shoc-backend/Api.SeaHavenIndustries/Middleware/LegacyDeprecationMiddleware.cs

using Api.SeaHavenIndustries.Options;
using Microsoft.Extensions.Options;

namespace Api.SeaHavenIndustries.Middleware
{
    /// <summary>Adds Sunset/Deprecation headers to legacy WorkOrder REST routes.</summary>
    public class LegacyDeprecationMiddleware
    {
        private static readonly HashSet<string> LegacyPathSegments = new(StringComparer.OrdinalIgnoreCase)
        {
            "GetWorkOrderList",
            "AddWorkorder",
            "EditWorkorder",
            "ChangeStatus",
            "ChangeAssignment",
            "DeleteWorkorder",
            "GetWorkorderById"
        };

        private readonly RequestDelegate _next;
        private readonly LegacyEndpointOptions _options;

        public LegacyDeprecationMiddleware(RequestDelegate next, IOptions<LegacyEndpointOptions> options)
        {
            _next = next;
            _options = options.Value;
        }

        public async Task InvokeAsync(HttpContext context)
        {
            if (_options.DeprecationEnabled)
            {
                var path = context.Request.Path.Value ?? "";
                var isLegacyWo = (path.Contains("/WorkOrder", StringComparison.OrdinalIgnoreCase)
                        || path.Contains("/workorders", StringComparison.OrdinalIgnoreCase))
                    && LegacyPathSegments.Any(seg => path.Contains(seg, StringComparison.OrdinalIgnoreCase));

                if (isLegacyWo)
                {
                    context.Response.OnStarting(() =>
                    {
                        context.Response.Headers["Deprecation"] = "true";
                        if (!string.IsNullOrWhiteSpace(_options.SunsetDate)
                            && DateTimeOffset.TryParse(_options.SunsetDate, out var sunset))
                        {
                            context.Response.Headers["Sunset"] = sunset.UtcDateTime.ToString("r");
                        }
                        context.Response.Headers["Link"] = "</api/workorders/board>; rel=\"successor-version\"";
                        return Task.CompletedTask;
                    });
                }
            }

            await _next(context);
        }
    }
}