using Terrain;
using UI;
using UnityEngine;

namespace User {
    public class Player : MonoBehaviour {
        public float walkSpeed = 3.0f;
        public float sprintSpeed = 6.0f;
        public float jumpForce = 5.0f;

        public float playerRadius = 0.3f;
        public float playerHeight = 2.0f;

        public GameObject debugScreen;

        [Header("Block Breaking/Destroying")] public Transform highlightBlock;
        public float checkIncrement = 0.1f;
        public float reach = 8.0f;
        public Toolbar toolbar;

        private bool _grounded;
        private bool _sprinting;

        private Transform _camera;
        private World _world;
        private float _horizontal;
        private float _vertical;
        private float _mouseHorizontal;
        private float _mouseVertical;
        private Vector3 _velocity;
        private float _verticalMomentum;
        private bool _jumpRequest;

        private Vector3 _placeBlockPosition;
        private Vector3 _destroyBlockPosition;

        private void Start() {
            _camera = GameObject.Find("Main Camera").transform;
            _world = GameObject.Find("World").GetComponent<World>();

            _camera.Translate(new Vector3(0, playerHeight - 0.2f, 0), Space.Self);

            _world.MenuOpen = false;
        }

        private void Update() {
            if (Input.GetKeyDown(KeyCode.E)) {
                _world.MenuOpen = !_world.MenuOpen;
            }

            if (!_world.MenuOpen) {
                GetPlayerInputs();
                PlaceCursorBlock();
            }
            else {
                _horizontal = 0;
                _vertical = 0;
                _mouseHorizontal = 0;
                _mouseVertical = 0;
            }
        }

        private void FixedUpdate() {
            CalculateVelocity();
            if (_jumpRequest) Jump();

            transform.Rotate(Vector3.up * _mouseHorizontal * World.Settings.mouseSensitivity);
            _camera.Rotate(Vector3.right * -_mouseVertical * World.Settings.mouseSensitivity);
            transform.Translate(_velocity, Space.World);
        }

        private void GetPlayerInputs() {
            if (Input.GetKeyDown(KeyCode.Escape))
                Application.Quit();
            
            _horizontal = Input.GetAxis("Horizontal");
            _vertical = Input.GetAxis("Vertical");
            _mouseHorizontal = Input.GetAxis("Mouse X");
            _mouseVertical = Input.GetAxis("Mouse Y");

            if (Input.GetButtonDown("Fire3"))
                _sprinting = true;
            if (Input.GetButtonUp("Fire3"))
                _sprinting = false;

            if (_grounded && Input.GetButtonDown("Jump"))
                _jumpRequest = true;

            if (highlightBlock.gameObject.activeSelf) {
                if (Input.GetMouseButtonDown(0))
                    _world.GetChunkFromWorldPosition(_destroyBlockPosition)?.EditBlock(_destroyBlockPosition, 0);

                if (Input.GetMouseButtonDown(1)) {
                    ItemSlot slot = toolbar.slots[toolbar.slotIndex].itemSlot;
                    if (!slot.HasItem) return;
                    
                    _world.GetChunkFromWorldPosition(_placeBlockPosition)?.EditBlock(_placeBlockPosition, slot.Stack.Block);
                    slot.Take(1);
                }
            }

            if (Input.GetKeyDown(KeyCode.F3))
                debugScreen.SetActive(!debugScreen.activeSelf);
        }

        private void PlaceCursorBlock() {
            float step = checkIncrement;
            Vector3 lastPos = new Vector3();

            while (step < reach) {
                Vector3 pos = _camera.position + (_camera.forward * step);

                if (_world.CheckForBlock(pos)) {
                    highlightBlock.position = new Vector3(
                        Mathf.FloorToInt(pos.x),
                        Mathf.FloorToInt(pos.y),
                        Mathf.FloorToInt(pos.z)
                    );
                    highlightBlock.gameObject.SetActive(true);

                    _placeBlockPosition = lastPos;
                    _destroyBlockPosition = highlightBlock.position;

                    return;
                }

                lastPos = new Vector3(
                    Mathf.FloorToInt(pos.x),
                    Mathf.FloorToInt(pos.y),
                    Mathf.FloorToInt(pos.z)
                );

                step += checkIncrement;
            }

            highlightBlock.gameObject.SetActive(false);
        }

        private void Jump() {
            _verticalMomentum = jumpForce;
            _grounded = false;
            _jumpRequest = false;
        }

        private void CalculateVelocity() {
            if (_verticalMomentum > WorldData.Gravity)
                _verticalMomentum += Time.fixedDeltaTime * WorldData.Gravity;

            if (_sprinting)
                _velocity = ((transform.forward * _vertical) + (transform.right * _horizontal)) * Time.fixedDeltaTime *
                            sprintSpeed;
            else
                _velocity = ((transform.forward * _vertical) + (transform.right * _horizontal)) * Time.fixedDeltaTime *
                            walkSpeed;

            _velocity += Vector3.up * _verticalMomentum * Time.fixedDeltaTime;

            if ((_velocity.z > 0 && Front) || (_velocity.z < 0 && Back))
                _velocity.z = 0;
            if ((_velocity.x > 0 && Right) || (_velocity.x < 0 && Left))
                _velocity.x = 0;

            if (_velocity.y < 0)
                _velocity.y = CheckDownSpeed(_velocity.y);
            if (_velocity.y > 0)
                _velocity.y = CheckUpSpeed(_velocity.y);
        }

        private float CheckDownSpeed(in float downSpeed) {
            if (_world.CheckForBlock(new Vector3(transform.position.x - playerRadius, transform.position.y + downSpeed,
                    transform.position.z - playerRadius)) ||
                _world.CheckForBlock(new Vector3(transform.position.x + playerRadius, transform.position.y + downSpeed,
                    transform.position.z - playerRadius)) ||
                _world.CheckForBlock(new Vector3(transform.position.x + playerRadius, transform.position.y + downSpeed,
                    transform.position.z + playerRadius)) ||
                _world.CheckForBlock(new Vector3(transform.position.x - playerRadius, transform.position.y + downSpeed,
                    transform.position.z + playerRadius))) {
                _grounded = true;
                return 0;
            }

            _grounded = false;
            return downSpeed;
        }

        private float CheckUpSpeed(in float upSpeed) {
            if (_world.CheckForBlock(new Vector3(transform.position.x - playerRadius,
                    transform.position.y + playerHeight + upSpeed, transform.position.z - playerRadius)) ||
                _world.CheckForBlock(new Vector3(transform.position.x + playerRadius,
                    transform.position.y + playerHeight + upSpeed, transform.position.z - playerRadius)) ||
                _world.CheckForBlock(new Vector3(transform.position.x + playerRadius,
                    transform.position.y + playerHeight + upSpeed, transform.position.z + playerRadius)) ||
                _world.CheckForBlock(new Vector3(transform.position.x - playerRadius,
                    transform.position.y + playerHeight + upSpeed, transform.position.z + playerRadius))) {
                return 0;
            }

            return upSpeed;
        }

        private bool Front => _world.CheckForBlock(new Vector3(transform.position.x, transform.position.y,
                                  transform.position.z + playerRadius)) ||
                              _world.CheckForBlock(new Vector3(transform.position.x, transform.position.y + 1.0f,
                                  transform.position.z + playerRadius));

        private bool Back => _world.CheckForBlock(new Vector3(transform.position.x, transform.position.y,
                                 transform.position.z - playerRadius)) ||
                             _world.CheckForBlock(new Vector3(transform.position.x, transform.position.y + 1.0f,
                                 transform.position.z - playerRadius));

        private bool Left => _world.CheckForBlock(new Vector3(transform.position.x - playerRadius, transform.position.y,
                                 transform.position.z)) ||
                             _world.CheckForBlock(new Vector3(transform.position.x - playerRadius,
                                 transform.position.y + 1.0f, transform.position.z));

        private bool Right => _world.CheckForBlock(new Vector3(transform.position.x + playerRadius,
                                  transform.position.y, transform.position.z)) ||
                              _world.CheckForBlock(new Vector3(transform.position.x + playerRadius,
                                  transform.position.y + 1.0f, transform.position.z));
    }
}