using System;
using System.IO;
using System.Linq;
using UnityEditor;
using UnityEngine;
using UnityEngine.Events;
using Object = UnityEngine.Object;

public abstract class ResourceScanBase<T> where T : Object
{
    public event UnityAction onFinish;
    private readonly Predicate<string> _predicate;
    private string[] _assetPaths;
    private int _index;
    
    protected ResourceScanBase(string extension, string relativeAssetPath = null)
    {
        _predicate = a =>
        {
            if (string.IsNullOrEmpty(relativeAssetPath) || a.StartsWith(relativeAssetPath, StringComparison.OrdinalIgnoreCase))
            {
                var assetExt = Path.GetExtension(a);
                return string.IsNullOrEmpty(assetExt) ? string.IsNullOrEmpty(extension) : assetExt.Equals(extension, StringComparison.OrdinalIgnoreCase);
            }
            else
                return false;
        };
    }

    protected ResourceScanBase(Predicate<string> predicate)
    {
        _predicate = predicate;
    }
    
    protected void Start()
    {
        _assetPaths = (from assetPath in AssetDatabase.GetAllAssetPaths()
            let extension = Path.GetExtension(assetPath)
            where _predicate(assetPath)
            select assetPath).ToArray();
        _index = 0;
        EditorApplication.update += OnEditorUpdate;
    }

    private void OnEditorUpdate()
    {
        var finish = false;
        try
        {
            if (_index < _assetPaths.Length)
            {
                var path = _assetPaths[_index];
                var item = AssetDatabase.LoadAssetAtPath<T>(path);
                if (item != null)
                    FixOneAsset(item, path);
                _index++;
                Debug.Log(string.Format("完成扫描{0} / {1}, 路径{2}", _index, _assetPaths.Length, path));
            }
            else
            {
                Debug.LogWarning("完成全部扫描");
                finish = true;
            }
        }
        catch (Exception e)
        {
            Debug.LogError(e.ToString());
            Debug.LogError(string.Format("扫描中断于{0}", _index));
            finish = true;
        }

        if (finish)
        {
            EditorApplication.update = null;
            if(onFinish != null)
                onFinish.Invoke();
        }
    }
    
    protected abstract void FixOneAsset(T asset, string assetPath);
}