using UnityEngine;
using System;
using System.Collections.Generic;
using Debug = UnityEngine.Debug;
using Object = UnityEngine.Object;
using Random = UnityEngine.Random;

public class InGameVertexPaint : MonoBehaviour
{
	public Color32 color;

	[Range(1f, 100f)]
	public float strength = 2f;

	//if true, checks if shader has "VertexPaint" tag set.
	public bool checkVertexPaintable = true;

	public bool drawDebugInfo = true;

	public Material autoConvertFrom;
	public Material autoConvertTo;

	void Start()
	{
		
	}
	
	void Update()
	{
		//TODO: should start checking within selection on mouse down, not
		//just checking continuously
		// if(!Input.GetMouseButton(0))
			// return;

		Ray ray = camera.ScreenPointToRay(Input.mousePosition);
		RaycastHit hit;

		if(!Physics.Raycast(ray, out hit))
			return;

		//TODO: at this point check cached transform

		// var mf = hit.transform.GetComponent<MeshFilter>();
		// if(!ren
			// || !mf
			// || !mf.mesh)
			// return;

		Renderer ren = hit.transform.renderer;
		MeshCollider mc = hit.collider as MeshCollider;

		if(mc == null
			|| mc.sharedMesh == null
			|| !ren.sharedMaterial)
			return;

		if(ren.sharedMaterial == autoConvertFrom)
		{
			ren.sharedMaterial = autoConvertTo;
//HACK
			// mc.sharedMesh.colors32 = new Color32[mc.sharedMesh.vertices.Length];
		}
		else if(checkVertexPaintable && ren.sharedMaterial.GetTag("VertexPaint", false, "") == "")
			return;
		
		Mesh mesh = mc.sharedMesh;
		int[] triangles = mesh.triangles;

		var colors = mesh.colors32 ?? new Color32[mesh.vertices.Length];

		int i0 = triangles[hit.triangleIndex * 3 + 0];
		int i1 = triangles[hit.triangleIndex * 3 + 1];
		int i2 = triangles[hit.triangleIndex * 3 + 2];

		Vector3 bary = hit.barycentricCoordinate;

		colors[i0] = Color32.Lerp(colors[i0], color, bary.x * strength / 100f);
		colors[i1] = Color32.Lerp(colors[i1], color, bary.y * strength / 100f);
		colors[i2] = Color32.Lerp(colors[i2], color, bary.z * strength / 100f);

		mesh.colors32 = colors;
		
		if(drawDebugInfo)
		{
			var vertices = mesh.vertices;
			Transform hitTransform = hit.transform;
			Vector3 p0 = hitTransform.TransformPoint(vertices[i0]);
			Vector3 p1 = hitTransform.TransformPoint(vertices[i1]);
			Vector3 p2 = hitTransform.TransformPoint(vertices[i2]);
			Debug.DrawLine(p0, p1, Color.red, 0, false);
			Debug.DrawLine(p1, p2, Color.red, 0, false);
			Debug.DrawLine(p2, p0, Color.red, 0, false);

			if(Input.GetKeyDown("f"))
			{
				Debug.Log(hit.triangleIndex + "/" + triangles.Length / 3 + " (" + vertices.Length + " verts)");
			}
		}

	}
}