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

public class TileSplitter : MonoBehaviour
{
    public Texture2D tileset;
    public int tileWidth = 32;
    public int tileHeight = 32;

    public void SplitTiles()
    {
        int width = tileset.width / 32;
        int height = tileset.height / 32;
        string name = tileset.name;
        int totalTiles = width * height;

        string path = AssetDatabase.GetAssetPath(tileset) + ".meta";
        List<string> lines = new List<string>();
        string line = null;
        using (StreamReader file =  new StreamReader(path))
        {
            lines.Add(file.ReadLine());
            file.ReadLine();
            lines.Add("guid: " + System.Guid.NewGuid());

            while ((line = file.ReadLine()) != null)
            {
                lines.Add(line);
                if (line.Contains("sprites:"))
                    break;
            }
        }

        int xCount = 0;
        int yCount = height;
        for (int i = 0; i < totalTiles; ++i)
        {
            int x = xCount * tileWidth;
            int y = yCount * tileHeight;

            lines.Add("    - name: " + name + "_" + i);
            lines.Add("      rect:");
            lines.Add("        serializedVersion: 2");
            lines.Add("        x: " + x);
            lines.Add("        y: " + y);
            lines.Add("        width: " + tileWidth);
            lines.Add("        height: " + tileHeight);
            lines.Add("      alignment: 0");
            lines.Add("      pivot: {x: 0, y: 0}");
            lines.Add("      border: {x: 0, y: 0, z: 0, w: 0}");

            ++xCount;
            if(xCount >= width)
            {
                xCount = 0;
                --yCount;
            }
        }
        lines.Add("  spritePackingTag: ");
        lines.Add("  userData: ");

        File.Delete(path);
        File.WriteAllLines(path, lines.ToArray());
    }
}