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 EducationStatusStorage : IEducationStatusStorage
    {
        public EducationStatusViewModel? GetElement(EducationStatusSearchModel model)
        {
            if (!model.Id.HasValue)
            {
                return null;
            }
            using var context = new Database();
            return context.EducationStatuses
                .Include(record => record.User)
                .FirstOrDefault(record => record.Id == model.Id
                    || record.Name.Equals(model.Name))
                ?.GetViewModel;
        }

        public List<EducationStatusViewModel> GetFilteredList(EducationStatusSearchModel model)
        {
            using var context = new Database();
            if (model.UserId.HasValue && model.PageNumber.HasValue && model.PageSize.HasValue)
            {
                return context.EducationStatuses
                    .Include(record => record.User)
                    .Where(x => x.UserId == model.UserId)
                    .Skip(model.PageSize.Value * (model.PageNumber.Value - 1))
                    .Take(model.PageSize.Value)
                    .Select(x => x.GetViewModel)
                    .ToList();
            }
            else if (model.Id.HasValue)
            {
                return context.EducationStatuses
                    .Include(record => record.User)
                    .Where(record => record.Id.Equals(model.Id))
                    .Select(record => record.GetViewModel)
                    .ToList();
            }
            else if (model.UserId.HasValue)
            {
                return context.EducationStatuses
                   .Include(record => record.User)
                   .Where(record => record.UserId == model.UserId)
                   .Select(record => record.GetViewModel)
                   .ToList();
            }
            else
            {
                return new();
            }
        }

        public List<EducationStatusViewModel> GetFullList()
        {
            using var context = new Database();
            return context.EducationStatuses                
                .Select(record => record.GetViewModel)
                .ToList();
        }

        public EducationStatusViewModel? Insert(EducationStatusBindingModel model)
        {
            var newEducationStatus = EducationStatus.Create(model);
            if (newEducationStatus == null)
            {
                return null;
            }
            using var context = new Database();
            context.EducationStatuses.Add(newEducationStatus);
            context.SaveChanges();
            return context.EducationStatuses
                .Include(record => record.User)
                .FirstOrDefault(record => record.Id.Equals(newEducationStatus.Id))
                ?.GetViewModel;
        }

        public EducationStatusViewModel? Update(EducationStatusBindingModel model)
        {
            using var context = new Database();
            using var transaction = context.Database.BeginTransaction();
            try
            {
                var educationStatus = context.EducationStatuses
                    .Include(record => record.User)
                    .FirstOrDefault(record => record.Id.Equals(model.Id));
                if (educationStatus == null)
                {
                    return null;
                }
                educationStatus.Update(model);
                context.SaveChanges();
                transaction.Commit();
                return educationStatus.GetViewModel;
            }
            catch
            {
                transaction.Rollback();
                throw;
            }
        }

        public EducationStatusViewModel? Delete(EducationStatusBindingModel model)
        {
            using var context = new Database();
            var educationStatus = context.EducationStatuses
                .Include(record => record.User)
                .Include(record => record.Students)
                .FirstOrDefault(record => record.Id.Equals(model.Id));
            if (educationStatus == null)
            {
                return null;
            }
            context.EducationStatuses.Remove(educationStatus);
            context.SaveChanges();
            return educationStatus.GetViewModel;
        }

        public List<EducationStatusStudentsCountViewModel>? GetEducationStatusStudents()
        {
            using var context = new Database();
            var result = context.EducationStatuses
                .GroupJoin(
                    context.Students,
                    status => status.Id,
                    student => student.EducationStatusId,
                    (status, students) => new EducationStatusStudentsCountViewModel
                    {
                        Name = status.Name,
                        Count = students.Count()
                    })
                .ToList();

            return result;
        }

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