using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNet.Mvc;
using Microsoft.Framework.Cache.Memory;
using MusicStore.Models;

namespace MusicStore.Controllers
{
    public class HomeController : Controller
    {
        
        [FromServices]
        public MusicStoreContext DbContext
        {
            get;
            set;
        }

        [FromServices]
        public IMemoryCache Cache
        {
            get;
            set;
        }

        //
        // GET: /Home/
        public async Task<IActionResult> Index()
        {
            // Get most popular albums
            var albums = await Cache.GetOrSet("topselling", async context =>
            {
                //Refresh it every 10 minutes. Let this be the last item to be removed by cache if cache GC kicks in.
                context.SetAbsoluteExpiration(TimeSpan.FromMinutes(10));
                context.SetPriority(CachePreservationPriority.High);
                return await GetTopSellingAlbums(6);
            });

            return View(albums);
        }

        //Can be removed and handled when HandleError filter is implemented
        //https://github.com/aspnet/Mvc/issues/623
        public IActionResult Error()
        {
            return View("~/Views/Shared/Error.cshtml");
        }

        private async Task<List<Album>> GetTopSellingAlbums(int count)
        {
            // Group the order details by album and return
            // the albums with the highest count

            // TODO [EF] We don't query related data as yet, so the OrderByDescending isn't doing anything
            return await DbContext.Albums
                .OrderByDescending(a => a.OrderDetails.Count())
                .Take(count)
                .ToListAsync();
        }
    }
}