/*
 * Copyright (C) 2015 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.settingslib.location;

import android.app.AppOpsManager;
import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.graphics.drawable.Drawable;
import android.os.Process;
import android.os.UserHandle;
import android.os.UserManager;
import android.support.annotation.VisibleForTesting;
import android.text.format.DateUtils;
import android.util.IconDrawableFactory;
import android.util.Log;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

Retrieves the information of applications which accessed location recently.
/**
 * Retrieves the information of applications which accessed location recently.
 */
public class RecentLocationApps {
    private static final String TAG = RecentLocationApps.class.getSimpleName();
    @VisibleForTesting
    static final String ANDROID_SYSTEM_PACKAGE_NAME = "android";

    // Keep last 24 hours of location app information.
    private static final long RECENT_TIME_INTERVAL_MILLIS = DateUtils.DAY_IN_MILLIS;

    @VisibleForTesting
    static final int[] LOCATION_OPS = new int[] {
            AppOpsManager.OP_MONITOR_LOCATION,
            AppOpsManager.OP_MONITOR_HIGH_POWER_LOCATION,
    };

    private final PackageManager mPackageManager;
    private final Context mContext;
    private final IconDrawableFactory mDrawableFactory;

    public RecentLocationApps(Context context) {
        mContext = context;
        mPackageManager = context.getPackageManager();
        mDrawableFactory = IconDrawableFactory.newInstance(context);
    }

    
Fills a list of applications which queried location recently within specified time.
Apps are sorted by recency. Apps with more recent location requests are in the front.
/**
     * Fills a list of applications which queried location recently within specified time.
     * Apps are sorted by recency. Apps with more recent location requests are in the front.
     */
    public List<Request> getAppList() {
        // Retrieve a location usage list from AppOps
        AppOpsManager aoManager =
                (AppOpsManager) mContext.getSystemService(Context.APP_OPS_SERVICE);
        List<AppOpsManager.PackageOps> appOps = aoManager.getPackagesForOps(LOCATION_OPS);

        final int appOpsCount = appOps != null ? appOps.size() : 0;

        // Process the AppOps list and generate a preference list.
        ArrayList<Request> requests = new ArrayList<>(appOpsCount);
        final long now = System.currentTimeMillis();
        final UserManager um = (UserManager) mContext.getSystemService(Context.USER_SERVICE);
        final List<UserHandle> profiles = um.getUserProfiles();

        for (int i = 0; i < appOpsCount; ++i) {
            AppOpsManager.PackageOps ops = appOps.get(i);
            // Don't show the Android System in the list - it's not actionable for the user.
            // Also don't show apps belonging to background users except managed users.
            String packageName = ops.getPackageName();
            int uid = ops.getUid();
            int userId = UserHandle.getUserId(uid);
            boolean isAndroidOs =
                    (uid == Process.SYSTEM_UID) && ANDROID_SYSTEM_PACKAGE_NAME.equals(packageName);
            if (isAndroidOs || !profiles.contains(new UserHandle(userId))) {
                continue;
            }
            Request request = getRequestFromOps(now, ops);
            if (request != null) {
                requests.add(request);
            }
        }
        return requests;
    }

    public List<Request> getAppListSorted() {
        List<Request> requests = getAppList();
        // Sort the list of Requests by recency. Most recent request first.
        Collections.sort(requests, Collections.reverseOrder(new Comparator<Request>() {
            @Override
            public int compare(Request request1, Request request2) {
                return Long.compare(request1.requestFinishTime, request2.requestFinishTime);
            }
        }));
        return requests;
    }

    
Creates a Request entry for the given PackageOps.
This method examines the time interval of the PackageOps first. If the PackageOps is older
than the designated interval, this method ignores the PackageOps object and returns null.
When the PackageOps is fresh enough, this method returns a Request object for the package
/**
     * Creates a Request entry for the given PackageOps.
     *
     * This method examines the time interval of the PackageOps first. If the PackageOps is older
     * than the designated interval, this method ignores the PackageOps object and returns null.
     * When the PackageOps is fresh enough, this method returns a Request object for the package
     */
    private Request getRequestFromOps(long now,
            AppOpsManager.PackageOps ops) {
        String packageName = ops.getPackageName();
        List<AppOpsManager.OpEntry> entries = ops.getOps();
        boolean highBattery = false;
        boolean normalBattery = false;
        long locationRequestFinishTime = 0L;
        // Earliest time for a location request to end and still be shown in list.
        long recentLocationCutoffTime = now - RECENT_TIME_INTERVAL_MILLIS;
        for (AppOpsManager.OpEntry entry : entries) {
            if (entry.isRunning() || entry.getTime() >= recentLocationCutoffTime) {
                locationRequestFinishTime = entry.getTime() + entry.getDuration();
                switch (entry.getOp()) {
                    case AppOpsManager.OP_MONITOR_LOCATION:
                        normalBattery = true;
                        break;
                    case AppOpsManager.OP_MONITOR_HIGH_POWER_LOCATION:
                        highBattery = true;
                        break;
                    default:
                        break;
                }
            }
        }

        if (!highBattery && !normalBattery) {
            if (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, packageName + " hadn't used location within the time interval.");
            }
            return null;
        }

        // The package is fresh enough, continue.
        int uid = ops.getUid();
        int userId = UserHandle.getUserId(uid);

        Request request = null;
        try {
            ApplicationInfo appInfo = mPackageManager.getApplicationInfoAsUser(
                    packageName, PackageManager.GET_META_DATA, userId);
            if (appInfo == null) {
                Log.w(TAG, "Null application info retrieved for package " + packageName
                        + ", userId " + userId);
                return null;
            }

            final UserHandle userHandle = new UserHandle(userId);
            Drawable icon = mDrawableFactory.getBadgedIcon(appInfo, userId);
            CharSequence appLabel = mPackageManager.getApplicationLabel(appInfo);
            CharSequence badgedAppLabel = mPackageManager.getUserBadgedLabel(appLabel, userHandle);
            if (appLabel.toString().contentEquals(badgedAppLabel)) {
                // If badged label is not different from original then no need for it as
                // a separate content description.
                badgedAppLabel = null;
            }
            request = new Request(packageName, userHandle, icon, appLabel, highBattery,
                    badgedAppLabel, locationRequestFinishTime);
        } catch (NameNotFoundException e) {
            Log.w(TAG, "package name not found for " + packageName + ", userId " + userId);
        }
        return request;
    }

    public static class Request {
        public final String packageName;
        public final UserHandle userHandle;
        public final Drawable icon;
        public final CharSequence label;
        public final boolean isHighBattery;
        public final CharSequence contentDescription;
        public final long requestFinishTime;

        private Request(String packageName, UserHandle userHandle, Drawable icon,
                CharSequence label, boolean isHighBattery, CharSequence contentDescription,
                long requestFinishTime) {
            this.packageName = packageName;
            this.userHandle = userHandle;
            this.icon = icon;
            this.label = label;
            this.isHighBattery = isHighBattery;
            this.contentDescription = contentDescription;
            this.requestFinishTime = requestFinishTime;
        }
    }
}