Lab4/library/Services/RentService.cs - master - egopen/Lab1

Lab4/library/Services/RentService.cs
66 строк2 KB
Egopen
lab 4
01 ноя 2025, 18:03
01 ноя 2025, 18:0378d017c
using library.DB;
using library.DB.Models;
using library.Errors;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Caching.Memory;

namespace library.Services
{
    public class RentService
    {
        private readonly LibraryDBContext _db;
        private readonly IMemoryCache _memoryCache;

        public RentService(LibraryDBContext db, IMemoryCache memoryCache)
        {
            _db = db;
            _memoryCache = memoryCache;
        }

        public async Task<Rent> RentBook(Guid userId, Guid bookId)
        {
            var idempotencyKey = $"rent_book_{userId}_{bookId}";
            if (_memoryCache.TryGetValue(idempotencyKey, out Rent cachedRent))
            {
                return cachedRent;
            }

            if (!_db.Books.Any(b=>b.Id == bookId))
            {
                throw new NotFoundException("Book not found");
            }

            var existingRent = await _db.Rents
                .FirstOrDefaultAsync(r => r.BookId == bookId && r.UserId == userId);
            if (existingRent != null)
            {
                throw new NotFoundException("Book in usage");
            }

            Rent rent = new Rent();
            rent.UserId = userId;
            rent.BookId = bookId;
            rent.Id = Guid.NewGuid();
            await _db.Rents.AddAsync(rent);
            await _db.SaveChangesAsync();
            _memoryCache.Set(idempotencyKey, rent, TimeSpan.FromMinutes(10));
            return rent;
        }
        public async Task<Rent> EndRentBook(Guid rentId)
        {
            var rent = await _db.Rents.FirstOrDefaultAsync(r => r.Id == rentId);
            if (rent == null)
            {
                throw new NotFoundException("Rent not found");
            }
            _db.Rents.Remove(rent);
            await _db.SaveChangesAsync();
            return rent;
        }
        public async Task<List<Rent>> GetUserRents(Guid userId, int page, int pageSize)
        {
            var rents = await _db.Rents.Where(r=>r.UserId==userId).Skip(pageSize * (page-1)).Take(pageSize).ToListAsync();
            return rents;
        }
    }
}