<?php
// WString.php
// Created: 2021-06-22
// Updated: 2024-01-04

namespace Index;

use Stringable;

/**
 * Provides various helper methods for multibyte strings.
 */
final class WString {
    /**
     * Default characters for ::trim, ::trimStart and ::trimEnd.
     *
     * @var string
     */
    public const TRIM_CHARS = "\0\t\n\v\f\r \u{85}\u{a0}\u{1680}\u{180e}\u{2000}\u{2001}\u{2002}\u{2003}\u{2004}\u{2005}\u{2006}\u{2007}\u{2008}\u{2009}\u{200a}\u{200b}\u{200c}\u{200d}\u{2028}\u{2029}\u{202f}\u{205f}\u{2060}\u{3000}\u{feff}";
    private const TRIM_CHARS_CHARSET = 'UTF-8';

    private const TRIM_START = 0x01;
    private const TRIM_END = 0x02;
    private const TRIM_ALL = self::TRIM_START | self::TRIM_END;

    /**
     * Checks if a multibyte string starts with a given substring.
     *
     * @param Stringable|string $haystack String to search in.
     * @param Stringable|string $needle Sustring to search for in the haystack.
     * @param ?string $encoding String character encoding. null for mb_internal_encoding value.
     * @return bool true if haystack begins with needle, false otherwise.
     */
    public static function startsWith(Stringable|string $haystack, Stringable|string $needle, ?string $encoding = null): bool {
        return mb_strpos((string)$haystack, (string)$needle, encoding: $encoding) === 0;
    }

    /**
     * Checks if a multibyte string ends with a given substring.
     *
     * @param Stringable|string $haystack String to search in.
     * @param Stringable|string $needle Sustring to search for in the haystack.
     * @param ?string $encoding String character encoding. null for mb_internal_encoding value.
     * @return bool true if haystack ends with needle, false otherwise.
     */
    public static function endsWith(Stringable|string $haystack, Stringable|string $needle, ?string $encoding = null): bool {
        $haystack = (string)$haystack;
        $haystackLength = mb_strlen($haystack, $encoding);

        $needle = (string)$needle;
        $needleLength = mb_strlen($needle, $encoding);

        return mb_substr($haystack, -$needleLength, encoding: $encoding) === $needle;
    }

    private static function trimInternal(Stringable|string $string, string $chars, ?string $encoding, ?string $charsEncoding, int $flags): string {
        $encoding = $encoding === null ? mb_internal_encoding() : mb_preferred_mime_name($encoding);
        $charsEncoding = $charsEncoding === null ? self::TRIM_CHARS_CHARSET : mb_preferred_mime_name($charsEncoding);

        // this fucks, i hate character sets
        if($encoding !== $charsEncoding) {
            $questionMarkCharsEnc = mb_convert_encoding('?', $charsEncoding, 'utf-8');
            $questionMarkStrEnc = mb_convert_encoding('?', $encoding, 'utf-8');
            $hasQuestionMark = mb_strpos($chars, $questionMarkCharsEnc, encoding: $charsEncoding) !== false;
            $chars = mb_convert_encoding($chars, $encoding, $charsEncoding);

            if(!$hasQuestionMark) {
                $charsSplit = mb_str_split($chars, encoding: $encoding);
                $chars = [];
                foreach($charsSplit as $char) {
                    if(in_array($char, $chars))
                        continue;
                    $chars[] = $char;
                }

                $chars = implode($chars);
            }
        }

        $string = (string)$string;
        $split = mb_str_split($string, encoding: $encoding);
        $length = mb_strlen($string, $encoding);

        $start = 0;
        $end = $length - 1;

        if($flags & self::TRIM_START)
            for(; $start < $length; ++$start)
                if(mb_strpos($chars, $split[$start], encoding: $encoding) === false)
                    break;

        if($flags & self::TRIM_END)
            for(; $end > 0; --$end)
                if(mb_strpos($chars, $split[$end], encoding: $encoding) === false)
                    break;

        return mb_substr($string, $start, $end - $start + 1, $encoding);
    }

    /**
     * Strip whitespace (or other characters) from the start and end of a multibyte string.
     *
     * @param Stringable|string $string Input string.
     * @param string $chars Characters to strip. List all characters you want. .. operator from trim is not supported.
     * @param ?string $encoding String character encoding. null for mb_internal_encoding value.
     * @return string Trimmed string.
     */
    public static function trim(Stringable|string $string, string $chars = self::TRIM_CHARS, ?string $encoding = null, ?string $charsEncoding = null): string {
        return self::trimInternal($string, $chars, $encoding, $charsEncoding, self::TRIM_ALL);
    }

    /**
     * Strip whitespace (or other characters) from the start of a multibyte string.
     *
     * @param Stringable|string $string Input string.
     * @param string $chars Characters to strip. List all characters you want. .. operator from ltrim is not supported.
     * @param ?string $encoding String character encoding. null for mb_internal_encoding value.
     * @return string Trimmed string.
     */
    public static function trimStart(Stringable|string $string, string $chars = self::TRIM_CHARS, ?string $encoding = null, ?string $charsEncoding = null): string {
        return self::trimInternal($string, $chars, $encoding, $charsEncoding, self::TRIM_START);
    }

    /**
     * Strip whitespace (or other characters) from the end of a multibyte string.
     *
     * @param Stringable|string $string Input string.
     * @param string $chars Characters to strip. List all characters you want. .. operator from rtrim is not supported.
     * @param ?string $encoding String character encoding. null for mb_internal_encoding value.
     * @return string Trimmed string.
     */
    public static function trimEnd(Stringable|string $string, string $chars = self::TRIM_CHARS, ?string $encoding = null, ?string $charsEncoding = null): string {
        return self::trimInternal($string, $chars, $encoding, $charsEncoding, self::TRIM_END);
    }

    /**
     * Reverses a multibyte string.
     *
     * @param Stringable|string $string String to reverse.
     * @param ?string $encoding String character encoding. null for mb_internal_encoding value.
     * @return string Reversed string.
     */
    public static function reverse(Stringable|string $string, ?string $encoding = null): string {
        return implode(array_reverse(mb_str_split((string)$string, encoding: $encoding)));
    }

    /**
     * Counts unique characters in a string.
     *
     * @param Stringable|string $string String to count unique characters of.
     * @param ?string $encoding String character encoding. null for mb_internal_encoding value.
     * @return int Unique character count.
     */
    public static function countUnique(Stringable|string $string, ?string $encoding = null): int {
        $string = mb_str_split((string)$string, encoding: $encoding);
        $chars = [];

        foreach($string as $char)
            if(!in_array($char, $chars, true))
                $chars[] = $char;

        return count($chars);
    }

    /**
     * Check if a multibyte string is null or whitespace.
     *
     * @param Stringable|string|null $string String to check for whitespace.
     * @param ?string $encoding String character encoding. null for mb_internal_encoding value.
     * @return bool true if the string is whitespace, false if not.
     */
    public static function nullOrWhitespace(Stringable|string|null $string, ?string $encoding = null): bool {
        return $string === null || self::trim((string)$string, encoding: $encoding) === '';
    }
}