using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;
using AcaMate.V1.Models;
using Microsoft.Extensions.Hosting;

namespace AcaMate.V1.Services;

public interface IPushQueue
{
    void Enqueue(PushRequest request);
    Task<PushRequest> DequeueAsync(CancellationToken cancellationToken);
}

public class InMemoryPushQueue: IPushQueue
{
    private readonly ConcurrentQueue<PushRequest> _queue = new ConcurrentQueue<PushRequest>();
    private readonly SemaphoreSlim _signal = new SemaphoreSlim(0);

    public void Enqueue(PushRequest request)
    {
        if( request is null ) 
            throw new ArgumentNullException(nameof(request));
        _queue.Enqueue(request);
        _signal.Release();
    }

    public async Task<PushRequest> DequeueAsync(CancellationToken cancellationToken)
    {
        await _signal.WaitAsync(cancellationToken);
        _queue.TryDequeue(out var request);
        return request;
    }
}

public class PushBackgroundService : BackgroundService
{
    private readonly IPushQueue _queue;
    private readonly IApnsPushService _pushService;

    public PushBackgroundService(IPushQueue queue, IApnsPushService pushService)
    {
        _queue = queue;
        _pushService = pushService;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            var pushRequest = await _queue.DequeueAsync(stoppingToken);
            try
            {
                await _pushService.SendPushNotificationAsync(pushRequest.deviceToken, pushRequest.payload);
            }
            catch (Exception ex)
            {
                Console.WriteLine($"푸시 전송 실패: {ex.Message}");
            }
        }
    }
}