using ConsoleApp2.Const;
using ConsoleApp2.HostedServices.Abstractions;
using ConsoleApp2.Options;
using ConsoleApp2.Services;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

namespace ConsoleApp2.HostedServices;

/// <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 DataRecordQueue _consumerQueue;
    private readonly IOptions<DatabaseOutputOptions> _options;
    private readonly ProcessContext _context;
    private readonly TaskManager _taskManager;

    public OutputService(ILogger<OutputService> logger,
        [FromKeyedServices(ProcessStep.Consumer)] DataRecordQueue consumerQueue,
        IOptions<DatabaseOutputOptions> options,
        ProcessContext context,
        TaskManager taskManager)
    {
        _logger = logger;
        _consumerQueue = consumerQueue;
        _options = options;
        _context = context;
        _taskManager = taskManager;
    }

    public async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("***** Mysql output service started *****");

        var records = new List<DataRecord>();
        while (!_context.IsTransformCompleted || _consumerQueue.Count > 0)
        {
            if (!_consumerQueue.TryDequeue(out var record)) continue;
            records.Add(record);

            if (records.Count >= _options.Value.FlushCount)
            {
                var recordsCopy = records;
                _taskManager.CreateTask(async () => await FlushAsync(recordsCopy), stoppingToken);
                records = [];
            }

            if (_taskManager.TaskCount >= _options.Value.MaxTask)
            {
                await _taskManager.WaitAll();
                _taskManager.ClearTask();
            }
        }

        await _taskManager.WaitAll();
        await FlushAsync(records);

        _context.CompleteOutput();

        _logger.LogInformation("***** Mysql output service completed *****");
    }

    private async Task FlushAsync(IEnumerable<DataRecord> records)
    {
        var count = 0;
        await using var output = new MySqlDestination(
            _options.Value.ConnectionString ?? throw new InvalidOperationException("Connection string is required"),
            _logger, true);
        
        foreach (var record in records)
        {
            await output.WriteRecordAsync(record);
            count++;
        }

        await output.FlushAsync();
        _context.AddOutput(count);
    }
}