using MAX.Core.DependencyInjection;
using MAX.Framework.Commons;
using MAX.Plugins;
using Microsoft.Extensions.DependencyInjection;
using MySql.Data.MySqlClient;
using System.Security.Cryptography;
using System.Text;

namespace Store.Modules.CloudProduct.Services;

/// <summary>跨实例串行化违规上报和商品索引写入，防止下架后被旧批次写回。</summary>
public class GoodsIndexLock([FromKeyedServices("CloudProduct")] PluginContext context) : ISingletonDependency
{
    public Task<IAsyncDisposable> AcquireAsync() => AcquireAsync("goods-index:");

    /// <summary>收藏重建、整条文档写入和安全状态更新共用独立锁，防止旧快照覆盖新结论。</summary>
    public virtual Task<IAsyncDisposable> AcquireFavoritesAsync() => AcquireAsync("favorites-index:");

    private async Task<IAsyncDisposable> AcquireAsync(string prefix)
    {
        // 禁用连接池：即使释放锁失败，关闭物理连接也会释放会话锁。
        var settings = new MySqlConnectionStringBuilder(context.Configuration["CloudProductConnection"])
        {
            Pooling = false
        };
        var connection = new MySqlConnection(settings.ConnectionString);
        var name = prefix + Convert.ToHexString(SHA256.HashData(
            Encoding.UTF8.GetBytes(settings.Database)))[..40];
        try
        {
            await connection.OpenAsync();
            using var command = connection.CreateCommand();
            command.CommandText = "SELECT GET_LOCK(@name, 30)";
            command.CommandTimeout = 35;
            command.Parameters.AddWithValue("@name", name);
            var result = await command.ExecuteScalarAsync();
            if (result == null || result == DBNull.Value || Convert.ToInt32(result) != 1)
                throw new AppException("商品索引正在处理，请稍后重试");
            return connection;
        }
        catch
        {
            await connection.DisposeAsync();
            throw;
        }
    }
}