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

public class TextureAtlasSlicer : EditorWindow {
    [MenuItem("CONTEXT/TextureImporter/Slice Sprite Using XML")]
    public static void SliceUsingXML(MenuCommand command)
    {
        TextureImporter textureImporter = command.context as TextureImporter;

        TextureAtlasSlicer window = ScriptableObject.CreateInstance<TextureAtlasSlicer>();

        window.importer = textureImporter;

        window.ShowUtility();
    }

    [MenuItem("CONTEXT/TextureImporter/Slice Sprite Using XML", true)]
    public static bool ValidateSliceUsingXML(MenuCommand command)
    {
        TextureImporter textureImporter = command.context as TextureImporter;

        //valid only if the texture type is 'sprite' or 'advanced'.
        return textureImporter && textureImporter.textureType == TextureImporterType.Sprite ||
               textureImporter.textureType == TextureImporterType.Default;
    }

    public TextureImporter importer;

    public TextureAtlasSlicer()
    {
        title = "Texture Atlas Slicer";
    }


    [SerializeField] private TextAsset xmlAsset;

    public SpriteAlignment spriteAlignment = SpriteAlignment.Center;

    public Vector2 customOffset = new Vector2(0.5f, 0.5f);

    public void OnGUI() {
        xmlAsset = EditorGUILayout.ObjectField("XML Source", xmlAsset, typeof (TextAsset), false) as TextAsset;

        spriteAlignment = (SpriteAlignment) EditorGUILayout.EnumPopup("Pivot", spriteAlignment);

        bool enabled = GUI.enabled;
        if (spriteAlignment != SpriteAlignment.Custom) {
            GUI.enabled = false;
        }

        EditorGUILayout.Vector2Field("Custom Offset", customOffset);

        GUI.enabled = enabled;

        if (xmlAsset == null) {
            GUI.enabled = false;
        }

        if (GUILayout.Button("Slice")) {
            PerformSlice();
        }

        GUI.enabled = enabled;
    }

    private void PerformSlice()
    {
        XmlDocument document = new XmlDocument();
        document.LoadXml(xmlAsset.text);

        XmlElement root = document.DocumentElement;
        if (root.Name == "TextureAtlas") {
            bool failed = false;

            Texture2D texture = AssetDatabase.LoadMainAssetAtPath(importer.assetPath) as Texture2D;
            int textureHeight = texture.height;

            List<SpriteMetaData> metaDataList = new List<SpriteMetaData>();

            foreach (XmlNode childNode in root.ChildNodes)
            {
                if (childNode.Name == "SubTexture") {
                    try {
                        int width = Convert.ToInt32(childNode.Attributes["width"].Value);
                        int height = Convert.ToInt32(childNode.Attributes["height"].Value);
                        int x = Convert.ToInt32(childNode.Attributes["x"].Value);
                        int y = textureHeight - (height + Convert.ToInt32(childNode.Attributes["y"].Value));

                        SpriteMetaData spriteMetaData = new SpriteMetaData
                        {
                            alignment = (int)spriteAlignment,
                            border = new Vector4(),
                            name = childNode.Attributes["name"].Value,
                            pivot = GetPivotValue(spriteAlignment, customOffset),
                            rect = new Rect(x, y, width, height)
                        };

                        metaDataList.Add(spriteMetaData);
                    }
                    catch (Exception exception) {
                        failed = true;
                        Debug.LogException(exception);
                    }
                }
                else
                {
                    Debug.LogError("Child nodes should be named 'SubTexture' !");
                    failed = true;
                }
            }

            if (!failed) {
                importer.spriteImportMode = SpriteImportMode.Multiple; 
                importer.spritesheet = metaDataList.ToArray();

                EditorUtility.SetDirty(importer);

                try
                {
                    AssetDatabase.StartAssetEditing();
                    AssetDatabase.ImportAsset(importer.assetPath);
                }
                finally
                {
                    AssetDatabase.StopAssetEditing();
                    Close();
                }
            }
        }
        else
        {
            Debug.LogError("XML needs to have a 'TextureAtlas' root node!");
        }
    }

    //SpriteEditorUtility
    public static Vector2 GetPivotValue(SpriteAlignment alignment, Vector2 customOffset)
    {
        switch (alignment)
        {
            case SpriteAlignment.Center:
                return new Vector2(0.5f, 0.5f);
            case SpriteAlignment.TopLeft:
                return new Vector2(0.0f, 1f);
            case SpriteAlignment.TopCenter:
                return new Vector2(0.5f, 1f);
            case SpriteAlignment.TopRight:
                return new Vector2(1f, 1f);
            case SpriteAlignment.LeftCenter:
                return new Vector2(0.0f, 0.5f);
            case SpriteAlignment.RightCenter:
                return new Vector2(1f, 0.5f);
            case SpriteAlignment.BottomLeft:
                return new Vector2(0.0f, 0.0f);
            case SpriteAlignment.BottomCenter:
                return new Vector2(0.5f, 0.0f);
            case SpriteAlignment.BottomRight:
                return new Vector2(1f, 0.0f);
            case SpriteAlignment.Custom:
                return customOffset;
            default:
                return Vector2.zero;
        }
    }
}