FrontOffice/src/FrontOffice.Main/Utilities/ProductService.cs

using System.Collections.Concurrent;
using FrontOffice.BFF.Products.Protobuf.Protos.Products;

namespace FrontOffice.Main.Utilities;

public record Product(
    long Id,
    string Title,
    string Description,
    string ImageUrl,
    long Price,
    int Discount = 0,
    int Rate = 0,
    int RemainingCount = 0)
{
    public IReadOnlyList<ProductGalleryImage> Gallery { get; init; } = Array.Empty<ProductGalleryImage>();
}

public record ProductGalleryImage(
    long ProductGalleryId,
    long ProductImageId,
    string Title,
    string ImageUrl,
    string ThumbnailUrl);

public class ProductService
{

    private readonly ConcurrentDictionary<long, Product> _cache = new();
    private readonly ProductsContract.ProductsContractClient _client;

    public ProductService(ProductsContract.ProductsContractClient client)
    {
        _client = client;
    
    }

    public async Task<List<Product>> GetProductsAsync(string? query = null)
    {
        try
        {
            var resp = await _client.GetAllProductsByFilterAsync(new GetAllProductsByFilterRequest
            {
                Filter = new GetAllProductsByFilterFilter
                {
                    Title = query ?? string.Empty,
                    Description = query ?? string.Empty,
                    ShortInfomation = query ?? string.Empty,
                    FullInformation = query ?? string.Empty
                }
            });
            return MapAndCache(resp.Models);
        }
        catch
        {
            IEnumerable<Product> list = _cache.Values;
            if (!string.IsNullOrWhiteSpace(query))
            {
                var q = query.Trim();
                list = list.Where(p => p.Title.Contains(q, StringComparison.OrdinalIgnoreCase) || p.Description.Contains(q, StringComparison.OrdinalIgnoreCase));
            }
            return list.OrderBy(p => p.Id).ToList();
        }
    }

    public async Task<Product?> GetByIdAsync(long id)
    {
        if (_cache.TryGetValue(id, out var cached)) return cached;

        try
        {
            var resp = await _client.GetProductsAsync(new GetProductsRequest { Id = id });
            if (resp == null)
            {
                return null;
            }

            return MapAndCache(resp);
        }
        catch
        {
            _cache.TryGetValue(id, out var result);
            return result;
        }
    }

    private List<Product> MapAndCache(Google.Protobuf.Collections.RepeatedField<GetAllProductsByFilterResponseModel> models)
    {
        var list = new List<Product>();
        foreach (var m in models)
        {
            var p = new Product(
                Id: m.Id,
                Title: m.Title ?? string.Empty,
                Description: m.Description ?? string.Empty,
                ImageUrl: string.IsNullOrWhiteSpace(m.ImagePath) ? string.Empty : UrlUtility.DownloadUrl + m.ImagePath,
                Price: m.Price,
                Discount: m.Discount,
                Rate: m.Rate,
                RemainingCount: m.RemainingCount
            );
            _cache[p.Id] = p;
            list.Add(p);
        }
        return list;
    }

    private Product MapAndCache(GetProductsResponse model)
    {
        var gallery = model.Gallery
            .Select(item => new ProductGalleryImage(
                ProductGalleryId: item.ProductGalleryId,
                ProductImageId: item.ProductImageId,
                Title: item.Title ?? string.Empty,
                ImageUrl: BuildUrl(item.ImagePath),
                ThumbnailUrl: BuildUrl(item.ImageThumbnailPath)))
            .ToList();

        var product = new Product(
            Id: model.Id,
            Title: model.Title ?? string.Empty,
            Description: model.Description ?? string.Empty,
            ImageUrl: BuildUrl(model.ImagePath),
            Price: model.Price,
            Discount: model.Discount,
            Rate: model.Rate,
            RemainingCount: model.RemainingCount)
        {
            Gallery = gallery
        };

        _cache[product.Id] = product;
        return product;
    }

    private static string BuildUrl(string? path) => string.IsNullOrWhiteSpace(path) ? string.Empty : UrlUtility.DownloadUrl + path;
}