// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using HtmlGenerationWebSite.Models;
using Microsoft.Extensions.Caching.Memory;
 
namespace HtmlGenerationWebSite;
 
public class ProductsService
{
    private readonly IMemoryCache _memoryCache;
    private readonly ISignalTokenProviderService<Product> _tokenProviderService;
    private readonly Dictionary<string, Product[]> _products = new Dictionary<string, Product[]>
    {
        ["Books"] = new[]
        {
                new Product { ProductName = "Book1" },
                new Product { ProductName = "Book2" }
            },
        ["Electronics"] = new[]
        {
                new Product { ProductName = "Laptops" }
            }
    };
 
    public ProductsService(
        IMemoryCache memoryCache,
        ISignalTokenProviderService<Product> tokenProviderService)
    {
        _memoryCache = memoryCache;
        _tokenProviderService = tokenProviderService;
    }
 
    public IEnumerable<string> GetProductNames(string category)
    {
        IEnumerable<Product> products;
        var key = typeof(ProductsService).FullName;
        if (!_memoryCache.TryGetValue(key, out products))
        {
            var changeToken = _tokenProviderService.GetToken(key);
            products = _memoryCache.Set<IEnumerable<Product>>(
                key,
                _products[category],
                new MemoryCacheEntryOptions().AddExpirationToken(changeToken));
        }
 
        return products.Select(p => p.ProductName);
    }
 
    public void UpdateProducts(string category, IEnumerable<Product> products)
    {
        _products[category] = products.ToArray();
        var key = typeof(ProductsService).FullName;
        _tokenProviderService.SignalToken(key);
    }
}