package com.baiyue.lastleg.service;

import net.sourceforge.pinyin4j.PinyinHelper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;

import java.time.Instant;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.Locale;

/** Allocates suffix-free document numbers across all service instances. */
@Component
public class CompactBusinessNumberService {
    private static final ZoneId ZONE = ZoneId.of("Asia/Shanghai");
    private static final DateTimeFormatter FORMAT = DateTimeFormatter.ofPattern("yyMMddHHmmss", Locale.ROOT).withZone(ZONE);
    private final JdbcTemplate jdbc;
    private final ReturnOrderReferenceResolver customers;

    public CompactBusinessNumberService(JdbcTemplate jdbc, ReturnOrderReferenceResolver customers) {
        this.jdbc = jdbc;
        this.customers = customers;
    }

    @Transactional
    public String next(String prefix, String customerId) {
        return allocate(prefix, initials(customers.customerName(customerId)), Instant.now());
    }

    String allocate(String prefix, String initials, Instant now) {
        String key = prefix + "-" + initials;
        long seconds = now.getEpochSecond();
        // The row lock serializes identical prefixes/initials even across customers and JVMs.
        jdbc.update("INSERT INTO ll_compact_number_clock(number_key,last_second) VALUES(?,LAST_INSERT_ID(?)) "
            + "ON DUPLICATE KEY UPDATE last_second=LAST_INSERT_ID(GREATEST(last_second+1,?))", key, seconds, seconds);
        Long allocated = jdbc.queryForObject("SELECT LAST_INSERT_ID()", Long.class);
        if (allocated == null || allocated < seconds) throw new IllegalStateException("业务编号生成失败");
        return key + "-" + FORMAT.format(Instant.ofEpochSecond(allocated));
    }

    static String initials(String name) {
        if (name == null || name.isBlank()) return "KH";
        StringBuilder result = new StringBuilder();
        boolean latinWord = false;
        for (char c : name.trim().toCharArray()) {
            if (result.length() >= 4) break;
            if (Character.UnicodeScript.of(c) == Character.UnicodeScript.HAN) {
                String[] pinyin = PinyinHelper.toHanyuPinyinStringArray(c);
                if (pinyin != null && pinyin.length > 0) result.append(Character.toUpperCase(pinyin[0].charAt(0)));
                latinWord = false;
            } else if (c < 128 && Character.isLetterOrDigit(c)) {
                if (!latinWord) result.append(Character.toUpperCase(c));
                latinWord = true;
            } else latinWord = false;
        }
        return result.isEmpty() ? "KH" : result.toString();
    }
}