using System;

using UnityEngine;

using Framework.Services;

namespace Framework.State {

  /// <summary>Manages the game object currently being controlled by the player</summary>
  [ServiceScope(Scope.Scene)]
  public class ControlManager : Service, IControlManager {

    /// <summary>Called when the player switches control to another controllable</summary>
    public event Action<int, IControllable> ControlSwitched;

    /// <summary>Maximum number of players the control manager will deal with</summary>
    public int MaximumPlayerCount = 4;

    /// <summary>Called when the component gets loaded into a game object</summary>
    protected override void Awake() {
      base.Awake();

      this.frozenMaximumPlayerCount = this.MaximumPlayerCount;
      this.activeControllables = new IControllable[this.frozenMaximumPlayerCount];
    }

    /// <summary>Lets a player assume control of the specified controllable</summary>
    /// <param name="playerIndex">Index of the player that will assume control</param>
    /// <param name="controllable">Controllable the player will be controlling</param>
    public void AssumeControl(int playerIndex, IControllable controllable) {
      if(playerIndex > this.frozenMaximumPlayerCount) {
        string controllableName = "controllable";
        MonoBehaviour behavior = controllable as MonoBehaviour;
        if(behavior != null) {
          controllableName = behavior.gameObject.name;
        }

        Debug.LogError(
          "Player " + playerIndex.ToString() + " tried to take control of '" +
          controllableName + "' but control manager has been configured to only " +
          "support " + this.frozenMaximumPlayerCount.ToString() + " players!"
        );
        return;
      }

      IControllable previousControllable = this.activeControllables[playerIndex];
      if((previousControllable as Component) != null) {
        previousControllable.OnReleaseControl(playerIndex);
      }

      this.activeControllables[playerIndex] = controllable;
      controllable.OnTakeControl(playerIndex);

      OnControlSwitched(playerIndex, controllable);
    }

    /// <summary>Gets the controllable currently active for the specified player</summary>
    /// <param name="playerIndex">
    ///   Index of the player whose active controllable will be returned
    /// </param>
    /// <returns>The controllable currently active for the specified player</returns>
    public IControllable GetControllable(int playerIndex) {
      if(playerIndex > this.frozenMaximumPlayerCount) {
        Debug.LogError(
          "Tried to look up controllable for player " + playerIndex.ToString() + ", " +
          "but control manager has been configured to only support " +
          this.frozenMaximumPlayerCount.ToString() + " players!"
        );
        return null;
      }

      if((this.activeControllables[playerIndex] as Component) == null) {
        return null;
      } else {
        return this.activeControllables[playerIndex];
      }
    }

    /// <summary>Fires the ControlSwitched event</summary>
    /// <param name="playerIndex">Index of the player that has switched control</param>
    /// <param name="controllable">Controllable that has obtained control</param>
    protected void OnControlSwitched(int playerIndex, IControllable controllable) {
      if(ControlSwitched != null) {
        ControlSwitched(playerIndex, controllable);
      }
    }

    /// <summary>Value of <see cref="MaximumPlayerCount" /> when the game started</summary>
    private int frozenMaximumPlayerCount;
    /// <summary>Controllables currently being controlled by each player</summary>
    private IControllable[/*frozenMaximumPlayerCount*/] activeControllables;

  }

} // namespace Framework.State