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

namespace AsbCloudInfrastructure.Services
{
    public class UserRoleService : IUserRoleService
    {
        private readonly IAsbCloudDbContext db;
        private readonly CacheTable<UserRole> cacheUserRoles;
        private readonly CacheTable<Permission> cachePermissions;
        private readonly CacheTable<RelationUserRolePermission> cacheUserRolesPermissions;

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

        public async Task<IEnumerable<UserRoleDto>> GetAllAsync(CancellationToken token)
        {
            var rolesDtos = (await cacheUserRoles.WhereAsync(token).ConfigureAwait(false))
                .Adapt<UserRoleDto>();

            return rolesDtos.Select(FillUserRoleWithPermissions);
        }

        public async Task<UserRoleDto> GetAsync(int id, CancellationToken token)
        {
            var roleDto = (await cacheUserRoles.FirstOrDefaultAsync(r => r.Id == id, token)
                .ConfigureAwait(false)).Adapt<UserRoleDto>();

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

        public async Task<int> InsertAsync(UserRoleDto dto, CancellationToken token = default)
        {
            var newRole = dto.Adapt<UserRole>();
            db.UserRoles.Add(newRole);
            var result = await db.SaveChangesAsync(token);

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

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

        public async Task UpdateAsync(UserRoleDto dto, CancellationToken token = default)
        {
            var entity = dto.Adapt<UserRole>();
            db.UserRoles.Update(entity);
            await db.SaveChangesAsync(token);

            if (dto.PermissionIds != default)
            {
                await cacheUserRolesPermissions.RemoveAsync(r => r.IdUserRole == dto.Id, token)
                    .ConfigureAwait(false);

                var newRelations = dto.PermissionIds.Select(p => new RelationUserRolePermission()
                {
                    IdUserRole = dto.Id,
                    IdPermission = p
                });
                await cacheUserRolesPermissions.InsertAsync(newRelations, token);
            }
        }
        
        public async Task<int> DeleteAsync(IEnumerable<int> ids, CancellationToken token)
        {
            var entities = cacheUserRoles.Where(e => ids.Contains(e.Id));
            if (entities == default)
                return 0;
            db.UserRoles.RemoveRange(entities);
            return await db.SaveChangesAsync(token);
        }

        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;
        }
    }
}