namespace Uwaa.HTTP.Routing;

/// <summary>
/// Handles CORS preflight requests.
/// </summary>
public class CORS : RouterBase
{
    public override HttpMethod Method => HttpMethod.OPTIONS;

    public override int Arguments => 0;

    protected override Task<HttpResponse?> GetResponseInner(HttpRequest req, HttpClientInfo info, ArraySegment<string> path)
    {
        return Task.FromResult<HttpResponse?>(new HttpResponse(200, "OK", PreflightResponseFields.Singleton));
    }
}

record PreflightResponseFields : HttpFields
{
    public static readonly PreflightResponseFields Singleton = new PreflightResponseFields();

    PreflightResponseFields()
    {
    }

    public override void EmitAll(FieldCallback callback)
    {
        base.EmitAll(callback);
        callback("Access-Control-Allow-Origin", "*");
        callback("Methods", "GET,HEAD,POST,PUT,DELETE,CONNECT,OPTIONS,TRACE,PATCH");
        callback("Vary", "Origin");
    }
}