using DownloadManager.Core.Data.Repositories;
using DownloadManager.Core.Engine;
using DownloadManager.Core.Models;
using DownloadManager.Core.Queue;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;

namespace DownloadManager.Core.Services;

public interface IDownloadService
{
    Task<IEnumerable<DownloadItem>> GetAllDownloadsAsync();
    Task AddDownloadAsync(DownloadItem item);
    Task UpdateDownloadAsync(DownloadItem item);
    Task PauseDownloadAsync(Guid id);
    Task ResumeDownloadAsync(Guid id);
    Task DeleteDownloadAsync(Guid id);
}

public class DownloadService : IDownloadService
{
    private readonly IDownloadRepository _repository;
    private readonly DownloadEngine _engine;
    private readonly DownloadQueue _queue;

    public DownloadService(IDownloadRepository repository, DownloadEngine engine, DownloadQueue queue)
    {
        _repository = repository;
        _engine = engine;
        _queue = queue;
    }

    public Task<IEnumerable<DownloadItem>> GetAllDownloadsAsync() 
        => _repository.GetAllAsync();

    public async Task AddDownloadAsync(DownloadItem item)
    {
        await _repository.AddAsync(item);
        _queue.Enqueue(item);
    }

    public async Task UpdateDownloadAsync(DownloadItem item)
    {
        await _repository.UpdateAsync(item);
    }

    public Task PauseDownloadAsync(Guid id)
    {
        _engine.CancelDownload(id);
        return Task.CompletedTask;
    }

    public async Task ResumeDownloadAsync(Guid id)
    {
        var item = await _repository.GetByIdAsync(id);
        if (item != null && item.Status != Enums.DownloadStatus.Completed)
        {
            item.Status = Enums.DownloadStatus.Queued;
            await _repository.UpdateAsync(item);
            _queue.Enqueue(item);
        }
    }


    public async Task DeleteDownloadAsync(Guid id)
    {
        await _repository.DeleteAsync(id);
        _engine.CancelDownload(id);
    }
}