using JiShe.CollectBus.DataMigration.Options;
using JiShe.CollectBus.IotSystems.MeterReadingRecords;
using LiteDB;
using Microsoft.Extensions.Options;
using System;
using System.Data;
using System.Linq;
using System.Threading.Channels;
using System.Threading.Tasks;
using Volo.Abp.Domain.Repositories;

namespace JiShe.CollectBus.DataMigration
{
    /// <summary>
    /// 数据迁移服务
    /// </summary>
    public class DataMigrationService: CollectBusAppService, IDataMigrationService
    { 
        private readonly IRepository<MeterReadingRecords, Guid> _meterReadingRecordsRepository; 
        private readonly DataMigrationOptions _options;


        public DataMigrationService(IOptions<DataMigrationOptions> options, 
            IRepository<MeterReadingRecords, Guid> meterReadingRecordsRepository)
        {
            _options = options.Value;
            _meterReadingRecordsRepository = meterReadingRecordsRepository;
        }

        /// <summary>
        /// 开始迁移
        /// </summary>
        /// <returns></returns>
        public async Task StartMigrationAsync()
        {
            var rawDataChannel = Channel.CreateBounded<MeterReadingRecords[]>(new BoundedChannelOptions(_options.ChannelCapacity)
            {
                SingleWriter = false,
                SingleReader = false,
                FullMode = BoundedChannelFullMode.Wait
            });

            var cleanDataChannel = Channel.CreateBounded<DataTable>(new BoundedChannelOptions(_options.ChannelCapacity)
            {
                SingleWriter = false,
                SingleReader = false,
                FullMode = BoundedChannelFullMode.Wait
            });

            // 启动生产者和消费者
            var producer = Task.Run(() => ProduceDataAsync(rawDataChannel.Writer));

            var processors = Enumerable.Range(0, _options.ProcessorsCount)
                .Select(_ => Task.Run(() => ProcessDataAsync(rawDataChannel.Reader, cleanDataChannel.Writer)))
                .ToArray();

            var consumer = Task.Run(() => ConsumeDataAsync(cleanDataChannel.Reader));

            await Task.WhenAll(new[] { producer }.Union(processors).Union(new[] { consumer }));
        }

        /// <summary>
        /// 生产者，生产数据,主要是从MongoDB中读取数据
        /// </summary>
        /// <param name="writer"></param>
        /// <returns></returns>
        private async Task ProduceDataAsync(ChannelWriter<MeterReadingRecords[]> writer)
        {
            while (true)
            {
                var queryable = await _meterReadingRecordsRepository.GetQueryableAsync();
                var batchRecords =  queryable.Where(d => d.MigrationStatus == Common.Enums.RecordsDataMigrationStatusEnum.NotStarted)
                    .Take(_options.MongoDbDataBatchSize)
                    .ToArray();

                if (batchRecords == null || batchRecords.Length == 0)
                {
                    writer.Complete();
                    break;
                }

                await writer.WriteAsync(batchRecords);
            }
        }

        /// <summary>
        /// 清洗数据
        /// </summary>
        /// <param name="reader"></param>
        /// <param name="writer"></param>
        /// <returns></returns>
        private async Task ProcessDataAsync(ChannelReader<MeterReadingRecords[]> reader, ChannelWriter<DataTable> writer)
        {
            await foreach (var batch in reader.ReadAllAsync())
            {
                //var dataTable = new DataTable();
                //dataTable.Columns.Add("Id", typeof(string));
                //dataTable.Columns.Add("CleanName", typeof(string));
                //dataTable.Columns.Add("ProcessedTime", typeof(DateTime));

                //foreach (var doc in batch)
                //{
                //    // 业务清洗逻辑
                //    var cleanName = doc["name"].AsString.Trim().ToUpper();
                //    dataTable.Rows.Add(
                //        doc["_id"].ToString(),
                //        cleanName,
                //        DateTime.UtcNow);
                //}

                //await writer.WriteAsync(dataTable);

                // 批量更新标记
                var ids = batch.Select(d => d.Id).ToArray(); 
                foreach (var item in batch)
                {
                    item.MigrationStatus = Common.Enums.RecordsDataMigrationStatusEnum.InProgress;
                    item.MigrationTime = DateTime.Now;
                }

                await _meterReadingRecordsRepository.UpdateManyAsync(batch);
            }
            writer.Complete();
        }

        /// <summary>
        /// 消费清洗后的数据入库
        /// </summary>
        /// <param name="reader"></param>
        /// <returns></returns>
        private async Task ConsumeDataAsync(ChannelReader<DataTable> reader)
        {
            //await using var connection = new SqlConnection(_sqlConnectionString);
            //await connection.OpenAsync();

            //await foreach (var dataTable in reader.ReadAllAsync())
            //{
            //    using var bulkCopy = new SqlBulkCopy(connection)
            //    {
            //        DestinationTableName = "CleanData",
            //        BatchSize = 5000,
            //        BulkCopyTimeout = 300
            //    };

            //    bulkCopy.ColumnMappings.Add("Id", "Id");
            //    bulkCopy.ColumnMappings.Add("CleanName", "CleanName");
            //    bulkCopy.ColumnMappings.Add("ProcessedTime", "ProcessedTime");

            //    await bulkCopy.WriteToServerAsync(dataTable);
            //}
        }
    }
}