<?php
// +----------------------------------------------------------------------
// | YwxApp [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2026-2036 http://ywxapp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Author: ywxapp<admin@ywxapp.cn>
// +----------------------------------------------------------------------

declare(strict_types=1);

namespace addon\haonav\library;

/**
 * 轻量拼音工具（零依赖）
 *
 * - 首字母：基于 GBK 编码区间推导（覆盖 GB2312 常用汉字），如「淘宝网」-> tbw
 * - 全拼：若安装了 overtrue/pinyin 则自动启用；未安装时降级为仅首字母
 * - keywordsOf() 产出「首字母 + 全拼」搜索串，存入 links.pinyin 供 LIKE 检索
 */
class Pinyin
{
    /**
     * GBK 双字节码位 -> 拼音首字母 区间表（GB2312 一级/二级汉字按拼音排序的特性）
     * 每项：[起始码位, 结束码位, 字母]
     */
    protected const RANGES = [
        [0xB0A1, 0xB0C4, 'a'],
        [0xB0C5, 0xB2C0, 'b'],
        [0xB2C1, 0xB4ED, 'c'],
        [0xB4EE, 0xB6E9, 'd'],
        [0xB6EA, 0xB7A1, 'e'],
        [0xB7A2, 0xB8C0, 'f'],
        [0xB8C1, 0xB9FD, 'g'],
        [0xB9FE, 0xBBF6, 'h'],
        [0xBBF7, 0xBFA5, 'j'],
        [0xBFA6, 0xC0AB, 'k'],
        [0xC0AC, 0xC2E7, 'l'],
        [0xC2E8, 0xC4C2, 'm'],
        [0xC4C3, 0xC5B5, 'n'],
        [0xC5B6, 0xC5BD, 'o'],
        [0xC5BE, 0xC6D9, 'p'],
        [0xC6DA, 0xC8BA, 'q'],
        [0xC8BB, 0xC8F5, 'r'],
        [0xC8F6, 0xCBF9, 's'],
        [0xCBFA, 0xCDD9, 't'],
        [0xCDDA, 0xCEF3, 'w'],
        [0xCEF4, 0xD1B8, 'x'],
        [0xD1B9, 0xD4D0, 'y'],
        [0xD4D1, 0xD7F9, 'z'],
    ];

    /**
     * 取单字符的拼音首字母；ASCII 字母数字原样小写返回，非汉字返回空串
     */
    public static function firstLetter(string $char): string
    {
        if ($char === '') {
            return '';
        }
        if (preg_match('/^[a-zA-Z0-9]$/', $char)) {
            return strtolower($char);
        }
        $gbk = @iconv('UTF-8', 'GBK//IGNORE', $char);
        if ($gbk === false || strlen($gbk) < 2) {
            return '';
        }
        $code = ord($gbk[0]) * 256 + ord($gbk[1]);
        foreach (self::RANGES as [$min, $max, $letter]) {
            if ($code >= $min && $code <= $max) {
                return $letter;
            }
        }
        return '';
    }

    /**
     * 整串首字母：如「淘宝网」-> "tbw"，「哔哩哔哩B站」-> "blblbz"
     */
    public static function initials(string $str): string
    {
        $out = '';
        foreach (preg_split('//u', $str, -1, PREG_SPLIT_NO_EMPTY) ?: [] as $ch) {
            $out .= self::firstLetter($ch);
        }
        return $out;
    }

    /**
     * 全拼（依赖 overtrue/pinyin，未安装返回空串）
     */
    public static function full(string $str): string
    {
        if (!class_exists(\Overtrue\Pinyin\Pinyin::class)) {
            return '';
        }
        try {
            // v5 静态 API
            if (method_exists(\Overtrue\Pinyin\Pinyin::class, 'sentence')) {
                $r = \Overtrue\Pinyin\Pinyin::sentence($str);
                $s = is_object($r) && method_exists($r, 'join') ? $r->join('') : (string)$r;
                return preg_replace('/[^a-z0-9]/', '', strtolower($s)) ?? '';
            }
            // v4 实例 API
            $py = new \Overtrue\Pinyin\Pinyin();
            return preg_replace('/[^a-z0-9]/', '', strtolower(implode('', $py->convert($str)))) ?? '';
        } catch (\Throwable $e) {
            return '';
        }
    }

    /**
     * 生成搜索串：「首字母 全拼」（全拼可能为空），限长 250
     */
    public static function keywordsOf(string $str): string
    {
        $initials = self::initials($str);
        $full     = self::full($str);
        $out      = trim($initials . ($full !== '' && $full !== $initials ? ' ' . $full : ''));
        return mb_substr($out, 0, 250);
    }
}