LANCommander/LANCommander.Server/Middlewares/BearerSecuritySchemeTransformer.cs

using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.OpenApi;
using Microsoft.OpenApi.Models;

namespace LANCommander.Server;

// https://yogeshhadiya33.medium.com/implement-scalar-in-net-api-91d284479d1d
internal sealed class BearerSecuritySchemeTransformer : IOpenApiDocumentTransformer
{
    private readonly IAuthenticationSchemeProvider _authenticationSchemeProvider;

    public BearerSecuritySchemeTransformer(IAuthenticationSchemeProvider authenticationSchemeProvider)
    {
        _authenticationSchemeProvider = authenticationSchemeProvider;
    }

    public async Task TransformAsync(OpenApiDocument document, OpenApiDocumentTransformerContext context, CancellationToken cancellationToken)
    {
        var authenticationSchemes = await _authenticationSchemeProvider.GetAllSchemesAsync();

        if (authenticationSchemes.Any(authScheme => authScheme.Name == "Bearer"))
        {
            var requirements = new Dictionary<string, OpenApiSecurityScheme>
            {
                ["Bearer"] = new OpenApiSecurityScheme
                {
                    Type = SecuritySchemeType.Http,
                    Scheme = "Bearer",
                    In = ParameterLocation.Header,
                    BearerFormat = "JWT"
                }
            };

            document.Components ??= new OpenApiComponents();
            document.Components.SecuritySchemes = requirements;

            foreach (var operation in document.Paths.Values.SelectMany(path => path.Operations))
            {
                operation.Value.Security.Add(new OpenApiSecurityRequirement
                {
                    [new OpenApiSecurityScheme
                    {
                        Reference = new OpenApiReference
                        {
                            Id = "Bearer",
                            Type = ReferenceType.SecurityScheme
                        }
                    }] = Array.Empty<string>()
                });
            }
        }
    }
}