using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using UniversityContracts.BindingModels;
using UniversityContracts.SearchModels;
using UniversityContracts.StoragesContracts;
using UniversityContracts.ViewModels;
using UniversityDataBaseImplemet.Models;

namespace UniversityDataBaseImplemet.Implements
{
    public class EducationGroupStorage : IEducationGroupStorage
    {
        public EducationGroupViewModel? GetElement(EducationGroupSearchModel model)
        {
            if (!model.Id.HasValue)
            {
                return null;
            }
            using var context = new Database();
            return context.EducationGroups
                .FirstOrDefault(record => record.Id == model.Id
                    || record.Name.Equals(model.Name))
                ?.GetViewModel;
        }
        public List<EducationGroupViewModel> GetFilteredList(EducationGroupSearchModel model)
        {
            using var context = new Database();
            if (model.Id.HasValue)
            {
                return context.EducationGroups
                    .Where(record => record.Id.Equals(model.Id))
                    .Select(record => record.GetViewModel)
                    .ToList();
            }
            else if (model.UserId.HasValue)
            {
                return context.EducationGroups
                   .Where(record => record.UserId == model.UserId)
                   .Select(record => record.GetViewModel)
                   .ToList();
            }
            else
            {
                return new();
            }
        }
        public List<EducationGroupViewModel> GetFullList()
        {
            using var context = new Database();
            return context.EducationGroups                
                .Select(record => record.GetViewModel)
                .ToList();
        }
        public EducationGroupViewModel? Insert(EducationGroupBindingModel model)
        {
            var newEducationGroup = EducationGroup.Create(model);
            if (newEducationGroup == null)
            {
                return null;
            }
            using var context = new Database();
            context.EducationGroups.Add(newEducationGroup);
            context.SaveChanges();
            return newEducationGroup.GetViewModel;
        }
        public EducationGroupViewModel? Update(EducationGroupBindingModel model)
        {
            using var context = new Database();
            using var transaction = context.Database.BeginTransaction();
            try
            {
                var educationgroup = context.EducationGroups
                    .FirstOrDefault(record => record.Id.Equals(model.Id));
                if (educationgroup == null)
                {
                    return null;
                }
                educationgroup.Update(model);
                context.SaveChanges();
                transaction.Commit();
                return educationgroup.GetViewModel;
            }
            catch
            {
                transaction.Rollback();
                throw;
            }
        }

        public int GetNumberOfPages(int userId, int pageSize)
        {
            using var context = new Database();
            int carsCount = context.EducationGroups.Where(c => c.UserId == userId).Count();
            int numberOfpages = (int)Math.Ceiling((double)carsCount / pageSize);
            return numberOfpages != 0 ? numberOfpages : 1;
        }

        public EducationGroupViewModel? Delete(EducationGroupBindingModel model)
        {
            using var context = new Database();
            var educationgroup = context.EducationGroups
                .FirstOrDefault(record => record.Id.Equals(model.Id));
            if (educationgroup == null)
            {
                return null;
            }
            context.EducationGroups.Remove(educationgroup);
            context.SaveChanges();
            return educationgroup.GetViewModel;
        }
    }
}