using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Threading.Tasks;
using Jellyfin.Data.Entities;
using Jellyfin.Data.Entities.Security;
using Jellyfin.Data.Enums;
using Jellyfin.Data.Events;
using Jellyfin.Data.Queries;
using Jellyfin.Extensions;
using MediaBrowser.Controller.Devices;
using MediaBrowser.Controller.Library;
using MediaBrowser.Model.Devices;
using MediaBrowser.Model.Querying;
using MediaBrowser.Model.Session;
using Microsoft.EntityFrameworkCore;

namespace Jellyfin.Server.Implementations.Devices
{
    /// <summary>
    /// Manages the creation, updating, and retrieval of devices.
    /// </summary>
    public class DeviceManager : IDeviceManager
    {
        private readonly JellyfinDbProvider _dbProvider;
        private readonly IUserManager _userManager;
        private readonly ConcurrentDictionary<string, ClientCapabilities> _capabilitiesMap = new();

        /// <summary>
        /// Initializes a new instance of the <see cref="DeviceManager"/> class.
        /// </summary>
        /// <param name="dbProvider">The database provider.</param>
        /// <param name="userManager">The user manager.</param>
        public DeviceManager(JellyfinDbProvider dbProvider, IUserManager userManager)
        {
            _dbProvider = dbProvider;
            _userManager = userManager;
        }

        /// <inheritdoc />
        public event EventHandler<GenericEventArgs<Tuple<string, DeviceOptions>>>? DeviceOptionsUpdated;

        /// <inheritdoc />
        public void SaveCapabilities(string deviceId, ClientCapabilities capabilities)
        {
            _capabilitiesMap[deviceId] = capabilities;
        }

        /// <inheritdoc />
        public async Task UpdateDeviceOptions(string deviceId, string deviceName)
        {
            await using var dbContext = _dbProvider.CreateContext();
            var deviceOptions = await dbContext.DeviceOptions.AsQueryable().FirstOrDefaultAsync(dev => dev.DeviceId == deviceId).ConfigureAwait(false);
            if (deviceOptions == null)
            {
                deviceOptions = new DeviceOptions(deviceId);
                dbContext.DeviceOptions.Add(deviceOptions);
            }

            deviceOptions.CustomName = deviceName;
            await dbContext.SaveChangesAsync().ConfigureAwait(false);

            DeviceOptionsUpdated?.Invoke(this, new GenericEventArgs<Tuple<string, DeviceOptions>>(new Tuple<string, DeviceOptions>(deviceId, deviceOptions)));
        }

        /// <inheritdoc />
        public async Task<Device> CreateDevice(Device device)
        {
            await using var dbContext = _dbProvider.CreateContext();

            dbContext.Devices.Add(device);

            await dbContext.SaveChangesAsync().ConfigureAwait(false);
            return device;
        }

        /// <inheritdoc />
        public async Task<DeviceOptions> GetDeviceOptions(string deviceId)
        {
            await using var dbContext = _dbProvider.CreateContext();
            var deviceOptions = await dbContext.DeviceOptions
                .AsQueryable()
                .FirstOrDefaultAsync(d => d.DeviceId == deviceId)
                .ConfigureAwait(false);

            return deviceOptions ?? new DeviceOptions(deviceId);
        }

        /// <inheritdoc />
        public ClientCapabilities GetCapabilities(string deviceId)
        {
            return _capabilitiesMap.TryGetValue(deviceId, out ClientCapabilities? result)
                ? result
                : new ClientCapabilities();
        }

        /// <inheritdoc />
        public async Task<DeviceInfo?> GetDevice(string id)
        {
            await using var dbContext = _dbProvider.CreateContext();
            var device = await dbContext.Devices
                .AsQueryable()
                .Where(d => d.DeviceId == id)
                .OrderByDescending(d => d.DateLastActivity)
                .Include(d => d.User)
                .FirstOrDefaultAsync()
                .ConfigureAwait(false);

            var deviceInfo = device == null ? null : ToDeviceInfo(device);

            return deviceInfo;
        }

        /// <inheritdoc />
        public async Task<QueryResult<Device>> GetDevices(DeviceQuery query)
        {
            await using var dbContext = _dbProvider.CreateContext();

            var devices = dbContext.Devices.AsQueryable();

            if (query.UserId.HasValue)
            {
                devices = devices.Where(device => device.UserId == query.UserId.Value);
            }

            if (query.DeviceId != null)
            {
                devices = devices.Where(device => device.DeviceId == query.DeviceId);
            }

            if (query.AccessToken != null)
            {
                devices = devices.Where(device => device.AccessToken == query.AccessToken);
            }

            var count = await devices.CountAsync().ConfigureAwait(false);

            if (query.Skip.HasValue)
            {
                devices = devices.Skip(query.Skip.Value);
            }

            if (query.Limit.HasValue)
            {
                devices = devices.Take(query.Limit.Value);
            }

            return new QueryResult<Device>
            {
                Items = await devices.ToListAsync().ConfigureAwait(false),
                StartIndex = query.Skip ?? 0,
                TotalRecordCount = count
            };
        }

        /// <inheritdoc />
        public async Task<QueryResult<DeviceInfo>> GetDeviceInfos(DeviceQuery query)
        {
            var devices = await GetDevices(query).ConfigureAwait(false);

            return new QueryResult<DeviceInfo>
            {
                Items = devices.Items.Select(device => ToDeviceInfo(device)).ToList(),
                StartIndex = devices.StartIndex,
                TotalRecordCount = devices.TotalRecordCount
            };
        }

        /// <inheritdoc />
        public async Task<QueryResult<DeviceInfo>> GetDevicesForUser(Guid? userId, bool? supportsSync)
        {
            await using var dbContext = _dbProvider.CreateContext();
            var sessions = dbContext.Devices
                .Include(d => d.User)
                .AsQueryable()
                .OrderByDescending(d => d.DateLastActivity)
                .ThenBy(d => d.DeviceId)
                .AsAsyncEnumerable();

            if (supportsSync.HasValue)
            {
                sessions = sessions.Where(i => GetCapabilities(i.DeviceId).SupportsSync == supportsSync.Value);
            }

            if (userId.HasValue)
            {
                var user = _userManager.GetUserById(userId.Value);

                sessions = sessions.Where(i => CanAccessDevice(user, i.DeviceId));
            }

            var array = await sessions.Select(device => ToDeviceInfo(device)).ToArrayAsync().ConfigureAwait(false);

            return new QueryResult<DeviceInfo>(array);
        }

        /// <inheritdoc />
        public async Task DeleteDevice(Device device)
        {
            await using var dbContext = _dbProvider.CreateContext();
            dbContext.Devices.Remove(device);
            await dbContext.SaveChangesAsync().ConfigureAwait(false);
        }

        /// <inheritdoc />
        public bool CanAccessDevice(User user, string deviceId)
        {
            if (user == null)
            {
                throw new ArgumentNullException(nameof(user));
            }

            if (string.IsNullOrEmpty(deviceId))
            {
                throw new ArgumentNullException(nameof(deviceId));
            }

            if (user.HasPermission(PermissionKind.EnableAllDevices) || user.HasPermission(PermissionKind.IsAdministrator))
            {
                return true;
            }

            return user.GetPreference(PreferenceKind.EnabledDevices).Contains(deviceId, StringComparison.OrdinalIgnoreCase)
                   || !GetCapabilities(deviceId).SupportsPersistentIdentifier;
        }

        private DeviceInfo ToDeviceInfo(Device authInfo)
        {
            var caps = GetCapabilities(authInfo.DeviceId);

            return new DeviceInfo
            {
                AppName = authInfo.AppName,
                AppVersion = authInfo.AppVersion,
                Id = authInfo.DeviceId,
                LastUserId = authInfo.UserId,
                LastUserName = authInfo.User.Username,
                Name = authInfo.DeviceName,
                DateLastActivity = authInfo.DateLastActivity,
                IconUrl = caps.IconUrl
            };
        }
    }
}