using Microsoft.EntityFrameworkCore;
using SharedLibraryCore.Database;
using SharedLibraryCore.Database.Models;
using SharedLibraryCore.Dtos;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Threading.Tasks;
using SharedLibraryCore.Interfaces;

namespace SharedLibraryCore.Services
{
    public class PenaltyService : Interfaces.IEntityService<EFPenalty>
    {
        private readonly IDatabaseContextFactory _contextFactory;
        
        public PenaltyService(IDatabaseContextFactory contextFactory)
        {
            _contextFactory = contextFactory;
        }
        
        public virtual async Task<EFPenalty> Create(EFPenalty newEntity)
        {
            await using var context = _contextFactory.CreateContext();
            var penalty = new EFPenalty()
            {
                Active = true,
                OffenderId = newEntity.Offender.ClientId,
                PunisherId = newEntity.Punisher.ClientId,
                LinkId = newEntity.Link.AliasLinkId,
                Type = newEntity.Type,
                Expires = newEntity.Expires,
                Offense = newEntity.Offense,
                When = DateTime.UtcNow,
                AutomatedOffense = newEntity.AutomatedOffense ?? newEntity.Punisher.AdministeredPenalties?.FirstOrDefault()?.AutomatedOffense,
                IsEvadedOffense = newEntity.IsEvadedOffense
            };

            context.Penalties.Add(penalty);
            await context.SaveChangesAsync();

            return newEntity;
        }

        public Task<EFPenalty> Delete(EFPenalty entity)
        {
            throw new NotImplementedException();
        }

        public async Task<IList<EFPenalty>> Find(Func<EFPenalty, bool> expression)
        {
            throw await Task.FromResult(new Exception());
        }

        public Task<EFPenalty> Get(int entityID)
        {
            throw new NotImplementedException();
        }

        public Task<EFPenalty> GetUnique(long entityProperty)
        {
            throw new NotImplementedException();
        }

        public Task<EFPenalty> Update(EFPenalty entity)
        {
            throw new NotImplementedException();
        }

        public async Task<IList<PenaltyInfo>> GetRecentPenalties(int count, int offset, EFPenalty.PenaltyType showOnly = EFPenalty.PenaltyType.Any, bool ignoreAutomated = true)
        {
            await using var context = _contextFactory.CreateContext(false);
            var iqPenalties = context.Penalties
                .Where(p => showOnly == EFPenalty.PenaltyType.Any ? p.Type != EFPenalty.PenaltyType.Any : p.Type == showOnly)
                .Where(_penalty => ignoreAutomated ? _penalty.PunisherId != 1 : true)
                .OrderByDescending(p => p.When)
                .Skip(offset)
                .Take(count)
                 .Select(_penalty => new PenaltyInfo()
                 {
                     Id = _penalty.PenaltyId,
                     Offense = _penalty.Offense,
                     AutomatedOffense = _penalty.AutomatedOffense,
                     OffenderId = _penalty.OffenderId,
                     OffenderName = _penalty.Offender.CurrentAlias.Name,
                     PunisherId = _penalty.PunisherId,
                     PunisherName = _penalty.Punisher.CurrentAlias.Name,
                     PunisherLevel = _penalty.Punisher.Level,
                     PenaltyType = _penalty.Type,
                     Expires = _penalty.Expires,
                     TimePunished = _penalty.When,
                     IsEvade = _penalty.IsEvadedOffense
                 });

            return await iqPenalties.ToListAsync();
        }

        /// <summary>
        /// retrieves penalty information for meta service
        /// </summary>
        /// <param name="clientId">database id of the client</param>
        /// <param name="count">how many items to retrieve</param>
        /// <param name="offset">not used</param>
        /// <param name="startAt">retreive penalties older than this</param>
        /// <returns></returns>
        public async Task<IList<PenaltyInfo>> GetClientPenaltyForMetaAsync(int clientId, int count, int offset, DateTime? startAt)
        {
            var linkedPenaltyType = Utilities.LinkedPenaltyTypes();

            await using var context = _contextFactory.CreateContext(false);
            var linkId = await context.Clients.AsNoTracking()
                .Where(_penalty => _penalty.ClientId == clientId)
                .Select(_penalty => _penalty.AliasLinkId)
                .FirstOrDefaultAsync();

            var iqPenalties = context.Penalties.AsNoTracking()
                .Where(_penalty => _penalty.OffenderId == clientId || _penalty.PunisherId == clientId || (linkedPenaltyType.Contains(_penalty.Type) && _penalty.LinkId == linkId))
                .Where(_penalty => _penalty.When <= startAt)
                .OrderByDescending(_penalty => _penalty.When)
                .Skip(offset)
                .Take(count)
                .Select(_penalty => new PenaltyInfo()
                {
                    Id = _penalty.PenaltyId,
                    Offense = _penalty.Offense,
                    AutomatedOffense = _penalty.AutomatedOffense,
                    OffenderId = _penalty.OffenderId,
                    OffenderName = _penalty.Offender.CurrentAlias.Name,
                    PunisherId = _penalty.PunisherId,
                    PunisherName = _penalty.Punisher.CurrentAlias.Name,
                    PunisherLevel = _penalty.Punisher.Level,
                    PenaltyType = _penalty.Type,
                    Expires = _penalty.Expires,
                    TimePunished = _penalty.When,
                    IsEvade = _penalty.IsEvadedOffense
                });

            return await iqPenalties.Distinct().ToListAsync();
        }

        public async Task<List<EFPenalty>> GetActivePenaltiesAsync(int linkId, int? ip = null, bool includePunisherName = false)
        {
            var now = DateTime.UtcNow;

            Expression<Func<EFPenalty, bool>> filter = (p) => (new EFPenalty.PenaltyType[]
                         {
                            EFPenalty.PenaltyType.TempBan,
                            EFPenalty.PenaltyType.Ban,
                            EFPenalty.PenaltyType.Flag
                         }.Contains(p.Type) &&
                         p.Active &&
                         (p.Expires == null || p.Expires > now));

            await using var context = _contextFactory.CreateContext(false);
            var iqLinkPenalties = context.Penalties
                .Where(p => p.LinkId == linkId)
                .Where(filter);

            var iqIPPenalties = context.Aliases
                .Where(a => a.IPAddress != null && a.IPAddress == ip)
                .SelectMany(a => a.Link.ReceivedPenalties)
                .Where(filter);

            var activePenalties = (await iqLinkPenalties.ToListAsync())
                .Union(await iqIPPenalties.ToListAsync())
                .Distinct();

            // this is a bit more performant in memory (ordering)
            return activePenalties.OrderByDescending(p => p.When).ToList();
        }

        public virtual async Task RemoveActivePenalties(int aliasLinkId)
        {
            await using var context = _contextFactory.CreateContext();

            var now = DateTime.UtcNow;
            await context.Penalties
                .Where(p => p.LinkId == aliasLinkId)
                .Where(p => p.Expires > now || p.Expires == null)
                .ForEachAsync(p =>
                {
                    p.Active = false;
                    p.Expires = now;
                });

            await context.SaveChangesAsync();
        }
    }
}