using BookContract.BindingModels;
using BookContract.StorageContracts;
using BookContract.ViewModels;
using BookDatabaseImplement.Model;
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace BookDatabaseImplement.Implements
{
    public class BookStorage : IBookStorage
    {
        private Book CreateModel(BookBindingModel model, Book book)
        {
            book.Title = model.Title;
            book.BookType = model.BookType;
            book.Annotation = model.Annotation;

            return book;
        }

        private BookViewModel CreateModel(Book book)
        {
            return new BookViewModel
            {
                Id = book.Id,
                Title = book.Title,
                BookType = book.BookType,
                Annotation = book.Annotation,
                LastReaders = book.LastReaders
                .OrderByDescending(h => h.DateBorrowed)
                .Select(h => new ReaderViewModel
                {
                    Id = h.Reader.Id,
                    Name = h.Reader.Name
                })
                .Take(6)
                .ToList()
            };
        }

        public List<BookViewModel> GetFullList()
        {
            using var context = new BookLibraryDatabase();
            return context.Books
                            .Include(b => b.LastReaders)
                                .ThenInclude(h => h.Reader)
                            .ToList()
                            .Select(CreateModel)
                            .ToList();
        }

        public List<BookViewModel> GetFilterList(BookBindingModel model)
        {
            using var context = new BookLibraryDatabase();
            return context.Books
                .Where(book => book.BookType.Contains(model.BookType))
                .ToList().Select(CreateModel).ToList();
        }

        public BookViewModel? GetElement(BookBindingModel model)
        {
            using var context = new BookLibraryDatabase();
            var book = context.Books.FirstOrDefault(rec => rec.Id == model.Id || rec.Title == model.Title);
            return book != null ? CreateModel(book) : null;
        }

        public void Insert(BookBindingModel model)
        {
            using var context = new BookLibraryDatabase();
            using var transaction = context.Database.BeginTransaction();
            try
            {
                context.Books.Add(CreateModel(model, new Book()));
                context.SaveChanges();
                transaction.Commit();
            }
            catch
            {
                transaction.Rollback();
                throw;
            }
        }

        public void Update(BookBindingModel model)
        {
            using var context = new BookLibraryDatabase();
            using var transaction = context.Database.BeginTransaction();
            try
            {
                var book = context.Books.FirstOrDefault(rec => rec.Id == model.Id);
                if (book == null)
                {
                    throw new Exception("Книга не найдена");
                }
                CreateModel(model, book);
                context.SaveChanges();
                transaction.Commit();
            }
            catch
            {
                transaction.Rollback();
                throw;
            }
        }

        public void Delete(BookBindingModel model)
        {
            using var context = new BookLibraryDatabase();
            var book = context.Books.FirstOrDefault(rec => rec.Id == model.Id);

            if (book != null)
            {
                context.Books.Remove(book);
                context.SaveChanges();
            }
            else
            {
                throw new Exception("Книга не найдена");
            }
        }
    }
}