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

namespace GB5Shared.Swagger;

/// <summary>
/// Groups every Swagger operation under its owning module by matching the assembly-name
/// prefix baked into NSwag's generated OperationId (e.g. "DevadminSLEndPointsReplicateGetReplicate"),
/// with a route-path fallback for non-FastEndpoints actions (e.g. Dapr [Topic] subscriber controllers)
/// whose OperationId doesn't carry that prefix.
///
/// Stashes the resolved module name in the operation's ExtensionData under <see cref="ModuleKey"/> -
/// read back by <see cref="ModuleScopedProcessor"/> to decide whether this operation belongs in a
/// given module's document - and sets the VISIBLE tag to "{Module}.{Feature}" (Feature = the next
/// path segment after the module, e.g. "MM.BOM", "MM.Scheduling") so Swagger UI groups a module's
/// page into per-feature sections instead of one flat list of every endpoint in that module.
/// </summary>
public sealed class ModuleTagProcessor : IOperationProcessor
{
    /// <summary>ExtensionData key under which the owning module name is stashed for ModuleScopedProcessor.</summary>
    public const string ModuleKey = "x-gb5-module";

    private readonly Dictionary<string, string> _moduleByAssembly;
    private readonly Dictionary<string, string> _pathAliases;

    public ModuleTagProcessor(Dictionary<string, string> moduleByAssembly, Dictionary<string, string>? pathAliases = null)
    {
        _moduleByAssembly = moduleByAssembly;
        _pathAliases = pathAliases ?? new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
    }

    public bool Process(OperationProcessorContext context)
    {
        var operationId = context.OperationDescription.Operation.OperationId ?? string.Empty;
        var path = context.OperationDescription.Path?.Trim('/') ?? string.Empty;
        var segments = path.Split('/');
        var firstSegment = segments.Length > 0 ? segments[0] : string.Empty;

        foreach (var (assemblyName, moduleName) in _moduleByAssembly)
        {
            if (operationId.StartsWith(assemblyName, StringComparison.Ordinal))
            {
                Assign(context, moduleName, firstSegment);
                return true;
            }
        }

        foreach (var moduleName in _moduleByAssembly.Values)
        {
            if (string.Equals(firstSegment, moduleName, StringComparison.OrdinalIgnoreCase))
            {
                // The module IS the first segment here (e.g. Dapr [Topic] routes with no feature
                // sub-path), so group by the next segment instead, if there is one.
                var feature = segments.Length > 1 ? segments[1] : firstSegment;
                Assign(context, moduleName, feature);
                return true;
            }
        }

        if (_pathAliases.TryGetValue(firstSegment, out var aliasedModule))
            Assign(context, aliasedModule, firstSegment);

        return true;
    }

    private static void Assign(OperationProcessorContext context, string moduleName, string featureSegment)
    {
        var operation = context.OperationDescription.Operation;
        operation.ExtensionData ??= new Dictionary<string, object?>();
        operation.ExtensionData[ModuleKey] = moduleName;

        var feature = string.IsNullOrWhiteSpace(featureSegment) ? moduleName : featureSegment;
        operation.Tags = new List<string> { $"{moduleName}.{feature}" };
    }
}