using System.Buffers;
using System.Text;
using MesETL.App.Const;
using MesETL.App.Helpers;
using MesETL.App.HostedServices.Abstractions;
using MesETL.App.Options;
using MesETL.App.Services;
using MesETL.App.Services.ErrorRecorder;
using MesETL.Shared.Helper;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using MySqlConnector;
using MySqlDestination = MesETL.App.Services.ETL.MySqlDestination;
using TaskExtensions = MesETL.Shared.Helper.TaskExtensions;

namespace MesETL.App.HostedServices;

public record DataOutputContext(IServiceProvider Serivces);

/// <summary>
/// 数据导出服务，将数据导出至MySql服务
/// </summary>
public class OutputService : IOutputService
{
    private readonly ILogger _logger;
    private readonly IOptions<DatabaseOutputOptions> _outputOptions;
    private readonly ProcessContext _context;
    private readonly ErrorRecorderFactory _errorRecorderFactory;
    private readonly RecordQueuePool _queuePool;
    private readonly IServiceProvider _services;

    public OutputService(ILogger<OutputService> logger,
        IOptions<DatabaseOutputOptions> outputOptions,
        ProcessContext context,
        RecordQueuePool queuePool, 
        ErrorRecorderFactory errorRecorderFactory, 
        IServiceProvider services)
    {
        _logger = logger;
        _outputOptions = outputOptions;
        _context = context;
        _queuePool = queuePool;
        _errorRecorderFactory = errorRecorderFactory;
        _services = services;
    }

    public async Task ExecuteAsync(CancellationToken ct)
    {
        _logger.LogInformation("***** 输出服务已启动 *****");
        var dbTaskManager = new TaskManager(_queuePool.Queues.Count);
        var dbTasks = new Dictionary<string, Task>();
        while (!_context.IsTransformCompleted)
        {
            foreach (var (db, queue) in _queuePool.Queues)
            {
                if (!dbTasks.ContainsKey(db))
                {
                    dbTasks.Add(db, await dbTaskManager.CreateTaskAsync(
                        async () => await StartDatabaseWorker(db, queue, ct), ct));
                }
            }

            await Task.Delay(500, ct);
        }

        await TaskExtensions.WaitUntil(() => dbTaskManager.RunningTaskCount == 0, 25, ct);
        
        _context.CompleteOutput();
        _outputOptions.Value.OutputFinished?.Invoke(new DataOutputContext(_services));
        _logger.LogInformation("***** 输出服务执行完毕 *****");
    }

    private async Task StartDatabaseWorker(string db, DataRecordQueue queue, CancellationToken ct = default)
    {
        _logger.LogInformation("*****开启输出线程，数据库: {db} *****", db);
        var taskManager = new TaskManager(_outputOptions.Value.MaxDatabaseOutputTask);
        var ignoreOutput = new HashSet<string>(_outputOptions.Value.NoOutput);
        var tmp = new List<DataRecord>(_outputOptions.Value.FlushCount);
        while (!_context.IsTransformCompleted || queue.Count > 0)
        {
            if (ct.IsCancellationRequested)
                break;

            if (!queue.TryDequeue(out var record) || record.Ignore || ignoreOutput.Contains(record.TableName))
                continue;
            
            var dbName = record.Database ?? throw new ApplicationException("输出的记录缺少数据库名");
            if(dbName != db)
                throw new ApplicationException($"输出记录的数据与当前输出线程不匹配，记录：{dbName}, 输出线程：{db}");
            tmp.Add(record);

            if (tmp.Count >= _outputOptions.Value.FlushCount)
            {
                var list = tmp;
                tmp = [];
                await taskManager.CreateTaskAsync(async arg => // 转换为方法组
                {
                    var tuple = arg as Tuple<string, List<DataRecord>>;
                    try
                    {
                        await FlushAsync(tuple!.Item1, tuple.Item2);
                    }
                    catch (Exception e)
                    {
                        _logger.LogError(e, "输出记录时发生错误");
                        throw;
                    }
                }, Tuple.Create(dbName, list), ct);
            }
        }

        // 等待所有子任务完成
        await TaskExtensions.WaitUntil(() => taskManager.RunningTaskCount == 0, 10, ct);
        
        _logger.LogDebug("输出线程结束，清理剩余记录[{Count}]", tmp.Count);
        
        // 清理剩余记录
        if (tmp.Count > 0)
        {
            await FlushAsync(db, tmp);
        }

        _logger.LogInformation("***** 输出线程结束，数据库: {db} *****", db);
    }

    private async Task FlushAsync(string dbName, IEnumerable<DataRecord> records)
    {
        var connStr = new MySqlConnectionStringBuilder(_outputOptions.Value.ConnectionString 
                                                       ?? throw new ApplicationException("未配置数据库连接字符串"))
            {
                CharacterSet = "utf8mb4",
                AllowUserVariables = true,
                IgnoreCommandTransaction = true,
                TreatTinyAsBoolean = false,
                ConnectionTimeout = 60,
                DefaultCommandTimeout = 0,
                SslMode = MySqlSslMode.None,
                Database = dbName
            }.ConnectionString;
        await using var output = new MySqlDestination(connStr, _logger,
            _outputOptions, _errorRecorderFactory.CreateOutput(dbName), _context);

        var tableOutput = new Dictionary<string, int>();
        foreach (var record in records)
        {
            await output.WriteRecordAsync(record);
            tableOutput.AddOrUpdate(record.TableName, 1, (_, v) => v + 1);
        }

        await output.FlushAsync(_outputOptions.Value.MaxAllowedPacket);
        foreach (var (key, value) in tableOutput)
        {
            _context.AddOutput(value);
            _context.AddTableOutput(key, value);
        }
        _logger.LogTrace("输出任务：刷新了 {Count} 条记录", tableOutput.Values.Sum(i => i));
    }
}