using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Linq;
using UnityEngine.UI;
using System;

public class Snake : MonoBehaviour {

    private List<Transform> tail = new List <Transform>();
    private bool ate = false;
    public GameObject tailPrefab;
    public Text scoreText;
    public GameObject gameOverPanel;
    public Button startButton;
    public float speed = 5;
    public Text highscorePanel;
    private bool gameOver;
    private int score;
    private Vector3 rot;


    // Use this for initialization
    void Start ()
    {
        highscorePanel.text = PlayerPrefs.GetInt("Highscore").ToString();
        InvokeRepeating ("Move", 0.0f, (float)(1 / speed));
        DisplayMenu ();
        gameOver = true;
    }
    void Restart() {
        foreach (Transform t in tail) {
            Destroy (t.gameObject);
        }
        tail.Clear();
        ate = false;
        CancelInvoke();
        InvokeRepeating ("Move", 0.0f, (float)(1 / speed));
        transform.position = new Vector2(0,0);
        UpdateScore ();
        gameOver = false;
        gameOverPanel.SetActive(false);
        Text startButtonText = startButton.GetComponentInChildren<Text>();
        if(startButtonText.text.Equals("Play")){
            startButtonText.text = "Restart";
        }
    }

    void GameOver()
    {
        gameOver = true;
        gameOverPanel.SetActive (true);
        HighScoreManager.SaveHighscore(score, name);
        HighScoreManager.ShowHighscores();
        if (score > PlayerPrefs.GetInt("Highscore", 0)) {
            PlayerPrefs.SetInt("Highscore", score);
            highscorePanel.text = score.ToString();
        }
    }
    void OnTriggerEnter2D(Collider2D coll)
    {
        //On collision with food
        if (coll.name.StartsWith ("FoodPrefab")) {
            //get longer in next Move call
            ate = true;
            //Remove the food
            Destroy (coll.gameObject);
            UpdateScore (1);
        }
        //On collision with border
        if (coll.name.StartsWith ("Border")) {
            GameOver ();
        }
        //On collision with tail
        if (coll.name.StartsWith ("Tail")) {
            if(!(coll.transform.position.x == tail[0].position.x && coll.transform.position.y == tail[0].position.y))
                GameOver ();
        }
    }

    // Update is called once per frame
    void Update () {
        if(!gameOver){
            CheckGameInput ();
        }
    }

    void CheckGameInput(){
        //Move in a new direction?
        if (Input.GetKey (KeyCode.RightArrow)) {
            rot = new Vector3 (0, 0, -90);
        } else if (Input.GetKey (KeyCode.DownArrow)) {
            rot = new Vector3 (0, 0, 180);
        } else if (Input.GetKey (KeyCode.LeftArrow)) {
            rot = new Vector3 (0, 0, 90);
        } else if (Input.GetKey (KeyCode.UpArrow)) {
            rot = new Vector3 (0, 0, 0);
        }
        transform.rotation = Quaternion.Euler(rot);
    }


    void Move() {
        if (!gameOver) {

            //Save current position (Gap will be here)
            Vector2 previousPos = transform.position;

            //Move forward
            transform.Translate(Vector2.up);

            if (ate) {

                //Load Prefab into the world
                GameObject newTail = Instantiate(tailPrefab, previousPos, Quaternion.identity);

                //Keep track of it in our tail list
                tail.Insert(0, newTail.transform);

                //Reset the flag
                ate = false;
            } else if (tail.Count > 0) { //Do we have a tail?

                //move Last tail element to where the head was
                tail.Last().position = previousPos;

                //Add to front of list, remove from back
                tail.Insert(0, tail.Last());
                tail.RemoveAt(tail.Count - 1);
            }
        }
    }

    void UpdateScore (int score = 0){
        if (score == 0) {
            this.score = 0;
        } else {
            this.score += score;
        }
        scoreText.text = this.score.ToString ();
    }

    public void SetSpeed(int speedChange){
        if(speed + speedChange >= 1){
            speed += speedChange;
        }
    }

    public void StartOver (){
        Restart ();
    }


    public void DisplayMenu() {
        gameOverPanel.SetActive(true);
    }

}