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

/// <summary>
/// This component is responsible for creating scenery props randomly selected from <code>sceneryPrefabs</code>
/// The randomness does not use the <code>RandomSingleton</code>. This is due to the fact that we don't have control
/// of order of execution (unless we use Execution Order feature which we find hacky). So since it doesn't affect the
/// gameplay as such, for now we decided to use Unity's random which is independent from RandomSingleton used to
/// generate the enemies.
/// </summary>
public class SceneryGenerator : MonoBehaviour
{
    public static SceneryGenerator Instance;
    /// <summary>
    /// Prefabs will be randomly selected from here with gamedesigner-set weights
    /// To create prefabs, the sprites will probably be normal textures, rather than part of an atlas. This is because
    /// they will be quite big and would defeat the purpose of putting them in an atlas. So in NGUI you can create
    /// a texture widget, where you just drag and drop the texture on the widget's texture field. You might need
    /// to change the shader so it's transparent as well. The widget's pivot needs to be set carefully.
    /// The horizontal pivolt must always be set to the right pivot. If it's a top-bottom prop, leave the vertical pivot to middle.
    /// Otherwise set it accordingly, e.g. if it's a prop coming from the top, set the vertical pivot to top.
    /// Reset the transform's position to zero
    /// </summary>
    public LootTable sceneryPrefabs;
	public int minSpacing = 300;
	public int maxSpacing = 600;
 
	/// <summary>
	/// Tweak this value to get a parallax effect
	/// </summary>
	public float speed = 150;

	/// <summary>
	/// This is the z value used for the generated props, where together with the appropriate speed
	/// will achieve a parallax effect.
	/// For foreground we are currently using -2 (in front of bullets)
	/// For midground we are currently using 9 (just in front of backgrounds)
	/// </summary>
	public float zValue;

	Transform _anchor;
	List<Transform> _sceneryPropsTransforms = new List<Transform>();
	List<SceneryProp> _sceneryProps = new List<SceneryProp>();
	float _nextSceneryX;

	float _originalSpeed;
	bool _isSpawning;
    public bool _isPlaying = false;
	const int STOP_SPAWNING_AT_TIME_LEFT = 18;

	#region Unity Callbacks
	void Awake()
	{
	    Instance = this;
        _anchor = SkinDownloadManager.Instance.sceneryAnchor;
		_originalSpeed = speed;
		if (enabled) //for debugging purposes so we can disable the component at design time for a debug session
		{
			enabled = false;
			NotificationCenter.AddListener(OnGameStart, NotificationType.GameStart);
            NotificationCenter.AddListener(OnEndLife, NotificationType.EndLife);
            NotificationCenter.AddListener(OnGetLife, NotificationType.GetLife);
            NotificationCenter.AddListener(OnGameOver, NotificationType.GameOver);
			NotificationCenter.AddListener(OnChangeScrollingSpeed, NotificationType.ChangeScrollingSpeed);
			NotificationCenter.AddListener(OnTimeLeftUpdate, NotificationType.TimeLeftUpdate);
		}
	}

    private void OnGetLife(Notification note)
    {
        //_isPlaying = true;
    }

    private void OnEndLife(Notification note)
    {
        _isPlaying = false;
    }

    void OnDestroy()
	{
		NotificationCenter.RemoveListener(OnGameStart, NotificationType.GameStart);
		NotificationCenter.RemoveListener(OnGameOver, NotificationType.GameOver);
		NotificationCenter.RemoveListener(OnChangeScrollingSpeed, NotificationType.ChangeScrollingSpeed);
		NotificationCenter.RemoveListener(OnTimeLeftUpdate, NotificationType.TimeLeftUpdate);
        NotificationCenter.RemoveListener(OnEndLife, NotificationType.EndLife);
        NotificationCenter.RemoveListener(OnGetLife, NotificationType.GetLife);
    }

	void Update()
	{
	    if (!BackgroundManager.Instance._isPlaying)
	    {
	        return;
	    }
		float deltaX = speed * Time.deltaTime;
		if (_isSpawning)
		{
			_nextSceneryX += deltaX;
			//if the next scenery marker is visible, create the next prop
			if (_nextSceneryX > -GameConstants.GAME_WIDTH/2)
			{
				CreateNextSceneryProp();
			}
		}

		for (int i = _sceneryPropsTransforms.Count-1; i >= 0; i--)
		{
			Transform sceneryPropTransform = _sceneryPropsTransforms[i];
			SceneryProp sceneryProp = _sceneryProps[i];
			//move scenery
			sceneryPropTransform.localPosition += new Vector3(deltaX, 0, 0);

			//check if needs to be removed
			if (sceneryPropTransform.localPosition.x + sceneryProp.MinX > GameConstants.GAME_WIDTH/2)
			{
				sceneryProp.Despawn();
				_sceneryPropsTransforms.RemoveAt(i);
				_sceneryProps.RemoveAt(i);
			}
		}
	}
	#endregion

	#region Notification Callbacks
	void OnGameStart(Notification note)
	{
		enabled = true;
		_isSpawning	= true;
	    _isPlaying = true;
		_nextSceneryX -= UnityEngine.Random.Range(minSpacing, maxSpacing);
	}

	void OnGameOver(Notification note)
	{
		enabled = false;
		foreach (SceneryProp s in _sceneryProps)
		{
			s.Despawn();
		}
		_sceneryPropsTransforms.Clear();
		_sceneryProps.Clear();
	}

	void OnChangeScrollingSpeed(Notification note)
	{
		float scrollingSpeedFactor = (float)note.data;
		speed = _originalSpeed * scrollingSpeedFactor;
	}

	void OnTimeLeftUpdate(Notification note)
	{
		float timeLeft = (float)note.data;
		//Stop spawning stuff so that it doesn't intermingle with the end of level scenery
		if (_isSpawning && timeLeft <= STOP_SPAWNING_AT_TIME_LEFT)
		{
			_isSpawning = false;
		}
	}
	#endregion

	void CreateNextSceneryProp()
	{
		Transform sceneryPropTransform = sceneryPrefabs.GetRandomItem();
		SceneryProp sceneryProp = sceneryPropTransform.GetComponent<SceneryProp>();
		Vector3 originalPos = sceneryPropTransform.localPosition;
		originalPos.x = _nextSceneryX - sceneryProp.MaxX;
		originalPos.z = zValue;
		Vector3 originalScale = sceneryPropTransform.localScale;
		sceneryPropTransform.parent = _anchor;
		sceneryPropTransform.localPosition = originalPos;
		sceneryPropTransform.localScale = originalScale;
		_sceneryPropsTransforms.Add(sceneryPropTransform);
		_sceneryProps.Add(sceneryProp);
		_nextSceneryX += sceneryProp.MinX;
		_nextSceneryX -= UnityEngine.Random.Range(minSpacing, maxSpacing);
		//add some randomness in flipping on the X axis
		bool isXFlipped = UnityEngine.Random.value < 0.5f;
		if (isXFlipped)
		{
			UITexture uiTexture = sceneryPropTransform.GetComponent<UITexture>();
			if (uiTexture != null) //if it is null, it must be some composite scenery prop with multiple UITextures... just skip it in that case
			{
			   
				Rect r = uiTexture.uvRect;
				r.x = 1;
				r.width = -1;
				uiTexture.uvRect = r;
			}
		}
	}
}