/*
 * 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.server.wifi.util;

import android.annotation.Nullable;

import java.util.Collection;
import java.util.Objects;

/**
 * Copied over from frameworks/base/core/java/com/android/internal/util/ArrayUtils.java
 */
public class ArrayUtils {
    private ArrayUtils() { /* cannot be instantiated */ }

    /**
     * Checks if the beginnings of two byte arrays are equal.
     *
     * @param array1 the first byte array
     * @param array2 the second byte array
     * @param length the number of bytes to check
     * @return true if they're equal, false otherwise
     */
    public static boolean equals(byte[] array1, byte[] array2, int length) {
        if (length < 0) {
            throw new IllegalArgumentException();
        }

        if (array1 == array2) {
            return true;
        }
        if (array1 == null || array2 == null || array1.length < length || array2.length < length) {
            return false;
        }
        for (int i = 0; i < length; i++) {
            if (array1[i] != array2[i]) {
                return false;
            }
        }
        return true;
    }

    /**
     * Checks if given array is null or has zero elements.
     */
    public static boolean isEmpty(@Nullable Collection<?> array) {
        return array == null || array.isEmpty();
    }

    /**
     * Checks if given array is null or has zero elements.
     */
    public static <T> boolean isEmpty(@Nullable T[] array) {
        return array == null || array.length == 0;
    }

    /**
     * Checks if given array is null or has zero elements.
     */
    public static boolean isEmpty(@Nullable int[] array) {
        return array == null || array.length == 0;
    }

    /**
     * Checks if given array is null or has zero elements.
     */
    public static boolean isEmpty(@Nullable long[] array) {
        return array == null || array.length == 0;
    }

    /**
     * Checks if given array is null or has zero elements.
     */
    public static boolean isEmpty(@Nullable byte[] array) {
        return array == null || array.length == 0;
    }

    /**
     * Checks if given array is null or has zero elements.
     */
    public static boolean isEmpty(@Nullable boolean[] array) {
        return array == null || array.length == 0;
    }

    /**
     * Length of the given array or 0 if it's null.
     */
    public static int size(@Nullable Object[] array) {
        return array == null ? 0 : array.length;
    }

    /**
     * Length of the given collection or 0 if it's null.
     */
    public static int size(@Nullable Collection<?> collection) {
        return collection == null ? 0 : collection.size();
    }

    /**
     * Checks that value is present as at least one of the elements of the array.
     *
     * @param array the array to check in
     * @param value the value to check for
     * @return true if the value is present in the array
     */
    public static <T> boolean contains(@Nullable T[] array, T value) {
        return indexOf(array, value) != -1;
    }

    /**
     * Checks that value is present as at least one of the elements of the array.
     *
     * @param array the array to check in
     * @param value the value to check for
     * @return true if the value is present in the array
     */
    public static boolean contains(@Nullable int[] array, int value) {
        if (array == null) return false;
        for (int element : array) {
            if (element == value) {
                return true;
            }
        }
        return false;
    }

    /**
     * Checks that value is present as at least one of the elements of the array.
     *
     * @param array the array to check in
     * @param value the value to check for
     * @return true if the value is present in the array
     */
    public static boolean contains(@Nullable long[] array, long value) {
        if (array == null) return false;
        for (long element : array) {
            if (element == value) {
                return true;
            }
        }
        return false;
    }

    /**
     * Checks that value is present as at least one of the elements of the array.
     *
     * @param array the array to check in
     * @param value the value to check for
     * @return true if the value is present in the array
     */
    public static boolean contains(@Nullable char[] array, char value) {
        if (array == null) return false;
        for (char element : array) {
            if (element == value) {
                return true;
            }
        }
        return false;
    }

    /**
     * Return first index of {@code value} in {@code array}, or {@code -1} if
     * not found.
     */
    public static <T> int indexOf(@Nullable T[] array, T value) {
        if (array == null) return -1;
        for (int i = 0; i < array.length; i++) {
            if (Objects.equals(array[i], value)) return i;
        }
        return -1;
    }
}