/*
 * Copyright 2013-present the original author or authors.
 *
 * 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 com.alibaba.cloud.commons.lang;

import org.jspecify.annotations.Nullable;

/**
 * StringUtils. copy from apache common-lang3.
 *
 * @author <a href="mailto:chenxilzx1@gmail.com">theonefx</a>
 */
public final class StringUtils {

	/**
	 * The empty String {@code ""}.
	 *
	 * @since 2.0
	 */
	public static final String EMPTY = "";

	/**
	 * Represents a failed index search.
	 * @since 2.1
	 */
	public static final int INDEX_NOT_FOUND = -1;

	private StringUtils() {
	}

	/**
	 * <p>
	 * Checks if a CharSequence is empty ("") or null.
	 * </p>
	 *
	 * <pre>
	 * StringUtils.isEmpty(null)      = true
	 * StringUtils.isEmpty("")        = true
	 * StringUtils.isEmpty(" ")       = false
	 * StringUtils.isEmpty("bob")     = false
	 * StringUtils.isEmpty("  bob  ") = false
	 * </pre>
	 *
	 * <p>
	 * NOTE: This method changed in Lang version 2.0. It no longer trims the CharSequence.
	 * That functionality is available in isBlank().
	 * </p>
	 * @param cs the CharSequence to check, may be null
	 * @return {@code true} if the CharSequence is empty or null
	 * @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)
	 */
	public static boolean isEmpty(final @Nullable CharSequence cs) {
		return cs == null || cs.length() == 0;
	}

	/**
	 * <p>
	 * Checks if a CharSequence is not empty ("") and not null.
	 * </p>
	 *
	 * <pre>
	 * StringUtils.isNotEmpty(null)      = false
	 * StringUtils.isNotEmpty("")        = false
	 * StringUtils.isNotEmpty(" ")       = true
	 * StringUtils.isNotEmpty("bob")     = true
	 * StringUtils.isNotEmpty("  bob  ") = true
	 * </pre>
	 * @param cs the CharSequence to check, may be null
	 * @return {@code true} if the CharSequence is not empty and not null
	 * @since 3.0 Changed signature from isNotEmpty(String) to isNotEmpty(CharSequence)
	 */
	public static boolean isNotEmpty(final @Nullable CharSequence cs) {
		return !isEmpty(cs);
	}

	/**
	 * <p>
	 * Checks if a CharSequence is whitespace, empty ("") or null.
	 * </p>
	 *
	 * <pre>
	 * StringUtils.isBlank(null)      = true
	 * StringUtils.isBlank("")        = true
	 * StringUtils.isBlank(" ")       = true
	 * StringUtils.isBlank("bob")     = false
	 * StringUtils.isBlank("  bob  ") = false
	 * </pre>
	 * @param cs the CharSequence to check, may be null
	 * @return {@code true} if the CharSequence is null, empty or whitespace
	 */
	public static boolean isBlank(final CharSequence cs) {
		if (cs == null || cs.length() == 0) {
			return true;
		}
		int strLen = cs.length();
		for (int i = 0; i < strLen; i++) {
			if (!Character.isWhitespace(cs.charAt(i))) {
				return false;
			}
		}
		return true;
	}

	/**
	 * <p>
	 * Checks if a CharSequence is not empty (""), not null and not whitespace only.
	 * </p>
	 *
	 * <p>
	 * Whitespace is defined by {@link Character#isWhitespace(char)}.
	 * </p>
	 *
	 * <pre>
	 * StringUtils.isNotBlank(null)      = false
	 * StringUtils.isNotBlank("")        = false
	 * StringUtils.isNotBlank(" ")       = false
	 * StringUtils.isNotBlank("bob")     = true
	 * StringUtils.isNotBlank("  bob  ") = true
	 * </pre>
	 * @param cs the CharSequence to check, may be null
	 * @return {@code true} if the CharSequence is not empty and not null and not
	 * whitespace only
	 * @since 2.0
	 * @since 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence)
	 */
	public static boolean isNotBlank(final CharSequence cs) {
		return !isBlank(cs);
	}

	// Trim
	// -----------------------------------------------------------------------

	/**
	 * <p>
	 * Removes control characters (char &lt;= 32) from both ends of this String, handling
	 * {@code null} by returning {@code null}.
	 * </p>
	 *
	 * <p>
	 * The String is trimmed using {@link String#trim()}. Trim removes start and end
	 * characters &lt;= 32.
	 * </p>
	 *
	 * <pre>
	 * StringUtils.trim(null)          = null
	 * StringUtils.trim("")            = ""
	 * StringUtils.trim("     ")       = ""
	 * StringUtils.trim("abc")         = "abc"
	 * StringUtils.trim("    abc    ") = "abc"
	 * </pre>
	 * @param str the String to be trimmed, may be null
	 * @return the trimmed string, {@code null} if null String input
	 */
	public static @Nullable String trim(final String str) {
		return str == null ? null : str.trim();
	}

	// Equals
	// -----------------------------------------------------------------------

	/**
	 * <p>
	 * Compares two CharSequences, returning {@code true} if they represent equal
	 * sequences of characters.
	 * </p>
	 *
	 * <p>
	 * {@code null}s are handled without exceptions. Two {@code null} references are
	 * considered to be equal. The comparison is case sensitive.
	 * </p>
	 *
	 * <pre>
	 * StringUtils.equals(null, null)   = true
	 * StringUtils.equals(null, "abc")  = false
	 * StringUtils.equals("abc", null)  = false
	 * StringUtils.equals("abc", "abc") = true
	 * StringUtils.equals("abc", "ABC") = false
	 * </pre>
	 * @param cs1 the first CharSequence, may be {@code null}
	 * @param cs2 the second CharSequence, may be {@code null}
	 * @return {@code true} if the CharSequences are equal (case-sensitive), or both
	 * {@code null}
	 * @see Object#equals(Object)
	 */
	public static boolean equals(final CharSequence cs1, final CharSequence cs2) {
		if (cs1 == cs2) {
			return true;
		}
		if (cs1 == null || cs2 == null) {
			return false;
		}
		if (cs1 instanceof String && cs2 instanceof String) {
			return cs1.equals(cs2);
		}
		return StringUtils.regionMatches(cs1, false, 0, cs2, 0,
				Math.max(cs1.length(), cs2.length()));
	}

	/**
	 * Green implementation of regionMatches.
	 * @param cs the {@code CharSequence} to be processed
	 * @param ignoreCase whether or not to be case insensitive
	 * @param thisStart the index to start on the {@code cs} CharSequence
	 * @param substring the {@code CharSequence} to be looked for
	 * @param start the index to start on the {@code substring} CharSequence
	 * @param length character length of the region
	 * @return whether the region matched
	 */
	public static boolean regionMatches(final CharSequence cs, final boolean ignoreCase,
			final int thisStart, final CharSequence substring, final int start,
			final int length) {
		if (cs instanceof String && substring instanceof String) {
			return ((String) cs).regionMatches(ignoreCase, thisStart, (String) substring,
					start, length);
		}
		int index1 = thisStart;
		int index2 = start;
		int tmpLen = length;

		while (tmpLen-- > 0) {
			final char c1 = cs.charAt(index1++);
			final char c2 = substring.charAt(index2++);

			if (c1 == c2) {
				continue;
			}

			if (!ignoreCase) {
				return false;
			}

			// The same check as in String.regionMatches():
			if (Character.toUpperCase(c1) != Character.toUpperCase(c2)
					&& Character.toLowerCase(c1) != Character.toLowerCase(c2)) {
				return false;
			}
		}

		return true;
	}

	/**
	 * <p>
	 * Gets the substring after the first occurrence of a separator. The separator is not
	 * returned.
	 * </p>
	 *
	 * <p>
	 * A <code>null</code> string input will return <code>null</code>. An empty ("")
	 * string input will return the empty string. A <code>null</code> separator will
	 * return the empty string if the input string is not <code>null</code>.
	 * </p>
	 *
	 * <p>
	 * If nothing is found, the empty string is returned.
	 * </p>
	 *
	 * <pre>
	 * StringUtils.substringAfter(null, *)      = null
	 * StringUtils.substringAfter("", *)        = ""
	 * StringUtils.substringAfter(*, null)      = ""
	 * StringUtils.substringAfter("abc", "a")   = "bc"
	 * StringUtils.substringAfter("abcba", "b") = "cba"
	 * StringUtils.substringAfter("abc", "c")   = ""
	 * StringUtils.substringAfter("abc", "d")   = ""
	 * StringUtils.substringAfter("abc", "")    = "abc"
	 * </pre>
	 * @param str the String to get a substring from, may be null
	 * @param separator the String to search for, may be null
	 * @return the substring after the first occurrence of the separator,
	 * <code>null</code> if null String input
	 * @since 2.0
	 */
	public static String substringAfter(String str, String separator) {
		if (isEmpty(str)) {
			return str;
		}
		if (separator == null) {
			return EMPTY;
		}
		int pos = str.indexOf(separator);
		if (pos == INDEX_NOT_FOUND) {
			return EMPTY;
		}
		return str.substring(pos + separator.length());
	}

	// Substring between
	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Gets the String that is nested in between two instances of the same String.
	 * </p>
	 *
	 * <p>
	 * A <code>null</code> input String returns <code>null</code>. A <code>null</code> tag
	 * returns <code>null</code>.
	 * </p>
	 *
	 * <pre>
	 * StringUtils.substringBetween(null, *)            = null
	 * StringUtils.substringBetween("", "")             = ""
	 * StringUtils.substringBetween("", "tag")          = null
	 * StringUtils.substringBetween("tagabctag", null)  = null
	 * StringUtils.substringBetween("tagabctag", "")    = ""
	 * StringUtils.substringBetween("tagabctag", "tag") = "abc"
	 * </pre>
	 * @param str the String containing the substring, may be null
	 * @param tag the String before and after the substring, may be null
	 * @return the substring, <code>null</code> if no match
	 * @since 2.0
	 */
	public static @Nullable String substringBetween(String str, String tag) {
		return substringBetween(str, tag, tag);
	}

	/**
	 * <p>
	 * Gets the String that is nested in between two Strings. Only the first match is
	 * returned.
	 * </p>
	 *
	 * <p>
	 * A <code>null</code> input String returns <code>null</code>. A <code>null</code>
	 * open/close returns <code>null</code> (no match). An empty ("") open and close
	 * returns an empty string.
	 * </p>
	 *
	 * <pre>
	 * StringUtils.substringBetween("wx[b]yz", "[", "]") = "b"
	 * StringUtils.substringBetween(null, *, *)          = null
	 * StringUtils.substringBetween(*, null, *)          = null
	 * StringUtils.substringBetween(*, *, null)          = null
	 * StringUtils.substringBetween("", "", "")          = ""
	 * StringUtils.substringBetween("", "", "]")         = null
	 * StringUtils.substringBetween("", "[", "]")        = null
	 * StringUtils.substringBetween("yabcz", "", "")     = ""
	 * StringUtils.substringBetween("yabcz", "y", "z")   = "abc"
	 * StringUtils.substringBetween("yabczyabcz", "y", "z")   = "abc"
	 * </pre>
	 * @param str the String containing the substring, may be null
	 * @param open the String before the substring, may be null
	 * @param close the String after the substring, may be null
	 * @return the substring, <code>null</code> if no match
	 * @since 2.0
	 */
	public static @Nullable String substringBetween(String str, String open, String close) {
		if (str == null || open == null || close == null) {
			return null;
		}
		int start = str.indexOf(open);
		if (start != INDEX_NOT_FOUND) {
			int end = str.indexOf(close, start + open.length());
			if (end != INDEX_NOT_FOUND) {
				return str.substring(start + open.length(), end);
			}
		}
		return null;
	}

}
