using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography.X509Certificates;
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 StudentStorage : IStudentStorage
    {
        public StudentViewModel? GetElement(StudentSearchModel model)
        {
			using var context = new Database();
			if (model.Id.HasValue)
            {
				return context.Students
			   .Include(record => record.User)
			   .Include(record => record.EducationStatus)
			   .FirstOrDefault(record => record.Id.Equals(model.Id))
			   ?.GetViewModel;
			}
            else if (model.StudentCard.HasValue)
            {
				return context.Students
				.Include(record => record.User)
				.Include(record => record.EducationStatus)
				.FirstOrDefault(record => record.StudentCard.Equals(model.StudentCard))
				?.GetViewModel;
			}
            return null;
        }
        public List<StudentViewModel> GetFilteredList(StudentSearchModel model)
        {
            using var context = new Database();
			if (model.UserId.HasValue && model.PageNumber.HasValue && model.PageSize.HasValue)
			{
				return context.Students
                    .Include(record => record.User)
                    .Include(record => record.EducationStatus)
                    .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.Students
                .Include(record => record.User)
                .Include(record => record.EducationStatus)
                .Where(record => record.Id.Equals(model.Id))
                .Select(record => record.GetViewModel)
                .ToList();
            }
            else if (model.DateFrom != null && model.DateTo != null && model.UserId.HasValue)
            {
                return context.Students
                    .Where(s => s.DateOfAddmission >= model.DateFrom && s.DateOfAddmission <= model.DateTo && s.UserId == model.UserId)
                    .Include(s => s.EducationStatus)                  
                    .Select(result => result.GetViewModel)
                    .ToList();
            }
            else if (model.UserId.HasValue && model.EducationStatusId.HasValue)
            {
                return context.Students
                   .Include(record => record.User)
                   .Include(record => record.EducationStatus)
                   .Where(record => record.UserId == model.UserId && record.EducationStatusId != model.EducationStatusId)
                   .Select(record => record.GetViewModel)
                   .ToList();
            }
            else if (model.UserId.HasValue)
            {
                return context.Students
                   .Include(record => record.User)
                   .Include(record => record.EducationStatus)
                   .Where(record => record.UserId == model.UserId)
                   .Select(record => record.GetViewModel)
                   .ToList();
            }
            else
            {
                return new();
            }
        }
        public List<StudentViewModel> GetFullList()
        {
            using var context = new Database();
            return context.Students
                .Include(record => record.User)
                .Include(record => record.EducationStatus)
                .Select(record => record.GetViewModel)
                .ToList();
        }
        public StudentViewModel? Insert(StudentBindingModel model)
        {
            var newStudent = Student.Create(model);
            if (newStudent == null)
            {
                return null;
            }
            using var context = new Database();
            context.Students.Add(newStudent);
            context.SaveChanges();
            return newStudent.GetViewModel;
        }
        public StudentViewModel? Update(StudentBindingModel model)
        {
            using var context = new Database();
            using var transaction = context.Database.BeginTransaction();
            try
            {
                var student = context.Students
                    .Include(record => record.User)
                    .Include(record => record.EducationStatus)
                    .FirstOrDefault(record => record.Id.Equals(model.Id));
                if (student == null)
                {
                    return null;
                }
                student.Update(model);
                context.SaveChanges();
                transaction.Commit();
                return student.GetViewModel;
            }
            catch
            {
                transaction.Rollback();
                throw;
            }
        }
        public StudentViewModel? Delete(StudentBindingModel model)
        {
            using var context = new Database();
            var student = context.Students
                .Include(record => record.User)
                .Include(record => record.EducationStatus)
                .FirstOrDefault(record => record.Id.Equals(model.Id));
            if (student == null)
            {
                return null;
            }
            context.Students.Remove(student);
            context.SaveChanges();
            return student.GetViewModel;
        }

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

        public List<StreamViewModel> GetStudentStreams(StudentSearchModel model)
        {
            if (model == null)
            {
                return new();
            }
            using var context = new Database();
            var streams = context.StudentStreams
                .Where(x => x.StudentId == model.Id)
                .Select(x => x.Stream.GetViewModel)
                .ToList();
            return streams;
        }
	}
}