using System.Collections;
using System.Collections.Generic;
using UnityEngine;
#if UNITY_EDITOR
using UnityEditor;
#endif

/// <summary>
/// 用于TopDown的Transform，支持模拟垂直高度，不允许旋转和缩放
/// TopDownTransform的父节点必须也是TopDownTransform，Transform的父节点可以是TopDownTransform
/// </summary>
[ExecuteInEditMode]
[RequireComponent(typeof(Transform))]
public class TopDownTransform : MonoBehaviour
{
	// 右手系
	//  z
	//  |
	//  |  /y
	//  | /
	//  |/______x

	// x, y, z ( z = height)
	[SerializeField] private Vector3 m_LocalPosition;

	// 只能绕一个虚拟轴旋转
	//[SerializeField] private float m_LocalRotation;

	// x, z
	//[SerializeField] private Vector2 m_LocalScale;

	public Vector3 localPosition
	{
		get
		{
			return m_LocalPosition;
		}
		set
		{
			m_LocalPosition = value;
			Project();
		}
	}

	public float x
	{
		get
		{
			return m_LocalPosition.x;
		}
		set
		{
			m_LocalPosition.x = value;
			Project();
		}
	}
	public float y
	{
		get
		{
			return m_LocalPosition.y;
		}
		set
		{
			m_LocalPosition.y = value;
			Project();
		}
	}

	public float z
	{
		get
		{
			return m_LocalPosition.z;
		}
		set
		{
			m_LocalPosition.z = value;
			Project();
		}
	}

	public float height
	{
		get
		{
			return z;
		}
		set
		{
			z = value;
		}
	}

	/// <summary>
	/// 全局坐标
	/// </summary>
	public Vector3 position
	{
		get
		{
			Vector3 pos = m_LocalPosition;
			Transform self = this.transform; 
			while(self.parent != null)
			{
				TopDownTransform parentTransform = self.parent.GetComponent<TopDownTransform>();
				if (parentTransform == null)
				{
					Debug.LogError("Parent is not TopDownTransform");
					continue;
				}
				pos += parentTransform.m_LocalPosition;
				self = self.parent;
			}
			return pos;
		}
		set
		{
			Vector3 pos = value;
			Transform self = this.transform;
			while (self.parent != null)
			{
				TopDownTransform parentTransform = self.parent.GetComponent<TopDownTransform>();
				if (parentTransform == null)
				{
					Debug.LogError("Parent is not TopDownTransform");
					continue;
				}
				pos -= parentTransform.m_LocalPosition;
				self = self.parent;
			}
			m_LocalPosition = pos;
			Project();
		}
	}

	/// <summary>
	/// 地表坐标（Topdown空间）
	/// </summary>
	public Vector3 positionOnGround
	{
		get
		{
			Vector3 pos = position;
			pos.z = 0;
			return pos;
		}
		set
		{
			Vector3 pos = position;
			pos.x = value.x;
			pos.y = value.y;
			position = pos;
			Project();
		}
	}

	/// <summary>
	/// “投影”，把坐标转换到Transform上
	/// </summary>
	public void Project()
	{
		Vector3 pos = transform.localPosition;
		pos.x = m_LocalPosition.x;
		pos.y = m_LocalPosition.y + m_LocalPosition.z;

		transform.localPosition = pos;
	}

	private void Awake()
	{
		SpriteRenderer sr = GetComponent<SpriteRenderer>();
		if (sr)
		{
			gameObject.AddOrGetComponent<TopDownSorting>();
			//gameObject.AddOrGetComponent<TopDownShadowCaster>();
		}
	}

	private void Update()
	{
		Project();
	}

	#region 转换到Transform坐标
	public Vector3 GetProjectedPosition()
	{
		Vector3 posTD = position;

		Vector3 pos = new Vector3();
		pos.x = posTD.x;
		pos.y = posTD.y + posTD.z;
		pos.z = transform.position.z;
		return pos;
	}

	/// <summary>
	/// 注意是在3D空间下
	/// </summary>
	/// <returns></returns>
	public Vector3 GetProjectedGroundPosition()
	{
		Vector3 posTD = position;

		Vector3 pos = new Vector3();
		pos.x = posTD.x;
		pos.y = posTD.y;
		pos.z = transform.position.z;
		return pos;
	}
	#endregion 

#if UNITY_EDITOR
	private void OnDrawGizmos()
	{
		Vector3 start = TopDownUtils.Project(position);
		Vector3 end = TopDownUtils.Project(positionOnGround);

		Handles.DrawDottedLine(start, end, 1f);
		Handles.DrawWireCube(end, new Vector3(0.1f, 0.1f, 0f));
	}
#endif

}