using System.Diagnostics;
using OpenTelemetry;

namespace Nexus.Api.Observability;

/// <summary>
/// Removes content-bearing attributes before an activity reaches an exporter.
/// Standard HTTP exception recording is disabled separately so exception
/// events cannot contain messages or stack traces.
/// </summary>
public sealed class NexusTelemetryRedactionProcessor : BaseProcessor<Activity>
{
    private static readonly HashSet<string> RedactedTagNames = new(
        [
            "url.query",
            "url.full",
            "url.path",
            "http.url",
            "http.target",
            "exception.message",
            "exception.stacktrace",
            "db.statement",
            "db.query.text"
        ],
        StringComparer.OrdinalIgnoreCase);

    public override void OnEnd(Activity activity)
    {
        foreach (var tag in activity.TagObjects.ToArray())
        {
            if (RedactedTagNames.Contains(tag.Key))
                activity.SetTag(tag.Key, null);
        }
    }
}