using UnityEngine;
using UnityEditor;
using System.Collections;
using System.IO;
using System.Text;

public class ObjExporterScript
{
	private static int StartIndex = 0;

	public static void Start()
	{
		StartIndex = 0;
	}
	public static void End()
	{
		StartIndex = 0;
	}


	public static string MeshToString(MeshFilter mf, Transform t) 
	{	
		Vector3 s 		= t.localScale;
		Vector3 p 		= t.localPosition;
		Quaternion r 	= t.localRotation;


		int numVertices = 0;
		Mesh m = mf.sharedMesh;
		if (!m)
		{
			return "####Error####";
		}
		Material[] mats = mf.GetComponent<Renderer>().sharedMaterials;

		StringBuilder sb = new StringBuilder();

		foreach(Vector3 vv in m.vertices)
		{
			Vector3 v = t.TransformPoint(vv);
			numVertices++;
			sb.Append(string.Format("v {0} {1} {2}\n",v.x,v.y,v.z));
		}
		sb.Append("\n");
		foreach(Vector3 nn in m.normals) 
		{
			Vector3 v = r * nn;
			sb.Append(string.Format("vn {0} {1} {2}\n",v.x,v.y,v.z));
		}
		sb.Append("\n");
		foreach(Vector3 v in m.uv) 
		{
			sb.Append(string.Format("vt {0} {1}\n",v.x,v.y));
		}
		for (int material=0; material < m.subMeshCount; material ++) 
		{
			sb.Append("\n");
			sb.Append("usemtl ").Append(mats[material].name).Append("\n");
			sb.Append("usemap ").Append(mats[material].name).Append("\n");

			int[] triangles = m.GetTriangles(material);
			for (int i=0;i<triangles.Length;i+=3) {
				sb.Append(string.Format("f {0}/{0}/{0} {1}/{1}/{1} {2}/{2}/{2}\n", 
					triangles[i]+1+StartIndex, triangles[i+1]+1+StartIndex, triangles[i+2]+1+StartIndex));
			}
		}

		StartIndex += numVertices;
		return sb.ToString();
	}
}

public class ObjExporter : ScriptableObject
{
	[MenuItem ("Window/Infinity PBR/Wavefront OBJ")]
	static void DoExportWSubmeshes()
	{
		DoExport(true);
	}

	[MenuItem ("Window/Infinity PBR/Wavefront OBJ (No Submeshes)")]
	static void DoExportWOSubmeshes()
	{
		DoExport(false);
	}


	static void DoExport(bool makeSubmeshes)
	{
		if (Selection.gameObjects.Length == 0)
		{
			Debug.Log("Didn't Export Any Meshes; Nothing was selected!");
			return;
		}

		string meshName = Selection.gameObjects[0].name;
		string fileName = EditorUtility.SaveFilePanel("Export .obj file", "", meshName, "obj");

		ObjExporterScript.Start();

		StringBuilder meshString = new StringBuilder();

		meshString.Append("#" + meshName + ".obj"
			+ "\n#" + System.DateTime.Now.ToLongDateString() 
			+ "\n#" + System.DateTime.Now.ToLongTimeString()
			+ "\n#-------" 
			+ "\n\n");

		Transform t = Selection.gameObjects[0].transform;

		Vector3 originalPosition = t.position;
		t.position = Vector3.zero;

		if (!makeSubmeshes)
		{
			meshString.Append("g ").Append(t.name).Append("\n");
		}
		meshString.Append(processTransform(t, makeSubmeshes));

		WriteToFile(meshString.ToString(),fileName);

		t.position = originalPosition;

		ObjExporterScript.End();
		Debug.Log("Exported Mesh: " + fileName);
	}

	static string processTransform(Transform t, bool makeSubmeshes)
	{
		StringBuilder meshString = new StringBuilder();

		meshString.Append("#" + t.name
			+ "\n#-------" 
			+ "\n");

		if (makeSubmeshes)
		{
			meshString.Append("g ").Append(t.name).Append("\n");
		}

		MeshFilter mf = t.GetComponent<MeshFilter>();
		if (mf)
		{
			meshString.Append(ObjExporterScript.MeshToString(mf, t));
		}

		for(int i = 0; i < t.childCount; i++)
		{
			meshString.Append(processTransform(t.GetChild(i), makeSubmeshes));
		}

		return meshString.ToString();
	}

	static void WriteToFile(string s, string filename)
	{
		using (StreamWriter sw = new StreamWriter(filename)) 
		{
			sw.Write(s);
		}
	}
}