using System;
using System.Collections;
using System.Collections.Generic;
using MoreMountains.Feedbacks;
using MoreMountains.Tools;
using UnityEngine;
using UnityEngine.UI;

namespace MoreMountains.Feel
{
    /// <summary>
    /// A class used to handle Feel's Snake demo's snake "head", the part controlled by the player
    /// </summary>
    public class Snake : MonoBehaviour
    {
        [Header("Input")] 
        /// a key to press to turn
        public KeyCode ActionKey = KeyCode.Space;
        /// another key to press to turn
        public KeyCode ActionKeyAlt = KeyCode.Joystick1Button0;
        
        [Header("Movement")]
        /// the snake's movement speed
        public float Speed = 5f;
        /// the speed multiplier to apply at most times
        public float NormalSpeedMultiplier = 1f;
        /// the rate at which speed should vary
        public float SpeedChangeRate = 0.2f;
        /// the current direction of the snake
        public Vector3 Direction = Vector2.right;

        [Header("Boost")] 
        /// the speed multiplier to apply to the speed when boosting
        public float BoostMultiplier = 2f;
        /// the duration of the boost, in seconds
        public float BoostDuration = 2f;

        [Header("BodyParts")] 
        /// the prefab to use for body parts
        public SnakeBodyPart BodyPartPrefab;
        /// the offset to apply between two parts
        public int BodyPartsOffset = 7;
        /// the maximum amount of body parts for this snake
        public int MaxAmountOfBodyParts = 10;
        /// the minimum duration, in seconds, between 2 allowed parts losses
        public float MinTimeBetweenLostParts = 2f;

        [Header("Bindings")] 
        /// a Text component on which to display our current score
        public Text PointsCounter;

        [Header("Feedbacks")] 
        /// a feedback to play when the snake turns
        public MMFeedbacks TurnFeedback;
        /// a feedback to play when the snake teleports to the other side of the screen
        public MMFeedbacks TeleportFeedback;
        /// a feedback to play when teleporting once
        public MMFeedbacks TeleportOnceFeedback;
        /// a feedback to play when eating snake food
        public MMFeedbacks EatFeedback;
        /// a feedback to play when losing a body part
        public MMFeedbacks LoseFeedback;
        
        [Header("Debug")]
        [MMReadOnly]
        public int SnakePoints = 0;
        [MMReadOnly]
        public float _speed;
        [MMReadOnly]
        public float _speedMultiplier;
        [MMReadOnly]
        public float _lastFoodEatenAt = -100f;
        
        protected Vector3 _newPosition;
        protected MMPositionRecorder _recorder;
        public List<SnakeBodyPart> _snakeBodyParts;
        protected float _lastLostPart = 0f;
        
        /// <summary>
        /// On Awake, we initialize our snake's points, speed, position recorder, and body parts container
        /// </summary>
        protected void Awake()
        {
            _speed = Speed;
            SnakePoints = 0;
            _recorder = this.gameObject.GetComponent<MMPositionRecorder>();
            PointsCounter.text = "0";
            _snakeBodyParts = new List<SnakeBodyPart>();
        }
        
        /// <summary>
        /// Every frame, we check for input and move our snake's head
        /// </summary>
        protected virtual void Update()
        {
            HandleInput();   
            HandleMovement();
        }

        /// <summary>
        /// Every frame, looks for turn input
        /// </summary>
        protected virtual void HandleInput()
        {
            if (Input.GetKeyDown(ActionKey) || Input.GetKeyDown(ActionKeyAlt) || Input.GetMouseButtonDown(0))
            {
                Turn();
            }    
        }

        /// <summary>
        /// Every frame, moves the snake's head's position
        /// </summary>
        protected virtual void HandleMovement()
        {
            _speedMultiplier = (Time.time - _lastFoodEatenAt < BoostDuration) ? BoostMultiplier : NormalSpeedMultiplier;
            _speed = MMMaths.Lerp(_speed, Speed * _speedMultiplier, SpeedChangeRate, Time.deltaTime);
            _newPosition = (_speed * Time.deltaTime * Direction);
            this.transform.position += _newPosition;
        }
        
        /// <summary>
        /// Called when turning, rotates the snake's head, changes its direction, plays a feedback
        /// </summary>
        public virtual void Turn()
        {
            TurnFeedback?.PlayFeedbacks();
            Direction = MMMaths.RotateVector2(Direction, 90f);
            this.transform.Rotate(new Vector3(0f,0f,90f));
        }

        /// <summary>
        /// Called by the snake head's MMViewportEdgeTeleporter, defines what happens when the snake is teleported to the other side of the screen
        /// </summary>
        public virtual void Teleport()
        {
            StartCoroutine(TeleportCo());
        }

        /// <summary>
        /// A coroutine used to teleport the snake to the other side of the screen
        /// </summary>
        /// <returns></returns>
        protected virtual IEnumerator TeleportCo()
        {
            TeleportFeedback?.PlayFeedbacks();
            
            TeleportOnceFeedback?.PlayFeedbacks();
            
            yield return MMCoroutine.WaitForFrames(BodyPartsOffset);
            
            int total = _snakeBodyParts.Count;
            float feedbacksIntensity = 0f;
            float part = 1 / (float)total;    
            
            for (int i = 0; i < total; i++)
            {
                yield return MMCoroutine.WaitForFrames(BodyPartsOffset/2);
                feedbacksIntensity = 1 - i * part;
                TeleportFeedback?.PlayFeedbacks(this.transform.position, feedbacksIntensity);
            }
        }

        /// <summary>
        /// Called when eating food, triggers visual effects, increases points, plays a feedback
        /// </summary>
        public virtual void Eat()
        {
            EatEffect();
            
            EatFeedback?.PlayFeedbacks();
            SnakePoints++;
            PointsCounter.text = SnakePoints.ToString();
            StartCoroutine(EatCo());
        }

        /// <summary>
        /// A coroutine used to go through every snake body part and trigger its Eat MMFeedbacks
        /// </summary>
        protected virtual IEnumerator EatCo()
        {
            int total = _snakeBodyParts.Count;
            float feedbacksIntensity = 0f;
            float part = 1 / (float)total;    
            
            for (int i = 0; i < total; i++)
            {
                if (i >= _snakeBodyParts.Count)
                {
                    yield break;
                }
                yield return MMCoroutine.WaitForFrames(BodyPartsOffset/2);
                feedbacksIntensity = 1 - i * part;
                if (i == total - 1)
                {
                    if ((i < MaxAmountOfBodyParts - 1) && (_snakeBodyParts.Count > i))
                    {
                        if (_snakeBodyParts[i] != null)
                        {
                            _snakeBodyParts[i].New();    
                        }
                    }
                }
                else
                {
                    _snakeBodyParts[i].Eat(feedbacksIntensity);    
                }
            }
        }

        /// <summary>
        /// When eating food, we instantiate a new body part unless we've reached our limit
        /// </summary>
        public virtual void EatEffect()
        {
            _lastFoodEatenAt = Time.time;
            if (SnakePoints < MaxAmountOfBodyParts - 1)
            {
                SnakeBodyPart part = Instantiate(BodyPartPrefab);
                part.transform.position = this.transform.position;
                part.TargetRecorder = _recorder;
                part.Offset = ((SnakePoints) * BodyPartsOffset) + BodyPartsOffset + 1;
                part.Index = _snakeBodyParts.Count;
                part.name = "SnakeBodyPart_" + part.Index;
                _snakeBodyParts.Add(part);
            }
        }

        /// <summary>
        /// When we lose a body part, we play a feedback, destroy the last part, lose points, and update our points display 
        /// </summary>
        /// <param name="part"></param>
        public virtual void Lose(SnakeBodyPart part)
        {
            if (Time.time - _lastLostPart < MinTimeBetweenLostParts)
            {
                return;
            }

            _lastLostPart = Time.time;
            LoseFeedback?.PlayFeedbacks(part.transform.position);
            Destroy(_snakeBodyParts[_snakeBodyParts.Count-1].gameObject);
            _snakeBodyParts.RemoveAt(_snakeBodyParts.Count-1);
            SnakePoints--;
            PointsCounter.text = SnakePoints.ToString();
        }
    }
}