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;
using System;

namespace AsbCloudInfrastructure.Services
{
    public class UserRoleService : IUserRoleService
    {
        private readonly CacheTable<UserRole> cacheUserRoles;
        private readonly CacheTable<Permission> cachePermission;
        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.RelationUserRolePermissions) });
            cachePermission = cacheDb.GetCachedTable<Permission>((AsbCloudDbContext)context);
            this.permissionService = permissionService;
        }

        public async Task<int> InsertAsync(UserRoleDto dto, CancellationToken token = default)
        {
            var entity = dto.Adapt<UserRole>();
            var updatedEntity = await cacheUserRoles.InsertAsync(entity, token)
                .ConfigureAwait(false);
            await UpdatePermissionsAsync(dto, token);
            await cacheUserRoles.RefreshAsync(true, token)
                .ConfigureAwait(false);
            return updatedEntity?.Id ?? 0;
        }

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

        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<UserRoleDto> GetByNameAsync(string name, CancellationToken token = default)
        {
            var entity = await cacheUserRoles.FirstOrDefaultAsync(r => r.Caption == name, token)
                .ConfigureAwait(false);
            var dto = entity?.Adapt<UserRoleDto>();
            return dto;
        }

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

            await cacheUserRoles.UpsertAsync(entity, token)
                .ConfigureAwait(false);

            return id;
        }

        public List<UserRoleDto> GetNestedById(int id, int recursionLevel = 7)
        {
            var role = cacheUserRoles.FirstOrDefault(r => r.Id == id);
            if (role is null)
                return null;
            var dto = role.Adapt<UserRoleDto>();
            if (role.IdParent is null || recursionLevel == 0)
                return new List<UserRoleDto> { dto };
            var parentRoles = GetNestedById((int)role.IdParent, --recursionLevel) ??
                new List<UserRoleDto>();
            parentRoles.Add(dto);
            return parentRoles;
        }

        public IEnumerable<PermissionBaseDto> GetNestedPermissions(IEnumerable<UserRoleDto> roles)
        {
            var permissions = new Dictionary<int, PermissionBaseDto>(16);
            foreach (var roleDto in roles)
            {
                var role = cacheUserRoles.FirstOrDefault(r => r.Id == roleDto.Id);
                var rolePermissions = GetNestedPermissions(role, 10);
                if ((rolePermissions?.Any()) != true)                
                    continue;
                
                foreach (var newPermission in rolePermissions)
                {
                    if (permissions.ContainsKey(newPermission.Id))
                    {
                        permissions[newPermission.Id] = newPermission.Adapt<PermissionBaseDto>();
                    }
                    else
                    {
                        permissions.Add(newPermission.Id,
                            new PermissionBaseDto
                            {
                                Id = newPermission.Id,
                                Name = newPermission.Name ??
                                    cachePermission.FirstOrDefault(p => p.Id == newPermission.Id).Name
                            });
                    }
                }
            }

            return permissions.Values;
        }

        private async Task UpdatePermissionsAsync(UserRoleDto roleDto, CancellationToken token)
        {
            await permissionService.DeleteAllByRoleAsync(roleDto.Id, token)
                .ConfigureAwait(false);
            if (!roleDto.Permissions.Any())            
                return;
            
            var newPermissions = roleDto.Permissions.Select(p => new PermissionDto
            {
                Id = p.Id,
                IdUserRole = roleDto.Id,
                Name = p.Name
            });

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

        private IEnumerable<Permission> GetNestedPermissions(UserRole role, int recursionLevel = 7)
        {
            var permissionRelations = role.RelationUserRolePermissions.ToList();
            var permissionIds = permissionRelations.Select(p => p.IdPermission);
            if (role.IdParent is null) 
                return cachePermission.Where(c => permissionIds.Contains(c.Id));
            if (recursionLevel == 0)
            {
                Trace.WriteLine($"User role with id: {role.Id} has more than 10 nested children");
                cachePermission.Where(c => permissionIds.Contains(c.Id));
            }
            var parentRole = cacheUserRoles.FirstOrDefault(r => r.Id == role.IdParent);

            if (parentRole is null)
                return cachePermission.Where(c => permissionIds.Contains(c.Id));

            var parentPermissions = GetNestedPermissions(parentRole, --recursionLevel);
            
            return cachePermission.Where(c => permissionIds.Contains(c.Id)).Union(parentPermissions);
        }

        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);

        public bool HasPermission(IEnumerable<int> rolesIds, string permissionName)
        {
            var permissionInfo = cachePermission.FirstOrDefault(p => p.Name.ToLower() == permissionName.ToLower());

            if (permissionInfo is null)
                return false;

            var idPermissionInfo = permissionInfo.Id;
            var roles = cacheUserRoles.Where(r => rolesIds.Contains(r.Id));
            foreach (var role in roles)
                if (HasPermission(role, idPermissionInfo))
                    return true;
            return false;
        }

        private bool HasPermission(UserRole userRole, int idPermission, int recursionLevel = 7)
        {
            if (userRole.RelationUserRolePermissions.Any(p => p.IdPermission == idPermission))
                return true;
            if (userRole.IdParent is not null && recursionLevel > 0)
            {
                var parentRole = cacheUserRoles.FirstOrDefault(p => p.Id == userRole.IdParent);
                return HasPermission(parentRole, idPermission, --recursionLevel);
            }
            return false;
        }
    }
}