using System;
using Prism;

namespace FPSExample
{
    public class FPSPlayer : Entity
    {
        public float WalkingSpeed = 10.0F;
        public float RunSpeed = 20.0F;
        public float JumpForce = 50.0F;
        public float MouseSensitivity = 10.0F;
        public Vec3 Forward = new Vec3(0.0f, 0.0f, 1.0f);

        private bool m_Colliding = false;
        private float m_CurrentSpeed;

        private RigidBodyComponent m_RigidBody;
        private TransformComponent m_Transform;
        private TransformComponent m_CameraTransform;

        private Entity m_CameraEntity;

        private Vec2 m_LastMousePosition;
        private float m_CameraRotationX = 0.0f;
        private float m_RotationY = 0.0f;
        
        void OnCreate()
        {
            m_Transform = GetComponent<TransformComponent>();
            m_RigidBody = GetComponent<RigidBodyComponent>();

            m_CurrentSpeed = WalkingSpeed;

            AddCollisionBeginCallback((n) => { m_Colliding = true; });
            AddCollisionEndCallback((n) => { m_Colliding = false; });

            m_CameraEntity = FindEntityByTag("Camera");
            
            m_CameraTransform = m_CameraEntity.GetComponent<TransformComponent>();
            m_LastMousePosition = Input.GetMousePosition();
            
            Input.SetCursorMode(Input.CursorMode.Locked);
        }

        void OnUpdate(float ts)
        {
            Forward = m_Transform.Forward;
            
            if (Input.IsKeyPressed(KeyCode.Escape) && Input.GetCursorMode() == Input.CursorMode.Locked)
            {
                Input.SetCursorMode(Input.CursorMode.Normal);
            }
            
            m_CurrentSpeed = Input.IsKeyPressed(KeyCode.LeftControl) ? RunSpeed : WalkingSpeed;
            
            UpdateRotation(ts);
            UpdateMovement();
            UpdateCameraTransform();
        }

        private void UpdateRotation(float ts)
        {
            Vec2 currentMousePosition = Input.GetMousePosition(); 
            Vec2 delta = m_LastMousePosition -  currentMousePosition;
            if (delta.X != 0)
            {
                m_RotationY += delta.X * MouseSensitivity * ts;
            }
            
            m_RigidBody.Rotate(new Vec3(0.0F, delta.X * MouseSensitivity, 0.0f) * ts);
            
            if (delta.Y != 0.0F)
            {
                m_CameraRotationX += delta.Y * MouseSensitivity * ts;
                m_CameraRotationX = Mathf.Clamp(m_CameraRotationX, -80.0f, 80.0f);
            }
            
            m_LastMousePosition = currentMousePosition;
        }

        private void UpdateMovement()
        {

            if (Input.IsKeyPressed(KeyCode.W))
                m_RigidBody.AddForce(m_Transform.Forward * m_CurrentSpeed);
            else if (Input.IsKeyPressed(KeyCode.S))
                m_RigidBody.AddForce(m_Transform.Forward * -m_CurrentSpeed);

            if (Input.IsKeyPressed(KeyCode.A))
                m_RigidBody.AddForce(m_Transform.Right * -m_CurrentSpeed);
            else if (Input.IsKeyPressed(KeyCode.D))
                m_RigidBody.AddForce(m_Transform.Right * m_CurrentSpeed);

            if (Input.IsKeyPressed(KeyCode.Space) && m_Colliding)
                m_RigidBody.AddForce(Vec3.Up * JumpForce);

        }
        
        private void UpdateCameraTransform(){

        // TODO: This workflow needs to be improved. (Will be fixed by object parenting)
        
            Mat4 cameraTransform = m_CameraTransform.Transform;
            Vec3 cameraTranslation = cameraTransform.Translation;
            Vec3 translation = m_Transform.Transform.Translation;
            cameraTranslation.XZ = translation.XZ;
            cameraTranslation.Y = translation.Y + 1.5F;
            cameraTransform.Translation = cameraTranslation;
            m_CameraTransform.Transform = cameraTransform;
            
            m_CameraTransform.Rotation = new Vec3(m_CameraRotationX, m_RotationY, 0.0f);
            
        }
    }
}