using LANCommander.Launcher.Data;
using LANCommander.Launcher.Data.Models;
using LANCommander.Launcher.Models;
using LANCommander.SDK;
using LANCommander.SDK.Extensions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using System.Collections.ObjectModel;
using System.Diagnostics;
using LANCommander.SDK.Services;

namespace LANCommander.Launcher.Services
{
    public class LibraryService : BaseDatabaseService<Library>
    {
        private readonly AuthenticationService AuthenticationService;
        private readonly InstallService InstallService;
        private readonly GameService GameService;
        private readonly LibraryClient LibraryClient;

        public Dictionary<Guid, Process> RunningProcesses = new Dictionary<Guid, Process>();

        public ObservableCollection<ListItem> Items { get; set; } = new ObservableCollection<ListItem>();

        public delegate Task OnLibraryChangedHandler(IEnumerable<ListItem> items);
        public event OnLibraryChangedHandler? OnLibraryChanged;

        public delegate Task OnLibraryItemsUpdatedHandler(IEnumerable<ListItem> itemsUpdatedOrAdded, IEnumerable<ListItem> itemsRemoved);
        public event OnLibraryItemsUpdatedHandler? OnLibraryItemsUpdated;

        public delegate Task OnPreLibraryItemsFilteredHandler(IEnumerable<ListItem> items);
        public event OnPreLibraryItemsFilteredHandler OnPreLibraryItemsFiltered;

        public delegate Task OnItemsFilteredHandler(IEnumerable<ListItem> items);
        public event OnItemsFilteredHandler OnItemsFiltered;

        public LibraryFilter Filter { get; set; } = new LibraryFilter();

        public LibraryService(
            DatabaseContext databaseContext,
            ILogger<LibraryService> logger,
            AuthenticationService authenticationService,
            InstallService installService,
            GameService gameService,
            LibraryClient libraryClient) : base(databaseContext, logger)
        {
            AuthenticationService = authenticationService;
            InstallService = installService;
            GameService = gameService;
            LibraryClient = libraryClient;

            InstallService.OnInstallComplete += InstallService_OnInstallComplete;
            Filter.OnChanged += Filter_OnChanged;
        }

        private async Task Filter_OnChanged()
        {
            if (OnItemsFiltered != null)
                await OnItemsFiltered.Invoke(Filter.ApplyFilter(Items));
        }

        private async Task InstallService_OnInstallComplete(Game game)
        {
            await LibraryChanged();
        }

        public async Task<IEnumerable<ListItem>> RefreshItemsAsync(bool forcePersistent = false)
        {
            using (var op = Logger.BeginOperation("Refreshing library items"))
            {
                if (forcePersistent)
                {
                    // clearing pending changes in tracker to force load data from database
                    Context.ChangeTracker.Clear();
                }

                Items = new ObservableCollection<ListItem>(await GetItemsAsync());

                await LibraryChanged();

                if (OnItemsFiltered != null)
                    await OnItemsFiltered.Invoke(Filter.ApplyFilter(Items));
                
                op.Complete();

                return Items;
            }
        }

        public IEnumerable<ListItem> GetItems<T>()
        {
            return Items.Where(i => i.DataItem is T).DistinctBy(i => i.Key);
        }

        public async Task<Library> GetByUserAsync(Guid userId)
        {
            using (var op = Logger.BeginDebugOperation("Getting library by user"))
            {
                op.Enrich("UserId", userId);
                
                var user = await Context
                    .Users
                    .Include(u => u.Library)
                    .ThenInclude(l => l.Games)
                    .FirstOrDefaultAsync(u => u.Id == userId);

                try
                {
                    if (user == null)
                    {
                        user = new User
                        {
                            Id = userId,
                        };
                
                        user = Context.Users.Add(user).Entity;
                    
                        await Context.SaveChangesAsync();
                    }

                    if (user.Library == null)
                    {
                        user.Library = new Library();
                
                        user = Context.Users.Update(user).Entity;
                
                        await Context.SaveChangesAsync();
                    }
                }
                catch (Exception ex)
                {
                    Logger.LogError(ex, "Failed to get user library");
                }
                
                op.Complete();
                
                return user.Library;
            }
        }

        private static bool IsInstalled(ListItem item)
        {
            return item != null && (item.State == ListItemState.Installed || item.State == ListItemState.UpdateAvailable);
        }

        public bool IsInstalled(Guid itemId)
        {
            return Items.Any(i => i.Key == itemId && IsInstalled(i));
        }

        public async Task<bool> IsInstalledAsync(Guid itemId)
        {
            using (var op = Logger.BeginDebugOperation("Checking if library item is installed"))
            {
                var items = await GetItemsAsync();

                var installed = items.Any(i => IsInstalled(i));

                op.Complete();
                
                return installed;
            }
        }

        public bool IsInLibrary(Guid itemId)
        {
            return Items.Any(i => i.Key == itemId);
        }

        public async Task<IEnumerable<ListItem>> GetItemsAsync()
        {
            Items.Clear();

            using (var op = Logger.BeginDebugOperation("Loading library items from local database"))
            {
                var games = await Context
                    .Games
                    .AsSplitQuery()
                    .Where(g => g.Libraries.Any(l => l.UserId == AuthenticationService.GetUserId()))
                    .Include(g => g.Media)
                    .Include(g => g.Platforms)
                    .Include(g => g.Collections)
                    .Include(g => g.Genres)
                    .Include(g => g.Engine)
                    .Include(g => g.Publishers)
                    .Include(g => g.Developers)
                    .Include(g => g.Tags)
                    .Include(g => g.MultiplayerModes)
                    .Include(g => g.DependentGames)
                    .ToListAsync();

                Filter.Populate(games);

                foreach (var item in games.Select(g => new ListItem(g)).OrderByTitle(g => !String.IsNullOrWhiteSpace(g.SortName) ? g.SortName : g.Name))
                {
                    Items.Add(item);
                }

                op.Complete();
            }

            return Items;
        }

        public IEnumerable<ListItem> GetFilteredItems()
        {
            return Filter.ApplyFilter(Items);
        }

        public ListItem GetItem(Guid key)
        {
            var item = Items.FirstOrDefault(i => i.Key == key);

            if (item == null)
                item = Items.FirstOrDefault(i => i.Key == key);

            return item;
        }

        public async Task<ListItem> GetItemAsync(ListItem libraryItem)
        {
            return await GetItemAsync(libraryItem.Key);
        }

        public async Task<ListItem> GetItemAsync(Guid key)
        {
            using (var op = Logger.BeginOperation("Getting library item"))
            {
                op.Enrich("Key", key);
                
                var game = await Context.Games
                    .AsSplitQuery()
                    .Include(g => g.Collections)
                    .Include(g => g.Developers)
                    .Include(g => g.Genres)
                    .Include(g => g.Publishers)
                    .Include(g => g.Tags)
                    .Include(g => g.PlaySessions)
                    .Include(g => g.Engine)
                    .Include(g => g.Platforms)
                    .Include(g => g.Media)
                    .Include(g => g.MultiplayerModes)
                    .Include(g => g.DependentGames)
                    .FirstOrDefaultAsync(g => g.Id == key);
                
                op.Complete();

                return new ListItem(game);
            }
        }

        public async Task AddToLibraryAsync(Game game)
        {
            using (var op = Logger.BeginOperation("Adding game to library"))
            {
                op.Enrich("Id", game.Id);
                op.Enrich("Title", game.Title);
                
                var library = await GetByUserAsync(AuthenticationService.GetUserId());

                if (library.Games.Where(g => g != null).All(g => g.Id != game.Id))
                {
                    library.Games.Add(game);

                    await UpdateAsync(library);
                }

                if (Items.All(i => i.Key != game.Id))
                {
                    var item = new ListItem(game);
                    Items.Add(item);

                    await LibraryItemsUpdated(itemsUpdatedOrAdded: [item]);
                }
                
                op.Complete();
            }
        }

        public async Task AddToLibraryAsync(Guid id)
        {
            using (var op = Logger.BeginOperation("Adding game to library using ID"))
            {
                op.Enrich("Id", id);
                
                var localGame = await GameService.GetAsync(id);

                await AddToLibraryAsync(localGame);

                await LibraryClient.AddToLibrary(id);
                
                op.Complete();
            }
        }

        public Task RemoveFromLibraryAsync(Guid id)
        {
            return RemoveFromLibraryAsync(id, []);
        }

        public async Task RemoveFromLibraryAsync(Guid id, params Guid[] addonIds)
        {
            using (var op = Logger.BeginOperation("Removing game from library"))
            {
                op.Enrich("Id", id);
                op.Enrich("AddonId", addonIds);
                
                var localGame = await GameService.GetAsync(id);
                var library = await GetByUserAsync(AuthenticationService.GetUserId());

                // update library items

                addonIds ??= [];
                foreach (var addonId in addonIds)
                {
                    var localAddon = await GameService.GetAsync(addonId);
                    if (localAddon != null)
                    {
                        library.Games.Remove(localAddon);
                    }
                }

                library.Games.Remove(localGame);
            
                await UpdateAsync(library);

                await LibraryClient.RemoveFromLibrary(id, addonIds);


                // handle removing item from libray list locally
            
                var itemToRemove = Items.FirstOrDefault(i => i.Key == id);
            
                if (itemToRemove != null)
                    Items.Remove(itemToRemove);

                var addonsToRemove = Items.Where(i => addonIds.Contains(i.Key));
                Items.RemoveRange(addonsToRemove);

                var itemsRemoved = addonsToRemove.Concat([itemToRemove!]) ?? [];
                await LibraryItemsUpdated(itemsRemoved: itemsRemoved);
                
                op.Complete();
            }
        }

        public async Task LibraryChanged(IEnumerable<ListItem>? items = null)
        {
            if (OnLibraryChanged != null)
                await OnLibraryChanged.Invoke(items ?? Items);
        }

        public async Task LibraryItemsUpdated(IEnumerable<ListItem>? itemsUpdatedOrAdded = null, IEnumerable<ListItem>? itemsRemoved = null)
        {
            if (OnLibraryItemsUpdated != null)
            {
                itemsUpdatedOrAdded = itemsUpdatedOrAdded?.ToArray() ?? [];
                itemsRemoved = itemsRemoved?.ToArray() ?? [];
                await OnLibraryItemsUpdated(itemsUpdatedOrAdded: itemsUpdatedOrAdded, itemsRemoved: itemsRemoved);
            }
        }

        public async Task FilterChanged()
        {
            Items = new ObservableCollection<ListItem>(await GetItemsAsync());
        }
    }
}