The provided code is a typical setup for an ASP.NET...

The provided code is a typical setup for an ASP.NET Core MVC web application. Here's a step-by-step explanation of what the code does:

1. builder.Services.AddControllersWithViews();
   • Adds support for the MVC pattern, including controller-based web APIs and views (Razor Views) to the application.
   • This registers the necessary services to use MVC with both controllers and Razor view rendering.

2. var app = builder.Build();
   • Builds an application object (app) from the builder configuration. This represents the fully configured application and is used to set up middleware and define application behavior.

3. Non-development environment-related configuration:
   • if (!app.Environment.IsDevelopment()) { ... }
     • Checks if the environment is not set to "Development."
     • If true (i.e., the app is running in a staging or production environment):
       • app.UseExceptionHandler("/Home/Error");
         • Sets up exception handling middleware to display a custom error page (/Home/Error) when unhandled exceptions occur.
       • app.UseHsts();
         • Enables HTTP Strict Transport Security (HSTS), which enforces HTTPS connections for HTTP requests.

4. HTTPS redirection:
   • app.UseHttpsRedirection();
     • Redirects all HTTP requests to HTTPS to ensure secure communication.

5. Static files middleware:
   • app.UseStaticFiles();
     • Enables serving static files (e.g., CSS, JavaScript, images) from the application's wwwroot folder.

6. Routing middleware:
   • app.UseRouting();
     • Enables request routing, allowing the application to map incoming requests to specific routes.

7. Authorization middleware:
   • app.UseAuthorization();
     • Applies authorization middleware to ensure that endpoints are secured based on defined policies or attributes on controllers/actions.

8. Mapping the default route:
   • app.MapControllerRoute(...)
     • Defines a default route for controller actions:
       • This route maps to the {controller=Home}, {action=Index}, and an optional {id} parameter.
       • For example:
         • / maps to HomeController's Index action.
         • /Products/Details/5 maps to the ProductsController's Details action with an id value of 5.

9. Run the application:
   • app.Run();
     • Starts the application and begins listening for HTTP requests.

Summary:

This code sets up and configures an ASP.NET Core MVC application with the following:

• Default middleware for routing, static file serving, authorization, and HTTPS handling.
• Exception handling and HSTS configuration for non-development environments.
• A default controller/action-based routing system.
• Finally, it starts the web application to handle user requests.