using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.Entities.TV;
using MediaBrowser.Controller.Library;
using MediaBrowser.Controller.TV;
using MediaBrowser.Model.Entities;
using MediaBrowser.Model.Querying;
using System;
using System.Collections.Generic;
using System.Linq;
using MediaBrowser.Controller.Configuration;

namespace Emby.Server.Implementations.TV
{
    public class TVSeriesManager : ITVSeriesManager
    {
        private readonly IUserManager _userManager;
        private readonly IUserDataManager _userDataManager;
        private readonly ILibraryManager _libraryManager;
        private readonly IServerConfigurationManager _config;

        public TVSeriesManager(IUserManager userManager, IUserDataManager userDataManager, ILibraryManager libraryManager, IServerConfigurationManager config)
        {
            _userManager = userManager;
            _userDataManager = userDataManager;
            _libraryManager = libraryManager;
            _config = config;
        }

        public QueryResult<BaseItem> GetNextUp(NextUpQuery request)
        {
            var user = _userManager.GetUserById(request.UserId);

            if (user == null)
            {
                throw new ArgumentException("User not found");
            }

            var parentIdGuid = string.IsNullOrWhiteSpace(request.ParentId) ? (Guid?)null : new Guid(request.ParentId);

            string presentationUniqueKey = null;
            int? limit = null;
            if (!string.IsNullOrWhiteSpace(request.SeriesId))
            {
                var series = _libraryManager.GetItemById(request.SeriesId);

                if (series != null)
                {
                    presentationUniqueKey = GetUniqueSeriesKey(series);
                    limit = 1;
                }
            }

            if (string.IsNullOrWhiteSpace(presentationUniqueKey) && limit.HasValue)
            {
                limit = limit.Value + 10;
            }

            var items = _libraryManager.GetItemList(new InternalItemsQuery(user)
            {
                IncludeItemTypes = new[] { typeof(Series).Name },
                SortBy = new[] { ItemSortBy.SeriesDatePlayed },
                SortOrder = SortOrder.Descending,
                PresentationUniqueKey = presentationUniqueKey,
                Limit = limit,
                ParentId = parentIdGuid,
                Recursive = true,
                DtoOptions = new MediaBrowser.Controller.Dto.DtoOptions
                {
                    Fields = new List<ItemFields>
                    {

                    }
                }

            }).Cast<Series>().Select(GetUniqueSeriesKey);

            // Avoid implicitly captured closure
            var episodes = GetNextUpEpisodes(request, user, items);

            return GetResult(episodes, null, request);
        }

        public QueryResult<BaseItem> GetNextUp(NextUpQuery request, List<Folder> parentsFolders)
        {
            var user = _userManager.GetUserById(request.UserId);

            if (user == null)
            {
                throw new ArgumentException("User not found");
            }

            string presentationUniqueKey = null;
            int? limit = null;
            if (!string.IsNullOrWhiteSpace(request.SeriesId))
            {
                var series = _libraryManager.GetItemById(request.SeriesId);

                if (series != null)
                {
                    presentationUniqueKey = GetUniqueSeriesKey(series);
                    limit = 1;
                }
            }

            if (string.IsNullOrWhiteSpace(presentationUniqueKey) && limit.HasValue)
            {
                limit = limit.Value + 10;
            }

            var items = _libraryManager.GetItemList(new InternalItemsQuery(user)
            {
                IncludeItemTypes = new[] { typeof(Series).Name },
                SortBy = new[] { ItemSortBy.SeriesDatePlayed },
                SortOrder = SortOrder.Descending,
                PresentationUniqueKey = presentationUniqueKey,
                Limit = limit,
                DtoOptions = new MediaBrowser.Controller.Dto.DtoOptions
                {
                    Fields = new List<ItemFields>
                    {

                    },
                    EnableImages = false
                }

            }, parentsFolders.Cast<BaseItem>().ToList()).Cast<Series>().Select(GetUniqueSeriesKey);

            // Avoid implicitly captured closure
            var episodes = GetNextUpEpisodes(request, user, items);

            return GetResult(episodes, null, request);
        }

        public IEnumerable<Episode> GetNextUpEpisodes(NextUpQuery request, User user, IEnumerable<string> seriesKeys)
        {
            // Avoid implicitly captured closure
            var currentUser = user;

            var allNextUp = seriesKeys
                .Select(i => GetNextUp(i, currentUser));

            //allNextUp = allNextUp.OrderByDescending(i => i.Item1);

            // If viewing all next up for all series, remove first episodes
            // But if that returns empty, keep those first episodes (avoid completely empty view)
            var alwaysEnableFirstEpisode = !string.IsNullOrWhiteSpace(request.SeriesId);
            var isFirstItemAFirstEpisode = true;

            return allNextUp
                .Where(i =>
                {
                    if (alwaysEnableFirstEpisode || i.Item1 != DateTime.MinValue)
                    {
                        isFirstItemAFirstEpisode = false;
                        return true;
                    }

                    if (isFirstItemAFirstEpisode)
                    {
                        return false;
                    }

                    return true;
                })
                .Select(i => i.Item2())
                .Where(i => i != null)
                .Take(request.Limit ?? int.MaxValue);
        }

        private string GetUniqueSeriesKey(BaseItem series)
        {
            return series.GetPresentationUniqueKey();
        }

        /// <summary>
        /// Gets the next up.
        /// </summary>
        /// <returns>Task{Episode}.</returns>
        private Tuple<DateTime, Func<Episode>> GetNextUp(string seriesKey, User user)
        {
            var enableSeriesPresentationKey = _config.Configuration.EnableSeriesPresentationUniqueKey;

            var lastWatchedEpisode = _libraryManager.GetItemList(new InternalItemsQuery(user)
            {
                AncestorWithPresentationUniqueKey = enableSeriesPresentationKey ? null : seriesKey,
                SeriesPresentationUniqueKey = enableSeriesPresentationKey ? seriesKey : null,
                IncludeItemTypes = new[] { typeof(Episode).Name },
                SortBy = new[] { ItemSortBy.SortName },
                SortOrder = SortOrder.Descending,
                IsPlayed = true,
                Limit = 1,
                ParentIndexNumberNotEquals = 0,
                DtoOptions = new MediaBrowser.Controller.Dto.DtoOptions
                {
                    Fields = new List<ItemFields>
                    {

                    },
                    EnableImages = false
                }

            }).FirstOrDefault();

            Func<Episode> getEpisode = () =>
            {
                return _libraryManager.GetItemList(new InternalItemsQuery(user)
                {
                    AncestorWithPresentationUniqueKey = enableSeriesPresentationKey ? null : seriesKey,
                    SeriesPresentationUniqueKey = enableSeriesPresentationKey ? seriesKey : null,
                    IncludeItemTypes = new[] { typeof(Episode).Name },
                    SortBy = new[] { ItemSortBy.SortName },
                    SortOrder = SortOrder.Ascending,
                    Limit = 1,
                    IsPlayed = false,
                    IsVirtualItem = false,
                    ParentIndexNumberNotEquals = 0,
                    MinSortName = lastWatchedEpisode == null ? null : lastWatchedEpisode.SortName

                }).Cast<Episode>().FirstOrDefault();
            };

            if (lastWatchedEpisode != null)
            {
                var userData = _userDataManager.GetUserData(user, lastWatchedEpisode);

                var lastWatchedDate = userData.LastPlayedDate ?? DateTime.MinValue.AddDays(1);

                return new Tuple<DateTime, Func<Episode>>(lastWatchedDate, getEpisode);
            }

            // Return the first episode
            return new Tuple<DateTime, Func<Episode>>(DateTime.MinValue, getEpisode);
        }

        private QueryResult<BaseItem> GetResult(IEnumerable<BaseItem> items, int? totalRecordLimit, NextUpQuery query)
        {
            var itemsArray = totalRecordLimit.HasValue ? items.Take(totalRecordLimit.Value).ToArray() : items.ToArray();
            var totalCount = itemsArray.Length;

            if (query.Limit.HasValue)
            {
                itemsArray = itemsArray.Skip(query.StartIndex ?? 0).Take(query.Limit.Value).ToArray();
            }
            else if (query.StartIndex.HasValue)
            {
                itemsArray = itemsArray.Skip(query.StartIndex.Value).ToArray();
            }

            return new QueryResult<BaseItem>
            {
                TotalRecordCount = totalCount,
                Items = itemsArray
            };
        }
    }
}