using System;

using UnityEngine;

using Framework.Support;
using Framework.Services;

namespace Framework.Actors {

  /// <summary>Stores the movement range of an actor's head</summary>
  /// <remarks>
  ///   This is accessed by head movement components such as
  ///   the <see cref="AiHeadHeadController" /> and the
  ///   <see cref="Framework.Actors.Shooter.MouseLookHeadController" />
  ///   to limit how far these components will rotate an actor's head. Sharing it
  ///   this way allows AI characters that can be &quot;possessed&quot; by a human
  ///   player to keep their settings even when switching between different head controllers.
  /// </remarks>
  public class HeadMovementRange : ScriptComponent {

    /// <summary>How far the user can move the characters head left and right</summary>
    public Range YawRange = new Range(-80.0f, 80.0f);
    /// <summary>How far the user can move the characters head up and down</summary>
    public Range PitchRange = new Range(-40.0f, 85.0f);

    /// <summary>Downward pitch limit for the head based on its yaw</summary>
    /// <remarks>
    ///   The head can look further downward then centered than it can when
    ///   look to the side since the chin would be blocked by the shoulders.
    ///   This curve will ensure that mouse users can look into their shoulders
    ///   while turning the head.
    /// </remarks>
    public AnimationCurve MousePitchLimitByYaw = CreateDefaultPitchLimitCurve();

    /// <summary>Creates the default pitch limit curve for mouse users</summary>
    /// <returns>The default pitch limit curve for mouse users</returns>
    /// <remarks>
    ///   There are different limits for the pitch depending on the head's yaw so that
    ///   the head will be naturally limited from looking down when the chin would
    ///   sit on the character's shoulder.
    /// </remarks>
    private static AnimationCurve CreateDefaultPitchLimitCurve() {
      return new AnimationCurve(
        new Keyframe(-90.0f, 30.0f),
        new Keyframe(-30.0f, 90.0f),
        new Keyframe(+30.0f, 90.0f),
        new Keyframe(+90.0f, 30.0f)
      );
    }

    /// <summary>Clamps pitch and yaw by the limits set up for the head</summary>
    /// <param name="pitch">Pitch angle of the head that will be clamped</param>
    /// <param name="yaw">Yaw angle of the head that will be clamped</param>
    public void ClampPitchAndYaw(ref float pitch, ref float yaw) {
      yaw = Mathf.Clamp(
        yaw,
        this.YawRange.Start,
        this.YawRange.End
      );
      pitch = Mathf.Clamp(
        pitch,
        this.PitchRange.Start,
        this.PitchRange.End
      );

      // Also clamp pitch by the pitch-by-yaw limit curve if present
      if(this.MousePitchLimitByYaw != null) {
        float maximumPitch = this.MousePitchLimitByYaw.Evaluate(yaw);

        if(pitch > maximumPitch) {
          pitch = maximumPitch;
        }
      }
    }

  }

} // namespace Framework.Actors