using AsbCloudApp.Data;
using AsbCloudApp.Repositories;
using AsbCloudApp.Requests;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Threading;
using System.Linq;
using System.ComponentModel.DataAnnotations;
using AsbCloudApp.Exceptions;

namespace AsbCloudApp.Services
{
    /// <summary>
    /// 
    /// </summary>
    /// <typeparam name="TDto"></typeparam>
    /// <typeparam name="TRequest"></typeparam>
    public abstract class ChangeLogServiceAbstract<TDto, TRequest>
    where TDto : ChangeLogAbstract
    where TRequest : ChangeLogBaseRequest
    {
        /// <summary>
        /// Репозиторий
        /// </summary>
        public IChangeLogRepository<TDto, TRequest>  repository { get; }

        /// <summary>
        /// ctor
        /// </summary>
        /// <param name="repository"></param>
        public ChangeLogServiceAbstract(IChangeLogRepository<TDto, TRequest> repository)
        {
            this.repository = repository;
        }

        /// <summary>
        /// Добавляет Dto у которых id == 0, изменяет dto у которых id != 0
        /// </summary>
        /// <param name="idUser"></param>
        /// <param name="dtos"></param>
        /// <param name="token"></param>
        /// <returns></returns>
        public virtual async Task<int> UpdateOrInsertRange(int idUser, IEnumerable<TDto> dtos, CancellationToken token)
        {
            var validationResults = Validate(dtos);
            if (validationResults.Any())
            {
                var errors = validationResults.SelectMany(r => r.MemberNames.Select(member => $"{member}: {r.ErrorMessage}"));
                throw new ArgumentInvalidException(nameof(dtos), $"not valid: {string.Join("\n", errors)}");
            }

            var itemsToInsert = dtos.Where(e => e.Id == 0);
            var itemsToUpdate = dtos.Where(e => e.Id != 0);
            
            var result = await repository.InsertRange(idUser, itemsToInsert, token);
            result += await repository.UpdateRange(idUser, itemsToInsert, token);
            
            return result;
        }

        /// <summary>
        /// Валидация входных данных
        /// </summary>
        /// <param name="dtos"></param>
        /// <returns></returns>
        protected virtual IEnumerable<ValidationResult> Validate(IEnumerable<TDto> dtos) 
            => Enumerable.Empty<ValidationResult>();
    }
}