using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using MongoDB.Driver;
using System;
using System.Threading;
using System.Threading.Tasks;
using Volo.Abp;
using Volo.Abp.Data;
using Volo.Abp.MongoDB;
using Volo.Abp.MultiTenancy;
using Volo.Abp.Threading;
using Volo.Abp.Uow;

namespace Bussiness.MongoDB
{
    /// <summary>
    /// 自定义MongoDB上下文提供程序，禁用事务支持
    /// 用于解决Standalone MongoDB服务器不支持事务的问题
    /// </summary>
    public class NonTransactionalMongoDbContextProvider<TMongoDbContext> : IMongoDbContextProvider<TMongoDbContext>
        where TMongoDbContext : class, IAbpMongoDbContext
    {
        private readonly IUnitOfWorkManager _unitOfWorkManager;
        private readonly IConnectionStringResolver _connectionStringResolver;
        private readonly ICancellationTokenProvider _cancellationTokenProvider;
        private readonly ICurrentTenant _currentTenant;
        private readonly IServiceProvider _serviceProvider;
        private readonly ILogger<NonTransactionalMongoDbContextProvider<TMongoDbContext>> _logger;

        public NonTransactionalMongoDbContextProvider(
            IUnitOfWorkManager unitOfWorkManager,
            IConnectionStringResolver connectionStringResolver,
            ICancellationTokenProvider cancellationTokenProvider,
            ICurrentTenant currentTenant,
            IServiceProvider serviceProvider,
            ILogger<NonTransactionalMongoDbContextProvider<TMongoDbContext>> logger)
        {
            _unitOfWorkManager = unitOfWorkManager;
            _connectionStringResolver = connectionStringResolver;
            _cancellationTokenProvider = cancellationTokenProvider;
            _currentTenant = currentTenant;
            _serviceProvider = serviceProvider;
            _logger = logger;
        }

        public async Task<TMongoDbContext> GetDbContextAsync(CancellationToken cancellationToken = default)
        {
            var unitOfWork = _unitOfWorkManager.Current;
            if (unitOfWork == null)
            {
                throw new AbpException("A DbContext can only be created inside a unit of work!");
            }

            var targetTenantId = _currentTenant.Id;
            var connectionString = await ResolveConnectionStringAsync(targetTenantId);
            var dbContextKey = $"{typeof(TMongoDbContext).FullName}_{connectionString}";

            var databaseApi = unitOfWork.FindDatabaseApi(dbContextKey);
            if (databaseApi == null)
            {
                // 创建不带事务的数据库API
                databaseApi = new MongoDbDatabaseApi(await CreateDbContextAsync(unitOfWork, connectionString, cancellationToken));
                unitOfWork.AddDatabaseApi(dbContextKey, databaseApi);
            }

            return ((MongoDbDatabaseApi)databaseApi).DbContext.As<TMongoDbContext>();
        }

        [Obsolete("Use GetDbContextAsync method.")]
        public TMongoDbContext GetDbContext()
        {
            return AsyncHelper.RunSync(() => GetDbContextAsync());
        }

        private Task<IAbpMongoDbContext> CreateDbContextAsync(IUnitOfWork unitOfWork, string connectionString, CancellationToken cancellationToken)
        {
            var dbContext = unitOfWork.ServiceProvider.GetRequiredService<TMongoDbContext>();

            var mongoUrl = new MongoUrl(connectionString);
            var databaseName = mongoUrl.DatabaseName;
            if (databaseName.IsNullOrWhiteSpace())
            {
                databaseName = ConnectionStringNameAttribute.GetConnStringName<TMongoDbContext>();
            }

            // 创建MongoDB客户端（不使用事务）
            var client = new MongoClient(mongoUrl);
            var database = client.GetDatabase(databaseName);

            // 初始化DbContext，不传入session（即不使用事务）
            dbContext.ToAbpMongoDbContext().InitializeDatabase(database, client, null);

            _logger.LogDebug("MongoDB context created without transaction support for standalone server.");

            return Task.FromResult<IAbpMongoDbContext>(dbContext);
        }

        private async Task<string> ResolveConnectionStringAsync(Guid? tenantId)
        {
            if (tenantId == _currentTenant.Id)
            {
                return await _connectionStringResolver.ResolveAsync(ConnectionStringNameAttribute.GetConnStringName<TMongoDbContext>());
            }

            using (_currentTenant.Change(tenantId))
            {
                return await _connectionStringResolver.ResolveAsync(ConnectionStringNameAttribute.GetConnStringName<TMongoDbContext>());
            }
        }
    }

    /// <summary>
    /// MongoDB数据库API包装类
    /// </summary>
    public class MongoDbDatabaseApi : IDatabaseApi
    {
        public IAbpMongoDbContext DbContext { get; }

        public MongoDbDatabaseApi(IAbpMongoDbContext dbContext)
        {
            DbContext = dbContext;
        }
    }
}