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/*
 * Copyright 2017 VMware, Inc.
 *
 * 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
 *
 * https://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 io.micrometer.common.util;

import io.micrometer.common.lang.Nullable;

/**
 * Utilities for {@link String}.
 *
 * @author Johnny Lim
 */
public final class StringUtils {

    /**
     * Check if the String is null or has only whitespaces.
     *
     * Modified from {@code org.apache.commons.lang.StringUtils#isBlank(String)}.
     * @param string String to check
     * @return {@code true} if the String is null or has only whitespaces
     */
    public static boolean isBlank(@Nullable String string) {
        if (isEmpty(string)) {
            return true;
        }
        for (int i = 0; i < string.length(); i++) {
            if (!Character.isWhitespace(string.charAt(i))) {
                return false;
            }
        }
        return true;
    }

    /**
     * Check if the String has any non-whitespace character.
     * @param string String to check
     * @return {@code true} if the String has any non-whitespace character
     */
    public static boolean isNotBlank(@Nullable String string) {
        return !isBlank(string);
    }

    /**
     * Check if the String is null or empty.
     * @param string String to check
     * @return {@code true} if the String is null or empty
     */
    public static boolean isEmpty(@Nullable String string) {
        return string == null || string.isEmpty();
    }

    /**
     * Check if the String has any character.
     * @param string String to check
     * @return {@code true} if the String has any character
     * @since 1.1.0
     */
    public static boolean isNotEmpty(@Nullable String string) {
        return !isEmpty(string);
    }

    /**
     * Truncate the String to the max length.
     * @param string String to truncate
     * @param maxLength max length
     * @return truncated String
     */
    public static String truncate(String string, int maxLength) {
        if (string.length() > maxLength) {
            return string.substring(0, maxLength);
        }
        return string;
    }

    /**
     * Truncate the String to the max length and append string to indicate if truncation
     * was applied
     * @param string String to truncate
     * @param maxLength max length, which includes the length required for
     * {@code truncationIndicator}
     * @param truncationIndicator A string that is appended if {@code string} is truncated
     * @return truncated String
     */
    public static String truncate(String string, int maxLength, String truncationIndicator) {
        if (truncationIndicator.length() >= maxLength) {
            throw new IllegalArgumentException("maxLength must be greater than length of truncationIndicator");
        }
        if (string.length() > maxLength) {
            int remainingLength = maxLength - truncationIndicator.length();
            return string.substring(0, remainingLength) + truncationIndicator;
        }

        return string;
    }

    private StringUtils() {
    }

}