using System;
using System.Collections.Generic;
using UnityEngine;

namespace Fusion.Addons.Physics {

  /// <summary>
  /// This base class exists to allow for additional Physics Scenes to be accounted for in Physics simulation,
  /// in addition to the Physics Scenes associated with the NetworkRunner.
  /// </summary>
  /// <typeparam name="TPhysicsScene"></typeparam>
  public abstract class RunnerSimulatePhysicsBase<TPhysicsScene> : RunnerSimulatePhysicsBase where TPhysicsScene : struct, IEquatable <TPhysicsScene> {

    /// <summary>
    /// Wrapper for physics scene reference.
    /// </summary>
    protected struct AdditionalScene {
      public TPhysicsScene PhysicsScene;
      public ClientPhysicsSimulation ClientPhysicsSimulation;
    }

    /// <summary>
    /// List of additional physics scenes that should be simulated by Fusion.
    /// </summary>
    protected List<AdditionalScene> _additionalScenes;

    /// <summary>
    /// Register a Physics Scene to be simulated by Fusion.
    /// </summary>
    /// <param name="scene">The Physics Scene to include in simulation.</param>
    /// <param name="clientPhysicsSimulation">Defines physics simulation of the additional scene for clients.
    /// Typically this will be Disabled (physics not simulated) or SimulateForward (if you want to simulate physics locally for non-networked objects such as rag dolls).</param>
    public void RegisterAdditionalScene(TPhysicsScene scene, ClientPhysicsSimulation clientPhysicsSimulation = ClientPhysicsSimulation.Disabled) {
      if (_additionalScenes == null) {
        _additionalScenes = new List<AdditionalScene>();
      } else {
        foreach (var entry in _additionalScenes) {
          if (entry.PhysicsScene.Equals(scene)) {
            Debug.LogWarning("Scene already registered.");
            return;
          }
        }
      }
      _additionalScenes.Add(new AdditionalScene(){PhysicsScene = scene, ClientPhysicsSimulation = clientPhysicsSimulation});
    }

    /// <summary>
    /// Unregister a Physics Scene, and it will not longer have calls made to Simulate() by this component.
    /// </summary>
    /// <param name="scene"></param>
    public void UnregisterAdditionalScene(TPhysicsScene scene) {
      if (_additionalScenes == null) {
        Debug.LogWarning("Scene was never registered, cannot unregister.");
        return;
      }

      int? found = null;
      for (int i = 0; i < _additionalScenes.Count; i++) {
        if (_additionalScenes[i].PhysicsScene.Equals(scene)) {
          found = i;
          break;
        }
      }

      if (found.HasValue) {
        _additionalScenes.RemoveAt(found.Value);
      }
    }

    protected override sealed bool AnySceneRequiresSyncTransform() {
      if (_additionalScenes == null || _additionalScenes.Count == 0) {
        return false;
      }

      foreach (var scene in _additionalScenes) {
        if (RequiresSyncTransform(scene.ClientPhysicsSimulation))
          return true;
      }

      return false;
    }
  }
}