using Cinemachine.Utility;
using UnityEngine;

namespace Cinemachine
{
    /// <summary>
    /// This is a CinemachineComponent in the Aim section of the component pipeline.
    /// Its job is to place the camera on the Follow Target.
    /// </summary>
    [DocumentationSorting(DocumentationSortingAttribute.Level.UserRef)]
    [AddComponentMenu("")] // Don't display in add component menu
    [SaveDuringPlay]
    public class CinemachineHardLockToTarget : CinemachineComponentBase
    {
        /// <summary>
        /// How much time it takes for the position to catch up to the target's position
        /// </summary>
        [Tooltip("How much time it takes for the position to catch up to the target's position")]
        public float m_Damping = 0;
        Vector3 m_PreviousTargetPosition;

        /// <summary>True if component is enabled and has a LookAt defined</summary>
        public override bool IsValid { get { return enabled && FollowTarget != null; } }

        /// <summary>Get the Cinemachine Pipeline stage that this component implements.
        /// Always returns the Aim stage</summary>
        public override CinemachineCore.Stage Stage { get { return CinemachineCore.Stage.Body; } }

        /// <summary>
        /// Report maximum damping time needed for this component.
        /// </summary>
        /// <returns>Highest damping setting in this component</returns>
        public override float GetMaxDampTime() { return m_Damping; }

        /// <summary>Applies the composer rules and orients the camera accordingly</summary>
        /// <param name="curState">The current camera state</param>
        /// <param name="deltaTime">Used for calculating damping.  If less than
        /// zero, then target will snap to the center of the dead zone.</param>
        public override void MutateCameraState(ref CameraState curState, float deltaTime)
        {
            if (!IsValid)
                return;

            Vector3 dampedPos = FollowTargetPosition;
            if (deltaTime >= 0)
                dampedPos = m_PreviousTargetPosition + VirtualCamera.DetachedFollowTargetDamp(
                    dampedPos - m_PreviousTargetPosition, m_Damping, deltaTime);
            m_PreviousTargetPosition = dampedPos;
            curState.RawPosition = dampedPos;
        }
    }
}