/*
 * 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.settings.datausage;

import android.content.Context;
import android.net.NetworkStats;
import android.net.NetworkTemplate;
import android.telephony.SubscriptionInfo;
import android.telephony.SubscriptionManager;
import android.telephony.SubscriptionPlan;
import android.telephony.TelephonyManager;
import android.text.BidiFormatter;
import android.text.format.DateUtils;
import android.text.format.Formatter;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.VisibleForTesting;

import com.android.car.settings.R;
import com.android.internal.util.CollectionUtils;

import java.util.Calendar;
import java.util.List;
import java.util.Set;

/** Provides helpful utilities related to data usage. */
public final class DataUsageUtils {

    @VisibleForTesting
    static final long PETA = 1000000000000000L;

    private DataUsageUtils() {
    }

    /**
     * Returns the mobile network template given the subscription id.
     */
    public static NetworkTemplate getMobileNetworkTemplate(TelephonyManager telephonyManager,
            int subscriptionId) {
        String subscriberId = telephonyManager.getSubscriberId(subscriptionId);
        NetworkTemplate.Builder builder =
                new NetworkTemplate.Builder(NetworkTemplate.MATCH_MOBILE)
                .setMeteredness(NetworkStats.METERED_YES);
        if (subscriberId != null) {
            builder.setSubscriberIds(Set.of(subscriberId));
        }
        return normalizeMobileTemplate(builder.build(), telephonyManager.getMergedSubscriberIds());
    }

    private static NetworkTemplate normalizeMobileTemplate(
            @NonNull NetworkTemplate template, @Nullable String[] mergedSet) {
        if (template.getSubscriberIds().isEmpty() || mergedSet == null) return template;
        // The input template should have at most 1 subscriberId.
        String subscriberId = template.getSubscriberIds().iterator().next();

        if (Set.of(mergedSet).contains(subscriberId)) {
            // Requested template subscriber is part of the merge group; return
            // a template that matches all merged subscribers.
            return new NetworkTemplate.Builder(template.getMatchRule())
                    .setSubscriberIds(Set.of(mergedSet))
                    .setMeteredness(template.getMeteredness()).build();
        }

        return template;
    }

    /**
     * Returns the default subscription if available else returns
     * {@link SubscriptionManager#INVALID_SUBSCRIPTION_ID}.
     */
    public static int getDefaultSubscriptionId(SubscriptionManager subscriptionManager) {
        if (subscriptionManager == null) {
            return SubscriptionManager.INVALID_SUBSCRIPTION_ID;
        }
        SubscriptionInfo subscriptionInfo = subscriptionManager.getDefaultDataSubscriptionInfo();
        if (subscriptionInfo == null) {
            List<SubscriptionInfo> list = subscriptionManager.getAllSubscriptionInfoList();
            if (list.size() == 0) {
                return SubscriptionManager.INVALID_SUBSCRIPTION_ID;
            }
            subscriptionInfo = list.get(0);
        }
        return subscriptionInfo.getSubscriptionId();
    }

    /**
     * Format byte value to readable string using IEC units.
     */
    public static CharSequence bytesToIecUnits(Context context, long byteValue) {
        Formatter.BytesResult res = Formatter.formatBytes(context.getResources(), byteValue,
                Formatter.FLAG_IEC_UNITS);
        return BidiFormatter.getInstance().unicodeWrap(context.getString(
                com.android.internal.R.string.fileSizeSuffix, res.value, res.units));
    }

    /**
     * Generate a string that lists byte value to readable string using IEC units, and date range
     * from specified start date to current date.
     */
    public static CharSequence formatDataUsageInCycle(Context context, long byteValue,
            long fromTimeInMillis) {
        CharSequence usage = bytesToIecUnits(context, byteValue);
        int flags = DateUtils.FORMAT_ABBREV_MONTH | DateUtils.FORMAT_NO_YEAR;
        String fromText = DateUtils.formatDateTime(context, fromTimeInMillis, flags);
        String toText = DateUtils.formatDateTime(context, Calendar.getInstance().getTimeInMillis(),
                flags);
        return context.getString(R.string.network_and_internet_data_usage_time_range_summary, usage,
                fromText, toText);
    }

    /**
     * Returns the primary subscription plan. Returns {@code null} if {@link SubscriptionPlan}
     * doesn't exist for a given subscriptionId or if the first {@link SubscriptionPlan} has
     * invalid properties.
     */
    @Nullable
    public static SubscriptionPlan getPrimaryPlan(SubscriptionManager subManager,
            int subscriptionId) {
        List<SubscriptionPlan> plans = subManager.getSubscriptionPlans(subscriptionId);
        if (CollectionUtils.isEmpty(plans)) {
            return null;
        }
        // First plan in the list is the primary plan
        SubscriptionPlan plan = plans.get(0);
        return plan.getDataLimitBytes() > 0
                && saneSize(plan.getDataUsageBytes())
                && plan.getCycleRule() != null ? plan : null;
    }

    private static boolean saneSize(long value) {
        return value >= 0L && value < PETA;
    }
}