app.IVoiceActionCheckCallback;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * Util class providing helper methods to interact with the current active voice service,
 * while ensuring that the active voice service has the required permissions.
 */
public class CarAssistUtils {
    public static final String TAG = "CarAssistUtils";
    private static final List<Integer> REQUIRED_SEMANTIC_ACTIONS = Collections.unmodifiableList(
            Arrays.asList(
                    SEMANTIC_ACTION_MARK_AS_READ
            )
    );

    private static final List<Integer> SUPPORTED_SEMANTIC_ACTIONS = Collections.unmodifiableList(
            Arrays.asList(
                    SEMANTIC_ACTION_MARK_AS_READ,
                    SEMANTIC_ACTION_REPLY
            )
    );

    private final Context mContext;
    private final AssistUtils mAssistUtils;
    @Nullable
    private final FallbackAssistant mFallbackAssistant;
    private final String mErrorMessage;
    private final boolean mIsFallbackAssistantEnabled;

    /** Interface used to receive callbacks from voice action requests. */
    public interface ActionRequestCallback {
        /**
         * The action was successfully completed either by the active or fallback assistant.
         **/
        String RESULT_SUCCESS = "SUCCESS";

        /**
         * The action was not successfully completed, but the active assistant has been prompted to
         * alert the user of this error and handle it. The caller of this callback is recommended
         * to NOT alert the user of this error again.
         */
        String RESULT_FAILED_WITH_ERROR_HANDLED = "FAILED_WITH_ERROR_HANDLED";

        /**
         * The action has not been successfully completed, and the error has not been handled.
         **/
        String RESULT_FAILED = "FAILED";

        /**
         * The list of result states.
         */
        @StringDef({RESULT_FAILED, RESULT_FAILED_WITH_ERROR_HANDLED, RESULT_SUCCESS})
        @interface ResultState {
        }

        /** Callback containing the result of completing the voice action request. */
        void onResult(@ResultState String state);
    }

    public CarAssistUtils(Context context) {
        mContext = context;
        mAssistUtils = new AssistUtils(context);
        mErrorMessage = context.getString(R.string.assist_action_failed_toast);

        mIsFallbackAssistantEnabled =
                context.getResources().getBoolean(R.bool.config_enableFallbackAssistant);
        mFallbackAssistant = mIsFallbackAssistantEnabled ? new FallbackAssistant(context) : null;
    }

    /**
     * @return {@code true} if there is an active assistant.
     */
    public boolean hasActiveAssistant() {
        return mAssistUtils.getActiveServiceComponentName() != null;
    }

    /**
     * Returns {@code true} if the fallback assistant is enabled.
     */
    public boolean isFallbackAssistantEnabled() {
        return mIsFallbackAssistantEnabled;
    }

    /**
     * Returns true if the current active assistant has notification listener permissions.
     */
    public boolean assistantIsNotificationListener() {
        if (!hasActiveAssistant()) {
            if (Log.isLoggable(TAG, Log.DEBUG)) {
                Log.d(TAG, "No active assistant was found.");
            }
            return false;
        }
        final String activeComponent = mAssistUtils.getActiveServiceComponentName()
                .flattenToString();
        int slashIndex = activeComponent.indexOf("/");
        final String activePackage = activeComponent.substring(0, slashIndex);

        final String listeners = Settings.Secure.getStringForUser(mContext.getContentResolver(),
                Settings.Secure.ENABLED_NOTIFICATION_LISTENERS, ActivityManager.getCurrentUser());

        if (Log.isLoggable(TAG, Log.DEBUG)) {
            Log.d(TAG, "Current user: " + ActivityManager.getCurrentUser()
                    + " has active voice service: " + activePackage + " and enabled notification "
                    + " listeners: " + listeners);
        }

        if (listeners != null) {
            for (String listener : Arrays.asList(listeners.split(":"))) {
                if (listener.contains(activePackage)) {
                    return true;
                }
            }
        }
        Log.w(TAG, "No notification listeners found for assistant: " + activeComponent);
        return false;
    }

    /**
     * Checks whether the notification is a car-compatible messaging notification.
     *
     * @param sbn The notification being checked.
     * @return true if the notification is a car-compatible messaging notification.
     */
    public static boolean isCarCompatibleMessagingNotification(StatusBarNotification sbn) {
        Notification notification = sbn.getNotification();
        return hasMessagingStyle(notification)
                && hasRequiredAssistantCallbacks(notification)
                && ((getReplyAction(notification) == null)
                    || replyCallbackHasRemoteInput(notification))
                && assistantCallbacksShowNoUi(notification);
    }

    /** Returns true if the semantic action provided can be supported. */
    public static boolean isSupportedSemanticAction(int semanticAction) {
        return SUPPORTED_SEMANTIC_ACTIONS.contains(semanticAction);
    }

    /**
     * Returns true if the notification has a messaging style.
     * <p/>
     * This is the case if the notification in question was provided an instance of
     * {@link Notification.MessagingStyle} (or an instance of
     * {@link NotificationCompat.MessagingStyle} if {@link NotificationCompat} was used).
     */
    private static boolean hasMessagingStyle(Notification notification) {
        return NotificationCompat.MessagingStyle
                .extractMessagingStyleFromNotification(notification) != null;
    }

    /**
     * Returns true if the notification has the required Assistant callbacks to be considered
     * a car-compatible messaging notification. The callbacks must be unambiguous, therefore false
     * is returned if multiple callbacks exist for any semantic action that is supported.
     */
    private static boolean hasRequiredAssistantCallbacks(Notification notification) {
        List<Integer> semanticActionList = getAllActions(notification)
                .stream()
                .map(NotificationCompat.Action::getSemanticAction)
                .filter(REQUIRED_SEMANTIC_ACTIONS::contains)
                .collect(Collectors.toList());
        Set<Integer> semanticActionSet = new HashSet<>(semanticActionList);
        return semanticActionList.size() == semanticActionSet.size()
                && semanticActionSet.containsAll(REQUIRED_SEMANTIC_ACTIONS);
    }

    /** Retrieves visible and invisible {@link Action}s from the {@link Notification}. */
    public static List<Action> getAllActions(Notification notification) {
        List<Action> actions = new ArrayList<>(
                NotificationCompat.getInvisibleActions(notification)
        );
        int visibleActionCount = NotificationCompat.getActionCount(notification);
        for (int i = 0; i < visibleActionCount; i++) {
            actions.add(NotificationCompat.getAction(notification, i));
        }
        return actions;
    }

    /**
     * Retrieves the {@link NotificationCompat.Action} containing the
     * {@link NotificationCompat.Action#SEMANTIC_ACTION_MARK_AS_READ} semantic action.
     */
    @Nullable
    public static NotificationCompat.Action getMarkAsReadAction(Notification notification) {
        for (NotificationCompat.Action action : getAllActions(notification)) {
            if (action.getSemanticAction()
                    == NotificationCompat.Action.SEMANTIC_ACTION_MARK_AS_READ) {
                return action;
            }
        }
        return null;
    }

    /**
     * Retrieves the {@link NotificationCompat.Action} containing the
     * {@link NotificationCompat.Action#SEMANTIC_ACTION_MUTE semantic action.
     */
    @Nullable
    public static NotificationCompat.Action getMuteAction(Notification notification) {
        for (NotificationCompat.Action action : getAllActions(notification)) {
            if (action.getSemanticAction() == Action.SEMANTIC_ACTION_MUTE) {
                return action;
            }
        }
        return null;
    }

    /**
     * Retrieves the {@link NotificationCompat.Action} containing the
     * {@link NotificationCompat.Action#SEMANTIC_ACTION_REPLY} semantic action.
     */
    @Nullable
    private static NotificationCompat.Action getReplyAction(Notification notification) {
        for (NotificationCompat.Action action : getAllActions(notification)) {
            if (action.getSemanticAction()
                    == NotificationCompat.Action.SEMANTIC_ACTION_REPLY) {
                return action;
            }
        }
        return null;
    }

    /**
     * Returns true if the reply callback has at least one {@link RemoteInput}.
     * <p/>
     * Precondition: There exists only one reply callback.
     */
    private static boolean replyCallbackHasRemoteInput(Notification notification) {
        return getAllActions(notification)
                .stream()
                .filter(action -> action.getSemanticAction() == SEMANTIC_ACTION_REPLY)
                .map(NotificationCompat.Action::getRemoteInputs)
                .filter(Objects::nonNull)
                .anyMatch(remoteInputs -> remoteInputs.length > 0);
    }

    /** Returns true if all Assistant callbacks indicate that they show no UI, false otherwise. */
    private static boolean assistantCallbacksShowNoUi(final Notification notification) {
        return getAllActions(notification)
                .stream()
                .filter(Objects::nonNull)
                .filter(action -> SUPPORTED_SEMANTIC_ACTIONS.contains(action.getSemanticAction()))
                .noneMatch(NotificationCompat.Action::getShowsUserInterface);
    }

    /**
     * Requests a given action from the current active Assistant.
     *
     * @param sbn         the notification payload to deliver to assistant
     * @param voiceAction must be a valid {@link CarVoiceInteractionSession} VOICE_ACTION
     * @param callback    the callback to issue on success/error
     */
    public void requestAssistantVoiceAction(StatusBarNotification sbn, String voiceAction,
            ActionRequestCallback callback) {
        if (!isCarCompatibleMessagingNotification(sbn)) {
            Log.w(TAG, "Assistant action requested for non-compatible notification.");
            callback.onResult(ActionRequestCallback.RESULT_FAILED);
            return;
        }

        switch (voiceAction) {
            case CarVoiceInteractionSession.VOICE_ACTION_READ_NOTIFICATION:
                readMessageNotification(sbn, callback);
                return;
            case CarVoiceInteractionSession.VOICE_ACTION_REPLY_NOTIFICATION:
                replyMessageNotification(sbn, callback);
                return;
            default:
                Log.w(TAG, "Requested Assistant action for unsupported semantic action.");
                callback.onResult(ActionRequestCallback.RESULT_FAILED);
                return;
        }
    }

    /**
     * Requests a read action for the notification from the current active Assistant.
     * If the Assistant cannot handle the request, a fallback implementation will attempt to
     * handle it.
     *
     * @param sbn      the notification to deliver as the payload
     * @param callback the callback to issue on success/error
     */
    private void readMessageNotification(StatusBarNotification sbn,
            ActionRequestCallback callback) {
        Bundle args = BundleBuilder.buildAssistantReadBundle(sbn);
        String action = CarVoiceInteractionSession.VOICE_ACTION_READ_NOTIFICATION;

        requestAction(action, sbn, args, callback);
    }

    /**
     * Requests a reply action for the notification from the current active Assistant.
     * If the Assistant cannot handle the request, a fallback implementation will attempt to
     * handle it.
     *
     * @param sbn      the notification to deliver as the payload
     * @param callback the callback to issue on success/error
     */
    private void replyMessageNotification(StatusBarNotification sbn,
            ActionRequestCallback callback) {
        Bundle args = BundleBuilder.buildAssistantReplyBundle(sbn);
        String action = CarVoiceInteractionSession.VOICE_ACTION_REPLY_NOTIFICATION;

        requestAction(action, sbn, args, callback);
    }

    private void requestAction(String action, StatusBarNotification sbn, Bundle payloadArguments,
            ActionRequestCallback callback) {

        if (!hasActiveAssistant()) {
            if (mIsFallbackAssistantEnabled) {
                handleFallback(sbn, action, callback);
            } else {
                // If there is no active assistant, and fallback assistant is not enabled, then
                // there is nothing for us to do.
                callback.onResult(ActionRequestCallback.RESULT_FAILED);
            }
            return;
        }

        if (!assistantIsNotificationListener()) {
            if (mIsFallbackAssistantEnabled) {
                handleFallback(sbn, action, callback);
            } else {
                // If there is an active assistant, alert them to request permissions.
                Bundle handleExceptionBundle = BundleBuilder
                        .buildAssistantHandleExceptionBundle(
                                EXCEPTION_NOTIFICATION_LISTENER_PERMISSIONS_MISSING,
                                /* fallbackAssistantEnabled */ false);
                fireAssistantAction(CarVoiceInteractionSession.VOICE_ACTION_HANDLE_EXCEPTION,
                        handleExceptionBundle, callback);
            }
            return;
        }

        fireAssistantAction(action, payloadArguments, callback);
    }

    private void fireAssistantAction(String action, Bundle payloadArguments,
            ActionRequestCallback callback) {
        IVoiceActionCheckCallback actionCheckCallback = new IVoiceActionCheckCallback.Stub() {
            @Override
            public void onComplete(List<String> supportedActions) {
                String resultState = ActionRequestCallback.RESULT_FAILED;
                if (supportedActions != null && supportedActions.contains(action)) {
                    if (Log.isLoggable(TAG, Log.DEBUG)) {
                        Log.d(TAG, "Launching active Assistant for action: " + action);
                    }
                    if (mAssistUtils.showSessionForActiveService(payloadArguments,
                            SHOW_SOURCE_NOTIFICATION, null, null)) {
                        resultState = ActionRequestCallback.RESULT_SUCCESS;
                    }
                } else {
                    Log.w(TAG, "Active Assistant does not support voice action: " + action);
                }
                callback.onResult(resultState);
            }
        };

        Set<String> actionSet = new HashSet<>(Collections.singletonList(action));
        mAssistUtils.getActiveServiceSupportedActions(actionSet, actionCheckCallback);
    }

    private void handleFallback(StatusBarNotification sbn, String action,
            ActionRequestCallback callback) {
        if (mFallbackAssistant == null) {
            return;
        }

        FallbackAssistant.Listener listener = new FallbackAssistant.Listener() {
            @Override
            public void onMessageRead(boolean hasError) {
                // Tracks if the FallbackAssistant successfully handled the action.
                final String fallbackActionResult = hasError ? ActionRequestCallback.RESULT_FAILED
                        : ActionRequestCallback.RESULT_SUCCESS;
                if (hasActiveAssistant()) {
                    // If there is an active assistant, alert them to request permissions.
                    Bundle handleExceptionBundle = BundleBuilder
                            .buildAssistantHandleExceptionBundle(
                                    EXCEPTION_NOTIFICATION_LISTENER_PERMISSIONS_MISSING,
                                    /* fallbackAssistantEnabled */ true);
                    fireAssistantAction(CarVoiceInteractionSession.VOICE_ACTION_HANDLE_EXCEPTION,
                            handleExceptionBundle, new ActionRequestCallback() {
                                @Override
                                public void onResult(String requestActionFromAssistantResult) {
                                    if (fallbackActionResult.equals(
                                            ActionRequestCallback.RESULT_FAILED)
                                            && requestActionFromAssistantResult
                                            == ActionRequestCallback.RESULT_SUCCESS) {
                                        // Only change the callback.ResultState if fallback failed,
                                        // and assistant session is shown.
                                        callback.onResult(
                                                ActionRequestCallback
                                                        .RESULT_FAILED_WITH_ERROR_HANDLED);
                                    } else {
                                        callback.onResult(fallbackActionResult);
                                    }
                                }
                            });
                } else {
                    callback.onResult(fallbackActionResult);
                }
            }
        };

        switch (action) {
            case CarVoiceInteractionSession.VOICE_ACTION_READ_NOTIFICATION:
                mFallbackAssistant.handleReadAction(sbn, listener);
                break;
            case CarVoiceInteractionSession.VOICE_ACTION_REPLY_NOTIFICATION:
                mFallbackAssistant.handleErrorMessage(mErrorMessage, listener);
                break;
            default:
                Log.w(TAG, "Requested unsupported FallbackAssistant action.");
                callback.onResult(ActionRequestCallback.RESULT_FAILED);
                return;
        }
    }
}