using QYZH.InteractiveMagazine.Infrastructure.RabbitMQ;
using QYZH.InteractiveMagazine.Models.Entity;
using QYZH.InteractiveMagazine.Models.Enum;
using QYZH.InteractiveMagazine.Models.Settings;
using SqlSugar;
using System.Text.Json;

namespace QYZH.InteractiveMagazine.WorkService.Jobs;

/// <summary>
/// 消息Outbox派发服务。
/// </summary>
public class MessageOutboxDispatchService(
    IServiceScopeFactory scopeFactory,
    IRabbitMQService rabbitMQService,
    IConfiguration configuration,
    ILogger<MessageOutboxDispatchService> logger) : BackgroundService
{
    private const int BatchSize = 50;
    private readonly RabbitMQRetrySettings retrySettings = configuration.GetSection("RabbitMQRetrySettings").Get<RabbitMQRetrySettings>() ?? new RabbitMQRetrySettings();

    /// <summary>
    /// 执行Outbox派发循环。
    /// </summary>
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                await DispatchPendingMessagesAsync(stoppingToken);
            }
            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
            {
                break;
            }
            catch (Exception ex)
            {
                logger.LogError(ex, "Outbox消息派发循环异常");
            }

            await Task.Delay(TimeSpan.FromSeconds(5), stoppingToken);
        }
    }

    private async Task DispatchPendingMessagesAsync(CancellationToken cancellationToken)
    {
        using var scope = scopeFactory.CreateScope();
        var db = scope.ServiceProvider.GetRequiredService<ISqlSugarClient>();
        var now = DateTime.Now;
        var messages = await db.Queryable<MessageOutbox>()
            .Where(x => !x.IsDeleted
                && (x.Status == (int)MessageOutboxStatusEnum.Pending || x.Status == (int)MessageOutboxStatusEnum.Failed)
                && (x.NextRetryAt == null || x.NextRetryAt <= now))
            .OrderBy(x => x.CreatedAt)
            .Take(BatchSize)
            .ToListAsync(cancellationToken);

        foreach (var message in messages)
        {
            await DispatchMessageAsync(db, message, cancellationToken);
        }
    }

    private async Task DispatchMessageAsync(ISqlSugarClient db, MessageOutbox message, CancellationToken cancellationToken)
    {
        try
        {
            using var payload = JsonDocument.Parse(message.Payload);
            var sent = await rabbitMQService.SendAsync(new RabbitMQSendParam
            {
                Exchange = message.Exchange,
                Queue = message.Queue,
                RoutingKey = message.RoutingKey,
                Data = payload.RootElement.Clone()
            }, cancellationToken);

            if (!sent)
            {
                throw new InvalidOperationException("RabbitMQ SendAsync returned false");
            }

            await db.Updateable<MessageOutbox>()
                .SetColumns(x => x.Status == (int)MessageOutboxStatusEnum.Sent)
                .SetColumns(x => x.SentAt == DateTime.Now)
                .SetColumns(x => x.UpdatedAt == DateTime.Now)
                .Where(x => x.Id == message.Id && x.Status != (int)MessageOutboxStatusEnum.Sent)
                .ExecuteCommandAsync(cancellationToken);
        }
        catch (Exception ex)
        {
            var retryCount = message.RetryCount + 1;
            var abandoned = retryCount >= retrySettings.MaxRetryCount;
            await db.Updateable<MessageOutbox>()
                .SetColumns(x => x.Status == (int)(abandoned ? MessageOutboxStatusEnum.Abandoned : MessageOutboxStatusEnum.Failed))
                .SetColumns(x => x.RetryCount == retryCount)
                .SetColumns(x => x.NextRetryAt == (abandoned ? null : DateTime.Now.AddMilliseconds(retrySettings.RetryDelayMilliseconds)))
                .SetColumns(x => x.LastError == ex.Message)
                .SetColumns(x => x.UpdatedAt == DateTime.Now)
                .Where(x => x.Id == message.Id)
                .ExecuteCommandAsync(cancellationToken);

            logger.LogError(ex, "Outbox消息派发失败，MessageId: {MessageId}, RetryCount: {RetryCount}", message.Id, retryCount);
        }
    }
}