/*
 * 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 android.util;

import static android.Manifest.permission.DUMP;
import static android.Manifest.permission.PACKAGE_USAGE_STATS;

import android.Manifest;
import android.annotation.NonNull;
import android.annotation.RequiresPermission;
import android.annotation.SystemApi;
import android.content.Context;
import android.os.IStatsManager;
import android.os.RemoteException;
import android.os.ServiceManager;

/**
 * StatsLog provides an API for developers to send events to statsd. The events can be used to
 * define custom metrics inside statsd.
 */
public final class StatsLog extends StatsLogInternal {
    private static final String TAG = "StatsLog";
    private static final boolean DEBUG = false;

    private static IStatsManager sService;

    private static Object sLogLock = new Object();

    private StatsLog() {
    }

    /**
     * Logs a start event.
     *
     * @param label developer-chosen label.
     * @return True if the log request was sent to statsd.
     */
    public static boolean logStart(int label) {
        synchronized (sLogLock) {
            try {
                IStatsManager service = getIStatsManagerLocked();
                if (service == null) {
                    if (DEBUG) {
                        Slog.d(TAG, "Failed to find statsd when logging start");
                    }
                    return false;
                }
                service.sendAppBreadcrumbAtom(label,
                        StatsLog.APP_BREADCRUMB_REPORTED__STATE__START);
                return true;
            } catch (RemoteException e) {
                sService = null;
                if (DEBUG) {
                    Slog.d(TAG, "Failed to connect to statsd when logging start");
                }
                return false;
            }
        }
    }

    /**
     * Logs a stop event.
     *
     * @param label developer-chosen label.
     * @return True if the log request was sent to statsd.
     */
    public static boolean logStop(int label) {
        synchronized (sLogLock) {
            try {
                IStatsManager service = getIStatsManagerLocked();
                if (service == null) {
                    if (DEBUG) {
                        Slog.d(TAG, "Failed to find statsd when logging stop");
                    }
                    return false;
                }
                service.sendAppBreadcrumbAtom(label, StatsLog.APP_BREADCRUMB_REPORTED__STATE__STOP);
                return true;
            } catch (RemoteException e) {
                sService = null;
                if (DEBUG) {
                    Slog.d(TAG, "Failed to connect to statsd when logging stop");
                }
                return false;
            }
        }
    }

    /**
     * Logs an event that does not represent a start or stop boundary.
     *
     * @param label developer-chosen label.
     * @return True if the log request was sent to statsd.
     */
    public static boolean logEvent(int label) {
        synchronized (sLogLock) {
            try {
                IStatsManager service = getIStatsManagerLocked();
                if (service == null) {
                    if (DEBUG) {
                        Slog.d(TAG, "Failed to find statsd when logging event");
                    }
                    return false;
                }
                service.sendAppBreadcrumbAtom(
                        label, StatsLog.APP_BREADCRUMB_REPORTED__STATE__UNSPECIFIED);
                return true;
            } catch (RemoteException e) {
                sService = null;
                if (DEBUG) {
                    Slog.d(TAG, "Failed to connect to statsd when logging event");
                }
                return false;
            }
        }
    }

    /**
     * Logs an event for binary push for module updates.
     *
     * @param trainName        name of install train.
     * @param trainVersionCode version code of the train.
     * @param options          optional flags about this install.
     *                         The last 3 bits indicate options:
     *                             0x01: FLAG_REQUIRE_STAGING
     *                             0x02: FLAG_ROLLBACK_ENABLED
     *                             0x04: FLAG_REQUIRE_LOW_LATENCY_MONITOR
     * @param state            current install state. Defined as State enums in
     *                         BinaryPushStateChanged atom in
     *                         frameworks/base/cmds/statsd/src/atoms.proto
     * @param experimentIds    experiment ids.
     * @return True if the log request was sent to statsd.
     */
    @RequiresPermission(allOf = {DUMP, PACKAGE_USAGE_STATS})
    public static boolean logBinaryPushStateChanged(@NonNull String trainName,
            long trainVersionCode, int options, int state,
            @NonNull long[] experimentIds) {
        synchronized (sLogLock) {
            try {
                IStatsManager service = getIStatsManagerLocked();
                if (service == null) {
                    if (DEBUG) {
                        Slog.d(TAG, "Failed to find statsd when logging event");
                    }
                    return false;
                }
                service.sendBinaryPushStateChangedAtom(
                        trainName, trainVersionCode, options, state, experimentIds);
                return true;
            } catch (RemoteException e) {
                sService = null;
                if (DEBUG) {
                    Slog.d(TAG,
                            "Failed to connect to StatsCompanionService when logging "
                                    + "BinaryPushStateChanged");
                }
                return false;
            }
        }
    }

    /**
     * Logs an event for watchdog rollbacks.
     *
     * @param rollbackType          state of the rollback.
     * @param packageName           package name being rolled back.
     * @param packageVersionCode    version of the package being rolled back.
     *
     * @return True if the log request was sent to statsd.
     *
     * @hide
     */
    @RequiresPermission(allOf = {DUMP, PACKAGE_USAGE_STATS})
    public static boolean logWatchdogRollbackOccurred(int rollbackType, String packageName,
            long packageVersionCode) {
        synchronized (sLogLock) {
            try {
                IStatsManager service = getIStatsManagerLocked();
                if (service == null) {
                    if (DEBUG) {
                        Slog.d(TAG, "Failed to find statsd when logging event");
                    }
                    return false;
                }

                service.sendWatchdogRollbackOccurredAtom(rollbackType, packageName,
                        packageVersionCode);
                return true;
            } catch (RemoteException e) {
                sService = null;
                if (DEBUG) {
                    Slog.d(TAG,
                            "Failed to connect to StatsCompanionService when logging "
                                    + "WatchdogRollbackOccurred");
                }
                return false;
            }
        }
    }


    private static IStatsManager getIStatsManagerLocked() throws RemoteException {
        if (sService != null) {
            return sService;
        }
        sService = IStatsManager.Stub.asInterface(ServiceManager.getService("stats"));
        return sService;
    }

    /**
     * Write an event to stats log using the raw format.
     *
     * @param buffer    The encoded buffer of data to write.
     * @param size      The number of bytes from the buffer to write.
     * @hide
     */
    // TODO(b/144935988): Mark deprecated.
    @SystemApi
    public static void writeRaw(@NonNull byte[] buffer, int size) {
        // TODO(b/144935988): make this no-op once clients have migrated to StatsEvent.
        writeImpl(buffer, size, 0);
    }

    /**
     * Write an event to stats log using the raw format.
     *
     * @param buffer    The encoded buffer of data to write.
     * @param size      The number of bytes from the buffer to write.
     * @param atomId    The id of the atom to which the event belongs.
     */
    private static native void writeImpl(@NonNull byte[] buffer, int size, int atomId);

    /**
     * Write an event to stats log using the raw format encapsulated in StatsEvent.
     * After writing to stats log, release() is called on the StatsEvent object.
     * No further action should be taken on the StatsEvent object following this call.
     *
     * @param statsEvent    The StatsEvent object containing the encoded buffer of data to write.
     * @hide
     */
    public static void write(@NonNull final StatsEvent statsEvent) {
        writeImpl(statsEvent.getBytes(), statsEvent.getNumBytes(), statsEvent.getAtomId());
        statsEvent.release();
    }

    private static void enforceDumpCallingPermission(Context context) {
        context.enforceCallingPermission(android.Manifest.permission.DUMP, "Need DUMP permission.");
    }

    private static void enforcesageStatsCallingPermission(Context context) {
        context.enforceCallingPermission(Manifest.permission.PACKAGE_USAGE_STATS,
                "Need PACKAGE_USAGE_STATS permission.");
    }
}