namespace Admin.NET.Plugin.AiDOP.MaterialWarehouse.InventoryPosting.Numbering;

/// <summary>
/// 业务单号服务：基于原子 provider 取号 + 「DB UNIQUE 兜底 + duplicate-key 有限次数重试」消费。
/// 硬约束：禁 SELECT MAX()+1 / 禁 read-max-then-write / 禁仅靠进程锁 / 禁随机数假唯一。
/// 最终唯一性 = provider 原子性 + 目标表 DB UNIQUE 兜底；本服务负责有界重试，绝不无限循环。
/// </summary>
public sealed class BusinessNumberService
{
    public const int DefaultMaxRetry = 5;

    private readonly IBusinessNumberProvider _provider;

    public BusinessNumberService(IBusinessNumberProvider provider)
    {
        _provider = provider ?? throw new ArgumentNullException(nameof(provider));
    }

    /// <summary>取单个业务单号（原子）。</summary>
    public async Task<string> NextAsync(string ruleCode, string domain, string operatorNo)
    {
        var batch = await _provider.NextBatchAsync(ruleCode, domain, 1, operatorNo);
        return batch[0];
    }

    /// <summary>取一批业务单号（原子、连续）。</summary>
    public Task<IReadOnlyList<string>> NextBatchAsync(string ruleCode, string domain, int count, string operatorNo)
        => _provider.NextBatchAsync(ruleCode, domain, count, operatorNo);

    /// <summary>
    /// 取号 → 消费（tryConsume 尝试落库；返回 true=成功占用/唯一，false=撞 DB UNIQUE 需换号重试）。
    /// 有界重试 maxRetry 次；耗尽仍失败则返回 Success=false（不无限循环）。
    /// tryConsume 应捕获 duplicate-key(1062) 返回 false，其它异常向上抛。
    /// </summary>
    public async Task<BusinessNumberConsumeResult> NextWithUniqueRetryAsync(
        string ruleCode, string domain, string operatorNo,
        Func<string, Task<bool>> tryConsume, int maxRetry = DefaultMaxRetry)
    {
        if (tryConsume == null) throw new ArgumentNullException(nameof(tryConsume));
        if (maxRetry < 1) maxRetry = 1;

        string last = null;
        for (var attempt = 1; attempt <= maxRetry; attempt++)
        {
            last = await NextAsync(ruleCode, domain, operatorNo);
            if (await tryConsume(last))
                return new BusinessNumberConsumeResult { Success = true, Number = last, Attempts = attempt };
        }
        return new BusinessNumberConsumeResult { Success = false, Number = last, Attempts = maxRetry };
    }
}