using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using AsbCloudApp.Data;
using AsbCloudDb.Model;
using AsbCloudInfrastructure.Services.Cache;
using Mapster;

namespace AsbCloudInfrastructure.Services
{
    public class UserRoleService : CrudServiceBase<UserRoleDto, UserRole>
    {
        private readonly CacheTable<UserRole> cacheUserRoles;
        private readonly CacheTable<Permission> cachePermissions;
        private readonly CacheTable<RelationUserRolePermission> cacheUserRolesPermissions;
        private int counter = 0;

        public UserRoleService(IAsbCloudDbContext context, CacheDb cacheDb) : base(context)
        {
            cacheUserRoles = cacheDb.GetCachedTable<UserRole>((AsbCloudDbContext)context);
            cachePermissions = cacheDb.GetCachedTable<Permission>((AsbCloudDbContext)context);
            cacheUserRolesPermissions = 
                cacheDb.GetCachedTable<RelationUserRolePermission>((AsbCloudDbContext)context);
        }

        public override async Task<PaginationContainer<UserRoleDto>> GetPageAsync(int skip = 0, 
            int take = 32, CancellationToken token = default)
        {
            var rolesDtos = await base.GetPageAsync(skip, take,token);

            rolesDtos.Items = rolesDtos.Items.Select(FillUserRoleWithPermissions).ToList();

            return rolesDtos;
        }

        public override async Task<UserRoleDto> GetAsync(int id, CancellationToken token = default)
        {
            var roleDto = await base.GetAsync(id,token);

            return roleDto is null 
                ? null 
                : FillUserRoleWithPermissions(roleDto);
        }

        public override async Task<int> InsertAsync(UserRoleDto dto, CancellationToken token = default)
        {

            dto.PermissionIds = GetAncestorsPermissionIds(dto, ref counter);

            var newRoleId = await base.InsertAsync(dto, token);

            if (dto.PermissionIds == default)
                return newRoleId;
            
            foreach (var pId in dto.PermissionIds)
            {
                var relation = new RelationUserRolePermission()
                {
                    IdUserRole = newRoleId,
                    IdPermission = pId
                };

                context.RelationUserRolesPermissions.Add(relation);
            }
            
            return await context.SaveChangesAsync(token);
        }

        public override async Task<int> UpdateAsync(int id, UserRoleDto item, CancellationToken token = default)
        {
            var result = await base.UpdateAsync(id, item, token);

            if (item.PermissionIds == default) 
                return result;
            
            await cacheUserRolesPermissions.RemoveAsync(r => r.IdUserRole == item.Id, token)
                .ConfigureAwait(false);

            var newRelations = item.PermissionIds.Select(p => new RelationUserRolePermission()
            {
                IdUserRole = item.Id,
                IdPermission = p
            });
            await cacheUserRolesPermissions.InsertAsync(newRelations, token);

            return result;
        }

        private UserRoleDto FillUserRoleWithPermissions(UserRoleDto roleDto)
        {
            var rolePermissionIds = cacheUserRolesPermissions.Where(c =>
                c.IdUserRole == roleDto.Id).Select(p => p.IdPermission);
            roleDto.Permissions = cachePermissions.Where(permission => rolePermissionIds.Contains(permission.Id))
                .Adapt<PermissionDto>();

            return roleDto;
        }

        private IEnumerable<int> GetAncestorsPermissionIds(UserRoleDto userRoleDto, ref int counter)
        {
            var idParent = userRoleDto.IdParent;
            var resultPermissionsIds = userRoleDto.PermissionIds ?? new List<int>();

            if (idParent == default) 
                return resultPermissionsIds;

            if (counter > 10)
            {
                Trace.WriteLine($"User role with id: {userRoleDto.Id} has more than 10 nested parents");
                return resultPermissionsIds;
            }

            var parentRole = cacheUserRoles.FirstOrDefault(r => r.Id == idParent)
                .Adapt<UserRoleDto>();
            var parentRolePermissionsIds = cacheUserRolesPermissions.Where(p =>
                p.IdUserRole == parentRole.Id).Select(perm => perm.IdPermission);
            parentRole.PermissionIds = resultPermissionsIds.Union(parentRolePermissionsIds);

            counter++;

            return GetAncestorsPermissionIds(parentRole, ref counter);
        }
    }
}