using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PipeSpawner : MonoBehaviour {

    [System.Serializable]
    public struct SpawnHeight {
        public float min;
        public float max;
    }

    public GameObject PipePrefab;
    public float shiftSpeed;
    public float spawnRate;
    public SpawnHeight spawnHeight;
    public Vector3 spawnPos;
    public Vector2 targetAspectRatio;
    public bool beginInScreenCenter;
    List<Transform> pipes;
    float spawnTimer;
    GameManager game;
    float targetAspect;
    Vector3 dynamicSpawnPos;

    void Start() {
        pipes = new List<Transform>();
        game = GameManager.Instance;
        if (beginInScreenCenter)
            SpawnPipe();
    }

    void OnEnable() {
        GameManager.OnGameOverConfirmed += OnGameOverConfirmed;
    }

    void OnDisable() {
        GameManager.OnGameOverConfirmed -= OnGameOverConfirmed;
    }

    void OnGameOverConfirmed() {
        for (int i = pipes.Count - 1; i >= 0; i--) {
            GameObject temp = pipes[i].gameObject;
            pipes.RemoveAt(i);
            Destroy(temp);
        }
        if (beginInScreenCenter) SpawnPipe();
    }

    void Update() {
        if (game.GameOver) return;
        targetAspect = (float)targetAspectRatio.x / targetAspectRatio.y;
        dynamicSpawnPos.x = (spawnPos.x * Camera.main.aspect) / targetAspect;
        spawnTimer += Time.deltaTime;
        if (spawnTimer >= spawnRate) {
            SpawnPipe();
            spawnTimer = 0;
        }

        ShiftPipes();
    }

    void SpawnPipe() {
        GameObject pipe = Instantiate(PipePrefab) as GameObject;
        pipe.transform.SetParent(transform);
        pipe.transform.localPosition = dynamicSpawnPos;
        if (beginInScreenCenter && pipes.Count == 0) pipe.transform.localPosition = Vector3.zero;
        float randomYPos = Random.Range(spawnHeight.min, spawnHeight.max);
        pipe.transform.position += Vector3.up * randomYPos;
        pipes.Add(pipe.transform);
    }

    void ShiftPipes() {
        for (int i = pipes.Count - 1; i >= 0; i--) {
            pipes[i].position -= Vector3.right * shiftSpeed * Time.deltaTime;
            if (pipes[i].position.x < (-dynamicSpawnPos.x * Camera.main.aspect) / targetAspect) {
                GameObject temp = pipes[i].gameObject;
                pipes.RemoveAt(i);
                Destroy(temp);
            }
        }
    }
}