/*
 * 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.net;

import static android.net.ConnectivityManager.TYPE_MOBILE;
import static android.net.NetworkStatsHistory.FIELD_RX_BYTES;
import static android.net.NetworkStatsHistory.FIELD_TX_BYTES;
import static android.net.TrafficStats.MB_IN_BYTES;
import static android.telephony.TelephonyManager.SIM_STATE_READY;
import static android.text.format.DateUtils.FORMAT_ABBREV_MONTH;
import static android.text.format.DateUtils.FORMAT_SHOW_DATE;

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.INetworkStatsService;
import android.net.INetworkStatsSession;
import android.net.NetworkPolicy;
import android.net.NetworkPolicyManager;
import android.net.NetworkStatsHistory;
import android.net.NetworkTemplate;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.telephony.SubscriptionManager;
import android.telephony.TelephonyManager;
import android.text.format.DateUtils;
import android.util.Log;
import android.util.Pair;

import com.android.internal.R;

import java.time.ZonedDateTime;
import java.util.Date;
import java.util.Locale;

public class DataUsageController {

    private static final String TAG = "DataUsageController";
    private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
    private static final int FIELDS = FIELD_RX_BYTES | FIELD_TX_BYTES;
    private static final StringBuilder PERIOD_BUILDER = new StringBuilder(50);
    private static final java.util.Formatter PERIOD_FORMATTER = new java.util.Formatter(
            PERIOD_BUILDER, Locale.getDefault());

    private final Context mContext;
    private final TelephonyManager mTelephonyManager;
    private final ConnectivityManager mConnectivityManager;
    private final INetworkStatsService mStatsService;
    private final NetworkPolicyManager mPolicyManager;

    private INetworkStatsSession mSession;
    private Callback mCallback;
    private NetworkNameProvider mNetworkController;

    public DataUsageController(Context context) {
        mContext = context;
        mTelephonyManager = TelephonyManager.from(context);
        mConnectivityManager = ConnectivityManager.from(context);
        mStatsService = INetworkStatsService.Stub.asInterface(
                ServiceManager.getService(Context.NETWORK_STATS_SERVICE));
        mPolicyManager = NetworkPolicyManager.from(mContext);
    }

    public void setNetworkController(NetworkNameProvider networkController) {
        mNetworkController = networkController;
    }

    /**
     * Returns the default warning level in bytes.
     */
    public long getDefaultWarningLevel() {
        return MB_IN_BYTES
                * mContext.getResources().getInteger(R.integer.default_data_warning_level_mb);
    }

    private INetworkStatsSession getSession() {
        if (mSession == null) {
            try {
                mSession = mStatsService.openSession();
            } catch (RemoteException e) {
                Log.w(TAG, "Failed to open stats session", e);
            } catch (RuntimeException e) {
                Log.w(TAG, "Failed to open stats session", e);
            }
        }
        return mSession;
    }

    public void setCallback(Callback callback) {
        mCallback = callback;
    }

    private DataUsageInfo warn(String msg) {
        Log.w(TAG, "Failed to get data usage, " + msg);
        return null;
    }

    public DataUsageInfo getDataUsageInfo() {
        final String subscriberId = getActiveSubscriberId(mContext);
        if (subscriberId == null) {
            return warn("no subscriber id");
        }
        NetworkTemplate template = NetworkTemplate.buildTemplateMobileAll(subscriberId);
        template = NetworkTemplate.normalize(template, mTelephonyManager.getMergedSubscriberIds());

        return getDataUsageInfo(template);
    }

    public DataUsageInfo getWifiDataUsageInfo() {
        NetworkTemplate template = NetworkTemplate.buildTemplateWifiWildcard();
        return getDataUsageInfo(template);
    }

    public DataUsageInfo getDataUsageInfo(NetworkTemplate template) {
        final INetworkStatsSession session = getSession();
        if (session == null) {
            return warn("no stats session");
        }
        final NetworkPolicy policy = findNetworkPolicy(template);
        try {
            final NetworkStatsHistory history = session.getHistoryForNetwork(template, FIELDS);
            final long now = System.currentTimeMillis();
            final long start, end;
            if (policy != null) {
                final Pair<ZonedDateTime, ZonedDateTime> cycle = NetworkPolicyManager
                        .cycleIterator(policy).next();
                start = cycle.first.toInstant().toEpochMilli();
                end = cycle.second.toInstant().toEpochMilli();
            } else {
                // period = last 4 wks
                end = now;
                start = now - DateUtils.WEEK_IN_MILLIS * 4;
            }
            final long callStart = System.currentTimeMillis();
            final NetworkStatsHistory.Entry entry = history.getValues(start, end, now, null);
            final long callEnd = System.currentTimeMillis();
            if (DEBUG) Log.d(TAG, String.format("history call from %s to %s now=%s took %sms: %s",
                    new Date(start), new Date(end), new Date(now), callEnd - callStart,
                    historyEntryToString(entry)));
            if (entry == null) {
                return warn("no entry data");
            }
            final long totalBytes = entry.rxBytes + entry.txBytes;
            final DataUsageInfo usage = new DataUsageInfo();
            usage.startDate = start;
            usage.usageLevel = totalBytes;
            usage.period = formatDateRange(start, end);
            if (policy != null) {
                usage.limitLevel = policy.limitBytes > 0 ? policy.limitBytes : 0;
                usage.warningLevel = policy.warningBytes > 0 ? policy.warningBytes : 0;
            } else {
                usage.warningLevel = getDefaultWarningLevel();
            }
            if (usage != null && mNetworkController != null) {
                usage.carrier = mNetworkController.getMobileDataNetworkName();
            }
            return usage;
        } catch (RemoteException e) {
            return warn("remote call failed");
        }
    }

    private NetworkPolicy findNetworkPolicy(NetworkTemplate template) {
        if (mPolicyManager == null || template == null) return null;
        final NetworkPolicy[] policies = mPolicyManager.getNetworkPolicies();
        if (policies == null) return null;
        final int N = policies.length;
        for (int i = 0; i < N; i++) {
            final NetworkPolicy policy = policies[i];
            if (policy != null && template.equals(policy.template)) {
                return policy;
            }
        }
        return null;
    }

    private static String historyEntryToString(NetworkStatsHistory.Entry entry) {
        return entry == null ? null : new StringBuilder("Entry[")
                .append("bucketDuration=").append(entry.bucketDuration)
                .append(",bucketStart=").append(entry.bucketStart)
                .append(",activeTime=").append(entry.activeTime)
                .append(",rxBytes=").append(entry.rxBytes)
                .append(",rxPackets=").append(entry.rxPackets)
                .append(",txBytes=").append(entry.txBytes)
                .append(",txPackets=").append(entry.txPackets)
                .append(",operations=").append(entry.operations)
                .append(']').toString();
    }

    public void setMobileDataEnabled(boolean enabled) {
        Log.d(TAG, "setMobileDataEnabled: enabled=" + enabled);
        mTelephonyManager.setDataEnabled(enabled);
        if (mCallback != null) {
            mCallback.onMobileDataEnabled(enabled);
        }
    }

    public boolean isMobileDataSupported() {
        // require both supported network and ready SIM
        return mConnectivityManager.isNetworkSupported(TYPE_MOBILE)
                && mTelephonyManager.getSimState() == SIM_STATE_READY;
    }

    public boolean isMobileDataEnabled() {
        return mTelephonyManager.getDataEnabled();
    }

    private static String getActiveSubscriberId(Context context) {
        final TelephonyManager tele = TelephonyManager.from(context);
        final String actualSubscriberId = tele.getSubscriberId(
                SubscriptionManager.getDefaultDataSubscriptionId());
        return actualSubscriberId;
    }

    private String formatDateRange(long start, long end) {
        final int flags = FORMAT_SHOW_DATE | FORMAT_ABBREV_MONTH;
        synchronized (PERIOD_BUILDER) {
            PERIOD_BUILDER.setLength(0);
            return DateUtils.formatDateRange(mContext, PERIOD_FORMATTER, start, end, flags, null)
                    .toString();
        }
    }

    public interface NetworkNameProvider {
        String getMobileDataNetworkName();
    }

    public static class DataUsageInfo {
        public String carrier;
        public String period;
        public long startDate;
        public long limitLevel;
        public long warningLevel;
        public long usageLevel;
    }

    public interface Callback {
        void onMobileDataEnabled(boolean enabled);
    }
}