mesa-fab-approval/Fab2ApprovalMKLink/Extensions/ControllerExtensions.cs

#if NET8

using System;
using System.IO;
using System.Threading.Tasks;

using Fab2ApprovalSystem.PdfGenerator;

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewEngines;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.Extensions.DependencyInjection;

namespace Fab2ApprovalSystem.Extensions;

public static class ControllerExtensions {

    public static ActionResult GetBinaryContentResult<TModel>(this Controller controller, string viewName, string contentType, TModel model) {
        string pageTitle = string.Empty;

        string htmlText = RenderViewToString(controller, viewName, model);

        StandardPdfRenderer standardPdfRenderer = new();
        // Let the html be rendered into a PDF document through iTextSharp.
        byte[] buffer = standardPdfRenderer.Render(htmlText, pageTitle);

        // Return the PDF as a binary stream to the client.
        return new BinaryContentResult(buffer, contentType);
    }

    public static string RenderViewToString<TModel>(this Controller controller, string viewName, TModel model) {
        if (string.IsNullOrEmpty(viewName))
            viewName = controller.ControllerContext.ActionDescriptor.ActionName;

        controller.ViewData.Model = model;

        using (StringWriter writer = new()) {
            try {
                CompositeViewEngine compositeViewEngine = controller.HttpContext.RequestServices.GetRequiredService(typeof(ICompositeViewEngine)) as CompositeViewEngine;
                if (compositeViewEngine is null || compositeViewEngine.ViewEngines.Count == 0) { }

                ViewEngineResult viewResult = null;

                if (viewName.EndsWith(".cshtml"))
                    viewResult = compositeViewEngine.GetView(viewName, viewName, false);
                else
                    viewResult = compositeViewEngine.FindView(controller.ControllerContext, viewName, false);

                if (!viewResult.Success)
                    return $"A view with the name '{viewName}' could not be found";

                ViewContext viewContext = new(
                    controller.ControllerContext,
                    viewResult.View,
                    controller.ViewData,
                    controller.TempData,
                    writer,
                    new HtmlHelperOptions()
                );

                Task task = viewResult.View.RenderAsync(viewContext);
                task.Wait();

                return writer.GetStringBuilder().ToString();
            } catch (Exception ex) {
                return $"Failed - {ex.Message}";
            }
        }
    }

}

#endif