/*
 * 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.wifitrackerlib;

import static android.net.wifi.WifiConfiguration.NetworkSelectionStatus.NETWORK_SELECTION_ENABLED;
import static android.net.wifi.WifiConfiguration.NetworkSelectionStatus.NETWORK_SELECTION_PERMANENTLY_DISABLED;

import static com.android.wifitrackerlib.StandardWifiEntry.ssidAndSecurityToStandardWifiEntryKey;
import static com.android.wifitrackerlib.WifiEntry.SECURITY_EAP;
import static com.android.wifitrackerlib.WifiEntry.SECURITY_EAP_SUITE_B;
import static com.android.wifitrackerlib.WifiEntry.SECURITY_NONE;
import static com.android.wifitrackerlib.WifiEntry.SECURITY_OWE;
import static com.android.wifitrackerlib.WifiEntry.SECURITY_PSK;
import static com.android.wifitrackerlib.WifiEntry.SECURITY_SAE;
import static com.android.wifitrackerlib.WifiEntry.SECURITY_WEP;
import static com.android.wifitrackerlib.WifiEntry.SPEED_FAST;
import static com.android.wifitrackerlib.WifiEntry.SPEED_MODERATE;
import static com.android.wifitrackerlib.WifiEntry.SPEED_NONE;
import static com.android.wifitrackerlib.WifiEntry.SPEED_SLOW;
import static com.android.wifitrackerlib.WifiEntry.SPEED_VERY_FAST;
import static com.android.wifitrackerlib.WifiEntry.Speed;

import static java.util.Comparator.comparingInt;
import static java.util.stream.Collectors.groupingBy;

import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.net.NetworkCapabilities;
import android.net.NetworkInfo;
import android.net.NetworkInfo.DetailedState;
import android.net.NetworkKey;
import android.net.NetworkScoreManager;
import android.net.ScoredNetwork;
import android.net.wifi.ScanResult;
import android.net.wifi.WifiConfiguration;
import android.net.wifi.WifiConfiguration.NetworkSelectionStatus;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiNetworkScoreCache;
import android.os.PersistableBundle;
import android.os.UserHandle;
import android.provider.Settings;
import android.telephony.CarrierConfigManager;
import android.telephony.SubscriptionInfo;
import android.telephony.SubscriptionManager;
import android.telephony.TelephonyManager;
import android.text.Annotation;
import android.text.SpannableString;
import android.text.SpannableStringBuilder;
import android.text.TextUtils;
import android.text.format.DateUtils;
import android.text.style.ClickableSpan;
import android.view.View;

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

import com.android.settingslib.HelpUtils;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.StringJoiner;

/**
 * Utility methods for WifiTrackerLib.
 */
class Utils {
    private static NetworkScoreManager sNetworkScoreManager;

    private static String getActiveScorerPackage(@NonNull Context context) {
        if (sNetworkScoreManager == null) {
            sNetworkScoreManager = context.getSystemService(NetworkScoreManager.class);
        }
        return sNetworkScoreManager.getActiveScorerPackage();
    }

    // Returns the ScanResult with the best RSSI from a list of ScanResults.
    @Nullable
    static ScanResult getBestScanResultByLevel(@NonNull List<ScanResult> scanResults) {
        if (scanResults.isEmpty()) return null;

        return Collections.max(scanResults, comparingInt(scanResult -> scanResult.level));
    }

    // Returns a list of SECURITY types supported by a ScanResult.
    static List<Integer> getSecurityTypesFromScanResult(@NonNull ScanResult scan) {
        final List<Integer> securityTypes = new ArrayList<>();
        if (scan.capabilities == null) {
            securityTypes.add(SECURITY_NONE);
        } else if (scan.capabilities.contains("PSK") && scan.capabilities.contains("SAE")) {
            securityTypes.add(SECURITY_PSK);
            securityTypes.add(SECURITY_SAE);
        } else if (scan.capabilities.contains("OWE_TRANSITION")) {
            securityTypes.add(SECURITY_NONE);
            securityTypes.add(SECURITY_OWE);
        } else if (scan.capabilities.contains("OWE")) {
            securityTypes.add(SECURITY_OWE);
        } else if (scan.capabilities.contains("WEP")) {
            securityTypes.add(SECURITY_WEP);
        } else if (scan.capabilities.contains("SAE")) {
            securityTypes.add(SECURITY_SAE);
        } else if (scan.capabilities.contains("PSK")) {
            securityTypes.add(SECURITY_PSK);
        } else if (scan.capabilities.contains("EAP_SUITE_B_192")) {
            securityTypes.add(SECURITY_EAP_SUITE_B);
        } else if (scan.capabilities.contains("EAP")) {
            securityTypes.add(SECURITY_EAP);
        } else {
            securityTypes.add(SECURITY_NONE);
        }
        return securityTypes;
    }

    // Returns the SECURITY type supported by a WifiConfiguration
    @WifiEntry.Security
    static int getSecurityTypeFromWifiConfiguration(@NonNull WifiConfiguration config) {
        if (config.allowedKeyManagement.get(WifiConfiguration.KeyMgmt.SAE)) {
            return SECURITY_SAE;
        }
        if (config.allowedKeyManagement.get(WifiConfiguration.KeyMgmt.WPA_PSK)) {
            return SECURITY_PSK;
        }
        if (config.allowedKeyManagement.get(WifiConfiguration.KeyMgmt.SUITE_B_192)) {
            return SECURITY_EAP_SUITE_B;
        }
        if (config.allowedKeyManagement.get(WifiConfiguration.KeyMgmt.WPA_EAP)
                || config.allowedKeyManagement.get(WifiConfiguration.KeyMgmt.IEEE8021X)) {
            return SECURITY_EAP;
        }
        if (config.allowedKeyManagement.get(WifiConfiguration.KeyMgmt.OWE)) {
            return SECURITY_OWE;
        }
        return (config.wepKeys[0] != null) ? SECURITY_WEP : SECURITY_NONE;
    }

    /**
     * Maps ScanResults into any number of WifiEntry keys each ScanResult matches. If
     * chooseSingleSecurity is true, then ScanResults with multiple security capabilities will be
     * matched to a single security type for the purpose of user selection.
     *
     * @param scanResults ScanResults to be mapped.
     * @param chooseSingleSecurity If this is true, map scan results with multiple security
     *                             capabilities to a single security for coalescing into a single
     *                             WifiEntry.
     * @param wifiConfigsByKey Mapping of WifiConfiguration to WifiEntry key. Only used if
     *                         chooseSingleSecurity is true.
     * @param isWpa3SaeSupported If this is false, do not map to SECURITY_SAE
     * @param isWpa3SuiteBSupported If this is false, do not map to SECURITY_EAP_SUITE_B
     * @param isEnhancedOpenSupported If this is false, do not map to SECURITY_OWE
     * @return Map of WifiEntry key to list of corresponding ScanResults.
     */
    static Map<String, List<ScanResult>> mapScanResultsToKey(
            @NonNull List<ScanResult> scanResults,
            boolean chooseSingleSecurity,
            @Nullable Map<String, WifiConfiguration> wifiConfigsByKey,
            boolean isWpa3SaeSupported,
            boolean isWpa3SuiteBSupported,
            boolean isEnhancedOpenSupported) {
        if (wifiConfigsByKey == null) {
            wifiConfigsByKey = new HashMap<>();
        }
        final Map<String, List<ScanResult>> scanResultsBySsid = scanResults.stream()
                .filter(scanResult -> !TextUtils.isEmpty(scanResult.SSID))
                .collect(groupingBy(scanResult -> scanResult.SSID));
        final Map<String, List<ScanResult>> scanResultsByKey = new HashMap<>();

        for (String ssid : scanResultsBySsid.keySet()) {
            final boolean pskConfigExists = wifiConfigsByKey.containsKey(
                    ssidAndSecurityToStandardWifiEntryKey(ssid, SECURITY_PSK));
            final boolean saeConfigExists = wifiConfigsByKey.containsKey(
                    ssidAndSecurityToStandardWifiEntryKey(ssid, SECURITY_SAE));
            final boolean openConfigExists = wifiConfigsByKey.containsKey(
                    ssidAndSecurityToStandardWifiEntryKey(ssid, SECURITY_NONE));
            final boolean oweConfigExists = wifiConfigsByKey.containsKey(
                    ssidAndSecurityToStandardWifiEntryKey(ssid, SECURITY_OWE));

            boolean pskInRange = false;
            boolean saeInRange = false;
            boolean oweInRange = false;
            boolean openInRange = false;
            for (ScanResult scan : scanResultsBySsid.get(ssid)) {
                final List<Integer> securityTypes = getSecurityTypesFromScanResult(scan);
                if (securityTypes.contains(SECURITY_PSK)) {
                    pskInRange = true;
                }
                if (securityTypes.contains(SECURITY_SAE)) {
                    saeInRange = true;
                }
                if (securityTypes.contains(SECURITY_OWE)) {
                    oweInRange = true;
                }
                if (securityTypes.contains(SECURITY_NONE)) {
                    openInRange = true;
                }
            }

            for (ScanResult scan : scanResultsBySsid.get(ssid)) {
                List<Integer> securityTypes = getSecurityTypesFromScanResult(scan);
                List<Integer> chosenSecurityTypes = new ArrayList<>();
                // Ignore security types that are unsupported
                if (!isWpa3SaeSupported) {
                    securityTypes.remove((Integer) SECURITY_SAE);
                }
                if (!isWpa3SuiteBSupported) {
                    securityTypes.remove((Integer) SECURITY_EAP_SUITE_B);
                }
                if (!isEnhancedOpenSupported) {
                    securityTypes.remove((Integer) SECURITY_OWE);
                }

                final boolean isSae = securityTypes.contains(SECURITY_SAE)
                        && !securityTypes.contains(SECURITY_PSK);
                final boolean isPsk = securityTypes.contains(SECURITY_PSK)
                        && !securityTypes.contains(SECURITY_SAE);
                final boolean isPskSaeTransition = securityTypes.contains(SECURITY_PSK)
                        && securityTypes.contains(SECURITY_SAE);
                final boolean isOwe = securityTypes.contains(SECURITY_OWE)
                        && !securityTypes.contains(SECURITY_NONE);
                final boolean isOweTransition = securityTypes.contains(SECURITY_NONE)
                        && securityTypes.contains(SECURITY_OWE);
                final boolean isOpen = securityTypes.contains(SECURITY_NONE)
                        && !securityTypes.contains(SECURITY_OWE);

                if (chooseSingleSecurity) {
                    if (isPsk) {
                        if (!pskConfigExists && saeConfigExists && saeInRange) {
                            // If we don't have a PSK config, but there is an SAE AP in-range and
                            // an SAE config we can use for connection, then ignore the PSK AP so
                            // that the user only has the SAE AP to select.
                            continue;
                        } else {
                            chosenSecurityTypes.add(SECURITY_PSK);
                        }
                    } else if (isPskSaeTransition) {
                        // Map to SAE if we have an SAE config and no PSK config (use SAE config to
                        // connect). Else, map to PSK for wider compatibility.
                        if (!pskConfigExists && saeConfigExists) {
                            chosenSecurityTypes.add(SECURITY_SAE);
                        } else {
                            chosenSecurityTypes.add(SECURITY_PSK);
                        }
                    } else if (isSae) {
                        // Map to SAE if we either
                        // 1) have an SAE config and no PSK config (use SAE config to connect).
                        // 2) have no configs at all, and no PSK APs are in range. (save new
                        //    network with SAE security).
                        // Else, map to PSK for wider compatibility.
                        if (!pskConfigExists && (saeConfigExists || !pskInRange)) {
                            chosenSecurityTypes.add(SECURITY_SAE);
                        } else {
                            chosenSecurityTypes.add(SECURITY_PSK);
                        }
                    } else if (isOwe) {
                        // If an open AP is in range, use it instead if we have a config for it and
                        // no OWE config.
                        if (openInRange && openConfigExists && !oweConfigExists) {
                            continue;
                        } else {
                            chosenSecurityTypes.add(SECURITY_OWE);
                        }
                    } else if (isOweTransition) {
                        // Map to OWE if we either
                        // 1) have an OWE config (use OWE config to connect).
                        // 2) have no configs at all (save new network with OWE security).
                        // Otherwise, if we have an open config only, map to open security so that
                        // config is used for connection.
                        if (oweConfigExists || !openConfigExists) {
                            chosenSecurityTypes.add(SECURITY_OWE);
                        } else {
                            chosenSecurityTypes.add(SECURITY_NONE);
                        }
                    } else if (isOpen) {
                        // If an OWE AP is in-range, then use it instead if we have a config for it
                        // or no configs at all.
                        if (oweInRange && (oweConfigExists || !openConfigExists)) {
                            continue;
                        } else {
                            chosenSecurityTypes.add(SECURITY_NONE);
                        }
                    } else {
                        chosenSecurityTypes.addAll(securityTypes);
                    }
                } else {
                    chosenSecurityTypes.addAll(securityTypes);
                    if (isSae) {
                        // If we don't need to choose a single security type for the user to select,
                        // then SAE scans can also match to PSK configs, which will be dynamically
                        // upgraded to SAE by the framework at connection time.
                        chosenSecurityTypes.add(SECURITY_PSK);
                    }
                }

                for (int security : chosenSecurityTypes) {
                    final String key = ssidAndSecurityToStandardWifiEntryKey(ssid, security);
                    if (!scanResultsByKey.containsKey(key)) {
                        scanResultsByKey.put(key, new ArrayList<>());
                    }
                    scanResultsByKey.get(key).add(scan);
                }
            }
        }
        return scanResultsByKey;
    }

    @Speed
    static int getAverageSpeedFromScanResults(@NonNull WifiNetworkScoreCache scoreCache,
            @NonNull List<ScanResult> scanResults) {
        int count = 0;
        int totalSpeed = 0;
        for (ScanResult scanResult : scanResults) {
            ScoredNetwork scoredNetwork = scoreCache.getScoredNetwork(scanResult);
            if (scoredNetwork == null) {
                continue;
            }
            @Speed int speed = scoredNetwork.calculateBadge(scanResult.level);
            if (speed != SPEED_NONE) {
                count++;
                totalSpeed += speed;
            }
        }
        if (count == 0) {
            return SPEED_NONE;
        } else {
            return roundToClosestSpeedEnum(totalSpeed / count);
        }
    }

    @Speed
    static int getSpeedFromWifiInfo(@NonNull WifiNetworkScoreCache scoreCache,
            @NonNull WifiInfo wifiInfo) {
        ScoredNetwork scoredNetwork = scoreCache.getScoredNetwork(
                NetworkKey.createFromWifiInfo(wifiInfo));
        if (scoredNetwork == null) {
            return SPEED_NONE;
        }
        return roundToClosestSpeedEnum(scoredNetwork.calculateBadge(wifiInfo.getRssi()));
    }

    @Speed
    private static int roundToClosestSpeedEnum(int speed) {
        if (speed == SPEED_NONE) {
            return SPEED_NONE;
        } else if (speed < (SPEED_SLOW + SPEED_MODERATE) / 2) {
            return SPEED_SLOW;
        } else if (speed < (SPEED_MODERATE + SPEED_FAST) / 2) {
            return SPEED_MODERATE;
        } else if (speed < (SPEED_FAST + SPEED_VERY_FAST) / 2) {
            return SPEED_FAST;
        } else {
            return SPEED_VERY_FAST;
        }
    }

    /**
     * Get the app label for a suggestion/specifier package name, or an empty String if none exist
     */
    static String getAppLabel(Context context, String packageName) {
        try {
            String openWifiPackageName = Settings.Global.getString(context.getContentResolver(),
                    Settings.Global.USE_OPEN_WIFI_PACKAGE);
            if (!TextUtils.isEmpty(openWifiPackageName) && TextUtils.equals(packageName,
                    getActiveScorerPackage(context))) {
                packageName = openWifiPackageName;
            }

            ApplicationInfo appInfo = context.getPackageManager().getApplicationInfoAsUser(
                    packageName,
                    0 /* flags */,
                    UserHandle.getUserId(UserHandle.USER_CURRENT));
            return appInfo.loadLabel(context.getPackageManager()).toString();
        } catch (PackageManager.NameNotFoundException e) {
            return "";
        }
    }

    static String getDisconnectedStateDescription(Context context, WifiEntry wifiEntry) {
        if (context == null || wifiEntry == null) {
            return "";
        }
        WifiConfiguration wifiConfiguration = wifiEntry.getWifiConfiguration();
        if (wifiConfiguration == null) {
            return null;
        }

        if (wifiConfiguration.hasNoInternetAccess()) {
            int messageID =
                    wifiConfiguration.getNetworkSelectionStatus().getNetworkSelectionStatus()
                            == NETWORK_SELECTION_PERMANENTLY_DISABLED
                    ? R.string.wifi_no_internet_no_reconnect : R.string.wifi_no_internet;
            return context.getString(messageID);
        } else if (wifiConfiguration.getNetworkSelectionStatus().getNetworkSelectionStatus()
                != NETWORK_SELECTION_ENABLED) {
            WifiConfiguration.NetworkSelectionStatus networkStatus =
                    wifiConfiguration.getNetworkSelectionStatus();
            switch (networkStatus.getNetworkSelectionDisableReason()) {
                case WifiConfiguration.NetworkSelectionStatus.DISABLED_AUTHENTICATION_FAILURE:
                    return context.getString(R.string.wifi_disabled_password_failure);
                case WifiConfiguration.NetworkSelectionStatus.DISABLED_BY_WRONG_PASSWORD:
                    return context.getString(R.string.wifi_check_password_try_again);
                case WifiConfiguration.NetworkSelectionStatus.DISABLED_DHCP_FAILURE:
                    return context.getString(R.string.wifi_disabled_network_failure);
                case WifiConfiguration.NetworkSelectionStatus.DISABLED_ASSOCIATION_REJECTION:
                    return context.getString(R.string.wifi_disabled_generic);
                default:
                    break;
            }
        } else if (wifiEntry.getLevel() == WifiEntry.WIFI_LEVEL_UNREACHABLE) {
            // Do nothing because users know it by signal icon.
        } else { // In range, not disabled.
            if (wifiConfiguration.getRecentFailureReason()
                    == WifiConfiguration.RECENT_FAILURE_AP_UNABLE_TO_HANDLE_NEW_STA) {
                return context.getString(R.string.wifi_ap_unable_to_handle_new_sta);
            }
        }
        return "";
    }

    static String getAutoConnectDescription(@NonNull Context context,
            @NonNull WifiEntry wifiEntry) {
        if (context == null || wifiEntry == null || !wifiEntry.canSetAutoJoinEnabled()) {
            return "";
        }

        return wifiEntry.isAutoJoinEnabled()
                ? "" : context.getString(R.string.auto_connect_disable);
    }

    static String getMeteredDescription(@NonNull Context context, @Nullable WifiEntry wifiEntry) {
        if (context == null || wifiEntry == null) {
            return "";
        }

        if (!wifiEntry.canSetMeteredChoice()
                && wifiEntry.getMeteredChoice() != WifiEntry.METERED_CHOICE_METERED) {
            return "";
        }

        if (wifiEntry.getMeteredChoice() == WifiEntry.METERED_CHOICE_METERED) {
            return context.getString(R.string.wifi_metered_label);
        } else if (wifiEntry.getMeteredChoice() == WifiEntry.METERED_CHOICE_UNMETERED) {
            return context.getString(R.string.wifi_unmetered_label);
        } else { // METERED_CHOICE_AUTO
            return wifiEntry.isMetered() ? context.getString(R.string.wifi_metered_label) : "";
        }
    }

    static String getSpeedDescription(@NonNull Context context, @NonNull WifiEntry wifiEntry) {
        if (context == null || wifiEntry == null) {
            return "";
        }

        @Speed int speed = wifiEntry.getSpeed();
        switch (speed) {
            case SPEED_VERY_FAST:
                return context.getString(R.string.speed_label_very_fast);
            case SPEED_FAST:
                return context.getString(R.string.speed_label_fast);
            case SPEED_MODERATE:
                return context.getString(R.string.speed_label_okay);
            case SPEED_SLOW:
                return context.getString(R.string.speed_label_slow);
            case SPEED_NONE:
            default:
                return "";
        }
    }

    static String getVerboseLoggingDescription(@NonNull WifiEntry wifiEntry) {
        if (!BaseWifiTracker.isVerboseLoggingEnabled() || wifiEntry == null) {
            return "";
        }

        final StringJoiner sj = new StringJoiner(" ");

        final String wifiInfoDescription = wifiEntry.getWifiInfoDescription();
        if (!TextUtils.isEmpty(wifiInfoDescription)) {
            sj.add(wifiInfoDescription);
        }

        final String scanResultsDescription = wifiEntry.getScanResultDescription();
        if (!TextUtils.isEmpty(scanResultsDescription)) {
            sj.add(scanResultsDescription);
        }

        final String networkSelectionDescription = wifiEntry.getNetworkSelectionDescription();
        if (!TextUtils.isEmpty(networkSelectionDescription)) {
            sj.add(networkSelectionDescription);
        }

        return sj.toString();
    }

    static String getNetworkSelectionDescription(WifiConfiguration wifiConfig) {
        if (wifiConfig == null) {
            return "";
        }

        StringBuilder description = new StringBuilder();
        NetworkSelectionStatus networkSelectionStatus = wifiConfig.getNetworkSelectionStatus();

        if (networkSelectionStatus.getNetworkSelectionStatus() != NETWORK_SELECTION_ENABLED) {
            description.append(" (" + networkSelectionStatus.getNetworkStatusString());
            if (networkSelectionStatus.getDisableTime() > 0) {
                long now = System.currentTimeMillis();
                long elapsedSeconds = (now - networkSelectionStatus.getDisableTime()) / 1000;
                description.append(" " + DateUtils.formatElapsedTime(elapsedSeconds));
            }
            description.append(")");
        }

        int maxNetworkSelectionDisableReason =
                NetworkSelectionStatus.getMaxNetworkSelectionDisableReason();
        for (int reason = 0; reason <= maxNetworkSelectionDisableReason; reason++) {
            int disableReasonCounter = networkSelectionStatus.getDisableReasonCounter(reason);
            if (disableReasonCounter == 0) {
                continue;
            }
            description.append(" ")
                    .append(NetworkSelectionStatus.getNetworkSelectionDisableReasonString(reason))
                    .append("=")
                    .append(disableReasonCounter);
        }
        return description.toString();
    }

    static String getCurrentNetworkCapabilitiesInformation(Context context,
            NetworkCapabilities networkCapabilities) {
        if (context == null || networkCapabilities == null) {
            return "";
        }

        if (networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_CAPTIVE_PORTAL)) {
            return context.getString(context.getResources()
                    .getIdentifier("network_available_sign_in", "string", "android"));
        }

        if (networkCapabilities.hasCapability(
                NetworkCapabilities.NET_CAPABILITY_PARTIAL_CONNECTIVITY)) {
            return context.getString(R.string.wifi_limited_connection);
        }

        if (!networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)) {
            if (networkCapabilities.isPrivateDnsBroken()) {
                return context.getString(R.string.private_dns_broken);
            }
            return context.getString(R.string.wifi_connected_no_internet);
        }
        return "";
    }

    static String getNetworkDetailedState(Context context, NetworkInfo networkInfo) {
        if (context == null || networkInfo == null) {
            return "";
        }
        DetailedState detailState = networkInfo.getDetailedState();
        if (detailState == null) {
            return "";
        }

        String[] wifiStatusArray = context.getResources()
                .getStringArray(R.array.wifi_status);
        int index = detailState.ordinal();
        return index >= wifiStatusArray.length ? "" : wifiStatusArray[index];
    }

    /**
     * Check if the SIM is present for target carrier Id.
     */
    static boolean isSimPresent(@NonNull Context context, int carrierId) {
        SubscriptionManager subscriptionManager =
                (SubscriptionManager) context.getSystemService(
                        Context.TELEPHONY_SUBSCRIPTION_SERVICE);
        if (subscriptionManager == null) return false;
        List<SubscriptionInfo> subInfoList = subscriptionManager.getActiveSubscriptionInfoList();
        if (subInfoList == null || subInfoList.isEmpty()) {
            return false;
        }
        return subInfoList.stream()
                .anyMatch(info -> info.getCarrierId() == carrierId);
    }

    /**
     * Get the SIM carrier name for target subscription Id.
     */
    static @Nullable String getCarrierNameForSubId(@NonNull Context context, int subId) {
        if (subId == SubscriptionManager.INVALID_SUBSCRIPTION_ID) {
            return null;
        }
        TelephonyManager telephonyManager =
                (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
        if (telephonyManager == null) return null;
        TelephonyManager specifiedTm = telephonyManager.createForSubscriptionId(subId);
        if (specifiedTm == null) {
            return null;
        }
        CharSequence name = specifiedTm.getSimCarrierIdName();
        if (name == null) {
            return null;
        }
        return name.toString();
    }

    static boolean isSimCredential(@NonNull WifiConfiguration config) {
        return config.enterpriseConfig != null
                && config.enterpriseConfig.isAuthenticationSimBased();
    }

    /**
     * Get the best match subscription Id for target WifiConfiguration.
     */
    static int getSubIdForConfig(@NonNull Context context, @NonNull WifiConfiguration config) {
        if (config.carrierId == TelephonyManager.UNKNOWN_CARRIER_ID) {
            return SubscriptionManager.INVALID_SUBSCRIPTION_ID;
        }
        SubscriptionManager subscriptionManager =
                (SubscriptionManager) context.getSystemService(
                        Context.TELEPHONY_SUBSCRIPTION_SERVICE);
        if (subscriptionManager == null) {
            return SubscriptionManager.INVALID_SUBSCRIPTION_ID;
        }
        List<SubscriptionInfo> subInfoList = subscriptionManager.getActiveSubscriptionInfoList();
        if (subInfoList == null || subInfoList.isEmpty()) {
            return SubscriptionManager.INVALID_SUBSCRIPTION_ID;
        }

        int matchSubId = SubscriptionManager.INVALID_SUBSCRIPTION_ID;
        int dataSubId = SubscriptionManager.getDefaultDataSubscriptionId();
        for (SubscriptionInfo subInfo : subInfoList) {
            if (subInfo.getCarrierId() == config.carrierId) {
                matchSubId = subInfo.getSubscriptionId();
                if (matchSubId == dataSubId) {
                    // Priority of Data sub is higher than non data sub.
                    break;
                }
            }
        }
        return matchSubId;
    }

    /**
     * Check if target subscription Id requires IMSI privacy protection.
     */
    static boolean isImsiPrivacyProtectionProvided(@NonNull Context context, int subId) {
        CarrierConfigManager carrierConfigManager =
                (CarrierConfigManager) context.getSystemService(Context.CARRIER_CONFIG_SERVICE);
        if (carrierConfigManager == null) {
            return false;
        }
        PersistableBundle bundle = carrierConfigManager.getConfigForSubId(subId);
        if (bundle == null) {
            return false;
        }
        return (bundle.getInt(CarrierConfigManager.IMSI_KEY_AVAILABILITY_INT)
                & TelephonyManager.KEY_TYPE_WLAN) != 0;
    }

    static CharSequence getImsiProtectionDescription(Context context,
            @Nullable WifiConfiguration wifiConfig) {
        if (context == null || wifiConfig == null || !isSimCredential(wifiConfig)) {
            return "";
        }
        int subId;
        if (wifiConfig.carrierId == TelephonyManager.UNKNOWN_CARRIER_ID) {
            // Config without carrierId use default data subscription.
            subId = SubscriptionManager.getDefaultSubscriptionId();
        } else {
            subId = getSubIdForConfig(context, wifiConfig);
        }
        if (subId == SubscriptionManager.INVALID_SUBSCRIPTION_ID
                || isImsiPrivacyProtectionProvided(context, subId)) {
            return "";
        }

        // IMSI protection is not provided, return warning message.
        return linkifyAnnotation(context, context.getText(R.string.imsi_protection_warning), "url",
                context.getString(R.string.help_url_imsi_protection));
    }

    /** Find the annotation of specified id in rawText and linkify it with helpUriString. */
    static CharSequence linkifyAnnotation(Context context, CharSequence rawText, String id,
            String helpUriString) {
        SpannableString spannableText = new SpannableString(rawText);
        Annotation[] annotations = spannableText.getSpans(0, spannableText.length(),
                Annotation.class);

        for (Annotation annotation : annotations) {
            if (TextUtils.equals(annotation.getValue(), id)) {
                SpannableStringBuilder builder = new SpannableStringBuilder(spannableText);
                ClickableSpan link = new ClickableSpan() {
                    @Override
                    public void onClick(View view) {
                        view.startActivityForResult(HelpUtils.getHelpIntent(context, helpUriString,
                                view.getClass().getName()), 0);
                    }
                };
                builder.setSpan(link, spannableText.getSpanStart(annotation),
                        spannableText.getSpanEnd(annotation), spannableText.getSpanFlags(link));
                return builder;
            }
        }
        return rawText;
    }
}