using NSwag.Generation.Processors;
using NSwag.Generation.Processors.Contexts;

namespace GB5Shared.Swagger;

/// <summary>
/// Drops every operation whose owning module (stashed in ExtensionData by
/// <see cref="ModuleTagProcessor"/> under <see cref="ModuleTagProcessor.ModuleKey"/>) doesn't match
/// this document's target module. Registered as the last OperationProcessor on a per-module
/// SwaggerDocument() so that document ends up containing only that module's endpoints - covers
/// FastEndpoints AND MVC/Dapr-controller-sourced operations alike, since both get tagged by
/// ModuleTagProcessor through the same NSwag operation pipeline before this runs. This is what makes
/// /ads/GB5Documentation show only Admin instead of every module bundled into the same consolidated
/// Host process.
///
/// Checks ExtensionData rather than Operation.Tags - ModuleTagProcessor sets the visible tag to
/// "{Module}.{Feature}" (e.g. "MM.BOM") for Swagger UI's own per-feature grouping, so the plain
/// module name is no longer present as a tag to match against directly.
/// </summary>
public sealed class ModuleScopedProcessor : IOperationProcessor
{
    private readonly string _moduleName;

    public ModuleScopedProcessor(string moduleName)
    {
        _moduleName = moduleName;
    }

    public bool Process(OperationProcessorContext context)
    {
        var extensionData = context.OperationDescription.Operation.ExtensionData;
        return extensionData is not null
            && extensionData.TryGetValue(ModuleTagProcessor.ModuleKey, out var owningModule)
            && string.Equals(owningModule as string, _moduleName, StringComparison.OrdinalIgnoreCase);
    }
}