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

namespace AsbCloudInfrastructure.Services
{
    public class UserRoleService : IUserRoleService
    {
        private readonly CacheTable<UserRole> cacheUserRoles;
        private readonly IPermissionService permissionService;

        public List<string> Includes { get; } = new();

        public UserRoleService(IAsbCloudDbContext context, CacheDb cacheDb, IPermissionService permissionService)
        {
            cacheUserRoles = cacheDb.GetCachedTable<UserRole>((AsbCloudDbContext)context, new [] { nameof(UserRole.Permissions) });
            this.permissionService = permissionService;
        }

        public async Task<IEnumerable<UserRoleDto>> GetAllAsync(CancellationToken token = default)
        {
            var entities = await cacheUserRoles.WhereAsync(token)
                .ConfigureAwait(false);
            var dtos = entities.Adapt<UserRoleDto>();
            return dtos;
        }

        public async Task<UserRoleDto> GetAsync(int id, CancellationToken token = default)
        {
            var entity = await cacheUserRoles.FirstOrDefaultAsync(r=>r.Id == id, token)
                .ConfigureAwait(false);
            var dto = entity?.Adapt<UserRoleDto>();
            return dto;
        }

        public async Task<int> InsertAsync(UserRoleDto dto, CancellationToken token = default)
        {
            var entity = dto.Adapt<UserRole>();
            var updatedEntity = await cacheUserRoles.InsertAsync(entity, token).ConfigureAwait(false);
            if (dto.Permissions?.Any() != true)
                return updatedEntity?.Id ?? 0;
            foreach (var permission in dto.Permissions)
                permission.IdUserRole = updatedEntity.Id;
            await permissionService.InsertRangeAsync(dto.Permissions, token).ConfigureAwait(false);
            await cacheUserRoles.RefreshAsync(true, token)
                .ConfigureAwait(false);
            return updatedEntity?.Id ?? 0;
        }

        public async Task<int> InsertRangeAsync(IEnumerable<UserRoleDto> dtos, CancellationToken token = default)
        {
            var entities = dtos.Adapt<UserRole>();
            return await cacheUserRoles.InsertAsync(entities, token).ConfigureAwait(false);
        }

        public async Task<int> UpdateAsync(int id, UserRoleDto dto, CancellationToken token = default)
        {
            var entity = dto.Adapt<UserRole>();
            entity.Id = id;
            await cacheUserRoles.UpsertAsync(entity, token)
                .ConfigureAwait(false);

            if(dto.Permissions is not null)
            {
                await permissionService.DeleteAllByRoleAsync(id, token)
                    .ConfigureAwait(false);

                if (dto.Permissions.Any())
                {
                    foreach (var permission in dto.Permissions)
                        permission.IdUserRole = id;

                    await permissionService.InsertRangeAsync(dto.Permissions, token)
                        .ConfigureAwait(false);
                }

                await cacheUserRoles.RefreshAsync(true, token)
                    .ConfigureAwait(false);
            }

            return id;
        }

        private IEnumerable<Permission> GetNestedPermissions(UserRole role, int counter = 10)
        {
            var permissions = role.Permissions.ToList();
            if (role.IdParent is null) 
                return permissions;
            if (counter == 0)
            {
                Trace.WriteLine($"User role with id: {role.Id} has more than 10 nested childs");
                return permissions;
            }
            var parentRole = cacheUserRoles.FirstOrDefault(r => r.Id == role.IdParent);

            if (parentRole is null)
                return permissions;

            var parentPermissions = GetNestedPermissions(parentRole, --counter);
            Merge(ref permissions, parentPermissions);
            return permissions;
        }

        private static void Merge(ref List<Permission> permissions, IEnumerable<Permission> newPermissions)
        {
            foreach (var newPermission in newPermissions)
            {
                var permissionIndex = permissions.FindIndex(p => p.IdPermission == newPermission.IdPermission);
                if (permissionIndex == -1)
                    permissions.Add(newPermission);
                else
                {
                    var permission = permissions[permissionIndex];
                    permissions[permissionIndex] = new Permission
                    {
                        IdPermission = permission.IdPermission,
                        IdUserRole = permission.IdUserRole,
                        PermissionValue = permission.PermissionValue | newPermission.PermissionValue,
                    };
                }
            }
        }

        public Task<int> DeleteAsync(int id, CancellationToken token = default)
        => cacheUserRoles.RemoveAsync(r => r.Id == id, token);

        public Task<int> DeleteAsync(IEnumerable<int> ids, CancellationToken token = default)
        => cacheUserRoles.RemoveAsync(r => ids.Contains(r.Id), token);
    }
}