using Microsoft.EntityFrameworkCore;
using SharedLibraryCore.Database;
using SharedLibraryCore.Database.Models;
using SharedLibraryCore.Dtos;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using static SharedLibraryCore.Database.Models.EFClient;

namespace SharedLibraryCore.Services
{
    public class ClientService : Interfaces.IEntityService<EFClient>
    {
        public async Task<EFClient> Create(EFClient entity)
        {
            using (var context = new DatabaseContext())
            {
                int? linkId = null;
                int? aliasId = null;

                if (entity.IPAddress != null)
                {
                    var existingAliases = await context.Aliases
                        .Select(_alias => new { _alias.AliasId, _alias.LinkId, _alias.IPAddress, _alias.Name })
                        .Where(_alias => _alias.IPAddress == entity.IPAddress)
                        .ToListAsync();

                    if (existingAliases.Count > 0)
                    {
                        linkId = existingAliases.First().LinkId;

                        entity.CurrentServer.Logger.WriteDebug($"[create] client with new GUID {entity} has existing link {linkId}");

                        var existingExactAlias = existingAliases.FirstOrDefault(_alias => _alias.Name == entity.Name);

                        if (existingExactAlias != null)
                        {
                            entity.CurrentServer.Logger.WriteDebug($"[create] client with new GUID {entity} has existing alias {existingExactAlias.AliasId}");
                            aliasId = existingExactAlias.AliasId;
                        }
                    }
                }

                var client = new EFClient()
                {
                    Level = Permission.User,
                    FirstConnection = DateTime.UtcNow,
                    LastConnection = DateTime.UtcNow,
                    NetworkId = entity.NetworkId
                };


                entity.CurrentServer.Logger.WriteDebug($"[create] adding {entity} to context");
                context.Clients.Add(client);

                // they're just using a new GUID
                if (aliasId.HasValue)
                {
                    entity.CurrentServer.Logger.WriteDebug($"[create] setting {entity}'s alias id and linkid to ({aliasId.Value}, {linkId.Value})");
                    client.CurrentAliasId = aliasId.Value;
                    client.AliasLinkId = linkId.Value;
                }

                // link was found but they don't have an exact alias
                else if (!aliasId.HasValue && linkId.HasValue)
                {
                    entity.CurrentServer.Logger.WriteDebug($"[create] setting {entity}'s linkid to {linkId.Value}, but creating new alias");
                    client.AliasLinkId = linkId.Value;
                    client.CurrentAlias = new EFAlias()
                    {
                        Name = entity.Name,
                        SearchableName = entity.Name.StripColors().ToLower(),
                        DateAdded = DateTime.UtcNow,
                        IPAddress = entity.IPAddress,
                        LinkId = linkId.Value
                    };
                }

                // brand new players (supposedly)
                else
                {
                    entity.CurrentServer.Logger.WriteDebug($"[create] creating new Link and Alias for {entity}");
                    var link = new EFAliasLink();
                    var alias = new EFAlias()
                    {
                        Name = entity.Name,
                        SearchableName = entity.Name.StripColors().ToLower(),
                        DateAdded = DateTime.UtcNow,
                        IPAddress = entity.IPAddress,
                        Link = link
                    };

                    link.Children.Add(alias);

                    client.AliasLink = link;
                    client.CurrentAlias = alias;
                }

                await context.SaveChangesAsync();

                return client;
            }
        }

        private async Task UpdateAlias(string name, int? ip, EFClient entity, DatabaseContext context)
        {
            // entity is the tracked db context item
            // get all aliases by IP address and LinkId
            var iqAliases = context.Aliases
                .Include(a => a.Link)
                // we only want alias that have the same IP address or share a link
                .Where(_alias => _alias.IPAddress == ip || (_alias.LinkId == entity.AliasLinkId));

            var aliases = await iqAliases.ToListAsync();

            // see if they have a matching IP + Name but new NetworkId
            var existingExactAlias = aliases.FirstOrDefault(a => a.Name == name && a.IPAddress == ip);
            bool hasExactAliasMatch = existingExactAlias != null;

            // if existing alias matches link them
            var newAliasLink = existingExactAlias?.Link;
            // if no exact matches find the first IP or LinkId that matches
            newAliasLink = newAliasLink ?? aliases.OrderBy(_alias => _alias.LinkId).FirstOrDefault()?.Link;
            // if no matches are found, use our current one ( it will become permanent )
            newAliasLink = newAliasLink ?? entity.AliasLink;

            bool hasExistingAlias = aliases.Count > 0;
            bool isAliasLinkUpdated = newAliasLink.AliasLinkId != entity.AliasLink.AliasLinkId;

            await context.SaveChangesAsync();

            // this happens when the link we found is different than the one we create before adding an IP
            if (isAliasLinkUpdated)
            {
                entity.CurrentServer.Logger.WriteDebug($"[updatealias] found a link for {entity} so we are updating link from {entity.AliasLink.AliasLinkId} to {newAliasLink.AliasLinkId}");

                var oldAliasLink = entity.AliasLink;

                // update all the clients that have the old alias link
                await context.Clients
                    .Where(_client => _client.AliasLinkId == oldAliasLink.AliasLinkId)
                    .ForEachAsync(_client => _client.AliasLinkId = newAliasLink.AliasLinkId);

                // we also need to update all the penalties or they get deleted
                // scenario
                // link1 joins with ip1
                // link2 joins with ip2,
                // link2 receives penalty
                // link2 joins with ip1
                // pre existing link for link2 detected
                // link2 is deleted
                // link2 penalties are orphaned
                await context.Penalties
                    .Where(_penalty => _penalty.LinkId == oldAliasLink.AliasLinkId)
                    .ForEachAsync(_penalty => _penalty.LinkId = newAliasLink.AliasLinkId);

                entity.AliasLink = newAliasLink;
                entity.AliasLinkId = newAliasLink.AliasLinkId;

                // update all previous aliases
                await context.Aliases
                    .Where(_alias => _alias.LinkId == oldAliasLink.AliasLinkId)
                    .ForEachAsync(_alias => _alias.LinkId = newAliasLink.AliasLinkId);

                await context.SaveChangesAsync();
                // we want to delete the now inactive alias
                context.AliasLinks.Remove(oldAliasLink);
                await context.SaveChangesAsync();
            }

            // the existing alias matches ip and name, so we can just ignore the temporary one
            if (hasExactAliasMatch)
            {
                entity.CurrentServer.Logger.WriteDebug($"[updatealias] {entity} has exact alias match");

                var oldAlias = entity.CurrentAlias;
                entity.CurrentAliasId = existingExactAlias.AliasId;
                entity.CurrentAlias = existingExactAlias;
                await context.SaveChangesAsync();

                // the alias is the same so we can just remove it 
                if (oldAlias.AliasId != existingExactAlias.AliasId && oldAlias.AliasId > 0)
                {
                    await context.Clients
                        .Where(_client => _client.CurrentAliasId == oldAlias.AliasId)
                        .ForEachAsync(_client => _client.CurrentAliasId = existingExactAlias.AliasId);

                    await context.SaveChangesAsync();

                    if (context.Entry(oldAlias).State != EntityState.Deleted)
                    {
                        entity.CurrentServer.Logger.WriteDebug($"[updatealias] {entity} has exact alias match, so we're going to try to remove aliasId {oldAlias.AliasId} with linkId {oldAlias.AliasId}");
                        context.Aliases.Remove(oldAlias);
                        await context.SaveChangesAsync();
                    }
                }
            }

            // theres no exact match, but they've played before with the GUID or IP
            else
            {
                entity.CurrentServer.Logger.WriteDebug($"[updatealias] {entity} is using a new alias");

                var newAlias = new EFAlias()
                {
                    DateAdded = DateTime.UtcNow,
                    IPAddress = ip,
                    LinkId = newAliasLink.AliasLinkId,
                    Name = name,
                    SearchableName = name.StripColors().ToLower(),
                    Active = true,
                };

                entity.CurrentAlias = newAlias;
                entity.CurrentAliasId = 0;
                await context.SaveChangesAsync();
            }
        }

        /// <summary>
        /// updates the permission level of the given target to the given permission level
        /// </summary>
        /// <param name="newPermission"></param>
        /// <param name="temporalClient"></param>
        /// <param name="origin"></param>
        /// <param name="ctx"></param>
        /// <returns></returns>
        public async Task UpdateLevel(Permission newPermission, EFClient temporalClient, EFClient origin)
        {
            using (var ctx = new DatabaseContext())
            {
                var entity = await ctx.Clients
                    .Where(_client => _client.ClientId == temporalClient.ClientId)
                    .FirstAsync();

                var oldPermission = entity.Level;

                entity.Level = newPermission;
                await ctx.SaveChangesAsync();

#if DEBUG == true
                temporalClient.CurrentServer.Logger.WriteDebug($"Updated {temporalClient.ClientId} to {newPermission}");
#endif

                var linkedPermissionSet = new[] { Permission.Banned, Permission.Flagged };
                // if their permission level has been changed to level that needs to be updated on all accounts
                if (linkedPermissionSet.Contains(newPermission) || linkedPermissionSet.Contains(oldPermission))
                {
                    //get all clients that have the same linkId
                    var iqMatchingClients = ctx.Clients
                        .Where(_client => _client.AliasLinkId == entity.AliasLinkId);

                    // this updates the level for all the clients with the same LinkId
                    // only if their new level is flagged or banned
                    await iqMatchingClients.ForEachAsync(_client =>
                    {
                        _client.Level = newPermission;
#if DEBUG == true
                        temporalClient.CurrentServer.Logger.WriteDebug($"Updated linked {_client.ClientId} to {newPermission}");
#endif
                    });

                    await ctx.SaveChangesAsync();
                }
            }

            temporalClient.Level = newPermission;
        }

        public async Task<EFClient> Delete(EFClient entity)
        {
            using (var context = new DatabaseContext())
            {
                var client = context.Clients
                    .Single(e => e.ClientId == entity.ClientId);
                entity.Active = false;
                context.Entry(entity).State = EntityState.Modified;
                await context.SaveChangesAsync();
                return entity;
            }
        }

        public Task<IList<EFClient>> Find(Func<EFClient, bool> e)
        {
            throw new NotImplementedException();
        }

        public async Task<EFClient> Get(int entityId)
        {
            // todo: this needs to be optimized for large linked accounts
            using (var context = new DatabaseContext(true))
            {
                var client = context.Clients
                    .Select(_client => new EFClient()
                    {
                        ClientId = _client.ClientId,
                        AliasLinkId = _client.AliasLinkId,
                        Level = _client.Level,
                        Connections = _client.Connections,
                        FirstConnection = _client.FirstConnection,
                        LastConnection = _client.LastConnection,
                        Masked = _client.Masked,
                        NetworkId = _client.NetworkId,
                        CurrentAlias = new EFAlias()
                        {
                            Name = _client.CurrentAlias.Name,
                            IPAddress = _client.CurrentAlias.IPAddress
                        },
                        TotalConnectionTime = _client.TotalConnectionTime
                    })
                    .FirstOrDefault(_client => _client.ClientId == entityId);

                if (client == null)
                {
                    return null;
                }

                client.AliasLink = new EFAliasLink()
                {
                    AliasLinkId = client.AliasLinkId,
                    Children = await context.Aliases
                    .Where(_alias => _alias.LinkId == client.AliasLinkId)
                    .Select(_alias => new EFAlias()
                    {
                        Name = _alias.Name,
                        IPAddress = _alias.IPAddress
                    }).ToListAsync()
                };

                var foundClient = new
                {
                    Client = client,
                    LinkedAccounts = await context.Clients.Where(_client => _client.AliasLinkId == client.AliasLinkId)
                    .Select(_linkedClient => new
                    {
                        _linkedClient.ClientId,
                        _linkedClient.NetworkId
                    })
                    .ToListAsync()
                };

                if (foundClient == null)
                {
                    return null;
                }

                foundClient.Client.LinkedAccounts = new Dictionary<int, long>();
                // todo: find out the best way to do this
                // I'm doing this here because I don't know the best way to have multiple awaits in the query
                foreach (var linked in foundClient.LinkedAccounts)
                {
                    foundClient.Client.LinkedAccounts.Add(linked.ClientId, linked.NetworkId);
                }

                return foundClient.Client;
            }
        }

        private static readonly Func<DatabaseContext, long, Task<EFClient>> _getUniqueQuery =
            EF.CompileAsyncQuery((DatabaseContext context, long networkId) =>
                context.Clients
                .Include(c => c.CurrentAlias)
                .Select(_client => new EFClient()
                {
                    ClientId = _client.ClientId,
                    AliasLinkId = _client.AliasLinkId,
                    Level = _client.Level,
                    Connections = _client.Connections,
                    FirstConnection = _client.FirstConnection,
                    LastConnection = _client.LastConnection,
                    Masked = _client.Masked,
                    NetworkId = _client.NetworkId,
                    TotalConnectionTime = _client.TotalConnectionTime
                })
                .FirstOrDefault(c => c.NetworkId == networkId)
        );

        public async Task<EFClient> GetUnique(long entityAttribute)
        {
            using (var context = new DatabaseContext(true))
            {
                return await _getUniqueQuery(context, entityAttribute);
            }
        }

        public async Task UpdateAlias(EFClient temporalClient)
        {
            using (var context = new DatabaseContext())
            {
                var entity = context.Clients
                    .Include(c => c.AliasLink)
                    .Include(c => c.CurrentAlias)
                    .First(e => e.ClientId == temporalClient.ClientId);

                entity.CurrentServer = temporalClient.CurrentServer;

                await UpdateAlias(temporalClient.Name, temporalClient.IPAddress, entity, context);

                temporalClient.CurrentAlias = entity.CurrentAlias;
                temporalClient.CurrentAliasId = entity.CurrentAliasId;
                temporalClient.AliasLink = entity.AliasLink;
                temporalClient.AliasLinkId = entity.AliasLinkId;
            }
        }

        public async Task<EFClient> Update(EFClient temporalClient)
        {
            if (temporalClient.ClientId < 1)
            {
                temporalClient.CurrentServer?.Logger.WriteDebug($"[update] {temporalClient} needs to be updated but they do not have a valid client id, ignoring..");
                // note: we never do anything with the result of this so we can safely return null
                return null;
            }

            using (var context = new DatabaseContext())
            {
                // grab the context version of the entity
                var entity = context.Clients
                    .First(client => client.ClientId == temporalClient.ClientId);

                if (temporalClient.LastConnection > entity.LastConnection)
                {
                    entity.LastConnection = temporalClient.LastConnection;
                }

                if (temporalClient.Connections > entity.Connections)
                {
                    entity.Connections = temporalClient.Connections;
                }

                entity.Masked = temporalClient.Masked;

                if (temporalClient.TotalConnectionTime > entity.TotalConnectionTime)
                {
                    entity.TotalConnectionTime = temporalClient.TotalConnectionTime;
                }

                if (temporalClient.Password != null)
                {
                    entity.Password = temporalClient.Password;
                }

                if (temporalClient.PasswordSalt != null)
                {
                    entity.PasswordSalt = temporalClient.PasswordSalt;
                }

                // update in database
                await context.SaveChangesAsync();
                return entity;
            }
        }

        #region ServiceSpecific
        public async Task<IList<EFClient>> GetOwners()
        {
            using (var context = new DatabaseContext())
            {
                return await context.Clients
                    .Where(c => c.Level == Permission.Owner)
                    .ToListAsync();
            }
        }

        /// <summary>
        /// retrieves the number of owners 
        /// (client level is owner)
        /// </summary>
        /// <returns></returns>
        public async Task<int> GetOwnerCount()
        {
            using (var ctx = new DatabaseContext(true))
            {
                return await ctx.Clients
                    .CountAsync(_client => _client.Level == Permission.Owner);
            }
        }

        public async Task<EFClient> GetClientForLogin(int clientId)
        {
            using (var ctx = new DatabaseContext(true))
            {
                return await ctx.Clients
                    .Select(_client => new EFClient()
                    {
                        NetworkId = _client.NetworkId,
                        ClientId = _client.ClientId,
                        CurrentAlias = new EFAlias()
                        {
                            Name = _client.CurrentAlias.Name
                        },
                        Password = _client.Password,
                        PasswordSalt = _client.PasswordSalt,
                        Level = _client.Level
                    })
                    .FirstAsync(_client => _client.ClientId == clientId);
            }
        }

        public async Task<List<EFClient>> GetPrivilegedClients(bool includeName = true)
        {
            using (var context = new DatabaseContext(disableTracking: true))
            {
                var iqClients = from client in context.Clients.AsNoTracking()
                                where client.Level >= Permission.Trusted
                                where client.Active
                                select new EFClient()
                                {
                                    AliasLinkId = client.AliasLinkId,
                                    CurrentAlias = client.CurrentAlias,
                                    ClientId = client.ClientId,
                                    Level = client.Level,
                                    Password = client.Password,
                                    PasswordSalt = client.PasswordSalt,
                                    NetworkId = client.NetworkId,
                                    LastConnection = client.LastConnection
                                };

#if DEBUG == true
                var clientsSql = iqClients.ToSql();
#endif

                return await iqClients.ToListAsync();
            }
        }

        public async Task<IList<PlayerInfo>> FindClientsByIdentifier(string identifier)
        {
            if (identifier?.Length < 3)
            {
                return new List<PlayerInfo>();
            }

            using (var context = new DatabaseContext(disableTracking: true))
            {
                long? networkId = null;
                try
                {
                    networkId = identifier.ConvertGuidToLong();
                }
                catch { }

                int? ipAddress = identifier.ConvertToIP();

                IQueryable<EFAlias> iqLinkIds = context.Aliases.Where(_alias => _alias.Active);

                // we want to query for the IP ADdress
                if (ipAddress != null)
                {
                    iqLinkIds = iqLinkIds.Where(_alias => _alias.IPAddress == ipAddress);
                }

                // want to find them by name (wildcard)
                else
                {
                    iqLinkIds = iqLinkIds.Where(_alias => EF.Functions.Like((_alias.SearchableName ?? _alias.Name.ToLower()), $"%{identifier.ToLower()}%"));
                }

                var linkIds = await iqLinkIds
                    .Select(_alias => _alias.LinkId)
                    .ToListAsync();

                // get all the clients that match the alias link or the network id
                var iqClients = context.Clients
                    .Where(_client => _client.Active);


                iqClients = iqClients.Where(_client => networkId == _client.NetworkId || linkIds.Contains(_client.AliasLinkId));

                // we want to project our results 
                var iqClientProjection = iqClients.OrderByDescending(_client => _client.LastConnection)
                    .Select(_client => new PlayerInfo()
                    {
                        Name = _client.CurrentAlias.Name,
                        LevelInt = (int)_client.Level,
                        LastConnection = _client.LastConnection,
                        ClientId = _client.ClientId,
                    });
#if DEBUG == true
                var iqClientsSql = iqClients.ToSql();
#endif
                var clients = await iqClientProjection.ToListAsync();

                // this is so we don't try to evaluate this in the linq to entities query
                foreach (var client in clients)
                {
                    client.Level = ((Permission)client.LevelInt).ToLocalizedLevelName();
                }

                return clients;
            }
        }

        public async Task<int> GetTotalClientsAsync()
        {
            using (var context = new DatabaseContext(true))
            {
                return await context.Clients
                    .CountAsync();
            }
        }

        /// <summary>
        /// Returns the number of clients seen today
        /// </summary>
        /// <returns></returns>
        public async Task<int> GetRecentClientCount()
        {
            using (var context = new DatabaseContext(true))
            {
                var startOfPeriod = DateTime.UtcNow.AddHours(-24);
                var iqQuery = context.Clients.Where(_client => _client.LastConnection >= startOfPeriod);
#if DEBUG
                string sql = iqQuery.ToSql();
#endif
                return await iqQuery.CountAsync();
            }
        }

        /// <summary>
        /// gets the 10 most recently added clients to IW4MAdmin
        /// </summary>
        /// <returns></returns>
        public async Task<IList<PlayerInfo>> GetRecentClients()
        {
            var startOfPeriod = DateTime.UtcNow.AddHours(-24);

            using (var context = new DatabaseContext(true))
            {
                var iqClients = context.Clients
                    .Where(_client => _client.CurrentAlias.IPAddress != null)
                    .Where(_client => _client.FirstConnection >= startOfPeriod)
                    .OrderByDescending(_client => _client.FirstConnection)
                    .Select(_client => new PlayerInfo()
                    {
                        ClientId = _client.ClientId,
                        Name = _client.CurrentAlias.Name,
                        IPAddress = _client.CurrentAlias.IPAddress.ConvertIPtoString(),
                        LastConnection = _client.FirstConnection
                    });

#if DEBUG
                var sql = iqClients.ToSql();
#endif
                return await iqClients.ToListAsync();
            }
        }
        #endregion

        /// <summary>
        /// retrieves the number of times the given client id has been reported
        /// </summary>
        /// <param name="clientId">client id to search for report counts of</param>
        /// <returns></returns>
        public async Task<int> GetClientReportCount(int clientId)
        {
            using (var ctx = new DatabaseContext(true))
            {
                return await ctx.Penalties
                    .Where(_penalty => _penalty.Active)
                    .Where(_penalty => _penalty.OffenderId == clientId)
                    .Where(_penalty => _penalty.Type == EFPenalty.PenaltyType.Report)
                    .CountAsync();
            }
        }

        /// <summary>
        /// indicates if the given clientid has been autoflagged 
        /// </summary>
        /// <param name="clientId"></param>
        /// <returns></returns>
        public async Task<bool> IsAutoFlagged(int clientId)
        {
            using (var ctx = new DatabaseContext(true))
            {
                var now = DateTime.UtcNow;
                return await ctx.Penalties
                    .Where(_penalty => _penalty.Active)
                    .Where(_penalty => _penalty.OffenderId == clientId)
                    .Where(_penalty => _penalty.Type == EFPenalty.PenaltyType.Flag)
                    .Where(_penalty => _penalty.PunisherId == 1)
                    .Where(_penalty => _penalty.Expires == null || _penalty.Expires > now)
                    .AnyAsync();
            }
        }

        /// <summary>
        /// Unlinks shared GUID account into its own separate account
        /// </summary>
        /// <param name="clientId"></param>
        /// <returns></returns>
        public async Task UnlinkClient(int clientId)
        {
            using (var ctx = new DatabaseContext())
            {
                var newLink = new EFAliasLink() { Active = true };
                ctx.AliasLinks.Add(newLink);
                await ctx.SaveChangesAsync();

                var client = await ctx.Clients.Include(_client => _client.CurrentAlias)
                    .FirstAsync(_client => _client.ClientId == clientId);
                client.AliasLinkId = newLink.AliasLinkId;
                client.Level = Permission.User;

                await ctx.Aliases.Where(_alias => _alias.IPAddress == client.IPAddress)
                    .ForEachAsync(_alias => _alias.LinkId = newLink.AliasLinkId);

                await ctx.SaveChangesAsync();
            }
        }
    }
}