using ConsoleApp2.Entities;
using ConsoleApp2.Options;
using ConsoleApp2.Services;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using MySqlConnector;

namespace ConsoleApp2.HostedServices;

public class MysqlOutputService : BackgroundService
{
    private readonly ILogger _logger;
    private readonly DataRecordQueue _consumerQueue;
    private readonly IOptions<DatabaseOptions> _options;
    private readonly ProcessContext _context;

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

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

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

            if (records.Count >= 200)
            {
                var recordsCopy = records;
                tasks.Add(Task.Run(async () => await FlushAsync(recordsCopy), stoppingToken));
                records = [];
            }

            if (tasks.Count >= 10)
            {
                await Task.WhenAll(tasks);
                tasks.Clear();
            }
        }

        await Task.WhenAll(tasks);
        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(new MySqlConnectionStringBuilder
        {
            Server = _options.Value.Host,
            Port = _options.Value.Port,
            Database = _options.Value.Database,
            UserID = _options.Value.User,
            Password = _options.Value.Password,
            ConnectionTimeout = 180,
        }.ConnectionString, _logger, true);

        foreach (var record in records)
        {
            await output.WriteRecordAsync(record);
            count++;
        }

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