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

namespace TrafficSimulation{
    public class CarSituationSpawner : MonoBehaviour
    {
        public float spawnRate = 5.0f;
        public Transform[] spawns;
        public PresetTrigger[] despawns;
        public CarPool carPool;
        private List<IEnumerator> coroutines = new List<IEnumerator>();
        private bool isActive;
        private List<GameObject> cars = new List<GameObject>();

        // Use this for initialization
        void Start()
        {
            this.isActive = false;
        }

        // Update is called once per frame
        void Update()
        {
            if(this.isActive){
                CheckDespawns();   
            }
        }
        void OnDestroy() {
            StopSpawning();
        }
        /// <summary>
        /// Use this method to active the spawner
        /// </summary>
        public void StartSpawner(){
            this.isActive = true;
            StartSpawns();
        }

        /// <summary>
        /// Use this method to deactive the spawner
        /// </summary>
        public void StopSpawner(){
            this.isActive = false;
            StopSpawning();
            DespawnAllCars();
        }
        /// <summary>
        /// Check every set despawn area if cars have to be despawned
        /// </summary>
        private void CheckDespawns(){
            foreach(PresetTrigger despawn in despawns){
                if(despawn.checkLastTrigger()){
                    DespawnCar(despawn.getLastCollider());
                }
            }
        }
        /// <summary>
        /// Start a coroutine to spawn cars at every given spawn point
        /// </summary>
        private void StartSpawns(){
            foreach(Transform spawnPos in spawns){
                IEnumerator coroutine = AutoSpawning(spawnPos);
                this.coroutines.Add(coroutine);
                StartCoroutine(coroutine);
            }
        }
        /// <summary>
        /// Despawn all cars used from this spawner since it was active
        /// </summary>
        private void DespawnAllCars(){
            this.cars.ForEach(car => DespawnCar(car));
        }
        /// <summary>
        /// Stop all coroutines
        /// </summary>
        private void StopSpawning(){
            foreach(IEnumerator coroutine in this.coroutines){
                StopCoroutine(coroutine);
            }
        }
        /// <summary>
        /// Spawn a car on the given transform
        /// </summary>
        /// <param name="carSpawn">Transform</param>
        void SpawnCar(Transform carSpawn){
            this.cars.Add(this.carPool.SpawnCar(carSpawn));
        }
        /// <summary>
        /// Despawn the given car
        /// </summary>
        /// <param name="car">GameObject</param>
        void DespawnCar(GameObject car){
            this.carPool.despawnCar(car);
        }
        /// <summary>
        /// IEnumerator for the coroutine which spawns a car at the given position in the set spawnRate
        /// </summary>
        /// <param name="position">Transform</param>
        /// <returns></returns>
        public IEnumerator AutoSpawning(Transform position){
            while(true){
                SpawnCar(position);
                yield return new WaitForSeconds(this.spawnRate);
            }
        }
    }
}