using System;
using System.Collections.Generic;

public class LevelManager : SingletonBehaviour<LevelManager>
{
    public event Action<ILevelObject> Added;
    public event Action<ILevelObject> Removed;

    private List<ILevelObject> toAdd;
    private List<ILevelObject> toRemove;
    private List<ILevelObject> levelObjects;
    public LevelManager()
    {
        toAdd = new List<ILevelObject>();
        toRemove = new List<ILevelObject>();
        levelObjects = new List<ILevelObject>();
    }

    public void Add(ILevelObject levelObject)
    {
        if (levelObjects.Exists(obj => obj.Equals(levelObject))) return;
        toAdd.Add(levelObject);
    }
    public void Remove(ILevelObject levelObject)
    {
        if (!levelObjects.Contains(levelObject)) return;
        toRemove.Add(levelObject);
    }
    public void Clear()
    {
        toAdd.Clear();
        toRemove.Clear();
        levelObjects.Clear();
    }
    public T Get<T>(Func<T, bool> predicate = null) where T : ILevelObject
    {
        if (predicate == null) predicate = (t) => true;
        return (T)levelObjects.Find(t => t is T t1 && predicate(t1));
    }
    public List<T> GetAll<T>(Func<T, bool> predicate = null) where T : ILevelObject
    {
        if (predicate == null) predicate = (t) => true;
        List<T> ret = new List<T>();
        foreach (var t in levelObjects) if (t is T t1 && predicate(t1)) ret.Add(t1);
        return ret;
    }

    public int Count<T>(Func<T, bool> predicate = null) where T : ILevelObject
    {
        return GetAll(predicate).Count;
    }

    public bool Has<T>(Func<T, bool> predicate = null)
    {
        if (predicate == null) predicate = (t) => true;
        return levelObjects.Exists(t => t is T && predicate((T)t));
    }

    void Update()
    {
        levelObjects.ForEach(obj => obj.LevelUpdate());
        
        toAdd.ForEach(tile =>
        {
            levelObjects.Add(tile);
            Added?.Invoke(tile);
            tile.LevelStart();
        });
        toAdd.Clear();

        toRemove.ForEach(tile =>
        {
            levelObjects.Remove(tile);
            Removed?.Invoke(tile);
            tile.LevelDestroy();
        });
        toRemove.Clear();
    }
}