#nullable enable
using System;
using System.Diagnostics;

namespace Swan.Diagnostics {
  public static partial class Benchmark {
    /// <summary>
    /// Represents a disposable benchmark unit.
    /// </summary>
    /// <seealso cref="IDisposable" />
    private sealed class BenchmarkUnit : IDisposable {
      private readonly String _identifier;
      private Boolean _isDisposed; // To detect redundant calls
      private Stopwatch? _stopwatch = new Stopwatch();

      /// <summary>
      /// Initializes a new instance of the <see cref="BenchmarkUnit" /> class.
      /// </summary>
      /// <param name="identifier">The identifier.</param>
      public BenchmarkUnit(String identifier) {
        this._identifier = identifier;
        this._stopwatch?.Start();
      }

      /// <inheritdoc />
      public void Dispose() => this.Dispose(true);

      /// <summary>
      /// Releases unmanaged and - optionally - managed resources.
      /// </summary>
      /// <param name="alsoManaged"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
      private void Dispose(Boolean alsoManaged) {
        if(this._isDisposed) {
          return;
        }

        if(alsoManaged) {
          Add(this._identifier, this._stopwatch?.Elapsed ?? default);
          this._stopwatch?.Stop();
        }

        this._stopwatch = null;
        this._isDisposed = true;
      }
    }
  }
}