using System.Collections.Concurrent;
using Admin.NET.Plugin.AiDOP.Supply;

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

/// <summary>
/// 进程内原子取号 provider（线程安全）——用于单元/并发测试与「同进程强唯一」证明。
/// 用 ConcurrentDictionary 计数器按 scope(ruleCode|domain|dateBucket) 原子预留连续区段，
/// 复用 NumberRuleFormatter 做格式化。**不代表跨实例/真实 MySQL 唯一性**（那属 Phase 4B）。
/// </summary>
public sealed class InMemoryBusinessNumberProvider : IBusinessNumberProvider
{
    private readonly Dictionary<string, BusinessNumberRule> _rules;
    private readonly Func<DateTime> _clock;
    private readonly ConcurrentDictionary<string, int> _counters = new();

    public InMemoryBusinessNumberProvider(IEnumerable<BusinessNumberRule> rules, Func<DateTime> clock = null)
    {
        _rules = (rules ?? throw new ArgumentNullException(nameof(rules)))
            .ToDictionary(r => r.RuleCode, StringComparer.OrdinalIgnoreCase);
        _clock = clock ?? (() => DateTime.Now);
    }

    public Task<IReadOnlyList<string>> NextBatchAsync(string ruleCode, string domain, int count, string operatorNo)
    {
        if (string.IsNullOrWhiteSpace(ruleCode)) throw new ArgumentException("ruleCode 不能为空", nameof(ruleCode));
        if (count <= 0) throw new ArgumentException("count 必须大于 0", nameof(count));
        if (!_rules.TryGetValue(ruleCode.Trim(), out var rule))
            throw new InvalidOperationException($"未找到编号规则：{ruleCode}");

        var now = _clock();
        var sequenceDate = NumberRuleFormatter.ResolveSequenceDate(rule.DateType, rule.IsDateType, now);
        var bucket = sequenceDate?.ToString("yyyyMMdd") ?? "-";
        var key = $"{rule.RuleCode}|{domain ?? string.Empty}|{bucket}";

        // 原子预留连续 count 个流水：AddOrUpdate 经 CAS 串行化，返回值即本次区段末值，无重叠。
        var last = _counters.AddOrUpdate(key, rule.IniValue + count - 1, (_, v) => v + count);
        var first = last - count + 1;

        var numbers = Enumerable.Range(first, count)
            .Select(serial => NumberRuleFormatter.BuildNumber(
                rule.Prefix1, rule.Prefix2, rule.Prefix3,
                rule.DateType, rule.IsDateType, serial, rule.MaxValue, now))
            .ToList();

        return Task.FromResult<IReadOnlyList<string>>(numbers);
    }
}