Reimport png with settings

ImportHelper.cs

    [MenuItem("Custom tools/import icons")]
    public static void ImportIcons()
    {
        var rootPath = Path.Combine(Application.dataPath, "Resources/text_icons/");
        var icons = Directory.GetFiles(rootPath, "*.png", SearchOption.AllDirectories);
        if (icons.Length == 0)
        {
            UnityEngine.Debug.Log("Failed to find icons");
            return;
        }
        
        var assets = icons[0].IndexOf("Assets");
        for (int i = 0; i < icons.Length; i++)
        {
            var path = icons[i].Substring(assets);
            var icon = AssetDatabase.LoadAssetAtPath<Texture2D>(path); 
            if (icon == null)
            {
                continue;
            }
            
            var importer = TextureImporter.GetAtPath(AssetDatabase.GetAssetPath(icon)) as TextureImporter;

            var ppu = 100;
            var tag = "HD";
            if (icon.name.EndsWith("-md", System.StringComparison.OrdinalIgnoreCase))
            {
                ppu = 75;
                tag = "MD";
            }
            else if (icon.name.EndsWith("-sd", System.StringComparison.OrdinalIgnoreCase))
            {
                ppu = 50;
                tag = "SD";
            }
            importer.spritePixelsPerUnit = ppu;
            importer.spritePackingTag = tag;
            importer.mipmapEnabled = false;
            importer.alphaIsTransparency = true;
            importer.wrapMode = TextureWrapMode.Clamp;

            importer.SaveAndReimport();
        }
        AssetDatabase.Refresh();

        UnityEngine.Debug.Log("Done");
    }