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/*
 * 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 io.github.honhimw.ms.support;

/**
 * @author hon_him
 * @since 2024-01-08
 */

public class StringUtils {

    public static boolean equal(final CharSequence cs1, final CharSequence cs2) {
        if (cs1 == cs2) {
            return true;
        }
        if (cs1 == null || cs2 == null) {
            return false;
        }
        if (cs1.length() != cs2.length()) {
            return false;
        }
        if (cs1 instanceof String && cs2 instanceof String) {
            return cs1.equals(cs2);
        }
        // Step-wise comparison
        final int length = cs1.length();
        for (int i = 0; i < length; i++) {
            if (cs1.charAt(i) != cs2.charAt(i)) {
                return false;
            }
        }
        return true;
    }

    public static int length(final CharSequence cs) {
        return cs == null ? 0 : cs.length();
    }

    public static boolean isBlank(final CharSequence cs) {
        final int strLen = length(cs);
        if (strLen == 0) {
            return true;
        }
        for (int i = 0; i < strLen; i++) {
            if (!Character.isWhitespace(cs.charAt(i))) {
                return false;
            }
        }
        return true;
    }

    public static boolean isNotBlank(final CharSequence cs) {
        return !isBlank(cs);
    }

    public static boolean startsWith(final CharSequence str, final CharSequence prefix) {
        return startsWith(str, prefix, false);
    }

    public static boolean startsWithIgnoreCase(final CharSequence str, final CharSequence prefix) {
        return startsWith(str, prefix, true);
    }

    public static String removeStartIgnoreCase(final String str, final String remove) {
        if (str != null && startsWithIgnoreCase(str, remove)) {
            return str.substring(length(remove));
        }
        return str;
    }

    public static boolean isEmpty(final CharSequence cs) {
        return cs == null || cs.length() == 0;
    }

    public static boolean isNotEmpty(final CharSequence cs) {
        return !isEmpty(cs);
    }

    public static String defaultIfBlank(final String cs, String _default) {
        return isNotBlank(cs) ? cs : _default;
    }

    public static String defaultIfEmpty(final String cs, String _default) {
        return isNotEmpty(cs) ? cs : _default;
    }

    public static String removeStart(final String str, final String remove) {
        if (isEmpty(str) || isEmpty(remove)) {
            return str;
        }
        if (str.startsWith(remove)) {
            return str.substring(remove.length());
        }
        return str;
    }

    public static boolean startsWith(final CharSequence str, final CharSequence prefix, final boolean ignoreCase) {
        if (str == null || prefix == null) {
            return str == prefix;
        }
        // Get length once instead of twice in the unlikely case that it changes.
        final int preLen = prefix.length();
        if (preLen > str.length()) {
            return false;
        }
        return regionMatches(str, ignoreCase, 0, prefix, 0, preLen);
    }

    public static boolean containsIgnoreCase(final CharSequence str, final CharSequence searchStr) {
        if (str == null || searchStr == null) {
            return false;
        }
        final int len = searchStr.length();
        final int max = str.length() - len;
        for (int i = 0; i <= max; i++) {
            if (regionMatches(str, true, i, searchStr, 0, len)) {
                return true;
            }
        }
        return false;
    }

    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;

        // Extract these first so we detect NPEs the same as the java.lang.String version
        final int srcLen = cs.length() - thisStart;
        final int otherLen = substring.length() - start;

        // Check for invalid parameters
        if (thisStart < 0 || start < 0 || length < 0) {
            return false;
        }

        // Check that the regions are long enough
        if (srcLen < length || otherLen < length) {
            return false;
        }

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

            if (c1 == c2) {
                continue;
            }

            if (!ignoreCase) {
                return false;
            }

            // The real same check as in String.regionMatches():
            final char u1 = Character.toUpperCase(c1);
            final char u2 = Character.toUpperCase(c2);
            if (u1 != u2 && Character.toLowerCase(u1) != Character.toLowerCase(u2)) {
                return false;
            }
        }

        return true;
    }

}