using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using API.DTOs.ReadingLists;
using API.Entities;
using API.Helpers;
using API.Interfaces.Repositories;
using AutoMapper;
using AutoMapper.QueryableExtensions;
using Microsoft.EntityFrameworkCore;

namespace API.Data.Repositories
{
    public class ReadingListRepository : IReadingListRepository
    {
        private readonly DataContext _context;
        private readonly IMapper _mapper;

        public ReadingListRepository(DataContext context, IMapper mapper)
        {
            _context = context;
            _mapper = mapper;
        }

        public void Update(ReadingList list)
        {
            _context.Entry(list).State = EntityState.Modified;
        }

        public void Remove(ReadingListItem item)
        {
            _context.ReadingListItem.Remove(item);
        }

        public void BulkRemove(IEnumerable<ReadingListItem> items)
        {
            _context.ReadingListItem.RemoveRange(items);
        }


        public async Task<PagedList<ReadingListDto>> GetReadingListDtosForUserAsync(int userId, bool includePromoted, UserParams userParams)
        {
            var query = _context.ReadingList
                .Where(l => l.AppUserId == userId || (includePromoted &&  l.Promoted ))
                .OrderBy(l => l.LastModified)
                .ProjectTo<ReadingListDto>(_mapper.ConfigurationProvider)
                .AsNoTracking();

            return await PagedList<ReadingListDto>.CreateAsync(query, userParams.PageNumber, userParams.PageSize);
        }

        public async Task<ReadingList> GetReadingListByIdAsync(int readingListId)
        {
            return await _context.ReadingList
                .Where(r => r.Id == readingListId)
                .Include(r => r.Items.OrderBy(item => item.Order))
                .SingleOrDefaultAsync();
        }

        public async Task<IEnumerable<ReadingListItemDto>> GetReadingListItemDtosByIdAsync(int readingListId, int userId)
        {
            var userLibraries = _context.Library
                .Include(l => l.AppUsers)
                .Where(library => library.AppUsers.Any(user => user.Id == userId))
                .AsNoTracking()
                .Select(library => library.Id)
                .ToList();

            var items = await _context.ReadingListItem
                .Where(s => s.ReadingListId == readingListId)
                .Join(_context.Chapter, s => s.ChapterId, chapter => chapter.Id, (data, chapter) => new
                {
                    TotalPages = chapter.Pages,
                    ChapterNumber = chapter.Range,
                    readingListItem = data
                })
                .Join(_context.Volume, s => s.readingListItem.VolumeId, volume => volume.Id, (data, volume) => new
                {
                    data.readingListItem,
                    data.TotalPages,
                    data.ChapterNumber,
                    VolumeId = volume.Id,
                    VolumeNumber = volume.Name,
                })
                .Join(_context.Series, s => s.readingListItem.SeriesId, series => series.Id,
                    (data, s) => new
                    {
                        SeriesName = s.Name,
                        SeriesFormat = s.Format,
                        s.LibraryId,
                        data.readingListItem,
                        data.TotalPages,
                        data.ChapterNumber,
                        data.VolumeNumber,
                        data.VolumeId
                    })
                .Select(data => new ReadingListItemDto()
                {
                    Id = data.readingListItem.Id,
                    ChapterId = data.readingListItem.ChapterId,
                    Order = data.readingListItem.Order,
                    SeriesId = data.readingListItem.SeriesId,
                    SeriesName = data.SeriesName,
                    SeriesFormat = data.SeriesFormat,
                    PagesTotal = data.TotalPages,
                    ChapterNumber = data.ChapterNumber,
                    VolumeNumber = data.VolumeNumber,
                    LibraryId = data.LibraryId,
                    VolumeId = data.VolumeId,
                    ReadingListId = data.readingListItem.ReadingListId
                })
                .Where(o => userLibraries.Contains(o.LibraryId))
                .OrderBy(rli => rli.Order)
                .AsNoTracking()
                .ToListAsync();

            // Attach progress information
            var fetchedChapterIds = items.Select(i => i.ChapterId);
            var progresses = await _context.AppUserProgresses
                .Where(p => fetchedChapterIds.Contains(p.ChapterId))
                .AsNoTracking()
                .ToListAsync();

            foreach (var progress in progresses)
            {
                var progressItem = items.SingleOrDefault(i => i.ChapterId == progress.ChapterId && i.ReadingListId == readingListId);
                if (progressItem == null) continue;

                progressItem.PagesRead = progress.PagesRead;
            }

            return items;
        }

        public async Task<ReadingListDto> GetReadingListDtoByIdAsync(int readingListId, int userId)
        {
            return await _context.ReadingList
                .Where(r => r.Id == readingListId && (r.AppUserId == userId || r.Promoted))
                .ProjectTo<ReadingListDto>(_mapper.ConfigurationProvider)
                .SingleOrDefaultAsync();
        }

        public async Task<IEnumerable<ReadingListItemDto>> AddReadingProgressModifiers(int userId, IList<ReadingListItemDto> items)
        {
            var chapterIds = items.Select(i => i.ChapterId).Distinct().ToList();
            var userProgress = await _context.AppUserProgresses
                .Where(p => p.AppUserId == userId && chapterIds.Contains(p.ChapterId))
                .AsNoTracking()
                .ToListAsync();

            foreach (var item in items)
            {
                var progress = userProgress.Where(p => p.ChapterId == item.ChapterId);
                item.PagesRead = progress.Sum(p => p.PagesRead);
            }

            return items;
        }

        public async Task<ReadingListDto> GetReadingListDtoByTitleAsync(string title)
        {
            return await _context.ReadingList
                .Where(r => r.Title.Equals(title))
                .ProjectTo<ReadingListDto>(_mapper.ConfigurationProvider)
                .SingleOrDefaultAsync();
        }

        public async Task<IEnumerable<ReadingListItem>> GetReadingListItemsByIdAsync(int readingListId)
        {
            return await _context.ReadingListItem
                .Where(r => r.ReadingListId == readingListId)
                .OrderBy(r => r.Order)
                .ToListAsync();
        }


    }
}