EnvelopeGenerator/EnvelopeGenerator.Web/Middleware/CultureMiddleware.cs

using EnvelopeGenerator.Web.Models;
using Microsoft.AspNetCore.Localization;
using Microsoft.Extensions.Options;
using System.Globalization;

namespace EnvelopeGenerator.Web.Middleware;

public class CultureMiddleware
{
    private readonly RequestDelegate _next;
    private readonly Cultures _cultures;

    public CultureMiddleware(RequestDelegate next, IOptions<Cultures> culturesOpt)
    {
        _next = next;
        _cultures = culturesOpt.Value;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        var cookieName = CookieRequestCultureProvider.DefaultCookieName;
        var cookieValue = context.Request.Cookies[cookieName];

        if (string.IsNullOrEmpty(cookieValue))
        {
            var culture = new RequestCulture(_cultures.Default.Language);

            var cookieOptions = new CookieOptions
            {
                Secure = false,
                SameSite = SameSiteMode.Strict,
                HttpOnly = true
            };

            context.Response.Cookies.Append(
                cookieName,
                CookieRequestCultureProvider.MakeCookieValue(culture),
                cookieOptions);

            CultureInfo.CurrentCulture = new CultureInfo(_cultures.Default.Language);
            CultureInfo.CurrentUICulture = new CultureInfo(_cultures.Default.Language);
        }

        await _next(context);
    }
}