/*
 * Copyright (C) 2016 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.net.wifi.aware;

import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.wifi.V1_0.Constants;

/**
 * Provides utilities for the Wifi Aware manager/service.
 *
 * @hide
 */
public class WifiAwareUtils {
    /**
     * Per spec: The Service Name is a UTF-8 encoded string from 1 to 255 bytes in length. The
     * only acceptable single-byte UTF-8 symbols for a Service Name are alphanumeric values (A-Z,
     * a-z, 0-9), the hyphen ('-'), the underscore ('_') and the period ('.'). All valid multi-byte
     * UTF-8 characters are acceptable in a Service Name.
     */
    public static void validateServiceName(byte[] serviceNameData) throws IllegalArgumentException {
        if (serviceNameData == null) {
            throw new IllegalArgumentException("Invalid service name - null");
        }

        if (serviceNameData.length < 1 || serviceNameData.length > 255) {
            throw new IllegalArgumentException("Invalid service name length - must be between "
                    + "1 and 255 bytes (UTF-8 encoding)");
        }

        int index = 0;
        while (index < serviceNameData.length) {
            byte b = serviceNameData[index];
            if ((b & 0x80) == 0x00) {
                if (!((b >= '0' && b <= '9') || (b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z')
                        || b == '-' || b == '.' || b == '_')) {
                    throw new IllegalArgumentException("Invalid service name - illegal characters,"
                            + " allowed = (0-9, a-z,A-Z, -, _, .)");
                }
            }
            ++index;
        }
    }

    /**
     * Validates that the passphrase is a non-null string of the right size (per the HAL min/max
     * length parameters).
     *
     * @param passphrase Passphrase to test
     * @return true if passphrase is valid, false if not
     */
    public static boolean validatePassphrase(String passphrase) {
        if (passphrase == null
                || passphrase.length() < Constants.NanParamSizeLimits.MIN_PASSPHRASE_LENGTH
                || passphrase.length() > Constants.NanParamSizeLimits.MAX_PASSPHRASE_LENGTH) {
            return false;
        }

        return true;
    }

    /**
     * Validates that the PMK is a non-null byte array of the right size (32 bytes per spec).
     *
     * @param pmk PMK to test
     * @return true if PMK is valid, false if not
     */
    public static boolean validatePmk(byte[] pmk) {
        if (pmk == null || pmk.length != 32) {
            return false;
        }

        return true;
    }

    /**
     * Returns true if the App version is older than minVersion.
     */
    public static boolean isLegacyVersion(Context context, int minVersion) {
        try {
            if (context.getPackageManager().getApplicationInfo(context.getOpPackageName(), 0)
                    .targetSdkVersion < minVersion) {
                return true;
            }
        } catch (PackageManager.NameNotFoundException e) {
            // In case of exception, assume known app (more strict checking)
            // Note: This case will never happen since checkPackage is
            // called to verify valididity before checking App's version.
        }
        return false;
    }
}