using UnityEngine;

namespace GPUInstancer
{
    // Note: This is a stripped down version of the FirstPersonController script from the Unity Standard Assets package. 
    // It's dependencies have been removed/modified and it has been taken into the GPUInstancer namespace to avoid conflicts.
    // This class is only used in the demo scenes that showcase the GPU Instancer capabilities.

    [RequireComponent(typeof (CharacterController))]
    public class FPController : MonoBehaviour
    {
        [SerializeField] public float m_WalkSpeed;
        [SerializeField] public float m_RunSpeed;
        [SerializeField] public float m_JumpSpeed;
        
        private bool m_IsWalking;
        private MouseLook m_MouseLook;
        private Camera m_Camera;
        private bool m_Jump;
        private float m_YRotation;
        private Vector2 m_Input;
        private Vector3 m_MoveDir = Vector3.zero;
        private CharacterController m_CharacterController;
        private CollisionFlags m_CollisionFlags;
        private bool m_PreviouslyGrounded;
        private bool m_Jumping;
        private float m_StickToGroundForce = 10f;
        private float m_GravityMultiplier = 2f;

        private void Start()
        {
            m_CharacterController = GetComponent<CharacterController>();
            m_Camera = Camera.main;
            m_Jumping = false;
            m_MouseLook = new MouseLook();
			m_MouseLook.Init(transform , m_Camera.transform);
        }

        private void Update()
        {
            RotateView();
            // the jump state needs to read here to make sure it is not missed
            if (!m_Jump && Cursor.lockState == CursorLockMode.Locked)
            {
                m_Jump = Input.GetButtonDown("Jump");
            }

            if (!m_PreviouslyGrounded && m_CharacterController.isGrounded)
            {
                m_MoveDir.y = 0f;
                m_Jumping = false;
            }
            if (!m_CharacterController.isGrounded && !m_Jumping && m_PreviouslyGrounded)
            {
                m_MoveDir.y = 0f;
            }

            m_PreviouslyGrounded = m_CharacterController.isGrounded;
        }


        private void FixedUpdate()
        {
            float speed;
            GetInput(out speed);
            // always move along the camera forward as it is the direction that it being aimed at
            Vector3 desiredMove = transform.forward*m_Input.y + transform.right*m_Input.x;

            // get a normal for the surface that is being touched to move along it
            RaycastHit hitInfo;
            Physics.SphereCast(transform.position, m_CharacterController.radius, Vector3.down, out hitInfo,
                               m_CharacterController.height/2f, Physics.AllLayers, QueryTriggerInteraction.Ignore);
            desiredMove = Vector3.ProjectOnPlane(desiredMove, hitInfo.normal).normalized;

            m_MoveDir.x = desiredMove.x*speed;
            m_MoveDir.z = desiredMove.z*speed;


            if (m_CharacterController.isGrounded)
            {
                m_MoveDir.y = -m_StickToGroundForce;

                if (m_Jump)
                {
                    m_MoveDir.y = m_JumpSpeed;
                    m_Jump = false;
                    m_Jumping = true;
                }
            }
            else
            {
                m_MoveDir += Physics.gravity*m_GravityMultiplier*Time.fixedDeltaTime;
            }
            m_CollisionFlags = m_CharacterController.Move(m_MoveDir*Time.fixedDeltaTime);

            m_MouseLook.UpdateCursorLock();
        }

        private void GetInput(out float speed)
        {
            // Read input
            float horizontal = Input.GetAxis("Horizontal");
            float vertical = Input.GetAxis("Vertical");

            // On standalone builds, walk/run speed is modified by a key press.
            // keep track of whether or not the character is walking or running
            m_IsWalking = !Input.GetKey(KeyCode.LeftShift);

            // set the desired speed to be walking or running
            speed = m_IsWalking ? m_WalkSpeed : m_RunSpeed;
            m_Input = new Vector2(horizontal, vertical);

            // normalize input if it exceeds 1 in combined length:
            if (m_Input.sqrMagnitude > 1)
            {
                m_Input.Normalize();
            }
        }


        private void RotateView()
        {
            m_MouseLook.LookRotation (transform, m_Camera.transform);
        }


        private void OnControllerColliderHit(ControllerColliderHit hit)
        {
            Rigidbody body = hit.collider.attachedRigidbody;
            //dont move the rigidbody if the character is on top of it
            if (m_CollisionFlags == CollisionFlags.Below)
            {
                return;
            }

            if (body == null || body.isKinematic)
            {
                return;
            }
            body.AddForceAtPosition(m_CharacterController.velocity*0.1f, hit.point, ForceMode.Impulse);
        }
    }

    public class MouseLook
    {
        public float XSensitivity = 2f;
        public float YSensitivity = 2f;
        public bool clampVerticalRotation = true;
        public float MinimumX = -90F;
        public float MaximumX = 90F;
        public bool smooth;
        public float smoothTime = 5f;
        public bool lockCursor = true;


        private Quaternion m_CharacterTargetRot;
        private Quaternion m_CameraTargetRot;
        private bool m_cursorIsLocked = true;

        public void Init(Transform character, Transform camera)
        {
            m_CharacterTargetRot = character.localRotation;
            m_CameraTargetRot = camera.localRotation;
        }


        public void LookRotation(Transform character, Transform camera)
        {
            if (m_cursorIsLocked)
            {
                float yRot = Input.GetAxis("Mouse X") * XSensitivity;
                float xRot = Input.GetAxis("Mouse Y") * YSensitivity;

                m_CharacterTargetRot *= Quaternion.Euler(0f, yRot, 0f);
                m_CameraTargetRot *= Quaternion.Euler(-xRot, 0f, 0f);

                if (clampVerticalRotation)
                    m_CameraTargetRot = ClampRotationAroundXAxis(m_CameraTargetRot);

                if (smooth)
                {
                    character.localRotation = Quaternion.Slerp(character.localRotation, m_CharacterTargetRot,
                        smoothTime * Time.deltaTime);
                    camera.localRotation = Quaternion.Slerp(camera.localRotation, m_CameraTargetRot,
                        smoothTime * Time.deltaTime);
                }
                else
                {
                    character.localRotation = m_CharacterTargetRot;
                    camera.localRotation = m_CameraTargetRot;
                }
            }
            UpdateCursorLock();
        }

        public void SetCursorLock(bool value)
        {
            lockCursor = value;
            if (!lockCursor)
            {//we force unlock the cursor if the user disable the cursor locking helper
                Cursor.lockState = CursorLockMode.None;
                Cursor.visible = true;
            }
        }

        public void UpdateCursorLock()
        {
            //if the user set "lockCursor" we check & properly lock the cursos
            if (lockCursor)
                InternalLockUpdate();
        }

        private void InternalLockUpdate()
        {
            if (Input.GetKeyUp(KeyCode.Escape))
            {
                m_cursorIsLocked = false;
            }
            else if (Input.GetMouseButtonUp(0))
            {
                m_cursorIsLocked = true;
            }

            if (m_cursorIsLocked)
            {
                Cursor.lockState = CursorLockMode.Locked;
                Cursor.visible = false;
            }
            else if (!m_cursorIsLocked)
            {
                Cursor.lockState = CursorLockMode.None;
                Cursor.visible = true;
            }
        }

        Quaternion ClampRotationAroundXAxis(Quaternion q)
        {
            q.x /= q.w;
            q.y /= q.w;
            q.z /= q.w;
            q.w = 1.0f;

            float angleX = 2.0f * Mathf.Rad2Deg * Mathf.Atan(q.x);

            angleX = Mathf.Clamp(angleX, MinimumX, MaximumX);

            q.x = Mathf.Tan(0.5f * Mathf.Deg2Rad * angleX);

            return q;
        }

    }
}