using BookShopContracts.BindingModels;
using BookShopContracts.ViewModels;
using BookShopDataModels.Models;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Diagnostics;

namespace BookShopDataBaseImplement.Models
{
    public class Book : IBookModel
    {
        public int Id { get; private set; }
        [Required]
        public string BookName { get; set; } = string.Empty;
        [Required]
        public int Count { get; set; }
        [Required]
        public double Cost { get; set; }
        [Required]
        public int GenreId { get; set; }

        private Dictionary<int, IAuthorModel>? _bookAuthors = null;
        [NotMapped]
        public Dictionary<int, IAuthorModel> BookAuthors
        {
            get
            {
                if (_bookAuthors == null)
                {
                    _bookAuthors = Authors.ToDictionary(recPC => recPC.AuthorId, recPC => recPC.Author as IAuthorModel);
                }
                return _bookAuthors;
            }
        }
        [ForeignKey("BookId")]
        public virtual List<BookAuthor> Authors { get; set; } = new();
        [ForeignKey("BookId")]
        public virtual List<Order> Orders { get; set; } = new();
        public static Book Create(BookShopDatabase context, BookBindingModel model)
        {
            return new Book()
            {
                Id = model.Id,
                BookName = model.BookName,
                Cost = model.Cost,
                Count = model.Count,
                Authors = model.BookAuthors.Select(x => new BookAuthor
                {
                    Author = context.Authors.First(y => y.Id == x.Key)
                }).ToList()
            };
        }
        public void Update(BookBindingModel model)
        {
            BookName = model.BookName;
            Cost = model.Cost;
        }
        public BookViewModel GetViewModel => new()
        {
            Id = Id,
            BookName = BookName,
            Cost = Cost,
            BookAuthors = BookAuthors
        };
        public void UpdateAuthors(BookShopDatabase context, BookBindingModel model)
        {
            var bookAuthors = context.BookAuthors.Where(rec =>
           rec.BookId == model.Id).ToList();
            if (bookAuthors != null && bookAuthors.Count > 0)
            { // удалили те, которых нет в модели
                context.BookAuthors.RemoveRange(bookAuthors.Where(rec
               => !model.BookAuthors.ContainsKey(rec.AuthorId)));
                context.SaveChanges();
                // обновили количество у существующих записей
                foreach (var updateAuthor in bookAuthors)
                {
                    model.BookAuthors.Remove(updateAuthor.AuthorId);
                }
                context.SaveChanges();
            }
            var book = context.Books.First(x => x.Id == Id);
            foreach (var pc in model.BookAuthors)
            {
                context.BookAuthors.Add(new BookAuthor
                {
                    Book = book,
                    Author = context.Authors.First(x => x.Id == pc.Key)
                });
                context.SaveChanges();
            }
            _bookAuthors = null;
        }
    }
}