using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Linq_examples
{
    class Program
    {
        static void Main(string[] args)
        {
            var books = new BookRepository().GetBooks();

            //Books with price less than 10, method 1
            var cheapBooks = new List<Book>();
            foreach (var book in books)
            {
                if (book.Price < 10)
                    cheapBooks.Add(book);
            }
            foreach (var book in cheapBooks)
                Console.WriteLine(book.Title + " " + book.Price);
            //--------------------------------------------------------

            //Books with price less than 10, method 2
            var cheapBooks2 = books.Where(b => b.Price < 10);
            foreach (var book in cheapBooks2)
                Console.WriteLine(book.Title + " " + book.Price);

            var cheapBooks3 = books.Where(b => b.Price < 10).OrderBy(b => b.Title);
            foreach (var book in cheapBooks3)
                Console.WriteLine(book.Title + " " + book.Price);

            //LINQ Query Operators
            var cheaperBooks = 
                from b in books
                where b.Price < 10
                orderby b.Title
                select b.Title;

            foreach (var book in cheaperBooks)
                Console.WriteLine(book);
            //--------------------------------------------------------

            //LINQ Extension Methods
            var cheapBooks4 = books
                .Where(b => b.Price < 10)
                .OrderBy(b => b
                .Title).Select(b => b.Title);

            foreach (var book in cheapBooks4)
                Console.WriteLine(book);

            //--------------------------------------------------------

            var sngbook = books.Single(b => b.Title == "ASP.Net MVC");
            Console.WriteLine(sngbook.Title);

            var sngnbook = books.SingleOrDefault(b => b.Title == "ASP.Net MVC++");
            Console.WriteLine(sngnbook==null);

            var fbook = books.First(b => b.Title == "C# Advanced topics");
            Console.WriteLine(fbook.Title+" "+fbook.Price);

            var fdbook = books.FirstOrDefault(b => b.Title == "C# Advanced topicsx");
            Console.WriteLine(fdbook==null);

            var lbook = books.Last(b => b.Title == "C# Advanced topics");
            Console.WriteLine(lbook.Title + " " + lbook.Price);

            var ldbook = books.LastOrDefault(b => b.Title == "C# Advanced topicsx");
            Console.WriteLine(ldbook == null);

            var skiptakebooks = books.Skip(2).Take(3);
            foreach (var book in skiptakebooks)
                Console.WriteLine(book.Title + " " + book.Price);

            var count = books.Count();
            Console.WriteLine(count);

            var maxPrice = books.Max(b => b.Price);
            Console.WriteLine(maxPrice);

            var minPrice = books.Min(b => b.Price);
            Console.WriteLine(minPrice);

            var priceSum = books.Sum(b => b.Price);
            Console.WriteLine(priceSum);
        }
    }
}