using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using API.Comparators;
using API.DTOs;
using API.Entities;
using API.Extensions;
using API.Interfaces;
using AutoMapper;
using AutoMapper.QueryableExtensions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace API.Data
{
    public class VolumeRepository : IVolumeRepository
    {
        private readonly DataContext _context;
        private readonly IMapper _mapper;
        private readonly ILogger _logger;

        public VolumeRepository(DataContext context, IMapper mapper, ILogger logger)
        {
            _context = context;
            _mapper = mapper;
            _logger = logger;
        }
        
        public void Update(Volume volume)
        {
            _context.Entry(volume).State = EntityState.Modified;
        }

        /// <summary>
        /// Returns a Chapter for an Id. Includes linked <see cref="MangaFile"/>s.
        /// </summary>
        /// <param name="chapterId"></param>
        /// <returns></returns>
        public async Task<Chapter> GetChapterAsync(int chapterId)
        {
            return await _context.Chapter
                .Include(c => c.Files)
                .SingleOrDefaultAsync(c => c.Id == chapterId);
        }
        
        
        /// <summary>
        /// Returns Chapters for a volume id.
        /// </summary>
        /// <param name="volumeId"></param>
        /// <returns></returns>
        public async Task<IList<Chapter>> GetChaptersAsync(int volumeId)
        {
            return await _context.Chapter
                .Where(c => c.VolumeId == volumeId)
                .ToListAsync();
        }

        /// <summary>
        /// Returns the cover image for a chapter id.
        /// </summary>
        /// <param name="chapterId"></param>
        /// <returns></returns>
        public async Task<byte[]> GetChapterCoverImageAsync(int chapterId)
        {
            return await _context.Chapter
                .Where(c => c.Id == chapterId)
                .Select(c => c.CoverImage)
                .AsNoTracking()
                .SingleOrDefaultAsync();
        }


        public async Task<ChapterDto> GetChapterDtoAsync(int chapterId)
        {
            var chapter = await _context.Chapter
                .Include(c => c.Files)
                .ProjectTo<ChapterDto>(_mapper.ConfigurationProvider)
                .AsNoTracking()
                .SingleOrDefaultAsync(c => c.Id == chapterId);

            return chapter;
        }

        public async Task<IList<MangaFile>> GetFilesForChapter(int chapterId)
        {
            return await _context.MangaFile
                .Where(c => chapterId == c.Id)
                .AsNoTracking()
                .ToListAsync();
        }

        /// <summary>
        /// Gets the first (ordered) volume/chapter in a series where the user has progress on it. Only completed volumes/chapters, next entity shouldn't
        /// have any read progress on it. 
        /// </summary>
        /// <param name="userId"></param>
        /// <param name="libraryId"></param>
        /// <param name="limit"></param>
        /// <returns></returns>
        public async Task<IEnumerable<InProgressChapterDto>> GetContinueReading(int userId, int libraryId, int limit)
        {
            _logger.LogInformation("Get Continue Reading");
            var chapters = await _context.Chapter
                .Join(_context.AppUserProgresses, c => c.Id, p => p.ChapterId,
                    (chapter, progress) =>
                        new
                        {
                            Chapter = chapter,
                            Progress = progress
                        })
                .Join(_context.Series, arg => arg.Progress.SeriesId, series => series.Id, (arg, series) => 
                    new
                    {
                        arg.Chapter,
                        arg.Progress,
                        Series = series
                    })
                .AsNoTracking()
                .Where(arg => arg.Progress.AppUserId == userId 
                              && arg.Progress.PagesRead < arg.Chapter.Pages)
                .OrderByDescending(d => d.Progress.LastModified)
                .Take(limit)
                .ToListAsync();

            return chapters
                .OrderBy(c => float.Parse(c.Chapter.Number), new ChapterSortComparer())
                .DistinctBy(p => p.Series.Id)
                .Select(arg => new InProgressChapterDto()
                {
                    Id = arg.Chapter.Id,
                    Number = arg.Chapter.Number,
                    Range = arg.Chapter.Range,
                    SeriesId = arg.Progress.SeriesId,
                    SeriesName = arg.Series.Name,
                    LibraryId = arg.Series.LibraryId,
                    Pages = arg.Chapter.Pages,
                });
        }
    }
}